CA1179370A

CA1179370A - 3,7,11,15-tetramethyl-2,4,6,10,14-hexadecapentaenoic acid

Info

Publication number: CA1179370A
Application number: CA000374715A
Authority: CA
Inventors: Kouichi Abe; Kouji Yamada; Takeshi Suzuki; Yuichi Inai; Osamu Tagaya; Isao Yamatsu; Nozomu Koyanagi; Yoshikazu Suzuki; Kouichi Suzuki; Shinya Abe
Original assignee: Eisai Co Ltd
Current assignee: Eisai Co Ltd
Priority date: 1980-04-07
Filing date: 1981-04-06
Publication date: 1984-12-11
Also published as: ES501124A0; DK158457B; GB2073750A; DE3113149A1; AU6915981A; IT1194141B; GB2073750B; NL191744C; SE8102161L; NL191744B; FR2479807A1; DK158457C; ES8304058A1; ES509913A0; AU537402B2; SE447243B; FR2479807B1; NL8101630A; IT8120967A0; CH646682A5

Abstract

ABSTRACT

3,7,11,15-TETRAMETHYL-2,4,6,10,14-HEXADECAPENTAENOIC ACID

A novel compound, 3,7,11,15-tetramethyl-2,4,6,10,14-hexadecapentaenoic acid, and a pharmaceutically acceptable salt thereof are disclosed together witha number of different processes for the preparation of the compound. The uses of the novel compound as an anticancer agent cold a therapeutic agent for treat-ment of skin diseases with keratinization are also disclosed.

Description

1 ~7~370 3,7,11,15-TETRAMETHyL_2,4,6,1o~14-~ExADEcApENTA~NoIc ACID

This invention relates to a novel compound of 3,7,11,15~
tetramethyl-2,4,6,10,14-hexadecapentaenoic acid having the general formula (I):

~ \ ~ ~ COOH (I) ~_f~r. ~,~,i.~
and ~ alt thereof. his invention further relates to pro-cesses for the preparation of the same, an anticancer agent comprising the same, and a therapeutic agent for treatment of skin diseases with keratinization.
W. Bollag,et al. reported in Europ. J. Canccr, vol. 10,p 731(197l~)that retinoides such as ethyl g-(2~3~6-trimethyl-4-methoxyphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate have anticancer activity. These retlnoide compounds1 however~
are highly to~ic, and further have problems such as causing hypervitaminosis of Vitamin A when administered.
The compound of the above-mentioned general formula (I) provided by the present invention shows the anticancer acti-vity, causes substantially no hypervitaminosis of Vitamin A, and is low in other toxicities.
The compound of the present invention can be prepared by the following processes.
Process A
This process comprises:
(1) reacting a compound of the general formula (II):

~ ~ ~ O (II) and a Wittig reagent derived from a compound of the general formula (III): -X - CH2 - C02R1 (III)

- 2 - 117937~

in which X represents a halogen atom, and R1 represents a lower alkyl group, to obtain a compound of the general formula (IV):

~ C02R1 (IV) in which R1 has the same meaning as defined above; and ~ 2) hydrolyzing the so obtained compound ofthe general formula (IV) in the pregence of a base to prepare the com-pound of the general formula (I).
Examples of the Wittig reagents employed in the above-described (1) stage and derived from a compound of the general formula (III) include phosphoric compounds produced by the reaction between the compound of the general formula (III) and triphenylphosphine, phenyldialkoxyphosphine, tri-alkylphosphite, or the like~ 'rhe preparation of th~ reagent I and the Wittig reaction employing the reagent are carried out by the conventional methods such as the method given by Wadworth, et al. in J. ~m. Chem. Soc.~ vol. 83, p. 1733 (1961), the method given by Greenwald, et al in J. Org. Chem., vol.
28, p. 1128 ~1963~, and the method given by Horner, et al. in Ber. vol. g5, p.681 (1962).
In the above mentioned (2) stage, the hydrolysis is carried out in the presence of a base generally employed for hydrolysis of carboxylic acid esters, such as sodium hydroxide ; and potassium hydroxide.
Process B
This process comprises:
(1) reacting a compound of the general formula (V~:

I CHO (V) ~/\/~/

and a Wittig reagent derived from a compound of the general

3 _ ~ ~ 7 9 ~ l ~

formula (VI):

