EP1220843A1

EP1220843A1 - Pyridinium derivatives for the treatment of diabetic and aging-related vascular complications

Info

Publication number: EP1220843A1
Application number: EP99974071A
Authority: EP
Inventors: Alangudi B-7 Swastik Park SANKARANARAYANAN
Original assignee: Torrent Pharmaceuticals Ltd
Current assignee: Torrent Pharmaceuticals Ltd
Priority date: 1999-10-06
Filing date: 1999-10-15
Publication date: 2002-07-10
Also published as: PL348049A1; CZ20011808A3; BR9915962A; CN1329597A; AU5994499A; JP2003511370A; HK1044336A1; WO2001025209A1; HUP0301687A2; CA2351075A1; MXPA02003496A

Abstract

The invention discloses compounds of the pyridinium series useful for the management of diabetes and aging-related vascular complications, and particularly in the treatment of complications of diabetes mellitus and other aging-related conditions including kidney disease, nerve damage, atherosclerosis, retinopathy, dermatological conditions and discoloration of teeth by breaking preformed AGE, of general formula (I), or pharmaceutically acceptable salts thereof, wherein, R1, R2 and X are as defined in the specification. The invention also discloses method of preparation of the compounds of the series and pharmaceutical composition having one or more compounds as defined above as active ingredients. The invention further discloses a method of treatment of a diabetic patient by administering the compounds as defined above, either singly or in combination with other drugs for antidiabetic therapy.

Description

PYRIDINIUM DERIVATIVES FOR THE TREATMENT OF DIABETIC AND AGING-RELATED VASCULAR COMPLICATIONS

FIELD OF THE INVENTION

The present invention relates to a class of compounds of pyridinium series

and to their use in treatment of diabetes and related illnesses. More particularly

the invention relates to compounds of this series, methods for their preparation,

pharmaceutical composition containing these compounds and their use in the

treatment of complications of diabetes mellitus. The compounds of this series

exhibit AGE breaking activity, which is essential for the treatment of diabetic and

aging-related complications including kidney disease, nerve damage,

atherosclerosis, retinopathy and dermatological conditions. The invention also

extends to the method of reversing the discoloration of teeth resulting from

nonenzymatic browning in the oral cavity which comprises administration of an

amount effective to reverse pre-formed advanced glycosylation crosslinks.

BACKGROUND OF THE INVENTION

Maillard in 1912 found that reducing sugars, such as glucose and ribose

react with proteins to form brown pigments. Further studies have shown that this

is an irreversible non-enzymatic reaction, which occurs in several natural systems

including stored foodstuff. Maillard reaction occurs in two stages, early and advanced. Initially, proteins react with glucose to form stable Amadori products,

which subsequently cross-links to foπn advanced glycation end products (AGE).

In most cases, the formation of AGE also accompanies browning of the proteins

and increase in the fluorescence.

In diabetes, where blood glucose level is significantly higher than normal,

the reaction of glucose with several proteins such as haemoglobin, lens crystallin

and collagen, gives rise to the formation of AGE, which in turn, is responsible for

the complications associated with diabetes, such as nephropathy,

microangiopathy, endothelial dysfunction and other organ dysfunctions. In

addition, the activity of several growth factors, such as basic fibroblast growth

factor, is also impaired. AGE products, unlike normal proteins in tissue, have a

slower rate of turnover and replenishment. It has been reported that AGE

products may in fact elicit a complex immunological reaction involving RAGE

(Receptor for Advanced Glycation End Products) receptors and activation of

several incompletely defined immunological processes. It has been documented

that diabetes with evidence of microangiopathy and macroangiopathy also show

evidence of oxidative stress, the mechanism of which has not been elucidated.

In vitro AGE formation can be studied in the laboratory by incubating

reducing sugars, such as ribose or glucose with bovine serum albumin. AGE

formation can be detected by increase in the fluorescence or increased cross reactivity with anti-AGE antibodies. The increase in fluorescence seems to

precede formation of AGE specific antigenic epitopes. This increase in

fluorescence is used to monitor the increased AGE formation in vitro (Brownlee

M et al, Science 1986; 232:1629-1632). In addition to the increase in the

fluorescence, one of the most important features of in vitro AGE formation is the

formation of antigenic epitopes that are specific to AGE and not to the native

proteins. Therefore, it is possible to raise antibodies against advanced glycation

end products of one protein and use them to detect AGE formation in other

proteins. This has served as an important analytical tool in AGE research.

Due to the clinical significance of AGE formation, many approaches are

being used to diagnose, prevent, or revert AGE formation in the body. The

formation of AGE could be inhibited by reacting with an early glycosylation

product that results from the original reaction between the target protein and

glucose. The inhibition was believed to take place as the reaction between the

inhibitor and the early glycosylation product appeared to interrupt the subsequent

reaction of the glycosylated protein with additional protein material to form the

cross linked late stage product. Compounds like aminoguanidine act to inhibit

AGE formation by such mechanism.

