Synthesis and Evaluation of Some New Substituted 1, 4-Dihydropyridine Derivatives and Their Anti-inflammatory Activity

SR Pattan*¹, NS Dighe¹, SV Hiremath², AN Merekar³, VM Gaware¹, DS Musmade¹ and PM Gaikwad⁴

¹Dept of Pharmaceutical Chemistry, Pravara Rural College of Pharmacy, Pravaranagar, Loni 413713, India

²Dept of Pharmacology J.N Medical College Belgaum, India

³Dept of Pharmaceutics, Pravara Rural College of Pharmacy,    Pravaranagar, Loni 413713, India

⁴Dept of Pharmacology, Pd. Dr. Vitthalrao Vikhe Patil College of Pharmacy, Ahmednagar,  India

*Corresponding Author E-mail: shashipattan@yahoo.com

ABSTRACT A new series if substituted 1, 4-Dihydropyridine derivatives were synthesized and the structures of these compounds were established on the basis of spectral and elemental analysis. All the compounds were evaluated for anti-inflammatory activity by paw edema, xylene induced ear edema and cotton wool granuloma methods. Compounds C₄, C₅, C₆, C₇ and C₉ have been found to exhibit excellent anti-inflammatory activity.

KEYWORDS: 1, 4-Dihydropyridine, anti-inflammatory, CHN analysis

INTRODUCTION:

The term inflammation is derived from Latin “Inflammare” meaning to burn.An ideal anti-inflammatory drug should not interfere with the normal inflammatory response. 1, 4-dihydropyridines exhibit wide range of pharmacological activities like anti tubercular anti-inflammatory, antibacterial and antifungal. These observations promoted us to synthesis the title compounds with presumption that incorporation of using diketones, substituted aldheydes and aromatic amines with thiazole nuclei would produce new compounds with significant anti-inflammatory activity.

MATERIALS AND METHODS:

Anti-Inflammatory Evaluation:

The activity was conducted by paw edema, xylene induced ear edema and cotton wool granuloma methods. The animals were divided into different groups of six animals each one group served as control, another as a standard (Aspirin) 100mg/kg body and rest of the groups were used for the test drugs.

EXPERIMENTAL

All melting points were determined in open capillary method and are uncorrected. IR spectra were recorded on Thermo Nicolet IR 200 spectrophotometer using KBr disc method.

The 1H- NMR spectra were recorded on sophisticated multinuclear FT-NMR. Spectrometer model Avance- Ii (Bruker) using DMSO as solvent and TMS as internal standard. Perkin Elmer 2400 CHN Elemental Analyzer was used to determine the percentages of C, H, and N..

Synthesis of N-substituted Aryl Aectoacetmide.

An equimolar amount of ethylacetoacetate and aryl amine were taken in round bottom flask and dissolved in alcohol and refluxed for 2-3 hrs. The reaction mixtures was cooled, solid separated was filtered, washed with cold water and dried. The crude solid of anilide was purified by recrystallization form ethanol to get a colorless product.

Synthesis of 1, 4-Dihydropyridine

An exact quantity of 0.1 mole of N- aryl substituted acetoacetamide was dissolved in methanol and 0.1 mole of substituted aldehyde was added followed by addition of excess of ammonia (25%). The reaction was stirred for 10 min and then heated on water bath under reflux for 10-12 hr. Methanol was removed under pressure and cooled. The product separated was filtered and washed with methanol. It was recrystallized from methanol to get yellow crystalline prodouct.

Synthesis of 1, 4-Dihydro-2, 6-dimethyl pyridine.

A mixture of II (0.01 mole) and 1-chloro-2, 3-epoxypropane 25ml was refluxed on water bath in presence of basic catalyst, pyridine for about 4-6 hr.