X ~ ~ C02Rl ~VI) in which ~ represents a halogen cltOIII~ and Rl represents a lower alkyl group, to obtain a compound of the general formula (IV); and ~ 2) hydrolyzing the so obtained compound of the general formula ~IV) in the presence of a base to prepare the compound of the general formula ~I).
Each of the above-described stages ~1) and ~2) can be carried out in the same manner as in Process A.
Process C
~ his process comprises:
~1) react~ g a compo~uld of the general form-llll ~V:[:C~:

' ~ ~ ~ S02Y ~VII~

in which Y represents a lower alkyl group or an aryl group~ and a compound of the general formula ~VI~
to obtain a compound of the general formula ~VIII):

= C02Rl ~VIII) in which Y and Rl have the same meanings as defined above;
and ~2~ subjecting the so obtained compound of the general formula ~VIII~ to a desulfination and hydrolysis of ester in the presence of a base to prepare the compound of the general formula ~

~h

4 ~ ~ 7 g ~ 7 ~

The stage ~1) is carried out in the presence of a base. Examples of the bases include n-butyllithium and phenyllithium. Examples of the reaction solvents include tetrahydrofuran, diethyl ether and 1,2-dimethoxyethane. r~e reaction is generally carried out at a temperature lower than room temperature.
The stage (2) call be carried out in the same manller as the s-ta~e (2) of the aforementioned Process A.
Examples of the s~bstituents provided to the general fo-rmulae ~IlI), ~IV), (VI), ~VII) and ~VIII) are as follows:
halogen ato~s such as chlorine, bromine and iodine or the substituent X; lower alkyl groups such as methyl, ethyl and propyl for the substituent ~1 and lower alkyl groups such as methyl, ethyl and propyl, and aryl groups s~ch as phenyl and p-tolyl -eor the substituellt Y.
Examples oE the pharmace~ltically acceptable suLts oE tho COID~OUlld 0 the gencr.ll formula ~I) inclllde lts sodium salt ~m-l its po-tassiunl salt~
rlhe compouncl oE the aforelllelltioned gcncral Eormula (1) L)rovided by the present invention also shows therape~ltlc activity for treatment of skin diseases with keratinization.
Examples of the skin diseases with keratinization which can be treated by the compound of the general formula ~I) include skin diseases showing symptoms such as hyperkeratosis, parakeratosis and dyskeratosis. ~lore con-cretely, examples of the skin diseases include psoriasis, acne, acne vulgaris, Darier's disease, palmoplantar pustulosis, lichen planus, ichthyosis, erythroderma, pityriasis rubra pilasis, and keratosis senilis.
There are employed steroide-type external preparations for the treat-ment of the skin diseases with keratinization. These preparations, however, have strong side-effects, so that these are not applicable to the repeated administra-tion for a long period and the treatment with administration of a great amount ~ ,~

- 4a - ~ 1793~0 of the preparation.
In contrast, 3,7,11,15-tetramethyl-2,4,6,10,14-hexa~ecapelltaenoic acid of the present invention has the activity for

- 5 - ~ 17937~

inhibition of keratinization of skin and show low toxicity The results of the pharmacological tests and toxicity tests on the compound o~ the present invention are set forth below.
Pharmacological Tests (Anticancer Activity) _ . .
(1) Experimental procedure A mouse (ICR, female, 60 days age) was shaved at the back of the neck (5 cm2). 7,12-Dimethylbenzo-[2~-anthracene was dissolved in acetone to give 75 mg./100 ml.
solution. The so prepared solution was applied to the mouse on the 60th aged day and further on the 75th aged day in the amount of 0.2 ml. per a mouse.
Crotonic oil was dissolved in acetone to give 250 mgO/
100 ml. solution, and the so prepared solution was appliecl to the mouse in the amount of 0.2 ml. per a mouse, twice a week until the beginning of the treatment~ When 3 - 7 papi1-lomata ~diameter of 3 - 8 mm. for each, and total diameter o~
30 - 60 mm.) were produced per a mouse, the treatment was started.
The test compound was dissolved in groundnut oil to give 20 mg.tml solution, and administered orally to the mouse.
The solution was administered 10 times for 14 days (once a day), and the diameters of the papillomata were measured on the 14th day to determine the total diameter for each mouse.
(2) Test compound 3,7,11,15-Tetramethy1-2,4,6,10,14-hexadecapenta-enoic acid (the compound according to the Fresent invention) Ethyl-9-(2,3,6-trimethyl-4-methoxyphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate (control compound) (3) The results are set forth in Table 1.