The formation of AGE on long-lived proteins is also associated with cross-

linking of these proteins. The AGE derived protein cross-links have been shown to be cleaved by compounds like N- phenacyl thiazoUum bromide (PTB), which

reacts with and cleaves covalent, AGE derived protein cross links (Vasan et al.

Nature 1996; 382: 275-278; US 5,853,703, Date of Patent : Dec. 29, 1998). The

mechanism of reducing the AGE content in tissues is expected to take place

relatively rapidly, in contrast to aminoguanidine, which acts slowly by its very

nature of mechanism of action. This current specification is related to compounds

of pyridinium class, which break pre-formed AGE, like PTB, and in some cases

even more effectively than PTB.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a class of

compounds of the pyridinium series which are useful for the management of

diabetes and aging-related vascular complications, and particularly in the

treatment of complications of diabetes mellitus and other aging-related conditions

including kidney disease, nerve damage, atherosclerosis, retinopathy and

dermatological conditions. The invention also extends the method to reverse the

discoloration of teeth resulting from nonenzymatic browning in the oral cavity

which comprises administration of an amount effective to reverse the pre-formed

advanced glycosylation crosslinks etc.

Another object of the present invention is to provide compounds of the

pyridinium series, which exhibit AGE breaking activities. Yet another object of the present invention is to provide a method of

preparation of compounds of the pyridinium series which exhibit AGE breaking

activities.

Still another object of the invention is to provide pharmaceutical

compositions with a new class of compounds of the pyridinium series according

to the invention and their pharmaceutically acceptable salts in combination with

suitable carriers, solvents, excepients, diluents and other media normally

employed in preparing such compositions.

Still another object of the invention is to provide a method of treatment of a

diabetic patient by administration of the compounds of the invention, either singly

or in combination with drugs for anti-diabetic therapy, or pharmaceutically

acceptable salts thereof in required dosage in admixture with pharmaceutically

acceptable diluent, solvent, excepients, carriers or other media as may be

appropriate for the purpose.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a new class of AGE breakers, of general

formula I,

( I ) wherein

R¹ is -Y-R³

Y is selected from oxygen or NH.

R³ is selected from hydrogen, alkyl, aryl

R² is selected from group consisting of alkyl, -Oalkyl, aryl, -Oaryl, -NHalkyl and

-NHaryl

X is selected from group consisting of a halide ion, acetate ion, perchlorate ion,

sulfonate ion, oxalate ion, citrate ion, tosylate ion, maleate ion, mesylate ion,

carbonate ion, sulfite ion, phosphoric hydrogen ion, phosphonate ion, phosphate

with proviso that,

(a) when R¹ is phenyl, then R² is also phenyl, and

(b) when R² is phenyl and X is halide ion, then R¹ is other than -OCH₃.

As used herein "alkyl" refers to an optionally substituted, saturated

hydrocarbon group joined by single carbon-carbon bonds and having 1-4 carbon atoms joined together. The saturated alkyl hydrocarbon group may be linear or

branched. The substituent is -OH.

As used herein "aryl" refers to an optionally substituted aromatic group

with atleast one ring having a conjugated pi- electron system, containing upto two

conjugated or fused ring systems. Aryl includes carbocyclic aryl and heterocyclic

aryl all of which may be optionally substituted with halogen, sulfonamido, thio,

amino, cyano, -Oalkyl, -NHalkyl, hydroxy, formyl, -Oaryl and -NHaryl.

The representative compounds of general formula I which are novel are

listed in Table IA. These compounds with the following chemical names are

suggested by way of example alone and in no way restrict the invention.

3-Carbonylamino-l-(2-(2,4-dichlorophenyl)-2-oxoethyl)) pyridinium bromide

(compound 1 ).

3 -(Tetrahy drobenzotMazol-2-yl)aminocarbonyl- 1 -(2-(2 ,4-dichlorophenyl)-2-

oxoethyl)pyridinium bromide (compound 2 ).

l-(2-Phenyl-2-oxoethyl)-3-((2-hydroxyethyl)aminocarbonyl) pyridinium bromide

(compound 3).

3-Carbonylammo-l-(2-tlnen-2'-yl-2-oxoethyl)pyridimum bromide(compound 4 ).

1 -(2-Phenyl-2-oxoethyl)-3-((p-sulfonanndophenylene)aminocarbonyl) pyridinium

bromide (compound 5 ). l-(2-Ethoxy-2-oxoethyl)-3-((2-hydroxye yl)ammocarbonyl)pyridinium bromide.

(compound 6 ).

l-(2-Phenyl -2- oxoethyl) -3 -(isopropyloxy carbonyl) pyridinium bromide

(compound 7).

l-(2-Methyl-2-oxoethyl)-3-((2-hy(koxyethyl)aminocarbonyl) pyridinium chloride

(compound 8).

l-(2-Thien-2'-yl-2-oxoethyl)-3-((2-hydroxyethyl)an_imocarbonyl)pyridinium

bromide (compound 9 ).

l-(2-(2,4 - Dichlorophenyl-2-oxoethyl) -3- (isopropyloxycarbonyl) pyridinium

bromide (compound 10 ).

