AU6839094A - Use of natural products and related synthetic compounds for the treatment of cardiovascular disease - Google Patents

Description

USE OF NATURAL PRODUCTS AND RELATED SYNTHETIC COMPOUNDS FOR THE TREATMENT OF CARDIOVASCULAR DISEASE

Technical Field

The present invention relates to the use of naturally occurring phenolic compounds and related synthetic compounds in the treatment or prophylaxis of cardiovascular disease and to novel phenolic compounds and the use thereof in the treatment or prophylaxis of cardiovascular disease.

Background Art

Cardiovascular disease is a serious health problem and a major cause of death in Australia and most developed countries. It has been reported that calcium is central to cardiovascular function, in that the calcium ion controls the contraction of heart muscle and the tone of blood vessels. Certain drugs have been used to increase intracellular calcium in order to stimulate the failing heart (cardiotonic agents) . The major drugs used for congestive heart failure in the past are derived from digitalis, found naturally in plants such as foxglove. Their action to raise intracellular calcium, however, is indirect, as they inhibit Na⁺, K⁺-ATPase which results in an increase in intracellular Na⁺, which then in turn stimulates the inflow of extracellular calcium and in turn stimulates the failing heart. These drugs are not ideal as they are toxic at doses only slightly higher than therapeutic cardiotonic concentrations. There has been an active search for alternative cardiotonic agents in recent years and there is still a need for effective drugs to treat and prevent various aspects of cardiovascular disease.

Ca²⁺ has a variety of functions in most animal cells. The concentration of free calcium ion (Ca²⁺) in the cytoplasmic space acts as an intracellular messenger in both electrical and non-electrical excitable cells. The important role of Ca²⁺ is in relation to cellular contraction, and proliferation especially contraction and relaxation of the heart. The movement of Ca²⁺ across cells is regulated by number of mechanisms. If there are means that can pharmacologically manipulate these processes then the level of free intracellular Ca²⁺ may be altered, resulting in a change in cellular response.

There are number of calcium pools which contribute to the concentration of Ca²⁺ in the cytoplasmic space. Two major important pools are namely, the extracellular pool and the internal store, the so-called sarcoplasmic reticulum (SR) store.

The entry of extracellular Ca²⁺, down its electrochemical gradient, not only raises the level of intracellular Ca²⁺ but also initiates the release of Ca²⁺ from the SR store. This phenomenon explains the rapid contraction of cells. The rise of intracellular Ca²⁺ is compensated by a number of mechanisms to remove Ca²⁺ from the cytoplasmic space, either by extruding the Ca²⁺ out of the cell through the Ca²⁺ pump, which is biochemically coupled to Ca²⁺-ATPase, and the Ca²⁺/Na⁺ exchanger, and by sequestering of Ca²⁺ back into the SR store through SR Ca²⁺-ATPase. These removal mechanisms are energy-dependent processes that utilise ATP as the energy source.

The present inventors have found that a range of naturally occurring phenols and related synthetic compounds manipulate the plasma membrane Ca²⁺-ATPase process named, hereafter, as the plasma membrane Ca²⁺-ATPase. It is anticipated that they may also alter the SR Ca²⁺-ATPase, given the similarity of this enzyme to this plasma membrane Ca²⁺-ATPase. Compounds discovered can inhibit the plasma membrane Ca²⁺-ATPase causing an increased level of free Ca²⁺ inside cell. At the same time, some of the compounds may be chosen to stimulate the SR Ca²⁺-ATPase, thereby increasing Ca²⁺ uptake into the internal SR store and making more Ca²⁺ available for release from the SR. The overall effect of these compounds is to increase the rate of contraction as well as the force of contraction of the heart cells, and particular of the failing heart. It has been reported that a number of nonspecific reagents inhibit plasma membrane Ca²⁺-ATPase. It has also been reported that a number of long chain alcohols, hemin and nonhemin iron and fatty acids partially inhibit Ca²⁺-ATPase of erythrocyte membrane. The retinoids have been shown to have anti-calmodulin effects and therefore indirect effects on the Ca²⁺-pump enzyme. The sesguiterpene lactone thapsigargin was found to be a specific inhibitor of Ca²⁺-ATPase of skeletal muscle endoplasmic reticulum.

Disclosure of the Invention

In one aspect, the present invention provides the use of a compound of formula (I), a pharmaceutically acceptable salt or ester thereof in the inhibition of Ca²⁺-ATPase enzymes

wherein Ar is an aromatic ring system comprising one or more optionally substituted phenyl rings optionally linked to or fused with one or more other optionally substituted phenyl rings or one or more 5 or 6-membered, optionally substituted heterocyclic rings wherein the heteroatom is oxygen; and

wherein the ring system comprises 1-4 phenyl rings and

wherein Ar can be linked to another Ar via a group X wherein the Ar is independently selected;

where X is optionally substituted C_1-20alkylene, C_{2- 20}alkenylene or C_2-20alkynylene;

R is hydrogen; C_1-20alkyl, C_2-20alkenyl, C_2-20alkynyl, C_2-20alkanoyl, C_2-20alkenoyl, C_2-20alkynoyl, each of which can be optionally substituted;

R₁ is independently selected and is hydrogen; optionally substituted C_1-12alkyl, C_2-12alkenyl, C_2-12 alkynyl; -COOR' -NR'R', halogen, -OR', -COR', -CONR'R', =O, -SR', -SO₃R' , -SO₂NR'R', -SOR', SO₂R', -NO₂, -CN, glycoside, silyl;

where R' is independently hydrogen; alkyl, alkenyl or alkynyl each optionally substituted; and

where two groups R₁ can be joined;

wherein the optional substituents are one or more independently selected from C_1-10alkyl, C_2-10alkenyl, C_{2 - 10} alkynyl; -COOR" -NR"R", halogen, -OR", -COR", -CONR"R", -SR", =O, -SO₃R" , -SO₂NR"R", -SOR", -SO₂R", -NO₂, -CN; wherein R" is independently hydrogen, alkyl, alkenyl, or alkynyl ;

n = 1, 2 or 3

m = 1, 2, 3 or 4.

Preferably, the use of compounds of formula (I) is in the inhibition of plasma membrane Ca²⁺-ATPase.

In a second aspect, the present invention provides the use of a compound of formula (I), a pharmaceutically acceptable salt or ester thereof in the treatment or prophylaxis of cardiovascular disease.

In a third aspect, the present invention provides novel compounds of formulae (II), (III), (IV), (V), (VI) or pharmaceutically acceptable derivatives thereof:

where

l = 1, 2 or 3

r = 7-14 when 1 = 1

8-16 when 1 = 2 or 3

R₂ is (1) 2-hydroxy

(2) 2-hydroxy-4'-hydroxy

(3) 2-hydroxy-3-methyl

(4) 4-hydroxy-3-methyl

(5) 2,4-dihydroxy

(6) 3,5-dihydroxy-4-methyl (7) 2,6-dihydroxy-4-methyl

(8) 2,4-dihydroxy-3-methyl

(9) 3-hydroxy-4-methyl

provided that (1) when R₂ is 2-hydroxy and 1 = 1 then r is not 7-10 and

(2) when 1 = 3 and

R₂ is 3,5-dihydroxy-4-methyl then n is not 14 and

(3) when 1 = 2 and

R₂ is 2-hydroxy-3-methyl then n is not 10

(4) when 1 = 2 and

R₂ is 2,4-dihydroxy

then r is not 8-10 and 13 and

(5) when 1 = 2 and

R₂ is 4-hydroxy-3-methyl then r is not 10;

where s = 8-16

where t = 6-15

where p + q = 12

where p + q = 12

In a fourth aspect, the present invention provides a method of preparing compounds of formula (II) which comprises

(a) where l = 1 and R₂ is OH

(i) treating the corresponding diacid with a suitable agent to provide the acid dichloride as follows

(ii) treating the corresponding acid dichloride with phenol as follows

(iii) rearrangement of the diacyl groups as

follows

(iv) followed by reduction of the acyl groups to provide compounds of formula (II);

(b) where 1 = 2, R₂ is OH

(i) treating the corresponding diacid with zinc chloride and resorcinol; and

(ii) followed by reduction of the acyl groups to provide compounds of formula (II);

(c) where 1 = 2, R₂ is 2-hydroxy-3-methyl

carrying out steps (i) - (iv) in (a) above except in (ii) phenol is replaced with o-cresol;

(d) where 1 = 2 and R₂ is 3-hydroxy-4-methyl (i) nitrating the corresponding diketo compound of formula to give the corresponding bis-3-nitro compound

(ii) reducing the bis-3-nitro compound to give the bis-3-amino compound followed by

(iii) diazotisation and hydrolysis to

give the bis-3-hydroxy compound

(iv) followed by reduction of the keto groups to give the desired bis-3-hydroxy compound;

(e) where 1 = 3 and R₂ is 2,6-dihydroxy-4- methyl

(i) treatment of a compound of formula

with LDA to give the dianion followed by (ii) treatment with the desired protected alkane aldehyde of formula

to give

(iii) dehydrative decarboxylation followed by reduction to give an intermediate product of formula

(iv) oxidation to give

(v) followed by treatment with the dianion from step (i) to give

(vi) dehydrative decarboxylation followed by deprotection and reduction to give the desired product;

(f) where 1 = 3 and R₂ is 3,5-dihydroxy-4- methyl

(i) treatment of α-N,N-dimethylamino-α-cyano- (3,5-dimethoxy-4-methyl)benzylidene in tetrahydrofuran and

hexamethylphosphoramide (HMPA) with lithium diisopropylamide (LDA) to give the anion followed by

(ii) treatment with α,ω-dibromoalkanes to give

(iii) refluxing with 30% aqueous oxalic acid to give the corresponding diacyl compound (iv) reduction of the acyl groups

(v) followed by demethylation with hydrogen bromide in acetic acid to provide compounds of formula (II);

(g) where 1 = 3 and R₂ is 2,4-dihydroxy-3- methyl

(i) carrying out steps (i) and (ii) in (b) except in (i) resorcinol is replaced with

2-methylresorcinol;

(h) where 1 = 2 and R₂ is 4-hydroxy-3-methyl

(i) treating the corresponding diacid with ortho-cresol in the presence of polyphosphoric acid to give the corresponding diacyl compound

(ii) followed by reduction the acyl groups to provide compounds of formula (II) .

In a fifth aspect, the present invention provides a method of preparing compounds of formula (III) which comprises

(i) treating the corresponding diacid with a suitable agent to provide the acid dichloride (ii) treating the corresponding acid dichloride with 2-naphthol followed by

(iii) rearrangement of the diacyl groups and

(iv) followed by reduction of the acyl groups to provide compounds of formula (III)

In a sixth aspect, the present invention provides a method of preparing compounds of formula (IV) which comprises treatment of 4-alkylresorcinols with ethyl acetoacetate in the presence of an acid catalyst to give compounds of formula (IV).

Preferably, Ar is phenyl, naphthalene, anthracene, naphthacene or phenanthrene. More preferably, Ar is phenyl.

All alkyl, alkenyl or alkynyl carbon chains can be straight or branched chain.

Halogen includes bromo, chloro, fluoro or iodo.

The 5 or 6-membered heterocyclic ring can be saturated, partially unsaturated or unsaturated.

Pharmaceutically acceptable derivatives include pharmaceutically acceptable ethers, esters and acid addition salts.

In the preparation of compounds of formula (II), preferably, the acid dichloride is formed by treating the corresponding diacid with thionyl chloride. However, any other suitable agent can be used.

Preferably, in the preparation of compounds of formula (IV) the acid catalyst is boron trifluoride etherate or the like.

Preferably, the rearrangement of the acyl groups to the required positions on the phenyl ring is carried out using CS₂ and AlCl₃ as catalyst. The catalyst can generally be any Lewis acid such as BF₃, ZnCl₂, FeBr₃ or the like.