~ 6 - 1~.79370 Table 1 Test Compound Number Papilloma (~otal diameter/mouse) f Mean Value Mean'~alue Ratio of ~
mlce (Oth day) (14th day) Increase or Decrease _.
Groundnut oil 3 33.9 mm 39 7 mm -~ 17 1 %
only Compound of the -invention 5 37.5 mm 21 3 mm _ 43.2 %
day) Control (40 mg~/Kg l 58.1 mm 32.7 mm _ 43.7 /0 day) As seen from the above l'able 1, the compound of' the invention is effective againsk the papilloma.
Pharmacological Tests (Inhibition of Keratinization) (1) ~xperimental procedure Into a Petri dish (diameter 6 cm) in which 8 cover-glasses '(diameter 15 mm) were placed was poured 5 ml of a suspension of the varient epithelial cell of rat bladder named BES 20B (approximately 2 x'105 cells/ml ), and the incubation was carried out at 37C,` for 24 hours and at 5 %
carbon dioxide concentration. Each o~ the so treated cover-glasses was placed in 2 ml of Eagle's ME~ medium contain-ing the test compound at different concentrations, and then another incubation was carried out at 37C and at 5 % carbon dioxide concentration The medium was renewed at intervals of 2 - 3 days On the 2nd, 5th, 8th and 14th days from the beginning of the incubation, the cover glass wa~ taken out of the medium and subjected to the Papanicolaou stain to observe the degree of keratinization The observation was carried out by the measùrement of the absorption spectrum in _ 7 ~ g 3-7 ~

the region of 4no - 750 nm3 and tlle Kl (Keratiniza-tion Index) was calculated from the following equation.
Absorption peak ln the vicinity oE 490 nm ascribed to the keratinized cells KI = -- ~
Absorption peak in the vicinity of 640 nm ascribed to tlle non-keratinized cells A value of the KI of 1.0 or higller indicates high keratinization, a-nd a value of the KI of 0.5 or less indicates substantially no keratini2ation.
The BES 20B cell was incubated in a medium containing no compound of the invention, for comparison.
(2) Test compound 3,7,11.,15-Tetrclmethyl-2,4,6,10,14-llexndec.lpellt~lelloic aci~ lle compound according to tlle prescnt invention) ~ 3) Bxpcrilllental results The results are set Eorth in 'I'able 2.