Table I: Characterization data of compounds

Comp	R	R’	Molecular formula	Mol. Wt.	M.P. ^0C	Yield %	Rf Value	Elemental analysis
								C	H	N
C1	p-NO2		C34H32N6O10	684	236	30	0.61	59.65 (59.40)	4.71 (5.00)	12.27 (12.45)
C2	p-NO2		C31H30N10O8	670	239	25	0.52	55.52 (55.15)	4.51 (4.61)	20.89 (20.49)
C3	p-NO2		C37H34N6O10	722	195	20	0.55	61.49 (61.79)	4.51 (4.52)	11.63 (11.80)
C4	m-NO2		C34H32N6O10	684	229	25	0.54	59.65 (59.45)	4.71 (4.95)	12.27 (12.35)
C5	m-NO2		C31H30N10O8	670	199	35	0.49	55.52 (55.42)	4.51 (4.33)	20.89 (20.48)
C6	m-NO2		C37H34N6O10	722	209	27	0.49	61.49 (61.91)	4.74 (4.61)	11.63 (11.21)
C7	m-Cl		C34H32Cl2N4O6	663	216	30	0.52	61.54 (61.81)	4.86 (4.61)	8.44 (8.25)
C8	p-Cl		C31H30Cl2N8O4	649	228	30	0.42	57.32 (57.65)	4.66 (4.98)	17.25 (17.91)
C9	p-Cl		C37H34Cl2N4O6	701	229	25	0.61	63.34 (63.95)	4.88 (4.61)	7.99 (7.65)

Table no 2: Effect of 1, 4- Dihydropyridinees on Carrageenan Induced Paw Edema

SI No.	Groups	Dose (mg/kg)	Paw volume (ml) Mean ±SEM
			0h	1h	2h	3h	4h	5h
1.	Control	0.5% CMC	0.8500 ±0.04183	1.340 ±0.03674	1.460 ±0.03317	1.530 ±0.0200	1.580 ±0.01225	1.570 ±0.0200
2.	Aspirin	100	0.7900 ±0.03317	0.9800** ±0.01225	0.8600** ±0.02449	0.800** ±0.0273	0.7600** ±0.01871	0.7300** ±0.0200
3.	C4	200	0.8200 ±0.03742	1.200 ±0.05000	1.130** ±0.04637	1.040** ±0.03674	0.9600** ±0.02915	0.8400** ±0.01871
4.	C5	200	0.7900 ±0.02915	1.200 ±0.05000	1.100** ±0.04183	1.010** ±0.05099	0.9400** ±0.04301	0.8200** ±0.02550
5.	C6	200	0.8100 ±0.02915	1.230 ±0.02550	1.110** ±0.04301	1.010** ±0.05099	0.9400** ±0.04301	0.8200** ±0.02550
6.	C7	200	0.8200 ±0.0300	1.220 ±0.02550	1.140** ±0.02915	1.080** ±0.02550	0.9800** ±0.03391	0.9000** ±0.03536
7.	C9	200	0.7900 ±0.02915	1.230 ±0.05148	1.120** ±0.05148	1.020** ±0.04637	0.9100** ±0.02915	0.8200** ±0.02550

 One way ANOVA followed by Dunnett’s ‘t” test,        ** P< 0.01

Table No.3: Effect of 1, 4-Dihydropyridines on Xylene induced Ear Edema

SI No.	Groups	Dose (mg/kg)	Ear Edema (in mm)  (Mean±SEM)	Percentage Inhibition (%)
1	Control	0.5% CMC	7.200±0.3742
2	Aspirin	100	2.200±0.2000**	69.44
3	C4	200	4.400±0.5049**	52.77
4	C5	200	4.600±0.2449**	36.11
5	C6	200	4.800±0.3742	33.33
6	C7	200	4.200±0.3742**	41.66
7	C9	200	4.200±0.3742**	41.66

One way ANOVA followed by Dunnett’s ‘t” test,          ** P< 0.01

Table No. 4: Effect of 1,4-Dihydropyridines on Cotton Pellet Induced Granuloma in Rats

SI No.	Groups	Dose (mg/kg)	Mean weight of cotton pellets (in mg)	Percentage Inhibition (%)
1	Control	0.5% CMC	48.20±0.6633
2	Aspirin	100	23.00±0.7071**	52.28
3	C4	200	30.60±0.8718**	36.51
4	C5	200	35.40±0.7483**	26.55
5	C6	200	31.00±1.000**	35.68
6	C7	200	34.00±1.378**	29.46
7	C9	200	30.00±1.414**	37.75