1- (2-Phenyl - 2- oxoethyl) - 3- ((4-methylthiazol - 2 -yl) aminocarbonyl)

pyridinium bromide (compound 11 ).

1 -(2-Phenylammo-2-oxoethyl)-3-(n-butyloxycarrx)nyl)pyridinium chloride

(compound 12 ).

l-(2- Phenylamino - 2- oxoethyl ) - 3 - (n-butylaminocarbonyl ) pyridinium

chloride (compound 13 ).

1- (2- Phenylamino - 2- oxoethyl )- 3- ((2-hydroxyethyl)aminocarbonyl)

pyridinium chloride (compound 14 ). 1- (2- (2,4 - Dichlorophenyl ) - 2-oxoethyl) - 3- (n - butoxycarbonyl) pyridinium

bromide (compound 15 ).

l-(2 - (2, 4 - Dichlorophenyl) - 2-oxoethyl) - 3- (n-butylamino-carbonyl )

pyridinium bromide (compound 16 ).

Further, some known pyridine derivatives have also been studied for their AGE

breaking activity, which was not known earher for these molecules, and are as

listed in Table LB, with their chemical names as given below:

1- (2-Phenyl-2-oxoethyl) -3- (1 -phenyl- 1-oxomethyl) pyridinium bromide

(compound 17 : (Ref: Chemical Abstracts: 91, P47378Y, (1979))

1- (2 Phenyl - 2-oxoethyl ) - 3- (methoxycarbonyl ) pyridinium bromide

(compound 18 : (Ref: Chemical Abstracts: 91, P47378Y, (1979))

Table IB - Pyridinium Derivatives (Known)

According to one embodiment of the present invention, the present

compounds are used for the treatment of diabetic complications, aging-related

complications including kidney disease, nerve damage, atherosclerosis,

retinopathy, dermatological conditions and colouration of teeth occurring due to

the higher levels of preformed AGE. The increased levels of preformed AGE can

be brought under control by breaking the AGE products using compounds

mentioned in the invention.

The invention also provides a process for the preparation of compounds of

the pyridinium series.

The said process for the preparation of compound 1, comprises, adding a

solution of 2,4- dichlorophenacyl bromide in toluene to nicotinamide dissolved in

refluxing toluene, refluxing for seven and half hours, cooling, filtering the

precipitated solid, dissolving in methanol, treating with activated charcoal, concentrating under vacuum, cooling in ice-salt mixture, filtering the precipitated

sohd and washing with methanol to obtain the desired compound.

Similarly, the other compounds of general formula I, are prepared from

properly substituted pyridine derivatives followed by quarternization with

appropriate reagent by refluxing in alcoholic solvents like methanol, ethanol,

propanol, etc., and high boiling solvents like, toluene or xylene for 6 - 48 hrs. to

give the desired compounds.

The in vitro AGE formation, studied in the laboratory, by incubating

reducing sugar ribose, with protein bovine serum albumin, resulted in browning of

solution and increase in the fluorescence. Fluorescence was used as the criteria to

monitor the increased AGE formation.

Example 1

AGE breaker activity has been confirmed by the screening procedure as

mentioned below;

Materials:

Bovine serum albumin (fraction V) (BSA)

Ribose, analytical grade

Phosphate buffered saline (PBS)

Equipment:

Microplate ELISA Reader - Spectramax Plus (Molecular Devices, USA) Microplate washer, (Bio -Tec Instruments, USA)

pH meter

Methods of experiment:

160 mginl of protein, bovine serum albumin, BSA and 1.6M glucose sugar

were dissolved in phosphate buffered saline, PBS. Sodium azide was added at

0.02% concentration as a preservative. The solution was filtered asceptically

through a 0.22 μM filter and kept for aging at 37°C for 16 weeks. After 16 weeks

the solution was dialyzed against PBS, aliquoted and stored at -20°C.

To determine the AGE breaking activity, lOμg/ml and lOOμg/ml of the 16

weeks AGE-BSA was incubated with different concentrations of die test

compounds at 37°C for 24 hours and AGE breaking activity of the test

compounds by ELISA was determined.

ELISA was performed as follows:

1. Different concentrations of 16 weeks AGE-BSA were coated on a microtitre

plate as standard. Each concentration is coated in triplicates.

2. The test samples were coated on microtitre plate at a concentration of 5 ng. to

20 ng per well in triplicates.

3. The plate was incubated at 37°C for one hour.

4. After incubation the plate was washed with PBST (PBS with 0.05% Tween

20). 5. Blocking with 5% skimmed milk in PBS at 37°C for one hour was done.

6. The plate was washed with PBST.

7. Primary antibody against AGE-BSA was added and the plate is incubated at

37°C for one hour.

8. The plate was washed with PBST

9. Secondary antibody anti rabbit HRPO (Horse-Radish Per Oxidase) conjugate

was added and the plate is incubated at 37°C for one hour.

10. The plate was washed with PBST.

11. Colour development with OPD (orthophenylenediamine dihydrochloride) and

hydrogen peroxide was done.