Table 2 KI

Period of Incubation 2 days 5 days 8 days 14 days Control 0.43 1.10 3.27 3.08 Compound of the Invention 0.1 ~g./ml. 0.43 0.67 0.55 0.52 1.0 ~g./ml. 0.42 0.46 0.38 0.39 5.0 ~g./ml. 0.48 0.50 - 0.22 In the experiment on the control, the KI value exceeded 1.0 on the 5th day -from the beginning of incubation, which indicates high keratinization. In contrast to the result on the control, the results given by different concentrations of the compound o~ the present invention showed the KI values of less than 1.0 for all runs.to ind:icate inhibition of Kerati-nizatio~.
Toxicity Tests (1) Experimental procedure The test compound was administered repeatedly to a group of 6 mice (ICR strain, female) ~or 14 days. The amount of the administration was 40 mg./Kg./day, 200 mg /Kg./
day, and 400 ~go/Kg /day for the compound o~ the present invention, and 200 mg /Kg~/day for the control compound.
In the course of the administration, increase or decrease of the weight of the mouse, occurance of death, etc. were ob.-served.
(2) Test compound The compounds described in the pharmacological tests (anticancer activity) were employed I (3) Experimental results (a) Increase and decrease of the weight The results are set forth in Table 3.
(b) Death All mice treated with the control compound in the amount of 200 mg./Kg~/day died by the 8th day, and no death was o~eerved on the mice treated with the compound of the present invention.
tc) Falling-out of hair Falling-out of hair was observed by the 6th day on every mouse treated with the control compound in the amount of 200 mg /Kg /day, and no falling-out of hair was observed on the mouse treated with the compound of the pre-sent invention (d) Cyanosis Cyanosis was observed by the 7th day on every mouse treated with the control compound in the amount of 200 mg /KgO/day, and no cyanosis was observed on the mouse treated with the compound of the present inventiOn g .l7s37a ~D I C~ ~ C~
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" _ 10- ll7~370 .' Among the subjects in the toxicity tests, the falling-out o~ hair and the weight change are known to indicate the hypervitaminosis of Vitamin A. Since the falling-out of hair and decrease of the weight were observed at a prominently high level on the group of mice treated with the control compound, it is thought that the hypervitaminosis of Vitamin A occured. In contrast, there was observed no such problem on the group of mice treated with the compound of the present invention. -In view of the pharmacological test results and thetoxicity test results hereinbefore described, the compound of the present invention is considered to be of hig~ safety and to be of value as an anticancer agent and a therapeutic agent for treatment of skin diseases with keratinization.
Therefore, the compound of the present invention can be employed for the prevention and treatment of cancer and pre-cancerous conditions, and also employed ~or the treatment of skin diseases with keratinization such as acne and psoriasis vulgaris and the treatment of allergic and in~lammatory skin diseases. Moreover, the compound of the present invention can be employed for the treatment of muscosal diseases caused by inflammation, degeneration and displastic change For the applications as the anticancer agent and the therapeutic agent for treatment of skin disease with kerati-nization, the compound of the present invention is admini-stered orally in the form of powder, granule, pellet, hard capsule, etc.,or parenterally in the form of ointment, suppo-sitory, injection solution, etc. The dosage is generaily 40 mg. - 4 g /day for adult~ If the compound of the pre-sent invention is employed in the form of an external prepa-ration, the dosage can be ~aried depending on the conditions of the disease The compound of the present invention can be combined with a generally employable carrier for the medi-cal use in the conventionc.l manner to give the preparations described above - ~ ~ 7g370 The processes for the preparation of the comp~und of the present in~ention are illustrated by the following exam~les, but these examples are not intendecl to restric~ the present invention.
Example 1 To a suspension of 5.0 g. o~ 55 % sodium hydride (oily) in 60 ml. of n-hexane was adde~ 28.6 g. of triethyl phospho-noacetate. The mixture was then heated under reflux~ and ' 20 g. of 6,1'0,14-trimethyl-3,5,9,13-pentadecatetraen-2-on was added dropwise to the mixture under stirring. After 30 minutes, the reaction liquid was poured into 20Q ml of waterl i and then 500 ml. o ~hexane was added for extraction. The n-hexane phase was separated, washed with two 100 ml. por~ions of a mixture of methanol and water (2 1~ I and corlcentra~ed. '¦
The so obtained concentrate was purif'ied by the silica ~el i~
column chromatography to ~ive 18 g. of et~yl 3l7,l1,15- ' tetramethyl~2,ll,6,10~14-hexadecapentaenoate~
To 10 g. o~ the ethyl 3~7~ 5~tetranle~hy-l-2~ 6~1 hexadecapentaenoate obtained in the abo~e was added a sol~
tion of 3.9 g. of potassium hydroxide in 30 ml of isopropyl alcohol, and the mixture was stirred at 50 G for 1 hour.
The reaction liquid was then poured into ice-water, made acidic by addition of hydrochloric acid, and extracted with 100 ~l. of ethyl ether. The ether phase was washed with water, dried over magnesium sulfate, and concentratèd to give 9.0 g. of an oil. The oil was dissolved in sn ml~ of n-hexanè and crystallized at - 20 C to give 4.0 ~ of 3,7, 11,15-tetramethyl_2,4,6,10~14_hexadecapentaenoic acid in the form of pale yellow needles M~p. : 78.4 C
Mass spectrum (mte) : 302 (M ) Infrared absorption spectrum (cm 1, KBr tablet):
3450, 2900, 1680, 1595 NMR spectrum (~, CDC13): 1 &1 (6H, s), 1 68 (3H, s)g 1~86 (3H, s), 1.92 - 2.24 (8H, b~, 2 35 (3H, s), - 12 - ~ 1 7 g ~ ~ ~

5.10 ~2H, b), 5.76 (1~1, bs), 5.98 (11l, d, J = 11 llz), 6.20 (1~1, d, J = 15 Hz), 6.90 (1~1, dd, J = 11 llz, 15 l-l~), 11.63 (1ll, b) Ultraviolet absorption spectrum ~methal~oL 304 nm Example 2 To a suspension of ~.8 g. of sodium ethoxide in 100 ml. of n-hexane was added 18 g. of diethyl 3-e~hoxycarbonyl-2-methyl-2-propenylphosphonate. To the mixture was added 10 g. of 3,7,11-trimethyl-2,6,10-dodecatrien-1-al under stirring at room temperature. After 1 hour, the reaction liquid was poured into 50 ml. of water, and the n-hexane phase was separated. The n-hexane phase was washed with two 50 n~l. portions oE a mix-ture oE methanol alld water (2 : 1), alld concentrated. The so obtained concentrate was puri-Eied by the sllica gel coL~ullr chromatograp}ly -to give 14.5 g. oE ethyl 3,7,11,15-tetramethyl ?.,4,G,L0,14-llexa-decapentaelloate.
10 g. of the ethylester ob-tained in the above was hydroly~ed in the same malmer as in Example 1 to give 3.5 g. of 3,7,11,15-tetrclmethyl-2,4,6,10,14--hexadecapentaenoic acid in the -form of yellow needles.
The so obtained product was identified in the same manner as in Example 1, namely, by m.p., mass spectrum, NMR spectrum, infrared absorption ?.0 spectrum, and ultraviolet absorption spectrum.
Example 3 In 100 ml. of tetrahydrofuran was dissolved 10 g. of l-p-tolylsulfonyl--3,7,11-trimethyl-2,6,10-dodecatriene, and the solution was chilled to - 50 C.
To the solution was added dropwise 1~.5 ml. of 15 % n-butyllithium - n-hexane solution under stirring and in a stream of nitrogen, maintaining the temperature of the solution at - 50 C. Then, 300 ml. of tetrahydro-furan solution contain-ing 5.7 g. of ethyl 4-bromo-3-methyl-2-butenate was added dropwise to the so pro---, .