The reduction of the acyl group is preferably carried out using amalgamated zinc and a mixture of hydrochloric acid and optionally acetic acid.

Nitration is preferably carried out in the usual way using a combination of nitric acid and sulfuric acid (HNO₃/H₂SO₄). The reduction of the nitrate to the amine is preferably carried out using stannous chloride and hydrochloric acid (SnCl₂/HCl).

Diazotisation is preferably carried out by treatment with aq. H₂SO₄/NaNO₂ and hydrolysis is usually carried by using 10% H₂SO₄.

Dehydrative decarboxylation is preferably carried out by using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline and deprotection by using p-TsOH/MeOH.

In another aspect, the present invention provides the use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof in the manufacture of a medicament for inhibition of Ca²⁺-ATPase enzymes, preferably, plasma membrane Ca²⁺-ATPase.

In yet another aspect, the present invention provides the use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof in the manufacture of a medicament for the treatment or prophylaxis of cardiovascular disease.

Brief Description of the Drawings

Figure 1 is a graph showing concentration dependency of inhibition of erythrocyte plasma membrane of synthetic alkyl phenols.

□ 2 -nonylphenol ▲ 3 -nonylphenol

● 2-octylphenol O 4-octylphenol

▽ 2-decylphenol ■ 4-nonylphenol

▼ 4-decylphenol

Figure 2 is a graph showing concentration dependency of inhibition of erythrocyte plasma membrane of synthetic bis(hydroxyphenyl)alkanes.

● 1,10-bis(2-hydroxyphenyl)decane

□ 1,12-bis(2-hydroxyphenyl)dodecane

O 1,14-bis(2-hydroxyphenyl)tetradecane ▲ 1-(2-hydroxyphenyl)-10-(4-hydroxyphenyl)decane

▽ 1-(2-hydroxyphenyl)-12-(4-hydroxyphenyl)dodecane ▵ 1-(2-hydroxyphenyl)-14-(4-hydroxyphenyl)

tetradecane

■ 1,10-bis(4-hydroxyphenyl)decane

▼ 1,14-bis(4-hydroxyphenyl)tetradecane Figure 3 is a graph showing concentration dependency of inhibition of erythrocyte plasma membrane of resorcinol derivatives.

□ ethyl 3,5-dibromo-2,4-dihydroxy-6-nonylbenzoate

● ethyl 3,5-dibromo-2,4-dihydroxy-6-decylbenzoate ▵ ethyl 2,4-dihydroxy-6-nonylbenzoate

▲ ethyl 2,4-dihydroxy-6-decylbenzoate

Figure 4 is a graph showing concentration dependency of inhibition of erythrocyte plasma membrane of tert- butylphenols.

● 2, 3-di-tert-butyl-4-methoxyphenol

□ 2.6-di-tert-butylphenol

▲ 2,4,6-tri-tert-butylphenol

Figure 5 is a graph showing concentration dependence of Ca²⁺-ATPase inhibition of 2-nonylphenol derivatives. ● 2-nonylphenol/ O (+CaM)

▼3-methyl-6-nonylphenol/ ▽ (+CaM)

■ 4-methyl-6-nonylphenol/ □ (+CaM)

● 4-nitro-2-nonylphenol/ O (+CaM)

▽ 4-bromo-2-nitro-6-nonylphenol (+CaM)

□ 2-bromo-4-nitro-6-nonylphenol (+CaM)

▲ 4-bromo-2-nonylphenol/ △ (+CaM)

■ 4-nonylresorcinol

Figure 6 is a graph showing concentration dependence of Ca²⁺-ATPase inhibition of α,ω-bis[2-hydroxy(3,4 and 5-methyl)phenyl]alkanes.

● 1,8-bis(2-hydroxyphenyl)octane/ O (+CaM)

▼ 1,9-bis(2-hydroxyphenyl)nonane/ ▽ (+CaM)

■ 1,10-bis(2-hydroxyphenyl)decane/ □ (+CaM)

▲ 1,12-bis(2-hydroxyphenyl)dodecane/ ▵ (+CaM) ♦ 1,10-bis(2-hydroxy-3-methylphenyl)decane/ ◊ (+CaM)

● 1,10-bis(2-hydroxy-4-methylphenyl)decane/ O (+CaM)

■ 1,10-bis(2-hydroxy-5-methylphenyl)decan/ □ (+CaM)

Figure 7 is a graph showing concentration dependence of Ca²⁺-ATPase inhibition of α,ω-bis[2-4-dihydroxyphenyl]alkanes.

● 1,8-bis(2,4-dihydroxyphenyl)octane/ O (+CaM) ▼ 1,10-bis(2,4-dihydroxyphenyl)decane/ ▽ (+CaM)

■ 1,11-bis(2,4-dihydroxyphenyl)undecane/ □ (+CaM) ▲ 1,12-bis(2,4-dihydroxyphenyl)dodecane/ ▵ (+CaM)

Figure 8 is a graph showing concentration dependence of Ca²⁺-ATPase inhibition of α,ω-bis [hydroxy (methyl) phenyl and naphthyl]decanes.

♦ 1,10-bis(3-hydroxyphenyl)decane/ ◊ (+CaM)

● 1,10-bis(3-hydroxy-4-methylphenyl)decane/ O (+CaM) ▼ 1,10-bis(4-hydroxy-3-methylphenyl)decane/ ▽ (+CaM)

■ 1,10-bis(2-hydroxy-1-naphthyl)decane/ □ (+CaM) ▲ 1,1-bis(2-hydroxyphenyl)decane/ ▵ (+CaM)

Figure 9 is a graph showing concentration dependence of Ca²⁺-ATPase inhibition of phenolic natural products.

● 5,7,2',6'-tetrahydroxy-8-lavandulylflavanone

■ 5,7,6'-trihydroxy-8-lavandulylflavanone

▲ 5,2',6'-trihydroxy-8-lavandulyl-7-methoxyflavanone

Modes for Carrying Out the Invention Compounds of formula (I) encompasses naturally occurring compounds as well as synthetically prepared related compounds. The naturally occurring compounds of formula (I) were extracted from endemic Australian plants of the Proteaceae family according to standard literature procedure, for example, see Ritchie E, Taylor W C and Vautin S T K (1965), Chemical studies of the Proteaceae I Aust.J.Chem., 18, 2015-2020; Rasmussen M, et al (1968) Chemical studies of the Proteaceae III. Aust.J.Chem., 21, 2989-3000 and Ridley D D, et al (1970) Chemical studies of the Proteaceae IV. Aust.J.Chem., 23, 147-183.

Long-chain alkyl phenols were extracted from Grevillea and Persoonia . Novel compounds having the structural formulae (II) and (III) were extracted and isolated from Grevillea robusta collected in Sydney, Australia. A voucher specimen is available for inspection in the Department of Pharmacy, at the University of Sydney. Briefly, a sample of two kilograms was extracted by percolation with chloroform/ethanol (1:1) for three days. After concentration of the extract in vacuo, the residue was chromatographed using silica gel short column vacuum chromatography.

Other compounds falling within the scope of formula (I) were prepared according to literature procedures or are commercially available. Starting materials for the syntheses are commercially available or are prepared according to literature procedures.

The 2- and 4-substituted alkylphenols and α,ω-bis(hydroxyphenyl)alkanes were prepared by published methods (see E Miller and W H Hartung, Organic syntheses

(1943), collective volume II, 543-545 and R R Read and J

Wood, Organic syntheses (1955), collective volume III,

444-446). The syntheses were performed in three consecutive stages: firstly, the formation of the ester from an acid and phenol; secondly, the rearrangement of the acyl group, using AlCl₃ as catalyst, to the 2- and 4-positions relative to the hydroxy group on the phenol ring and thirdly, the reduction of the acyl group using amalgamated zinc and hydrochloric acid. The rearrangement is a time dependent reaction and generally a short reaction period provides the acyl group at the 4-position relative to the hydroxy group.

Short column vacuum chromatography was used at each stage of synthetic reactions to separate and purify the products from the reaction mixture. TLC methods were also employed to identify the products and to determine the eluent solvent required for column chromatography. The products at each stage were also characterised by NMR and CI-MS analysis.

The 3-substituted phenol derivatives were prepared according to another method, described by Itokawa H, et al (1989), A quantitative structure activity relationship for antitumor long-chain phenols from Ginkgo biloba L. Chem. Pharm.Bull. 37, 1619-1621. This method was used to prepare 3 -nonylphenol with the aim of comparing its Ca²⁺-ATPase inhibitory activity with those of the 2 -and 4-substituted isomers. Hence, the importance of substitution on the phenol ring for Ca²⁺-ATPase inhibition could be determined.

The bisphenol compounds were prepared, isolated and purified using procedures similar to those described above for alkylphenol, except that the preparation of esters was carried out in two separate steps.

For compounds of formula (II) where R₂ is 2-hydroxy-3-methyl the preparation is similar to that of the bishydroxyphenyl alkanes except instead of phenol, ortho- cresol is used following the procedure of K Kakemi et al in Antioxidants III Yakugaku Zasshi 86 [9], 791-796

(1966). 3-hydroxy-4-methyl compounds of formula (II) are prepared by a similar method to that used to prepare α,ω-bis(3-hydroxyphenyl) alkanes following the procedure of K.

Kakemi et al. above except that α,ω-bis(4-methylphenyl)-α,ω-alkanediones are used instead of α,ω-bisphenyl-α,ω-alkanediones. 2,4-dihydroxy compounds of formula (II) are prepared by the reaction of resorcinol with the corresponding dicarboxylic acids in the presence of zinc chloride to give the intermediate alkanediones which are then reduced.

Compounds of formula (II) where R₂ is 2,6-dihydroxy-4-methyl are prepared by a method similar to that used to prepare grifolin following the procedure of S Ohta et al A total synthesis of grifolin Chem. Pharm.Bull. 36 [6] 2239-2243 (1988).

The starting compound in step (e) (i) is obtained according to the procedure of S Ohta et al referred to above. The aldehyde at step (e) (ii) is obtained by alkylating commercially available compounds of formulae X-CH₂-(CH₂)_r-6CH₂-OR where R=H, X=Cl or Br with benzyl bromide (or iodide) to give an intermediate product where R=CH₂Ph followed by hydrolysis to give HOCH₂(CH₂)_{r- 6}CH₂OCH₂Ph followed by oxidation to give OHC(CH₂)_{r- 6}CH₂OCH₂Ph.

Compounds of formula (II) where R₂ is 3,5-dihydroxy-4-methyl are prepared by a procedure similar to that described by K. Takahashi et al., J. Org. Chem. 1983, 48, 1909-1912.

Compounds of formula (II) where R₂ is 2,4-dihydroxy- 3-methyl are prepared by a procedure similar to that described by J. von Braun et al.,, Ber. (1941), 74B, 1772- 1783 except that 2-methylresorcinol is used instead of resorcinol.

Compounds of formula (III) are prepared by a method similar to that used to prepare α,ω-bis(2- hydroxyphenyl) alkanes following the procedure of K. Kakemi et al. Yakugaku Zasshi (1966), 86 , 791-796.

Compounds of formula (IV) are prepared by a method similar to that used to prepare 6-alkyl-7-hydroxy-4-methylcoumarins following the procedure of S P Starkov, G A Goncharenko and A I Panasenko, Zh. Obshch. Khim (1993), 63 (5), 1111-1115.