12. OD (optical density) at (450nm reading - 620nm reading) was measured after

incubation at 37 °C for 15 minutes with Microplate ELISA Reader.

The breaker activity of the compounds were determined by the following

formula:

% Breaker activity = OD ₅o-₆₂oControl - OD₄₅o-_ό2oTest

x 100

OD 450-620 Control

OD₄₅o^₂oControl=Absorbance of 20ng AGE-BSA after incubation at 37°C for 24

hours without test compound OD₄₅o-₆₂oTest=Absorbance of 20ng AGE-BSA after incubation at 37°C for 24

hours with required concentration of test compound

Using specific examples, the % AGE breaking activity was calculated and

recorded in Table 2.

Table 2

Hence, for example, compound 12 has significant AGE - breaking activity i.e. a

comparatively much superior potency vis - a - vis PTB.

The following examples give method for preparation of the specific

compounds of the invention as given in Table 1. The following compounds

suggested are by way of example alone and in no way restrict the invention,

Example 2

Preparation of 3- carbonylamino -1- (2- (2,4-dichlorophenyl) -2- oxoethyl)

pyridinium bromide (compound 1)

Nicotinamide (1.22g, 0.01 mol) was dissolved in refluxing toluene (40 ml)

and a solution of 2,4-dichlorophenacyl bromide (3.0g, 0.012mol) in 10ml of

toluene was added. The reaction mixture was refluxed for 7.5 hours and cooled.

The precipitated sohd was filtered and dissolved in methanol, decolourized with

activated charcoal and concentrated under vacuum to one-fourth volume. It was

cooled in ice - salt mixture and the precipitated sohd was filtered and washed

with methanol (3x10ml) to afford a pure sohd.

Yield : 39%

m.p. : 237-239°C

IRKB^cm-¹) : 3331, 3133, 1706, 1678

*H NMR (DMSOdό, 400 MHz) δ : 9.54(lH,s), 9.18-9.1l(2H,m), 8.67(lH,s),

8.40(lH,t), 8.42-8.38(2H,m), 7.88(lH,s), 7.75 -7.72(lH,m), 6.49(2H,s) Mass (m/z): 309,310,311,312,187,159

According to the above mentioned procedure the following compounds are

synthesized by reacting the corresponding pyridine derivatives with appropriate

reagents by refluxing in alcoholic solvents like methanol, ethanol, propanol, etc.

and high boiling solvents like toluene or xylene for 6-48 hours to give the desired

compounds:

Example 3

3-(Tetrahvdrobenzothiazol-2-yl)aminocarbonyl)-l-(2-(2_<4-dichlorophepyl)-2-

oxoethyl) pyridinium bromide (compound 2):

Yield : 48%

m.p. : 165 - 167 °C(decomp.)

IR(KBr,cιn *) : 3333, 1714, 1684, 1635

Η NMR(CD₃OD, 400MHz) δ: 9.45(lH,s), 9.27-9.24(lH,m), 8.92-8.91(lH, m),

8.24 - 8.21(1H, m), 8.01 - 7.99(1H, m), 7.72 - 7.71(1H, m) 7.57-7.54(lH,m),

2.59-2.57 (4H,m), 1.85(4H,m)

Mass (m/z) : 446, 447, 448, 449, 416, 307 and 266

Example 4

l-(2- Phenyl -2- oxoethyl) -3- ((2- hydroxyethyl) aminocarbonyl) pyridinium

bromide (compound 3):

Yield : 98% m.p. : 182 - 184°C(decomp.)

IR(KBr,cιn *) : 3289, 3241, 1690 and 1660

*H NMR(DMSOd6, 400MHz) δ: 9.47(lH,s), 9.21(lH,t), 9.09(2H,t), 8.41-

8.37(lH,m), 8.08-8.04(2H,m), 7.82-7.78(lH,m), 7.69-7.65(2H,m), 6.52(2H,s),

4.86(lH,t), 3.58-3.54(2H,m), 3.42-3.38(2H,m)

Mass (m/z) : 285,242,149,119,91

Example 5

3-Carbonylamino-l- (2-thien-2'-yl-2-oxoethyl) pyridinium bromide

(compound 4 ).

Yield : 35%

m.p. : 212 - 215°C (decomp.)

IRKB^cm-¹) : 3295, 3126, 1680, 1671, 1640

ΗNMR (DMSOde, 400 MHz) δ: 9.49(lH,s), 9.13-9.1l(lH,d), 9.07-9.05(lH,d),

8.60(lH,bs), 8.40-8.38(lH,m), 8.25-8.19(3H,m),7.43-7.40,(lH,t), 6.44(2H,s)

Mass(m/z) : 247,248,249,193

Example 6

1- (2-Phenyl -2- oxoethyl) -3- ((p-sulfonamidophenylene) aminocarbonyl)

pyridinium bromide (compound 5):

Yield : 44%

m.p. : 188-190°C IR(KBr,cιn *) : 3296, 1700, 1679.