- 13 - ~ 1 ~ 9 370 duced solution. A-Eter 30 minutes, 100 ml. of 10 % aqueous ammonium chloride solution ~as added, and subsequently the mixture was treated to reach room temperature. The mixture was then extracted with two 200 ml. portions of n-hexane. The n-hexane phase was washed with three 100 ml. portions of water, dried over magnesium sulfate~ and concentrated to give 13 g. of cthyl 3,7,11,15--tetramethyl-5-p-tolylsulfonyl-2,6,10,14-hexadecatetraenoate.
To 10 g. of the ethylester obtained in the above was added a solution of 4.6 g. o~ potassium hydroxide in 50 ml. of isopropyl alcohol, and the mixture was stirred at 50 C for 3 hours. The reaction liquid was then poured into ice--water, made acidic by addition of hydrochloric acid, and ext~acted with 100 ml.
of ethyl ether. The ethyl ether phase was washed with water, dried over magne-sium sulfate, and concentrated to give 6 g. oE an oil. 'I'he oil was dissolvecl in 30 ml. of n-hexane and crystallized at - 20 C to give 1.8 g. of 3,7,11,15-tetrLI-methyl-2,4,6,10,14-hexadecapentaenoic acid ln the form of pale yellow needLes.
The so obtained product was identlEied in thc sallle nlanner, as in Example 1 namely, by m.p., mass spectrum, NMR spectrum, infrared absorption spec-trum, and ultraviolet absorption spectrum.
Example 4 .

Pellet 3,7,11,15-Tetramethyl-2,4,6,10,14-hexadecapentaenoic acid 50 g.

Silicic acid anhydride 30 g~

Crystalline cellulose 50 g.

Corn starch 36 g.

Hydroxypropylcellulose 10 g.

Magnesium stearate 4 g.

The above composition was processed in the conventional manner to give a pellet ~180 mg. for a pellet).

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of 3,7,11,15-tetramethyl-2,4,6,10,14-hexadecapentaenoic acid of the general formula (I):

(I) and pharmaceutically acceptable salts thereof, which comprises:
a) reacting a compound of the general formula (II):

(II) and a Wittig reagent derived from a compound of the general formula (III):
X - CH2 - CO2R1 (III) in which X represents a halogen atom, and R1 represents a lower alkyl group, to obtain a compound of the general formula (IV):

(IV) in which R1 has the same meaning as defined above; and hydrolyzing the so obtained compound in the presence of a base, b) reacting a compound of the general formula (V):

(V) and a Wittig reagent derived from a compound of the general formula (VI):

(VI) in which X represents a halogen atom, and R1 represents a lower alkyl group, to obtain a compound of the general formula (IV):

(IV) in which R1 has the same meaning as defined above; and hydrolyzing the so obtained compound in the presence of a base, or c) reacting a compound of the general formula (VII):

(VII) in which Y represents a lower alkyl group or an aryl group, and a compound of the general formula (VI):

(VI) in which X represents a halogen atom, and R1 represents a lower alkyl group, to obtain a compound of the general formula (VIII):

(VIII) in which Y and R1 have the same meanings as defined above;
and subjecting the so obtained compound to a desulfination and hydrolysis of the ester in the presence of a base.

2. 3,7,11,15-Tetramethyl-2,4,6,10,14-hexadecapentaenoic acid of the general formula (I):

(I) and pharmaceutically acceptable salts thereof, whenever prepared by the process of claim 1 or by an obvious chemical equivalent thereof.