Other compounds of formula (I) were prepared according to literature procedures as follows:

Bis-phenols

1,10-bis(2-hydroxyphenyl)decane and 1,10-bis(3- hydroxyphenyl)decane

Antioxidants III. K Kakemi, T Arita, R Hori, and H

Takenaka Yakugaku Zasshi 86 (1966) 791-796

1,10-bis(4-hydroxyphenyl)decane

α,ω-di-p-hydroxyphenyl Alkanes

E M Richardson and E E Reid J.Am. Chem.Soc. (1940) 62 413-415

Fries transformation of condensates of sebacic acid with phenols: 1,8-dibenzoyloctanes

J P Varma and J S Aggarwal J.Indian Chem.Soc. (1959)

36 41-45

Synthesis of α,ω-bis(p-hydroxyalkanes)

Y E Doroshenko and V A Sergeev

Zh. Organ. Khim. (1965) 1 (9) 1602-1604

1,12-bis(4-hydroxyphenyl)dodecane

Synthesis of α,ω-bis(p-hydroxyalkanes)

Y E Doroshenko and V A Sergeev Zh. Organ. Khim. (1965) 1 (9) 1602-1604

1,14-bis(4-hydroxyphenyl)tetradecane

H Goldmann et al. J.Am.Chem.Soc. (1988) 110 (20)

6811-6817

1,10-bis(4-hydroxy-3-methylphenyl)decane

P Schlack and W Roller Ger. 1,086,711 Aug 11, 1960.

1,1-bis(2-hydroxyphenyl)decane

G Casiraghi et al. J. Chem. Soc. Perkin Trans 1 (1982), 2, 805-808.

Alkylphenols

The synthesis of aromatic hydroxyketones. I. ortho and para-acylphenols with normal C₄-C₉ chains.

G Sandulesco and A Girard Bull.Soc.Chim.Fr. (1930) 47 (4) 1300-1314

Fungicidal activity and chemical constitution,

D Wood J.Chem. Soc. (1955), 4391-4393

Alkylation of phenol by 1-dodecane and 1-decanol. A literature correction.

B Campbell, S Donald et al. Bull.Chem.Soc. Japan (1990) 63 (12) 3665-3669 decylphenol and dodecylphenol Cyclohexylphenols (ortho & para)

The direct alkylation of phenol by cyclohexene in the presence of boron trifluoride

H Lejebure and E Levas Compt. Rend. (1945) 220 782- 784 and 826-827

H Lejebure and E Levas Compt . Rend. (1945) 221 301- 303

Syntheses of α,ω-bis(2,4-dihydroxy) compounds.

Reaction of aliphatic dicarboxylic acids with resorcinol, J von Braun et al Ber. 74B 1772-1783 (1941).

Fries transformations of condensates of sebacic acid with phenols: 1,8-dibenzoyloctanes, J P Varma et al, J.Indian Chem.Soc. 36 41-45 (1959). The Ca²⁺- stimulated, Mg²⁺- dependent, adenosine triphosphatase (Ca²⁺-ATPase) located on plasma membranes extrudes Ca²⁺ against its electrochemical Ca²⁺ gradient. It has been reported that Ca²⁺-ATPase not only plays a fundamental role in regulating the total cellular Ca²⁺concentration but also modulates or mediates the effects of Ca²⁺ mobilising hormones and neurotransmitters. (See Pripic V, Green K C, Blackmore P R and Exton J H Vasopressin-, angiotensin II-, and α₁-adrenergic -induced inhibition of Ca²⁺-transportation by rat liver plasma membrane vesicles, (1984) J.Biol.Chem. 259, 1382-1385 and Rega A F, Garahan P J, (1986) The Ca Pump of Plasma membranes, CRC Pres Inc., Florida.

Natural and synthetic compounds of formula (I) were tested for their ability to influence human erythrocyte plasma membrane Ca²⁺-ATPase. The enzyme Ca²⁺-ATPase in the human red blood cell plasma membrane has previously been studied and its stimulation by calmodulin and activation by lipids and proteolysis and its primary structure have been published (see Carafoli E (1991) Calcium pump of the plasma membrane, Physiological Reviews 71, 129-153. The activity of compounds of formula (I) in the inhibition of Ca²⁺-ATPase is shown in Table 1 and is interpreted graphically in figures 1, 2, 3 and 4.

Table 1 : Structures and IC₅₀ values of natural and synthetic compounds of formula (I) in the inhibition of Ca²⁺-ATPase (% inhibition was determined at a concentration of 100μM).

INHIBITION OF Ca²⁺-ATPase

COMPOUND SOURCE PERCENT (%) IC₅₀(μM)

2-octylphenol b 100 32 2-nonylphenol b 95 30 2-nonanoylphenol b 32 >100

2-decylphenol b 85 42 nonylphenol a 100 27.5 (commercial)

4-octylphenol b 28 92

4-tert-octylphenol a 94 60

3-nonylphenol b 69 64

4-nonylphenol b 22 114 4-decylphenol b 24 170

2-cyclohexylphenol h 28 186

4-cyclohexylphenol h 16 271

1,10-bis

(2-hydroxyphenyl)- b 100ⁱ 7.6 decane

1,12-bis

(2-hydroxyphenyl)- e 100ⁱ 8.3 dodecane

1,14-bis

(2-hydroxyphenyl)- e 84 28

tetradecane

1-(2-hydroxyphenyl)

-10-(4-hydroxyphenyl) e 100^j 12

decane i - at 25μM

j - at 50μM

k - at 37μM INHIBITION OF Ca²⁺-ATPase

COMPOUND SOURCE PERCENT(%) IC₅₀ (μM)

1-(2-hydroxyphenyl)

-12-(4-hydroxyphenyl) e 99 18.8 dodecane

1-(2-hydroxyphenyl)

-14-(4-hydroxyphenyl)- e 60 81 tetradecane

1,10-bis

(4-hydroxyphenyl)- b 52 93 decane

1-(3,5-dihydroxyphenyl)-14-(3,5- dihydroxy-4- c 100^j 17 methylphenyl)tetradecane

(grebustol-A)

1,14-bis(3,5-dihydroxy-4-methylphenyl)- f 98 16 tetradecane (striatol)

striatol-B f 100 40 norstriatol-B 61^k 35

5-nonylresorcinol f 44 108 1,14-bis

(4-hydroxyphenyl)- b 5 280 tetradecane

1,14-bis(3,5-dihydroxyphenyl)tetradecane f 35 >100 (bisnorstriatol)

1,14-bis(3,5-dihydroxyphenyl)tetradec-Z-6-ene c 90 50 (grebustol-B)

ethyl 2,4-dihydroxy-6- f 73 62nonylbenzoate

ethyl 3,5-dibromo-2,4-dihydroxy-6- f 95 44nonylbenzoate

grevillol c 44 143

5 -decylresorcinol f 30 135 ethyl 2,4- dihydroxy-6- f 60 85 decylbenzoate

ethyl 3, 5-dibromo-2,4- dihydroxy-6- f 73 69decylbenzoate INHIBITION OF Ca²⁺-ATPase

COMPOUND SOURCE PERCENT (%) IC₅₀(μM)

2-E,E-farnesyl-5- methyl-resorcinol 100 22.5 (grifolin)

4-E,E-farnesyl-5- methyl-resorcinol 100 23.3 (neogrifolin)

4-dodecylresorcinol a 68 69

4-hexylresorcinol a 17 259

2,4,6-tri-tert- a 79 15 butylphenol

3,5-di-tert-butyl- 76 84 catechol

2,6-di-tert-butyl- 69 66 4-methylphenol (BHT)

2,6-di-tert- 61 79 butylphenol

2,6-di-tert-butyl- a 44 >400 4-methoxyphenol (BHA)

2,2'-methylenebis

(4-methyl-6-tert- g 74 45 butylphenol)

The activity of the synthetic and natural compounds in the inhibition of Ca²⁺-ATPase in the presence (+CaM) and in the absence (-CaM) of Calmodulin (CaM) is shown in table 1A below and is interpreted graphically in the figures 5, 6, 7, 8, 9.

Source

a = commercially available from Aldrich,

Milwaukee, WI, USA

b = synthetic preparation from literature procedure

c = extracted from Grevillea

d = natural products provided by Prof Shibata

[Misasa H, Matsue Y, Vehara H, Tanaka H,

Ishihara M, Shibata H, (1992) Tyrosinase inhibitors from Albatrellus confluens,

Biosci.Biotech. Biochem., 56 1660-1661]

e = novel compounds of formula (II) according to the present invention

f = natural and synthetic substances provided by

Prof W C Taylor [see references, page 9, lines

25-30 also Cleaver L, Croft J A, Ritchie E and Taylor W C (1976) Chemical studies of the Proteaceae IX Aust.J.Chem., 29, 1989-2001] g = commercially available from Merck, Damnstardt,

Germany

h = synthetic substance provided by Prof Kanzo

Sakata, Shizuoka University, Shizuoka Japan

[see reference for cyclohexylphenols (ortho & para) on page 17

i = natural substances provided by Assoc. Prof. C

Chaichantipyuth, Chulalongkorn University of

Thailand (see Ruangrungsi N et al,

Photochemistry, 31, 999-1001, 1992 and Iinuma

M et al, Photochemistry, 33, 203-208, 1993. The potency of a compound for Ca²⁺-ATPase inhibition is characterised by either its % inhibition at a single dose or more informatively as its IC₅₀ value from the dose-response curve. The most potent compounds have, therefore, curves located at the left hand side of the graphs. From figure 2, it can be seen that 1,10-bis(2-hydroxyphenyl)decane and, to a lesser extent, 1,12-bis(2-hydroxyphenyl) dodecane have the strongest Ca²⁺-ATPase inhibition among the synthesised phenolic compounds. The inhibitory activity is two-fold higher than that of the natural product 1,14-bis(3,5-dihydroxy-4-methylphenyl)tetradecane (striatol) and is superior to the 2-alkylphenol series. Of the alkylphenols, the maximum activity appeared with 2 -nonylphenol (IC₅₀

30μm). The results of nonylphenols and octylphenols showed that the potency order of alkylphenols was 2-alkylphenols, 4 -branched alkylphenols, and 4-alkylphenols. Similarly, 4-dodecylresorcinol was the most potent among the alkylresorcinols tested and grifolin and neogrifolin the most potent among the alkyl and alkenyl resorcinols tested.

The results also show the importance of substitution at the 2- position of the phenol ring for strong Ca²⁺-ATPase inhibition. The results indicate that there is a significant difference in potency between ortho- and para - substituted compounds, whereas the activity of the ineta- substituted compound is intermediate.

The results further indicate a structural preference for the inhibitory potency of the synthetic compounds and an optimal methylene chain length for the bis compounds is ten. 1,10-bis(2-hydroxyphenyl)decane and 1,10-bis(2,4-dihydroxyphenyl)decane to lesser extent are the most potent inhibitors of plasma Ca²⁺-ATPase among the synthesised substances.

In the presence or absence of Calmodulin (CaM), in general, there is no significant difference in the inhibitory activity of the synthesised compounds (refer to table 1A). However, it is observed that at higher concentration of the test compounds, there was slightly higher inhibition of plasma membrane Ca²⁺-ATPase than in the absence of CaM (refer to figures 5,7,8,9). This would indicate that the compounds may also inhibit CaM stimulant activity.

4⁵Ca efflux from cultured vascular smooth muscle cells consists of two major mechanisms; one is dependent on extracellular sodium, mediated by the Na⁺-Ca²⁺ exchanger (Na⁺- dependent Ca²⁺ efflux), and the other is independent of extracellular sodium but is mediated by the Ca²⁺ pump (Na⁺- independent Ca²⁺ efflux). The effect of striatol on the efflux of calcium (⁴⁵Ca²⁺) from rat thoracic aorta smooth muscle cells in culture was studied. ⁴⁵Ca²⁺ efflux is a measure of plasma membrane Ca²⁺-ATPase (plus Na⁺: Ca²⁺ exchange) in intact (whole) cells. The results are as follows:

20μM 5 min - partial inhibition

20μM 10 min - partial inhibition

50μM 30 min - complete inhibition

Compounds of formula (I) show significant inhibitory activity against plasma membrane Ca²⁺-ATPase and typically would be suitable for use in the treatment of cardiovascular disease. These compounds would be useful by their action on Ca²⁺-ATPase enzymes in general or on Na⁺, K⁺-ATPase enzyme. In particular, compounds of formula (I) may be suitable for the treatment or prophylaxis of chronic heart failure, angina, hypertension or arrhythmia.