^!H NMR (DMSOde, 400MHz) δ: 11.25 (lH,s), 9.58 (lH,s), 925 (lH,d), 9.16

(IH, d), 8.45 (lH,t), 8.10 (2H,d), 7.94 (2H,d), 7.86 (2H,d), 7.82(lH,t),

7.68(2H,t), 7.36(2H,s), 6.5(2H,s)

Mass (m/z) : 396, 277

Example 7

1- (2- Ethoxy -2- oxoethyl) -3- ((2- hydroxyethyl) aminocarbonyl) pyridinium

bromide (compound 6):

Yield : 87%

m.p. : 138-140°C

IR(KBr, cm^"1) : 1748,1669

*H NMR (CD₃OD₇ 400 MHz) δ: 9.43 (lH,s), 9.09-9.02 (2H,m), 8.26 (lH,m),

5.64 (2H,s), 4.31 (2H,q), 3.73 (2H,t), 3.54 (2H,t), 1.32 (3H,t)

Mass (m/z) : 251, 252, 165, 166

Example 8

1- (2- Phenyl -2- oxoethyl) -3- (isopropyloxycarbonyl) pyridinium bromide

(compound 7):

Yield : 46%

m.p. : 172-174°C

IR(KBr, cm^"1) . 1726, 1692 ^]H NMR (DMSOds, 400MHz) δ: 9.55 (lH,s), 9.16 (lH,d), 9.08(lH,d), 8.39-8.36

(lH,m), 8.04 (2H,d), 7.77 (lH,t), 7.64 (2H,t), 6.53 (2H,s), 5.25-5.19 (lH,m),

1.34 (6H,d)

Mass (m/z) : 284, 285, 242

Example 9

1- (2- Methyl-2-oxoethyl) -3- ((2- hydroxyethyl) aminocarbonyl) pyridinium

chloride (compound 8);

Yield : 47%

m.p. : 178-180°C

IR(KBr, cm^"1) : 1727, 1660

Η NMR (DMSOdfi, 400 MHz) δ: 9.33 (lH,t), 9.30 (lH,s), 9.06(lH,d), 8.90

(lH,d), 8.25-8.21 (lH,m), 5.75 (2H,s), 4.84(lH,bs), 3.47 (2H,t), 3.30 (2H,t), 2.23

(3H,s)

Mass (m/z) : 223, 224, 225

Example 10

1- (2- Thien -2'-yl -2- oxoethyl) -3- ((2- hydroxyethyl) aminocarbonyl)

pyridinium bromide (compound 9):

Yield : 60%

m.p. : 207-209°C

IR(KBr, cm^"1) : 1673, 1656 Η NMR (DMSOdβ, 400MHz) δ: 9.47 (lH,s), 9.18-9.05 (3H,m),8.38-8.34

(lH,m), 8.23-8.19 (2H,m), 7.39 (lH,t), 6.44 (2H,s),3.55-3.50 (2H,m), 3.40-3.37

(2H,m)

Mass (m/z) : 291, 292, 293

Example 11

1- (2- (2,4- Dichlorophenyl) -2- oxoethyl) -3- (isopropyloxycarbonyl)

pyridinium bromide (compound 10):

Yield : 26%

m.p. : 160-162°C

IR (KBr, cm^"1) : 1726, 1705

Η NMR (DMSOds, 400 MHz) δ: 9.55 (lH,s), 9.15 (lH,d), 9.08(lH,d), 8.40-

8.36 (lH,m), 8.11 (lH,d), 7.89 (lH,bs), 7.75-7.72 (lH,m), 6.44 (2H,s), 5.26-5.20

(lH,m), 1.34 (6H,d).

Mass (m/z) : 352, 353, 354, 310

Example 12

1- (2- Phenyl -2- oxoethyl) -3- ((4- methylthiazol -2- yl) aminocarbonyl)

pyridinium bromide (compound 11):

Yield : 30%

m.p. : 165-167°C IR (KBr, cm^'1) : 3409, 3319 and 1698

*H NMR (DMSOd, 400 MHz) δ: 9.58 (lH,s), 9.22 (lH,d), 9.11(lH,d), 8.42-

8.38 (lH,m), 8.07 (2H,d), 7.81 (lH,t), 7.68(2H,t), 6.86 (lH,bs), 6.56 (2H,s), 2.30

(3H,s)

Mass (m/z) : 337, 338, 232, 105.

Example 13

1- (2- Phenylamino -2- oxoethyl) -3- (n- butoxycarbonyl) pyridinium chloride

(compound 12):

Yield : 10%

m.p. : 150-152°C

IR (KBr, cm^'1) : 3228, 1742, 1678 (bs)

*H NMR (DMSOde, 400 MHz) δ: 10.96 (lH,s), 9.65 (lH,s), 9.28(lH,t), 9.09

(lH,d), 8.37 - 8.34 (lH,m), 7.62 - 7.59 (2H,m),7.37 - 7.33 (2H,m), 7.11 (lH,t),

5.79 (2H,s), 4.41(2H,t), 1.76-1.72(2H,m), 1.48-1.43 (2H,m), 0.94 (3H,t)