One way ANOVA followed by Dunnett’s ‘t” test,  

** P< 0.01

The crude epoxide separated was added into equal volume of chloroform and excess of concentrated HCL 10 ml and the mixture was stirred for 30 min. The chloroform layer separated was washed with small amount of ice cold water to remove excess of HCL. The organic layer was dried and the resulting chlorohydrine compound was refluxed with succinimide/ 5-aminotetrozole and p-aminobenzonic acid in benzene and methanol for 6-8 hr. The mixture was then poured into ice cold water, the solid thus separated was filtered and recrystillized from alcohol.

SPECTRAL DATA:

C₁: FT-IR (KBr disc): 3450 (N-H Str.), 3239 (O-H Str.Amide),2947 (C-H Ar.str.), 1777 (C=O str.), 821 ( C-N str.), 1596 ( NO₂ str). δH ( 400 MHz,DMSO): 6.8-7.5 (12H, N-CH), 3.76 ( 2H, O-CH₂), 3.67 (2H, N-CH₂), 2.5  ( 1H, O-H).

C₃: FT-IR ( KBr disc) : 3460 (N-H Str.) 3363 (O-H str), 2968 (C-H Ar.str.), 1441(C-O str.), 1672 (CONH amide str.), 1515 ( NO₂ str).δH ( 400 MHz,DMSO): 7.0-7.9 (16H Ar-CH), 3.7  ( 2H, O-CH₂), 3.61 (2H, N-CH₂), 2.7   ( 6H,2CH₃), 2.1(1H,O-H)

C₄: FT-IR (KBr disc): 3450 (N-H Str.), 3239 (O-H Str.Amide),2947 (C-H Ar.str.), 1777 (C=O str.), 821 ( C-N str.), 1510 ( NO₂ str). δH ( 400 MHz,DMSO): 6.8-7.5 (12H, N-CH), 3.76 ( 2H, O-CH₂), 3.67 (2H, N-CH₂), 2.5  ( 1H, O-H).

C₆: FT-IR ( KBr disc) : 3460 (N-H Str.) 3363 (O-H str), 2968 (C-H Ar.str.), 1441(C-O str.), 1672 (CONH amide str.), 1518 ( NO₂ str).δH ( 400 MHz,DMSO): 7.0-7.9 (16H Ar-CH), 3.7  ( 2H, O-CH₂), 3.61 (2H, N-CH₂), 2.7   ( 6H,2CH₃), 2.1(1H,O-H)

C₇: FT-IR ( KBr disc) : 3184 (N-H Str.), 3367 (O-H str), 2951 (C-H Ar.str.), 1709 (C=O str.), 1773 (CONH amide str.), 1597 (C=C str.) .δH ( 400 MHz,DMSO):  6.6-7.4  (12H Ar-CH), 4.2 ( 2H, O-CH₂), 3.8 (2H, N-CH₂), 1.4      ( 6H,2CH₃),  2.75 (1H,O-H)

C₉: FT-IR ( KBr disc) : 3460 (N-H Str.) 3363 (O-H str), 2968 (C-H Ar.str.), 1441(C-O str.), 1672 (CONH amide str.), 1520 ( NO₂ str).δH ( 400 MHz,DMSO): 7.0-7.9 (16H Ar-CH), 3.7  ( 2H, O-CH₂), 3.61 (2H, N-CH₂), 2.7   ( 6H,2CH₃), 2.1(1H,O-H)

ACKNOWLEDGMENT:

The authors wish to express their sincere thank to Shri. Balasaheb.Vikhe Patil, Honorable M.P. and Chairman, Pravara Rural Education Society for his constant support.

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Received on  06.07.2008          Modified on 25.07.2009

Accepted on 03.08.2009       © AJRC All right reserved

Asian J. Research Chem.  2(3): July-Sept., 2009, page 310-313