Accordingly, in another aspect, the present invention provides the use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof in the manufacture of a medicament for the treatment or prophylaxis of cardiovascular disease.

The effective amount of the active compound required for use in the above conditions will vary both with the route of administration, the condition under treatment and the host undergoing treatment, and is ultimately at the discretion of the physician. In the above mentioned treatments, it is preferable to present the active compound as a pharmaceutical formulation. A pharmaceutical formulation of the present invention comprises the active compound together with one or more pharmaceutically acceptable carriers and optionally any other therapeutic ingredient. The formulation may conveniently be prepared in unit dosage form and may be prepared according to conventional pharmaceutical techniques. Additionally, the formulations may include one or more accessory ingredients, such as diluents, buffers, flavouring agents, binders, disintegrants, surface active agents, thickeners, lubricants, preservatives and the like.

A typical tablet formulation comprises 1-50mg of the active constituent, 50-200mg of lactose, 7-28mg of maize starch and 0.25-1mg of magnesium stearate. Preferably, the tablet formulation comprises 1-50mg of the active constituent, about 97mg of lactose, about 14mg of maize starch and about 0.5mg of magnesium stearate.

Compounds of formula (I) may also be useful for the treatment of ulcers (peptic ulcers) through H⁺, K⁺-ATPase inhibition (the proton pump in gastric parietal cells) or may act as depigmentation, antidiabetic, antithrombolytic, antiarteriosclerotic, antioxidant, anticancer, antiinflammatory or antiviral agents.

EXPERIMENTAL - SYNTHESES

Instrumentation

Thin layer chromatographic plates were visualised by a UVSL-58 mineral-light lamp, multiband UV-254/366nm. Precoated Si gel plates (Merck, Art. 5554) were utilised.

Analytical high-performance liquid chromatography were obtained with a Beckman HOB solvent module with a PC-3800 controller.

Detection was achieved with a Spectra-Physics Spectra 100 variable wavelength detector.

Analytical column was an Activon exsil 100/10 ODS, 250 × 4.6mm i.d. (reversed-phase C₁₈).

Preparative short column was 70 × 65 mm i.d. connected with an one litre glass bell jar.

¹H- and ¹³C-NMR spectra were obtained on a Varian Gemini 300 , and Joel FX90Q (for grevillol) spectrometer using CDCl₃ as solvent and referencing to tetramethylsilane.

UV spectra were measured on a Perkin-Elmer Lambda 5 UV/VIS spectrophotometer.

Chemical ionisation and electron impact mass spectra were performed on a Finnigan TSQ46 spectrometer. All chemical ionisation spectra were performed using methane as reagent gas.

Materials

Ethyl acetate and petroleum (70-75°C) were distilled prior to use. Thionyl chloride was distilled at 75 - 80°C

Dichloromethane, chloroform, methanol were HPLC grade. Merck silica gel 60H (Art. 7736) was used for preparative TLC and short column chromatography.

3,4,5-trimethoxybenzaldehyde, n-butyllithium, undecandioic acid, 1,6-dibromohexane, 1,8-dibromooctane, 1,10-dibromodecane, 1,12-dibromododecane, 2- methylresorcinol, 1,10-decanedicarboxylic acid and 1,12- dodecanedicarboxylic acid were purchased from Aldrich Chemical company.

I. Synthesis of alkylphenols

1. Preparation of 2- and 4-octylphenol

1.1 Preparation of phenyl octanoate

The ester was prepared by slowly adding thionyl chloride (10ml) to a mixture of pure phenol (6.5g) and octanoic acid(10g). The reaction mixture was warmed to drive off the sulfur dioxide and hydrogen chloride gases.

The crude mixture was distilled at 95-100°C/5mmHg.

Phenyl nonanoate and phenyl decanoate were prepared similarly. The esters were distilled at 105-110°C and 120-125 °C/5mmHg respectively.

The yield of the esters was 81-84%.

1.2.Preparation of 2- and 4-octanoylphenol

Anhydrous aluminium chloride (7g) and carbon disulfide (10ml) were placed in a three-necked round bottom flask fitted with a reflux condenser, a 50ml- dropping funnel and a large magnetic stirrer. Phenyl octanoate (10g) was slowly added to the stirred suspension through the dropping funnel. When all the ester was added, the mixture was further heated to gentle refluxing on a steam bath until the evolution of hydrogen chloride had almost ceased (about 1/2hr). The reflux condenser was turned downward and carbon disulfide was distilled. The steam bath was replaced by an oil bath which was heated to 140°C and maintained at 140-150°C for one hour. The mixture thickened and finally congealed to a brown resinous mass. The solid was allowed to cool and the aluminium complex was decomposed by first slowly adding a mixture of concentrated hydrochloric acid (6ml) with water (6ml) and then water (10ml). The mixture was left overnight and large solid portion (mainly 4-octanoylphenol) on the surface was collected. The liquid portion was extracted with ethyl acetate. The extract was combined with the solid portion and the resulting mixture was dried with anhydrous sodium sulfate, filtered and evaporated to obtain the crude mixture. The products, 2- and 4-octanoylphenols, were separated by short column vacuum chromatography based on the difference in their polarity.

The yield was 29-34% of 2-octanoylphenol and 46-50% of 4-octanoylphenol. The products were then characterised by NMR and CI-MS analysis (refer to tables 3 & 4).

Separation of the products using short column vacuum chromatography

The crude mixture was dissolved firstly in dichloromethane (one-part) then petroleum (four-parts). The resulting mixture (25ml) was loaded onto a (70mm diam.x 30mm) silica gel bed under vacuum and continuously washed with petroleum (40ml).

Eluent solvent mixtures used to isolate the products were a stepwise solvent gradient from petroleum spirit/ethyl acetate 9:1 to 1:1 (20 fractions).

Fractions were examined under UV light by TLC to determine the degree of separation between products. NMR and CI-MS analysis were performed on fractions #5-10 (identified as 2-octanoylphenol) and #14-20 (identified as 4-octanoylphenol).

1.3.Preparation of 2- and 4-octylphenol

Amalgamated zinc(10g) was placed in a 100ml round-bottom flask fitted with a stirrer and a reflux condenser. A mixture of acetic acid (10ml) and concentrated hydrochloric acid (10ml) was added and then a solution of 2-octanoylphenol (2g) (or 4-octanoylphenol) in acetic acid(5ml). The mixture was agitated and refluxed for 2 days. Aqueous 20% w/v NaCl solution (20ml) was added and the mixture was extracted with petroleum (20ml). The petroleum portion was dried with anhydrous sodium sulfate, filtered and purified by short column vacuum chromatography.

A yield of 82-84% was obtained.

The column chromatographic method used was the same as described above.

The products were characterised by NMR and CI-MS analysis (Refer to tables 3 & 4).

Note: l. The zinc was amalgamated in the reaction flask by covering it with a solution of mercuric chloride (0.2g) in water (15ml) and occasionally agitated over 30 minutes. The solution was poured off and the zinc was rinsed once with water.

2. Aqueous 20% w/v NaCl was added to increase the ionic strength of the aqueous phase so that the octylphenol could be extracted into the organic phase.

Nonyl- and decylphenols were prepared as described for octylphenol. The products at each stage were also characterised by NMR and CI-MS analysis. (Refer to tables 3 & 4).

2. Preparation of 3-nonylphenol 2.1 Preparation of 3 -benzyloxybenzaldehyde

In a 100ml round-bottom flask were placed 3- hydroxybenzaldehyde (5g), benzyl chloride (6g), sodium iodide (8g) and potassium carbonate (10g). The reaction mixture was sealed and stirred for one day. The crude product was extracted with ethyl acetate (20ml). The organic portion was washed twice with distilled water (20ml) to remove all aqueous soluble materials. The ethyl acetate portion was dried with anhydrous sodium sulfate and evaporated to obtain the crude solid. The solid was purified by the column chromatographic method described for octylphenol. The product was identified by NMR and CI-MS analysis (Refer to tables 3 & 4).

2.2 Preparation of 3 -nonylphenol

Grignard reagent was prepared from magnesium (248mg) and 1-bromooctane (1.8g) in dry diethyl ether (5ml). A tiny amount of solid iodine was added to initiate the reaction and ether (10ml) was further added. The reaction was stirred until all magnesium dissolved and 3-benzyloxybenzaldehyde(10g) was then added to the reaction mixture. The reaction was refluxed at room temperature for 4 hours. Ice water was then added. The organic phase was separated and washed with 1.5M sulfuric acid

(2×25ml), 10% potassium carbonate (2×25ml), water (20ml),

1M hydrochloric acid (20ml) in saturated sodium chloride, dried with anhydrous sodium sulfate and evaporated to obtain the product (79% of yield).

A portion of the product (500mg) was hydrogenated by catalytic reduction over 10% palladium-charcoal (130mg) in ethyl acetate (50ml) containing concentrated sulfuric acid (10 drops). The reaction mixture was stirred at room temperature for one day. The mixture was then filtered, evaporated and purified by the column chromatographic method.

The product was identified by NMR and CI-MS analysis (Refer to tables 3 & 4).

II. Synthesis of α,ω-bis(hydroxyphenyl)alkanes.

1. Preparation of bisphenyl decanedioate

The methods of preparation, isolation and purification were similar to those described for octylphenol except that the preparation of esters was done in two separate steps, as shown above, instead of one as described for phenyl octanoate.

Firstly, the acid dichloride was prepared by refluxing the mixture of dicarboxylic acid(5g) and thionyl chloride (20ml) at 60-70°C for two hours. Thionyl chloride was then removed by evaporation and the remaining product was dissolved in toluene (5ml). The toluene was evaporated to remove all traces of thionyl chloride.

Secondly, the phenol (2x moles of acid dichloride) was added to the acid dichloride. The mixture was warmed to drive off hydrogen chloride gas. The product solidified on cooling and was purified by the column chromatographic method.

The yield of the esters was 96-98%

2. Preparation of 1 ,10-bis(hydroxyphenyl)decane- 1,10-diones

3. Preparation of 1.10-bis (2 -hydroxyphenyl) decane

The product was characterised by NMR and CI-MS analysis

(Refer to NMR and CI-MS tables 3 & 4).

III. Synthesis of α,ω-bis[2-hydroxy-(3-,4- or 5- methyl)phenyl]alkanes

These were prepared according to K Kakemi et al. in

Antioxidants III. K Kakemi, Y Arita, R Hori and H

Takenaka. Yakugaku Zashi 86, 791-796 (1966) as follows: Aliphatic dicarboxylic acid chloride (1 mole) [for example sebacoyl chloride] was added to a solution of a phenol (2.2 moles) in tetrachloroethane containing anhydrous AlCl₃ (2.5 moles). The mixture was stirred for 5-6 hrs at 70-80°C. The product was decomposed with ice- water and concentrated HCl (1:1). The organic layer was separated and concentrated under reduced pressure. The residue was extracted with ethyl acetate and washed with water twice. After removal of the solvent the product was subjected to gradient chromatography to isolate the corresponding diketones which on Clemmensen reduction gave the title compounds.

The products were recrystallised from petroleum or petroleum - ethyl acetate to give colourless crystalline solids.

The procedure was similarly applied to prepare bis (2 -hydroxy- 1-naphthyl) decane.

IV. 1,10,Bis(4-hydroxy-3-methylphenyl)decane

This was prepared by the method reported by Schlack and Koller in Aromatic aliphatic diketones. P Schlack and W Koller. Ger. 1,086,711 Aug. 11, 1960.