Mass (m/z) : 314, 315

Example 14

1- (2- Phenylamino -2- oxoethyl) -3- (n- butylaminocarbonyl) pyridinium

chloride (compound 13):

Yield : 37%

m.p. : 182-185°C IR (KBr, cm^"1) : 3245, 1742, 1679

*H NMR (DMSOde, 400MHz) δ: 10.97 (lH,s), 9.50(lH,s), 9.24(lH,t), 9.13

(lH,d), 9.02 (Hid), 8.28-8.25 (Htm), 7.57 (2H,d), 7.30(2H,t), 7.05 (lH,t), 5.70

(2H,s), 3.30 - 3.26 (2H,m), 1.52 - 1.48 (2H,m), 1.34 - 1.30 (2H,m), 0.86 (3H,t)

Mass (m/z) : 312, 313

Example 15

1- (2- Phenylamino -2- oxoethyl) -3- ((2- hydroxyethyl) aminocarbonyl)

pyridinium chloride (compound 14):

Yield : 58%

m.p. : 225-227°C

IR (KBr, cm^"1) : 3448, 3271, 1702 and 1663

Η NMR (DMSOd6,400 MHz) δ: 11.07 (lH,s), 9.58 (lH,s) 9.35(lH,t), 9.17

(lH,d), 9.11 (lH,d), 8.33-8.29 (lH,m), 7.60(2H,d), 7.32 (2H,t), 7.08 (lH,t), 5.75

(2H,s), 4.90 (lH,t), 3.57-3.53 (2H,m), 3.40-3.36 (2H,m)

Mass (m/z) . 300, 301, 302

Example 16

1- (2- (2.4- Dichlorophenyl) -2- oxoethyl) -3- (n- butoxycarbonyl) pyridinium

bromide (compound 15):

Yield : 38%

m.p. : 154-156°C IR(KBr, cm⁴) : 3435, 3389, 1731 and 1704

*H NMR (DMSOde, 400 MHz) δ: 9.60 (lH,s), 9.21 (lH,d), 9.14(lH,d), 8.43

(lH,t), 8.16 (lH,d), 7.92 (lH,s), 7.78-7.76(lH,m), 6.51 (2H,s), 4.42 (2H,t), 1.76-

1.72 (2H,m), 1.48-1.42 (2H,m), 0.94 (3H,t)

Mass (m/z) : 366, 367, 368, 369, 370

Example 17

1- (2- (2,4- Dichlorophenyl) -2- oxoethyl) -3- (n-butylaminocarbonyl)

pyridinium bromide (compound 16):

Yield : 35%

m.p. : 142-144°C

IR(KBr, cm^"1) : 3382, 1698, 1672

Η NMR (DMSOde, 400 MHz) δ: 9.37 (lH,s), 9.07 (lH,t), 8.99(2H,t), 8.31-8.28

(lH,m), 8.04 (lH,d) 7.82-7.81 (lH,d), 7.68-7.65 (lH,m), 6.34(2H,s), 3.27-3.24

(2H,m), 1.47-1.43 (2H,m), 1.29- 1.24 (2H,m), 0.81 (3H,t)

Mass (m/z) : 365, 366, 367, 368, 369

Pharmaceutical Compositions

Pharmaceutical compositions may be prepared with a pharmaceutically

effective quantity of compounds of general formula I, individually or in

combination. The following pharmaceutical formulations suggested are by way of

example alone and in no way restrict the forms in which they can be used. Oral formulations

Oral formulations may be administered as solid dosage forms for example

pellets, powders, sachets or discreet units such as tablets or capsules and like.

Other orally aάministered pharmaceutical preparations include monophasic and

biphasic liquid dosage forms either in ready to use form or forms suitable for

reconstitution such as mixtures, syrups, suspensions or emulsions. The

preparations in addition may contain diluents, dispersing agents, buffers,

stabilizers, solubilizers, surfactants, preservatives, chelating agents and/ or other

pharmaceutical additives as are used. Aqueous or non-aqueous vehicle or their

combination may be used and if desired may contain suitable sweetener, flavoring

agent or similar substances. In case of suspension or emulsion a suitable

thickening agent or suspending agent or emulsifying agent may be present in

addition. Alternatively, the compounds may be administered as such in their pure

form unassociated with other additives for example as capsules or sachets. It may

also be administered with a vehicle. Pharmaceutical preparations can have a slow,

delayed or controlled release of active ingredients as is provided by a matrix or

diffusion controlled system.

When the present invention or its salts or suitable complexes is presented

as a discreet unit dosage form like a tablet, it may contain in addition medically

inert excipients as are used in the art. Diluents such as starch, lactose, dicalcium phosphate, talc, magnesium stearate, polymeric substances like methyl cellulose,

fatty acids and derivatives, sodium starch glycollate, etc. may also be used.

Example 18

Preparation of oral dosage form:

A typical tablet has the following composition:

Active ingredient of formula I as given above

Lactose 135 mg

Starch 76 mg

Polyvinyl pyrolidone (K-30) 2 mg

Talc 1.5 mg

Magnesium Stearate 1.0 mg

Parenteral Formulations

For parenteral administration, the compounds or their salts or suitable

complexes thereof may be present in a sterile vehicle which may be an aqueous

or non aqueous vehicle or a combination thereof. The examples of vehicles are

water, ethyl oleate, oils and derivatives of polyols, glycols and their derivatives. It

may contain additives common in injectable preparations like stabilizers,

solubilizers, pH modifiers, buffers, antioxidants, cosolvents, complexing agents,

tonicity modifiers, etc. Some suitable additives are for example tartrate, citrate or similar buffers,

alcohol, sodium chloride, dextrose and high molecular weight polymers. Another

alternative is sterile powder reconstitution. The compound may be administered

in the form of injection for more than once daily administration, or intravenous

infusion/ drip or suitable depot preparation.

Example 19

Preparation suitable for parenteral administration has the following

composition:

Active ingredient of formula I as given above

Polyethylene glycol (400) 0.75 ml

Sodium metabisulphite 0.01%

Isotonic saline/ WFI q.s.

Other Formulations.

For the dermatological application and for the discoloration of teeth, the

recommended formulations are lotions, oral rinse and toothpaste containing

appropriate amount of the compounds of general formula I.

The above examples are presented by way of illustration alone and in no

way limit the scope of the invention.

Claims

I CLAIM :

1. A compound of pyridinium series of general formula I and its

pharmaceutically acceptable salts, useful for the management of vascular

complications associated with diabetes and aging-related disorders,

O

( I )

wherein

R¹ is -Y-R³

Y is selected from oxygen or NH.

R³ is selected from hydrogen, alkyl, aryl

-NHaryl

X is selected from group consisting of a hahde ion, acetate ion, perchlorate ion, sulfonate ion, oxalate ion, citrate ion, tosylate ion, maleate ion, mesylate ion,

carbonate ion, sulfite ion, phosphoric hydrogen ion, phosphonate ion, phosphate

ion, BF₄ ^", PF₆ ^",

with proviso that,

(a) when R¹ is phenyl then R² is also phenyl, and

(b) when R² is phenyl and X is a hahde ion, R¹ is other than -OCH₃.

2. The compound as claimed in claim 1, wherein X is a halide ion.

3. The compound as claimed in claim 1, which is selected from the group

consisting of the following compounds :

a) l-(2-phenylamino-2-oxoethyl)-3-(n-butyloxycarbonyl) pyridinium chloride or

a pharmaceutically acceptable salt thereof.

b) l-(2-thien-2'-yl-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

c) l-(2-ethoxy-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl) pyridinium

bromide or a pharmaceutically acceptable salt thereof.

d) l-(2-phenylamino-2-oxoethyl)-3-(n-butylaminocarbonyl) pyridinium chloride

or a pharmaceutically acceptable salt thereof.

e)l -(2-phenylaπ__ino-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl)pyridinium

chloride or a pharmaceutically acceptable salt thereof,

f) l-(2-phenyl-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl)pyridinium bromide or a pharmaceutically acceptable salt thereof.

g) l-(2-methyl-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

h) l-(2-phenyl-2-oxoethyl)-3-((4-methylthiazol-2-yl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

i) l-(2-(2,4-mcMorophenyl-2-oxoethyl)-3-(isopropyloxycarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

j) 3-(tetiahyαι-obenzotlιiazol-2-yl)aminocarbonyl)-l-(2-(2,4-dichlorophenyl)-2-

oxoethyl)pyridinium bromide or a pharmaceutically acceptable salt thereof.

k) 1 -(2-phenyl-2-oxoethyl)-3-((p-suffonamidophenylene)aminocarbonyl))

pyridinium bromide or a pharmaceutically acceptable salt thereof.

l)3-carbonylarrιmo-l-(2-1hien-2'-yl-2-oxoethyl)pyridinium bromide or a

pharmaceutically acceptable salt thereof.

m) 1 -(2-(2,4-dicUorophenyl)-2-oxoethyl)-3-(n-burylaminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

n) l-(2-(2,4-dichlorophenyl)-2-oxoethyl)-3-(n-butoxycarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

4. A process for the preparation of compounds of the pyridinium series as

claimed in claim 1, wherein said process comprises preparation of the properly

substituted pyridine derivatives according to the desired end products followed by quaternization of the substituted pyridine derivatives with appropriate reagent

by refluxing in alcoholic solvents and/or high boiling solvents for 6 to 48 hrs. to

give the desired compounds.

5. The use of a compound of general formula I as defined in claim 1 , in the

manufacture of a medicament for diabetic complications and aging-related

diseases, including kidney disease, nerve damage, retinopathy, atherosclerosis,

microangiopathy, endothelial dysfunctions, dermatological conditions,

discoloration of teeth and other organ dysfunctions.