The title compound was prepare by treatment of ortho-cresol (2.2 moles) with sebacic acid (1 mole) in the presence of polyphosphoric acid ( 3 moles ) . The mixture was stirred for 4 hrs at 80°C and poured to ice-water after cooling. The precipitant was filtered, dissolved in ethyl acetate and washed with water three times. The solvent was evaporated to yield a crude 1,10-bis(4-hydroxy-3-methylphenyl)decane-1,10-dione which was then subjected to Clemmensen reduction to give the title compound.

The product was recrystallised to yield a colourless crystalline white solid.

V. Synthesis of α,ω-bis(2,4-dihydroxy-(3- methyl)phenyl)alkanes

These were prepared according the literature procedure in Reactions of aliphatic dicarboxylic acids with resorcinol. J von Braun, E Anton and F Meyer. Ber. 74B , 1772-1783 (1941) as follows:

The aliphatic dicarboxylic acid (1 mole) was heated with anhydrous ZnCl₂ (2 moles) at 140°C followed by added resorcinols (10 moles) in portions. Stirring of the mixture was maintained for 4-5 hrs at 140-160°C (except that for

2-methylresorcinol which was stirred at 170 °C) . The products were decomposed with ice-water. The solid was collected, washed with 10% Na₂CO₃ and then with water under vacuum.

The crude products were subjected to Clemmensen reduction to yield the title compounds and were recrystallised from ethanol - water to give colourless crystalline solids.

VI. Synthesis of 1,10-bis[3-hydroxy-4-methylphenyl]decane.

1,10-Bis(4-methylphenyl)decane-1,10-dione was prepared according to (III) above. The diketone dissolved in concentrated sulfuric acid were gradually added to the mixture of fuming nitric acid and concentrated sulfuric acid (2:1 in volume) at -5°C. The mixture was stirred at 0°C for 30mins and poured in to ice-water. The precipitate was filtered off and recrystallised from ethyl acetate to give 1,10-bis(3-nitro-4-methylphenyl)decane-1,10-diones which then underwent reduction with SnCl₂.2H₂O in the presence of concentrated HCl at elevated temperature of 90 °C for 30mins. The precipitate that formed on cooling was collected, washed with HCl and dissolved in dilute NaOH. The solid precipitating on the addition of dilute HCl was collected and recrystallised from ethanol to yield 1,10-bis(3-amino-4-methylphenyl)decane-1,10-dione.

This product was diazotised with aq. NaNO₂ in 3M H₂SO₄ at 5°C. The mixture was then hydrolysed with 10% H₂SO₄ at 160°C. The resulting solution was extracted with ethyl acetate and the solvent was evaporated to yield 1,10-(bis(3-hydroxy-4-methylphenyl)decane-1,10-dione which on Clemmensen reduction and gave the title compound which was recrystallised from petroleum dichloromethane.

VII. Synthesis of α ,ω-bis(3,5-dihydroxy-4- methylphenyl)alkanes.

a. 3,5-dimethoxy-4-methylbenzaldehyde was prepared by a procedure published in Regioselective reduction alkylation of 3,4,5-trimethoxy-benzaldehydes and dimethylacetal. U Azzena, S Cossu, T Denurra, G Melloni and A M Piroddi. Synthesis 1990, 313 and Regioselective reduction electrophilic substitution of derivatives of 3,4,5-trimethoxybenzaldehyde. U Azzena, G Melloni, A M Piroddi, E Azara, S Contini and E Fenude.

J. Org. Chem. 57, 3101-3106 (1992).

The diacetal intermediate was distilled at 130°C / 0.8 mmHg and 3,5-dimethoxy-4-methylbenzaldehyde (compound A) was recrystallised from petroleum.

b. Preparation of α-N,N-dimethylamino-α-cyano-(3,5-dimethoxy-4-methyl)benzylidene (Compound B) (see

Benzylation and related alkylation of α-dimethylaminophenylacetonitrile by mean of alkali. C R Hauser, H M Taylor and T G Ledford. J. Am. Chem. Soc. 82, 1786 (1960).

To a stirred solution of sodium bisulfite (1 mole) in 400 ml of water was added compound A (1 mole) in methanol followed by anhydrous dimethylamine (1.2 moles) in aq. methanol (80%) . The reaction mixture was cooled prior the addition of aq. sodium cyanide (1.2 moles). The mixture was stirred at room temperature for 20 hrs and diethyl ether (50 ml) was then added. The ethereal layer was washed with water twice and evaporated to yield the product Compound B (> 90%) which was sufficiently pure for the next reaction.

c. Preparation of α,ω-bis(3,5-dimethoxy-4-methylphenyl)alkane-α,ω-diones (see An efficient method for synthesis of symmetrical diketones via reaction of α-amino-α-arylacetonitriles with alkyl dibromides. K Takahashi, M Watsuzaki, K Ogura and H Iida. J. Org. Chem. 48, 1909-1912 (1983).

Under dry nitrogen diisopropylamine (1,5 ml, 9 mmol) dissolved in a mixture of 5 ml each of dry THF and HMPA was treated with n-butyllithium (4 ml of 2.5 M solution in hexane, 10 mmol) at -78°C. Compound B (8 mmol) dissolved in THF (2 ml) was added and the reaction mixture was stirred for 15mins at -78°C and for lhr at 0°C. To the mixture cooled to -20°C was added α,ω-dibromoalkanes (4 mmol) dropwise. After the mixture was stirred for 20mins at -20°C, the stirring was continue overnight at room temperature.

The reaction mixture was poured into ice-water and extracted with diethyl ether (3×50 ml). The combined ethereal layers was washed with brine and concentrated under reduced pressure. The residue dissolved in a solution of 3 ml each of THF and 30% aq. oxalic acid was refluxed for 90mins then extracted with diethyl ether.

After the solvent was evaporated the product was recrystallised from ethanol to give the diketones

(Compounds C).

d. Preparation of α ,ω-bis(3,5-dihydroxy-4-methylphenyl)alkanes.

The Compounds C were subjected to Clemmensen reduction and then demethylation with 47% HBr in the presence of acetic acid at 130°C for 10 hrs. The product was subjected to gradient chromatography and recrystallised from benzene to give a colourless crystalline solid.

1,1-Bis(2-hydroxyphenyl)decane was prepared according to the literature procedure of G Casiraghi et al. in Regiospecificity in reactions of metal phenoxides.

Synthesis of 2,2-alkylidenebisphenols. G Casiraghi, G

Casnati, A Pochini and R Ungaro. J. Chem. Soc.,Perkin Trans.1 (1982), 3, 805-808. The product was distilled at

210°C/0.4mmHg.

6-dodecyl-7-hydroxy-4-methylcoumarin was prepared according to the literature procedure of S P Starkov et al. in Condensation of ethyl acetoacetate and ethyl benzoylacetate with 4-alkylresorcinols in the presence of boron trifluoride etherate. S P Starkov, G A Goncharenko and A I Panasenko. Zh. Obshch. Khim. (1993), 63(5), 1111-1115. The product was recrystallised from ethanol.

Bromination of 2-nonylphenol was carried out according to D E Rearson et al. in The ortho bromination of phenols. D E Rearson, R D Wysong and C V Breder. J. Org. Chem. (1967), 35(19), 3221-3231.

Nitration of 2 -nonylphenol was carried out according to D S Ross et al. in Catalysis of aromatic nitration by the lower oxides of nitrogen. D S Ross, G P Hum and W G Blucher. J. Chem. Soc, Chem. Comm. 1980, 532-533.

Bromination of 4-dodecylresorcinol was carried out according to E Kiehlmann and R W Lauener in Bromophloroglucinols and their methyl ethers. E Kiehlmann and R W Lauener. Can. J. Chem. (1989), 67, 335-344.

4-bromo-6-dodecylresorcinol was prepared according to procedure 8 above in The ortho bromination of phenols. D E Rearson, R D Wysong and C V Breder. J. Org. Chem. (1967), 35(19), 3221-3231.

* Clemmensen reduction was carried out as follows:

The ketone compounds dissolved in toluene were added to the mixture of concentrated HCl and acetic acid (1:1) containing amalgamated zinc. The reaction mixture was refluxed for 10hrs with vigorous stirring or stirred at room temperature for 2 days.

Structures of synthetic alkylphenols and α ,ω-bis(hydroxyphenyl)alkanes.

- 52

2-nonylphenol derivatives

¹³C-NMR of n- C₉H₁₉ chain . 14 . 19 ( IC) ; 22 . 75 ( IC) ; 29 . 41

(1C); 29.55 (1C); 29.58 (1C); 29.64 (2C); 30.86 (1C);

31.97 (1C);

Aromatic ¹³C-NMR of substituted phenols:

2-bromo-6-nonylphenol. 110.52 (1C); 121.30 (1C); 129.34

(1C); 129.63 (1C); 130.75 (1C); 150.1 (1C).

4-bromo-2-nonylphenol. 112.71 (1C); 116.83 (1C); 129.59

(1C); 131.07 (1C); 132.68 (1C); 150.09 (1C).

2,4-dibromo-6-nonylphenol. 110. (1C); 125.08 (1C); 125.52

(1C); 129.62 (1C); 132.1 (1C); 150.2 (1C).

2-nitro-6-nonylphenol. 119.31 (1C); 122.6 (1C); 132.37

(1C); 134.04 (1C); 137.41 (1C); 153.36 (1C).

4-nitro-2-nonylphenol. 115.19 (1C); 119.3 (1C); 123.54 (1C); 126.02 (1C); 130.73 (1C); 159.47 (1C).

4-bromo-2-nitro-6-nonylphenol. 109.92 (1C); 125.07 (1C); 125.51 (1C); 131.18 (1C); 141.26 (1C); 155.58 (1C).

4-dodecylresorcinol derivatives

¹³C-NMR of n-C₁₂H₂₅ chain. 14.13 (1C); 22.7 (1C); 29.37 (1C); 29.41 (1C); 29.53 (1C); 29.62 (1C); 29.65 (1C); 29.68 (2C); 29.85 (1C); 30.17 (1C); 31.93 (1C).

Aromatic ¹³C-NMR of substituted resorcinols:

2-bromo-6-dodecylresorcinol. 99.63 (1C); 107.37 (1C); 122

(1C); 129.38 (1C); 150.24 (1C); 150.61 (1C).

4-bromo-6-dodecylresorcinol. 100.52 (1C); 103.17 (1C); 123 (1C); 132.17 (1C); 150.79 (1C); 154 (1C).

2,4-dibromo-6-dodecylresorcinol. 98.68 (1C); 99.62 (1C); 123.46 (1C); 131.1 (1C); 147.3 (1C); 150.52 (1C)

6-dodecyl-7-hydroxy-4-methylcoumarin

(¹³C-NMR of n-C₁₂H₂₅ are similar to those of resorcinol above)

Aromatic ¹³C. 102.62 (1C); 110.7 (1C); 112.37 (1C); 125 (1C); 127.28 (1C); 153.35 (1C); 159.12 (1C); 162.3 (1C). 1,11-bis(2,4-dihydroxyphenyl)undecane: 29.37 (2C); 29.41 (2C); 29.43 (3C); 29.46 (2C); 30.13 (2C); 102.93 (2C); 106.68 (2C); 120.50 (2C); 130.29 (2C); 155.24 (2C); 155.57 (2C).

1,12-bis(2,4-dihydroxyphenyl)dodecane: 28.91 (2C); 29.02 (2C); 29.05 (4C); 29.09 (2C); 29.69 (2C); 102.39 (2C);

105.79 (2C); 119.68 (2C); 129.54 (2C); 155.11 (2C);

155.45 (2C).

1,10-bis(2,4-dihydroxy-3-methylphenyl)decane: 8.51 (2C); 29.43 (2C); 29.47 (2C); 29.49 (2C); 29.86 (2C); 30.06

(2C); 107 (2C); 110.42 (2C); 119.76 (2C); 126.6 (2C);

152.65 (2C); 153.55 (2C).

1,10-bis(3-hydroxy-4-methylphenyl)decane: 15.31 (2C);

29.25 (2C); 29.46 (2C); 29.5 (2C); 31.41 (2C); 35.47 (2C); 114.92 (2C); 120.59 (2C); 120.76 (2C); 130.72 (2C);

142.31 (2C); 153.52 (2C).

2-methyl-5-nonylresorcinol: 7.73 (1C); 14.12 (1C); 22.69

(1C); 29.3 (1C); 29.35 (1C); 29.54 (1C); 31.21 (1C);

31.91 (1C); 107.31 (1C); 107.8 (2C); 142.05 (1C); 154.46 (2C).

1,8-bis(3,5-dihydroxy-4-methylphenyl)octane: 8.37 (2C);

29 . 93 (2C) ; 30 . 18 (2C) ; 32 . 11 (2C) ; 36 .24 (2C) ; 107. 34

(2C); 107.47 (4C); 141.59 (2C); 156.89 (4C).

1.10-bis(3,5-dihydroxy-4-methylphenyl)decane: 8.34 (2C); 29.94 (2C); 30.32 (4C); 32.13 (2C); 36.25 (2C); 107.34

(2C); 107.45 (4C); 141.59 (2C); 156.9 (4C).

1,12-bis(3,5-dihydroxy-4-methylphenyl)dodecane: 8.37

(2C) ; 29 . 97 (2C) ; 30 .26 (2C) ; 30 .34 (2C) ; 30 . 38 (2C) ;

32.15 (2C); 36.27 (2C); 107.34 (2C); 107.45 (4C); 141.58 (2C); 156.9 (4C).

Table 4: Chemical ionisation mass spectra of the synthesised alkylphenols and α, ω-bis

(hydroxyphenyl)alkanes.

Mass spectra of the intermediate products m/e intensity(%) inference

2-octanoylphenoI

261 4 M + 41

249 11 M + 29

221 100 M + 1

127 6 loss of phenol

2-nonanoylphenol

275 5 M + 41

263 10 M + 29

235 100 M + 1

141 9 loss of phenol

2-decanoylphenol

289 5 M + 41

277 16 M + 29

249 100 M + 1

155 15 loss of phenol

121 16 2-OH-benzoyl cation

4-octanoylphenol

221 100 M + 1

127 13 loss of phenol

113 6 loss of octane 4-nonanoylphenol

235 100 M + 1

221 5 loss of CH3 group

141 6 loss of phenol

135 7 loss of heptane

4-decanoylphenol

289 5 M + 41

277 12 M + 29

249 100 M + 1

221 8 loss of ethylene

155 10 loss of phenol

135 8 loss of octane

3-benzyloxybenzaldehyde

253 5 M + 41

241 12 M + 29

213 100 M + 1

135 16 loss of benzene diphenyl decanedioate

383 7 M + 29

355 12 M + 1

261 100 loss of phenol diphenyl dodecanedioate

411 20 M + 29

383 5 M + 1

289 100 loss of phenol diphenyl tetradecanedioate

439 15 M + 29

411 4 M + 1

317 100 loss of phenol

1,10-bis(2-hydroxyphenyl)decane-1,10-dione

383 6 M + 29

355 100 M + 1

261 10 loss of phenol

1,12-bis(2-hydroχyphenyl)dodecane-1,12-dione

423 8 M + 41

411 20 M + 29

383 100 M + 1

289 5 loss of phenol 1,14-bis(2-hydroxyphenyl)tetradecane-1,14-dione

451 6 M + 41

439 16 M + 29

411 100 M + 1

317 5 loss of phenol 1-(2-hydroxyρhenyl)-10-(4-hydroxyρhenyl)decane-1,10-dione

383 8 M + 29

355 100 M + 1

327 10 loss of 28 mass unit

261 14 loss of phenol

135 25 C₆H₄(OH)COCH₂ ⁺ ion

121 15 C₆H₄(OH)CO⁺ ion

1-(2-hydroxyphenyl)-12-(4-hydroxyphenyl)dodecane-1,12-dione

423 8 M + 41

411 20 M + 29

383 100 M + 1

289 10 loss of phenol

121 5 C₆H₄(OH)CO⁺ ion

1-(2-hydroxyphenyl)-14-(4-hydroxyphenyl)tetradecane-l,14-dione

451 6 M + 41

439 18 M + 29

411 100 M + 1

355 18 loss of butene

317 10 loss of phenol

1,10-bis(4-hydroxyphenyl)decane-1,10-dione

395 6 M + 41

383 15 M + 29

355 100 M + 1

261 8 loss of phenol

121 15 C₆H₄(OH)CO⁺ ion 1,12-bis(4-hydroxyphenyl)dodecane-1,12-dione

423 6 M + 41

411 16 M + 29

383 100 M + 1

289 8 loss of phenol

137 18 C₆H₄(OH)C(OH)⁺CH3

123 12 C₆H₄(OH)C(OH)⁺H

1,14-bis(4-hydroxyphenyl)tetradecane-1,14-dione

451 5 M + 41

439 18 M + 29

411 100 M + 1

317 8 loss of phenol

121 12 4-OH-benzoyl cation

Mass spectra of alkylphenols and α,ω-bis(hydroxyphenyl)aIkanes

2-and 4-octylphenols

247 8 M + 41

235 16 M + 29

207 100 M + 1

107 20 C₆H₄(OH)CH₂ ⁺ ion 2-, 3- and 4-nonylphenols

261 6 M + 41

249 12 M + 29

221 100 M + 1

107 18 C₆H₄(OH)CH₂ ⁺ ion 2- and 4-decylphenol

275 5 M + 41

263 16 M + 29

235 100 M + 1

107 16 C₆H₄(OH)CH₂ ⁺ ion

1,10-bis(hydroxyphenyl)decanes and

1-(2-hydroxyphenyl)-10-(4-hydroxyphenyl)decane

367 6 M + 41

355 20 M + 29

327 100 M + 1

107 15 C₆H₄(OH)CH₂ ⁺ ion

1,12-bis(hydroxyphenyl)dodecanes and

1-(hydroxyphenyl)-12-(4-hydroxyphenyl)dodecane

395 5 M + 41

383 20 M + 29

355 100 M + 1

107 6 C₆H₄(OH)CH₂ ⁺ ion

1,14-bis(hydroxyphenyl)tetradecanes and

1-(2-hydroxyphenyl)-14-(4-hydroxyphenyl)tetradecane

423 5 M + 41

411 20 M + 29

383 100 M + 1

107 5 C₆H₄(OH)CH₂ ⁺ ion

Note: The signals with intensity less than 5% were not accounted.

EXPERIMENTAL - NATURAL PRODUCTS

NOVEL RESORCINOLS FROM GREVILLEA ROBUSTA AND THEIR

INHIBITORY ACTIVITY TO ERYTHROCYTE Ca²⁺-ATPase

General experimental procedures for extraction and isolation - The mobile phase was MeOH/H₂O (82:18). Flow rate was 1.0 ml/min; Preparative HPLC were carried out with a Altex 100 solvent delivery system, equipped with Altex UV detector at 254nm, a Activon Partisil ODS-3 column, 9x500mm was used. The mobile phase was a gradient of MeOH/H₂O (3:7) to MeOH in 60 min. or an isocratic mobile phase 65% CH₃CN in H₂O, flow rate was 2.5 ml/min. 6251, 6252 were separated by these systems.

Plant Material - The stem of Grevillea robusta was collected in Sydney, Australia. A voucher specimen is available for inspection at the Department of Pharmacy, The University of Sydney. The stem wood, 5-10 cm in diameter, was sliced by an electrical plane and air dried.

Extraction and Isolation - A sample of 2 kg was extracted by percolation with CHCl₃/EtOH (1:1) for 3 days twice. After concentration of the extract in vacuo, the residue (20g) was chromatographed by Silica gel short column vacuum chromatography collecting 250ml fractions. The Ca²⁺-ATPase assay gave an inhibitory activity of 50% at a concentration of 0.5mg/ml. Fractions 1 to 4 (3.82g) were eluted with petroleum/EtOAc (9:1- 2:1). Fractions 7-9 (11.91g), eluted from CHCl₃/MeOH(2:1), were inactive in the assay. They were not further studied. Fraction 5 (2.78g), 6 (0.13g), 6b(1.38g) were eluted with CHCl₃/EtOAc(2:1), CHCl₃/MeOH (9:1), (8:2) respectively and gave strong inhibitory activity. Fraction 5 was further short column vacuum chromatographed with CHCl₃/EtOH (95:5) and gave grevillol (0.74g). Fraction 6b was similarly chromatographed with CH₂Cl₂/ EtOAc (4:1) to give 6b2 (37.4mg). Fraction 6 was similarly separated into 10 fractions (each 50ml) with petroleum /EtOAc (2:1), CH₂Cl₂/EtOAc (2:1), (1:1), (1:2), EtOAc, EtOAc/CH₃CN (1:1). Only fraction 4-5 (63.4mg) from CH₂Cl₂/EtOAc (2:1) gave strong inhibitory activity, 74% inhibition at 0.04mg/ml . This fraction was then separated by gradient HPLC to give synapic aldehyde (623, 1.8mg), and a nonpolar fraction 625 which was finally separated into 6251 (6.6mg) and 6252 (1.3mg) by preparative TLC, with CHCl₃/EtOH (95:5) as a solvent.

The methylation and ozonolysis is a method from Barrow R A, Capon R J (1991) Alkyl and alkenyl resorcinols from an Australian marine sponge, Haliclona sp. Aust.J.Chem 44 1393-1409. The sample to be methylated (2-8 mg) was stirred in acetone (3 ml) with K₂CO₃ (200mg) and CH₃I (0.5ml) at room temperature for 20 h. The methylated products were isolated by preparative TLC with CHCl₃/EtOH (9.3:0.7) for 6b2, petroleum / EtOAc (8:2) for 6251, 6252. The methylated compounds (0.5-1 mg ) in CS₂ (2ml) at -78 C were ozonolysed with a stream of O₃ and then triphenylphosphine (2mg) added. The reaction mixtures were analysed directly by CI-MS.

The long chain resorcinols gave a characteristic purple colour on TLC after exposure to I₂ vapour and being left on the bench overnight, while resorcinol, resorcinylic acid, orcinol gave a dust brown colour.

Grebustol-A (6251)- Colourless oil; R_f 0.51 (CHCl₃/EtOH 9:1); ¹Η-NMR (CDCl₃, ppm) 1.26-1.35 (m, 12H, CH₂), 1.55 (m, 4H, ArCH₂CH₂), 2.00 (m, 4H, CH=CHCH₂), 2.10 (s, 3H, ArCH₃), 2.42-2.50 (m, 4H, ArCH₂), 4.70 (br.s., OH), 5.32-5.39 (m, 2H, CH=CH), 6.17 (t, J=2.0Hz, 1H, ArH), 6.24(br.s., 4H, ArH); ¹³C-NMR 156.5, 154.4, 142.6, 142.0, 130.0, 129.7, 108.1, 107.9, 100.2, 35.9, 35.6, 31.3, 31.1, 29.8, 29.7, 29.6, 29.4, 29.2, 29.1, 27.2, 7.9; CI-MS (CH₄) m/z 427{M+1}, 397, 285, 257, 229. 207; UVmax(MeOH) 208.4 (loge 4.48), 274.4 (3.35), 279.4 (3.33).