6. The use as claimed in claim 5, wherein said compound is selected from the

group consisting of :

a) l-(2-phenylamino-2-oxoethyl)-3-(n-butyloxycarbonyl) pyridinium chloride or

a pharmaceutically acceptable salt thereof.

b) l-(2-thien-2'-yl-2-oxoethyl)-3-((2-hydroxyethyl) am ocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

c) 1 -(2-ethoxy-2-oxoethyl)-3 -((2-hydroxyethyl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

d) l-(2-phenylamino-2-oxoethyl)-3-(n-butylaminocarbonyl) pyridinium chloride

or a pharmaceutically acceptable salt thereof.

e) l-(2-phenylammo-2-oxoethyl)-3-((2-hydroxyethyl)aminocarbonyl) pyridinium

chloride or a pharmaceutically acceptable salt thereof. f) l-(2-phenyl-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

g) l-(2-methyl-2-oxoethyl)-3-((2-hydroxyethyl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

h) 1 -(2-ρhenyl-2-oxoethyl)-3 -((4-methylthiazol-2-yl) aminocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

i) l-(2-(2,4-dichlorophenyl-2-oxoethyl)-3-(isopropyloxycarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

j) 3-(tefrahyαi"obenzot azol-2-yl)aminocarbonyl-l-(2-(2,4-dichlorophenyl)-2-

oxoethyl)pyridinium bromide or a pharmaceutically acceptable salt thereof.

k) 1 -(2-phenyl-2-oxoethyl)-3-((p-suffonanndophenylene)aminocarbonyl)

pyridinium bromide or a pharmaceutically acceptable salt thereof.

1) 3-carbonylamino-l-(2-tWen-2'-yl-2-oxoethyl)pyridinium bromide or a

pharmaceutically acceptable salt thereof.

m) l-(2-(2,4-ώcUorophenyl)-2-oxoethyl)-3-(n-butylammocarbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

n) l-(2-(2,4-dichlorophenyl)-2-oxoethyl)-3-(n-butoxy carbonyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof.

7. The use of 1 -(2-phenyl-2-oxoethyl)-3 -( 1 -phenyl- 1 -oxomethyl)pyridinium

bromide or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for diabetic complications and ageing related diseases including

kidney disease, nerve damage, retinopathy, atherosclerosis, microangiopathy,

endothelial dysfunctions, dermatological conditions, discoloration of teeth and

other organ dysfunctions.

8. The use of l-(2-phenyl-2-oxoethyl)-3-(methoxycarbonyl) pyridinium bromide

or a pharmaceutically acceptable salt thereof in the manufacture of a medicament

for diabetic complications and ageing related diseases including kidney disease,

nerve damage, retinopathy, atherosclerosis, microangiopathy, endothelial

dysfunctions, dermatological conditions, discoloration of teeth and other

organ dysfunctions.

9. A pharmaceutical composition for treatment of diabetic complications and

aging related diseases which comprises a pharmaceutically effective amount of

one or more compounds of general formula I ,as defined in claim 1, or

pharmaceutically acceptable salt(s) thereof, in admixture with a pharmaceutically

acceptable carrier, diluent, solvent or excepient.

10. The pharmaceutical composition as claimed in claim 9, in the form of an oral

formulation.

11. The pharmaceutical composition as claimed in claim 10, wherein the said pharmaceutically acceptable carrier is selected from one or more of the

compounds starch, lactose, polyvinylpyrolidone (K-30), talc and magnesium

stearate.

12. The pharmaceutical composition as claimed in claim 9, in the form of

parenteral formulation.

13. A method for the preparation of a parenteral formulation as claimed in claim

12, which comprises dissolving the active ingredient of general formula I, as

defined in claim 1, in polyethylene glycol 400 and diluting the solution so

obtained, with an isotonic solution or water to the desired concentration.

14. The pharmaceutical composition as claimed in claim 9, in the form of

lotions, oral rinse and toothpaste.

15. A method for treating a diabetic patient by breaking the preformed AGE

within said patient, which comprises administering an effective amount of a

compound as claimed in claim 1 , either singly or in combination with other drugs

for antidiabetic therapy.

16. A method for treating a diabetic patient by breaking the preformed AGE

within said patient which comprises, administering an effective amount of l-(2-

phenyl-2-oxoethyl)-3-(l -phenyl- l-oxomethyl)pyridinium bromide or a

pharmaceutically acceptable salt thereof, either singly or in combination with

other drugs for antidiabetic therapy.

17. A method for treating a diabetic patient by breaking the preformed AGE,

within said patient, which comprises, achninistering an effective amount of l-(2-

phenyl-2-oxoethyl)-3-(methoxycarbonyl)pyridinium bromide or a

pharmaceutically acceptable salt thereof ,either singly or in combination with

other drugs for antidiabetic therapy.

18. A method of preventing or treating diseases caused by diabetes and aging-

related complications, which comprises, administering to a patient in need

thereof ,an effective amount of a compound of formula I, as claimed in claim 1,

either singly or in combination with a pharmaceutically acceptable carrier, diluent

or excepient.

19. The method as claimed in claim 18, wherein the disease caused to be

prevented or treated is a nephrological disorder, neurological disorder,

atherosclerosis, retinal disorder, dermatological disorder, non-enzymatic

browning of oral cavity, endothelial or other organ dysfunction and growth

impairment.