Methylated Grebustol-A (6251m)- ¹H-NMR 1.26-1.38 (m, 12H, CH₂), 1.55 (m, 4H, ArCH₂CH₂), 2.00 (m, 4H, =CHCH₂), 2.06 (s, 3H, ArCH₃), 2.55 (m, 4H, ArCH₂), 3.78 (s, 6H, 2 X OCH₃), 3.81 (s, 6H, 2 X OCH₃), 5.32-5.41 (m, 2H, CH=CH), 6.29 (t, J=2.3Hz, 1H, 2-H), 6.34 (d, J=2.3Hz, 2H, 4, 6,-H), 6.36 (s, 2H, 4'6'-H); CI-MS {M+l}+ 483, EI-MS 482{M}⁺ (32), 410(6), 386(13), 368(8), 353(3), 341(8), 149(12), 109(9); Ozonolysis of 6251m, ¹H-NMR 3.81, 3.78, 9.76, 9.77 (CHO), CI-MS 279, 237.

Norstriatol-B (6252)- colourless oil, R_f 0.55 (CHCl₃/EtOH 9:1); ¹H-NMR (CDCl₃, ppm) 1.25 (m, 12H, CH2), 1.58 (m, 4H, CH₂), 1.91 (m, 4H, =CH CH₂), 2.26 (m, 2H, 1- CH₂), 2.60 (m, 2H, 14-CH₂), 5 . 30 (m, 2H, CH=CH) , 4 . 66 (br . s . , OH) , 6 . 45 - 6 .49 (m, 4H, ArH); CI-MS 41l{M+1}⁺, 317, 285, 257; UV max (MeOH) 206.4 (loge 4.61), 279.2 (3.49).

Methylated norstriatol-B (6252m)- ¹H-NMR 1.25 (m, 12H, CH₂), 1.54 (m, 4H, CH₂), 1.87 (m, 4H, CH=CHCH₂), 2.23 (m, 2H, 1-CH₂), 2.66 (m, 2H, 14-CH₂), 3.68 (d, J=3.0Hz, 3H, 22-0CH₃), 3.69 (d, J=1.40 Hz, 6H, 17,19-OCH₃), 3.83 (d, J=1.45Hz, 3H, 24-OCH₃), 5.30 (m, 2H, CH=CH), 6.42- 6.45 (m, 4H, ArH); CI-MS 467 {m+1}⁺; EI-MS 466 {m}⁺ (100), 451(2), 302(5), 149(10);

1³C-NMR, 56.0, 56.1, 96.5, 104.8, 105.0;

Methylated striatol-B- ¹³C-NMR 56.0 , 56.1, 96.5, 105.0, 130.3, 145.5.

Results and Discussion

Grebustol-A (6251) - Compound (II)

Grebustol-A (6251) (6.6 mg, 3.3ppm), molecular weight 426 (CI-MS), UV Max 274nm, is different from striatol in having a double bond in the alkyl chain and a single benzyl methyl group as indicated by the ¹H-NMR signals at 5.32-5.39 ppm (m, 2H), and 2.10 ppm (s, 3H). The mass spectrum and ¹H-NMR spectrum of the methylated product revealed the presence of four OCH₃ groups (EI-MS 482), ¹H-NMR 3.78 ppm (s, 6H) 3.81 (s, 6H) ) , ¹H-NMR H-H COSY found the coupling of the signals 1.6-1.55, 1.26-2.00, 1.55-2.42, 2.00-5.35 ppm, but no coupling between the signals 1.55 and 2.00 ppm. This excludes the possibility of the double bond at C-10,11. ¹H-NMR data indicated a non- symmetric structure. The CI-MS of ozonolysis products indicated aldehydes of molecular weight 278 and 236, consistent with a C-8,9 (m=7, n=5), or , C-9,10 (m=8, n=4) position for the double bond. Norstriatol-B (6252) - Compound (III)

Norstriatol-B (6252) ( 1.3mg, 0.65ppm) is a desmethyl product of striatol-B. The CI-MS (CH₄ reagent gas) revealed a molecular weight 410. UV Max 279nm. The 1H-NMR , UV, mass spectrum of norstriatol-B was consistent with the reported data for striatol-B [Ridley D D, et al (1970) Chemical studies of the Proteaceae IV Aust.J.Chem. 23, 147-183] and an authentic sample of striatol-B. It is a biphenyl derivative rather than a diphenyl ether derivative as with robustol [Cannon J R, et al (1973) Phenolic constituents of Grevillea robusta

(Proteaceae). The structure of robustol, a novel macrocyclic phenol Aust .J.Chem. 26, 2257-2275]. The methylation of norstriatol-B gave tetramethyl norstriatol-B, which was identical to the substance formed by methylation of authentic striatol-B.

Table 1 shows that the inhibitory effect of grevillol to Ca²⁺-ATPase was weak. The most potent compounds are striatol and grebustol-A, with 1C₅₀ of 16 and 17μM respectively. Without the benzylic methyl group, the activity was weaker, as in grebustol-B. Bisnorstriatol gave only 69.1% inhibition at the concentration of 500 μM. After the methylation of the phenolic hydroxy group, the activity of grebustol-B was lost. The inhibitory activity of striatol has been confirmed with purified erythrocyte Ca²⁺-ATPase.

These results indicate the phenolic hydroxy groups were necessary for the inhibition to occur. The benzylic methyl group between the hydroxy groups enhances the activity. Also the double bond in the alkyl chain increased the inhibitory activity to Ca²⁺-ATPase.

Erythrocyte membranes

Calmodulin-depleted erythrocyte membranes were prepared by continuous filtration through a hollow fibre, Ashahi plasma separator as described by W S Price, B D Roufogalis, P W Kuchel (1989), A simple and inexpensive method for preparing erythrocyte membranes by filtration through a hollow-filtef system, Anal . Biochem.. 179. 190- 193. Packed cells were obtained from the New South Wales Red Cross Transfusion Service, Sydney. The whole preparation was carried out at 4°C. 1 unit of packed red cells was washed 3 times with isotonic buffer, containing 130 mM KCl, 20 mM Tris-HCl (pH 7.4), and the cells were collected by centrifugation at 4,000 RPM. The cells were haemolysed by the buffer containing 1 mM EDTA, 10 mM Tris-Hcl (pH 7.4), 0.5 mM PMSF (phenylmethyl sulfonyl fluoride). The haemolyzate mixture was passed through the hollow fibre system until the membrane appeared white, and then washed with 10 mM potassium Hepes (pH 7.4). The membranes were collected by centrifugation at 10,000 RPM for 20 min, the membranes were resuspended in storage buffer containing 130 mM KCl, 2 mM dithiothreitol, 0.5 mM MgCl₂, 20 mM potassium-Hepes (pH 7.5). The membranes with protein concentration of 1.5-5.4 mg/ml were stored at -80°C until required.

Ca²⁺-ATPase assay

Erythrocyte membranes (0.071-0.098 mg/ml) were incubated at 37°C for one hour in a total volume of 0.4 ml of 65 mM KC1 , 20 mM potassium-Hepes, 5 mM MgCl₂, 50 μM CaCl₂, 0.1 μM calmodulin, 0.1 mM EGTA. The reaction was started by adding 2 mM ATP(pH 7.4). The phosphate liberated to the medium was determined spectrometrically according to the procedure of B U Raess, F F Vincenzi

(1980), A semi-automated method for the determination of multiple membrane ATPase activities, J. Pharmacological

Methods 4, 273-283. The activity of the Mg²⁺-ATPase

(assayed in the absence of added CaCl₂) was subtracted from the total activity assayed in the presence of Ca²⁺. Phenols were dissolved in dimethyl sulfoxide (DMSO), the final concentration of DMSO in the assay mixture was 2.5%. DMSO itself had no effect on ATPase activities. A concentrated solution of the test substances was added to the reaction medium before adding ATP. Protein concentration was determined according to the method of 0 H Lowry, N J Rosebrough, A L Farr, R J Randall (1951) J.Biol.Chem. 193, 265-275; bovine serum albumin was used as a standard. The concentration of the free Ca²⁺ were calculated by computer using a program of D A Goldstein (1979) Calculation of the concentrations of free cations and cation-ligand complexes in solutions containing multiple divalent cations and ligands, Biophys. J., 26 , 235-242.

Control specific activity of the ATPases were (unit: nmoles/mg protein/min):Ca²⁺-ATPase, was 25.8±4.0 (n=20), calmodulin stimulated Ca²⁺-ATPase was 63.5+7.9 (n=16), while the Mg²⁺-ATPase was 7.4±1.0 (n=20) . The enzyme was inhibited by NAP-taurine by 60% at a concentration of 25 μM as shown by A Minocherhomj ee, B D Roufogalis (1982), Selective antagonism of the Ca transport ATPase of the red cell membrane by N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate (NAP-taurine), J.Biol.Chem. 257, 5426-5430.

Ca²⁺-ATPase assay (microplate method)

Erythrocyte membranes were incubated at 37°C for one hour in a total volume of 60 μl of 65 mM KC1, 50 mM HEPES (pH=7.4), 5 mM MgCl₂, 50 μM CaCl₂, 0.1 mM EGTA and in absence and presence of calmodulin (0.3 μM). Test compounds were dissolved in dimethyl sulfoxide DMSO and 2 μl was added to the assay mixture prior the addition of ATP. The final concentration of DMSO in the assay mixture was 3%. The reaction was started by adding 2 mM ATP

(pH=7.4). After 1 hour of incubation, colouring agent

(180 μl) was added and incubated at 37°C for 1/2hrs. The phosphate liberated to the assay medium was determined spectrometrically using a microplate reader at 750nm. The activity of the Mg²⁺-ATPase (assayed in the absence of added CaCl₂) was subtracted from the total activity assayed in the presence of Ca²⁺. The results are shown in Table 1A.

ABBREVIATIONS ATP Adenosine triphosphate

ATPase Adenosine triphosphatase

BHT 2,6-di-tert-butyl-4-methylphenol

CI-MS Chemical ionisation mass spectrometry DMSO Dimethyl sulfoxide

EI-MS Electron impact mass spectrometry

EGTA ethylenebis (oxyethylenenitrilo) tetraacetic acid

HEPES 4-(2-hydroxyethyl)-1- piperazineethanesulfonic acid

HPLC High-performance liquid chromatography

LDA Lithium diisopropylamide

NAP N-(4-azido-2-nitrophenyl)-2- aminoethanesulfonic acid

NMR Nuclear magnetic resonance

PMSF Phenylmethyl sulfonyl fluoride

SDS Sodium dodecylsulfate

TLC Thin layer chromatography

TOX1CITY BRINE SHRIMP ASSAY

The brine shrimp assay procedure determines LC₅₀ values of active compounds. Activities of a broad range of known active compounds are manifested as toxicity to brine shrimp (Artemia salina Leach). There are many applications of the assay including analysis of toxic substances, anaesthetics, morphine-like substances and cocarcinogenicity of phorbol esters. The assay shows good correlation with some cytotoxicities and its utility as a prescreen for some antitumour activities has been recently confirmed.

DMSO (dimethyl sulfoxide) was the solvent of choice because of its good solubilising properties and also because the phenolic substances used in the Ca²⁺-ATPase inhibition study were already prepared with DMSO.

The method for testing solvent toxicity used was basically that reported by J L McLaughlin in Methods of Plant Biochemistry (1991), vol. 6 (K Hostettman, ed.), Academ Press, London, 1-32. DMSO solutions of the substances to be tested were added directly to the vials containing the brine shrimp. As the concentration of DMSO that we wished to use was higher than the recommended 1% v/v testing of the toxicity of the DMSO was therefore necessary. The concentrations of DMSO tested on the shrimp, along with the results from the assay which was done in duplicate are listed in Table 5.

Table 5. Concentrations of DMSO tested.

Cone (% v/v) % Deaths

0 0

1 0

2 0

3 0

4 0

5 9

7 12

9 18

11 57

13 96

15 100

20 100

25 100

No toxicity towards brine shrimp was observed in a 24 hour period for concentrations of DMSO in brine up to 4% v/v.

Bioassay

Brine shrimp toxicity was assayed, except for some minor modifications, according to the method of

McLaughlin et al as reported in Brine Shrimp: A convenient general bioassay for active plant constituents, B N Meyer, N R Ferrigni, J E Putman, L B

Jacobsen, D E Nhols and J L McLaughlin. Planta Medica

(1982), 45, 31-34 and Crown gall tumours on potato discs and brine shrimp lethality: Two simple bioassay for higher plant screening and fractionation. J L McLaughlin.

Methods of Plant Biochemistry (1991), vol. 6 (K Hostettman, ed.), Academ Press, London, 1-32. Ten shrimp were added transferred to each of the vials and the volume adjusted to 4.9 mL. Each dose was performed in triplicate, including the control. In quick succession, the appropriate volume of additional DMSO for each dose, required to achieve a final concentration of 2%, was added before the appropriate volume of test solution. The vials were gently mixed and the time noted. After 24 hours, the number of survivors were counted and % mortality was determined. The test compounds were assayed at concentrations of 100 μM, 25 μM, 5 μM, 1 μM and 0.2 μM (and where appropriate concentrations of 0.04 μM and 0.008 μM).

The brine shrimp were able to survive without food in the vials over the 24 hour period and were therefore not fed.

The dose-response curves were constructed using the Sigmaplot computer program and the LC₅₀ value was calculated from the intersection point of the curve and the 50 % mortality line. The LC₅₀ values were expressed in both μM and μg/mL.

DISCUSSION

In this bioassay, the estimated LC₅₀ value of the test compound indicates its toxicity to brine shrimp. A more useful comparison of potencies can be obtained by looking at the μM instead of μg/mL concentrations in Table 6.

Simple alkylphenols were very toxic with certain alkyl chain lengths. The most active of the alkylphenols measured was 4-decylphenol (LC₅₀ = 0.27 μM) compared with the most active of all compounds measured 1-(2- hydroxyphenol)-12(4-hydroxyphenol) dodecane (LC₅₀ = 0.054 μM). Ketophenols were found to be more toxic than simple alkylphenols e.g. 4-nonanoylphenol (LC₅₀ = 0.10 μM). 4- and 5-Alkylresorcinols showed low toxicity except for 5- tridecylresorcinol (grevillol) (LC₅₀ = 2.8 μM) which was moderately toxic. The α,ω-bishydroxyphenylalkanes, for example 1,10-bis(2-hydroxyphenyl)decane (LC₅₀ = 1.9 μM), were moderately toxic. 1,10-Bis(2-hydroxy-4-methylphenyl)decane (LC₅₀ = 14 μM) and other substances with methyl groups on the phenyl groups showed reduced toxicity. The α,ω-bisresorcinylalkanes, including , striatol (LC₅₀ = 11 μM) , bisnorstriatol (LC₅₀ = 40 μM) and 1,10-bis(2,4-dihydroxyphenyl)decane (LC₅₀ = 37 μM) showed relatively low toxicity.

A significant difference in toxicity exists between grifolin and neogrifolin (LC₅₀ = 2.3 μM and LC₅₀ = 28 μM respectively). Neogrifolin appears to be about ten-fold weaker than grifolin. Ca²⁺-ATPase inhibition by these two compounds, on the other hand, was relatively strong and identical (grifolin's 1C₅₀ was 22.5 μM while neogrifolin's 1C₅₀ was 23.3 μM).

Podophyllotoxin was tested in order to check whether the bioassay's results were comparable with those of Meyer et al. The LC₅₀ from this study was 3.8 μM and is reasonably close to the LC₅₀ value of 5.8 μM determined by Meyer et al.

Claims (15)

1. Use of a compound of formula (I)

wherein Ar is an aromatic ring system comprising one or more optionally substituted phenyl rings optionally linked to or fused with one or more other optionally substituted phenyl rings or one or more 5 or 6-membered, optionally substituted heterocyclic rings wherein the heteroatom is oxygen; and

wherein the ring system comprises 1-4 phenyl rings and

wherein Ar can be linked to another Ar via a group X wherein the Ar is independently selected;

where X is optionally substituted C_1-20alkylene, C_{2- 20}alkenylene or C_2-20alkynylene;

R is hydrogen; C_1-20alkyl, C_2-20alkenyl, C_2-20alkynyl, C_2-20alkanoyl, C_2-20alkenoyl, C_2-20alkynoyl, each of which can be optionally substituted;

R₁ is independently selected and is hydrogen; optionally substituted C_1-12alkyl, C_2-12alkenyl, C_2-12 alkynyl; -COOR' -NR'R', halogen, -OR', -COR', -CONR'R',

=O, -SR', -SO₃R' , -SO₂NR'R', -SOR', SO₂R', -NO₂, -CN, glycoside, silyl;

where R' is independently hydrogen; alkyl, alkenyl or alkynyl each optionally substituted; and

where two groups R₁ can be joined;

wherein the optional substituents are one or more independently selected from C_1-10alkyl, C_2-10alkenyl, C_2-10 alkynyl; -COOR" -NR"R" , halogen, -OR", -COR", -C0NR"R", -SR", =O, -SO₃R", -SO₂NR"R", -SOR", -SO₂R", -NO₂, -CN; wherein R" is independently hydrogen, alkyl, alkenyl, or alkynyl;

n = 1, 2 or 3

m = 1, 2, 3 or 4

or a pharmaceutically acceptable derivative thereof in the manufacture of a medicament for inhibiting the action of Ca²⁺-ATPase enzymes.

2. Use according to claim 1 wherein the enzyme is plasma membrane Ca²⁺-ATPase.

3. Use of a compound of formula (I) as defined in claim 1 in the manufacture of a medicament for the treatment or prophylaxis of cardiovascular disease.

4. Use according to claim 1, 2 or 3 wherein the compound of formula (I) is a compound of formula (V) or (VI).

5. Use according to claim 1, 2 or 3 wherein the compound of formula (I) is 5,7,2',6'-tetrahydroxy-8- lavandulylflavanone, 5,7, 6' -trihydroxy-8- lavandulylflavanone, 5,2',6'-trihydroxy-8-lavandulyl-7-methoxyflavanone or a pharmaceutically acceptable derivative thereof.

6. Compounds of formulae (II), (III), (IV), (V), (VI) or pharmaceutically acceptable derivatives thereof:

where

1 = 1, 2 or 3

r = 7-14 when 1 = 1

8-16 when 1 = 2 or 3

R₂ is (1) 2-hydroxy

(2) 2-hydroxy-4'-hydroxy

(3) 2-hydroxy-3-methyl

(4) 4-hydroxy-3-methyl

(5) 2,4-dihydroxy

(6) 3,5-dihydroxy-4-methyl

(7) 2,6-dihydroxy-4-methyl

(8) 2,4-dihydroxy-3-methyl

(9) 3-hydroxy-4-methyl

provided that (1) when R₂ is 2 -hydroxy and 1 = 1 then r is not 7-10 and

(2) when 1 = 3 and

R₂ is 3,5-dihydroxy-4-methyl then n is not 14 and

(3) when 1 = 2 and

R₂ is 2-hydroxy-3-methyl then n is not 10

(4) when 1 = 2 and R₂ is 2,4-dihydroxy

then r is not 8-10 and 13 and

(5) when 1 = 2 and

R₂ is 4-hydroxy-3-methyl then r is not 10;

where s = 8-16

where t = 6-15

where p + q = 12

where p + q = 12 .

7. A method of preparing compounds of formula (II) as defined in claim 6 which comprises

(a) where 1 = 1 and R₂ is OH

(i) treating the corresponding diacid with a suitable agent to provide the acid dichloride as follows

(ii) treating the corresponding acid dichloride with phenol as follows

(iii) rearrangement of the diacyl groups as

follows

(iv) followed by reduction of the acyl groups to provide compounds of formula (II);

(b) where 1 = 2, R₂ is OH

(i) treating the corresponding diacid with zinc chloride and resorcinol; and

(ii) followed by reduction of the acyl groups to provide compounds of formula (II);

(c) where 1 = 2, R₂ is 2 -hydroxy-3-methyl

carrying out steps (i) - (iv) in (a) above except in (ii) phenol is replaced with o-cresol;

(d) where 1 = 2 and R₂ is 3-hydroxy-4-methyl

(i) nitrating the corresponding diketo compound of formula

to give the corresponding bis-3-nitro compound

(ii) reducing the bis-3-nitro compound to give the bis-3-amino compound followed by

(iii) diazotisation and hydrolysis to

give the bis-3-hydroxy compound

(iv) followed by reduction of the keto groups to give the desired bis-3-hydroxy compound;

(e) where 1 = 3 and R₂ is 2,6-dihydroxy-4-methyl

(i) treatment of a compound of formula

with LDA to give the dianion followed by

(ii) treatment with the desired protected alkane aldehyde of formula

(iii) dehydrative decarboxylation followed by reduction to give an intermediate product of formula

(iv) oxidation to give

(v) followed by treatment with the dianion from step (i) to give

(vi) dehydrative decarboxylation followed by deprotection and reduction to give the desired product; (f) where 1 = 3 and R₂ is 3 , 5 -dihydroxy-4-methyl

(i) treatment of α-N,N-dimethylamino-α-cyano- (3,5-dimethoxy-4-methyl)benzylidene in tetrahydrofuran and

hexamethylphosphoramide (HMPA) with lithium diisopropylamide (LDA) to give the anion followed by

(ii) treatment with α ,ω-dibromoalkanes to give

(iii) refluxing with 30% aqueous oxalic acid to give the corresponding diacyl compound

(iv) reduction of the acyl groups

(v) followed by demethylation with hydrogen bromide in acetic acid to provide compounds of formula (II);

(g) where 1 = 3 and R₂ is 2,4-dihydroxy-3-methyl

(i) carrying out steps (i) and (ii) in (b) except in (i) resorcinol is replaced with 2-methylresorcinol;

(h) where 1 = 2 and R₂ is 4-hydroxy-3-methyl

(i) treating the corresponding diacid with ortho-cresol in the presence of polyphosphoric acid to give the corresponding diacyl compound

(ii) followed by reduction the acyl groups to provide compounds of formula (II).

8. A method of preparing compounds of formula (III) as defined in claim 6 which comprises

(i) treating the corresponding diacid with a suitable agent to provide the acid dichloride (ii) treating the corresponding acid dichloride with 2-naphthol followed by

(iii) rearrangement of the diacyl groups and (iv) followed by reduction of the acyl groups to provide compounds of formula (III).

9. A method of preparing compounds of formula (IV) as defined in claim 6 which comprises treatment of 4- alkylresorcinols with ethyl acetoacetate in the presence of an acid catalyst.

10. A method for inhibiting the action of Ca²⁺-ATPase enzymes in a subject which comprises administering to the subject a compound of formula (I) as defined in claim 1.

11. A method according to claim 10 for the inhibition of plasma membrane Ca²⁺-ATPase.

12. A method of treatment or prophylaxis of cardiovascular disease in a subject which comprises administering to the subject a compound of formula (I) as defined in claim 1.

13. A method according to claim 10, 11 or 12 wherein the compound of formula (I) is a compound of formula (V) or (VI) .

14. A pharmaceutical formulation comprising a compound or formula (II), (III), (IV), (V) or (VI) or pharmaceutically acceptable derivatives thereof in a pharmaceutically acceptable carrier.

15. A pharmaceutical formulation comprising 5,7,2',6'-tetrahydroxy-8-lavandulylflavanone, 5,7,6'-trihydroxy-8-lavandulylflavanone, 5,2',6'-trihydroxy-8-lavandulyl-7-methoxyflavanone or a pharmaceutically acceptable derivative thereof in a pharmaceutically acceptable carrier.