synthesis of some novel mannich bases of … · antianginal, vasodilator ... spectrophotometer...

Vol-3, Issue-4, Suppl-2, Nov 2012 ISSN: 0976-7908 Anand et al

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PHARMA SCIENCE MONITOR

AN INTERNATIONAL JOURNAL OF PHARMACEUTICAL SCIENCES

SYNTHESIS OF SOME NOVEL MANNICH BASES OF 1,4-

DIHYDROPYRIDINE NUCLEUS OF BIOLOGICAL INTEREST

Kinjal Anand*, Hardi Bhavsar, Bhavika Patel, Prof. Vijayalakshmi Gudaparthi and Prof.

Hansa Parikh

Department of Pharmaceutical Chemistry, L.J.Institute of Pharmacy, S.G.Highway, Ahmedabad-382210

ABSTRACT Heterocyclic compounds are widely distributed in nature and are essential for life. Many heterocyclic compounds due to their specific activity are employed in the treatment of many diseases. Heterocyclic 1,4-dihydropyridines are important class of compounds. They may become promising candidates for exploiting more useful therapeutically active molecules. The compounds having 1,4-dihydropyridines moiety are associated with interesting wide spectrum biological activities, such as antibacterial, antihypertensive, antianginal, vasodilator, cardiac depressant activities, adenosine receptor antagonism, tumor growth inhibition and etc. Based on the above studies, an attempt was made to synthesize heterocyclic Mannich bases (Ia-If)) from parent molecule of 1,4-dihydropyridine and its derivatives. The synthesized compounds were then characterized by TLC, melting point determination, IR, 1H-NMR and Mass spectral studies and tested for their antibacterial and antifungal activity against both Gram+ ve and Gram- ve bacteria B.cereus, S. aureus and E.coli, B.subtillus and C.albicans respectively and compared with the standard drug and all the synthesized compounds showed significant antibacterial and antifungal activity. Keywords: 1,4-dihydropyridine, Mannich bases, antibacterial activity, antifungal activity. INTRODUCTION

1,4-Dihydropyridine (1) is the most feasible nitrogen containing heterocyclic ring with

various substitutions at several positions. This molecule binds to the L-type calcium

channel and acts as a multifunctional lead molecule for the various cardiovascular

activities which include antihypertensive, antianginal, vasodilator and cardiac depressant

activities. Apart from the CVS activities it also exhibit antitubercular, anticonvulsant,

antitumor, analgesic, anti-inflammatory, and stress protective activities. [1] Very

promising therapeutic applications have been obtained using the 1,4-dihydropyridine

system. The dihydropyridine skeleton is common in many drugs such as nifedipine (2),



felodipine (3), nicardipine (4), amlodipine (5), nitrendipine, nimodipine and others,

which are effective as cardiovascular agents and which are also used for the treatment of

hypertension.[2]

NH

MeO2C

H3C CH3

Nicardip ine

NO2

O

ON

CH2Ph

M e

4

Amlodipine

NH

ClCO2EtMeO2C

H3CO

NH2

5

NH

NO2

CO2MeMeO2C

H3C CH3

Nifedipine

2

NH

Cl

CO2EtMeO2C

H3C CH3

Felodipine

Cl

3

Ar = aryl aldehyde

where,

NH

Ar

COOC2H5C2H5OOC

H3C CH3

1,4-Dihydropyridine nucleus

1



The mannich reaction provides an excellent method for carbon-carbon bond

formation and its importance is reflected in the ever-increasing number of suitable

substrates and reaction conditions that have been developed.[3]In this context, literature

survey has revealed a number of reports on antimicrobial activity of N-mannich bases

derived from different heterocycles such as pyrrole, pyrazole, benzimidazole,

benzotriazole, etc. Mannich reaction of heterocyclic ring systems with formaldehyde and

primary or secondary amines have been tested for antibacterial, antifungal, antiviral,

anticancer, antileishmanial and antimalarial activity. [4]

In this regard in our present work we have synthesized some novel 1,4-

dihydropyridine derivatives from substituted quinoline aldehyde, its reaction with acetyl

acetone in presence of ammonia .The Mannich bases of these 1,4-dihydropyridines were

prepared in the second step by reacting these dihydropyridines with formaldehyde in a

base (scheme).

MATERIAL AND METHODS

Material: The chemicals and reagents used in the project work were of AR and LR

grade, procured from Astron chemicals, Ahmedabad and they are used as they obtained.

Equipments: Purity of compounds was checked by thin layer chromatography. Melting

points of synthesized compounds were determined by open capillary method. The IR

spectra of synthesized compounds were recorded on a Fourier-Transform IR

spectrophotometer (model-DRS 8400, Shimadzu) in the range of 400-4000 cm-1 using

KBr pellets. The 1H-NMR spectra of synthesized compounds were recorded on Bruker

Avance II 500MHz FT-NMR spectrophotometer (TOPSPIN 1.3 version) using DMSO-

d6 as solvent. Mass spectrum was recorded by MDS SCIEX API 2000 LCMS/MS

(Applied Biosystems) instrument.

Method:

STEP-I: Synthesis of 2-chloro-6-methylquinoline-3-carbaldehyde[5]

A Vilsmeier-Haack adduct prepared from phosphorus oxytrichloride (6.5 ml, 0.35 mol)

and N, N-dimethylformamide (2.3 ml, 0.125 mol) at 0 ºC was added to N-p-

tolylacetamide (1.49 gm, 0.05 mol) and refluxed for 10 h.The reaction mixture was

poured into ice followed by neutralization using sodium hydroxide. Crude product was



isolated and crystallised from ethanol. Molecular Formula: C11H8ClNO; Molecular

weight (g/mol): 205.64; Melting point: 120-122 ºC (Reported=120-125 ºC); Percentage

yield: 77.03 %; Rf: 0.41.

STEP-II: Synthesis of 1,1'-(4-(2-chloro-6-methylquinolin-3-yl)-2,6-dimethyl-1,4-

dihydropyridine-3,5-diyl)diethanone

A mixture of 2-chloro-6-methylquinoline-3-carbaldehyde (20.5 gm, 0.1 mol), acetyl

acetone (20.0 ml, 0.2 mol) and ammonium hydroxide (0.35 gm, 0.1 mol) in methanol was

heated under reflux for 4 hours. To the resulting mixture, warm water was added and then

allowed to cool. The product was filtered off, washed with aqueous ethanol and

recrystallized from alcohol. Molecular Formula: C21H21ClN2O2; Molecular weight

(g/mol): 368.86; Melting point: 138-140 ºC; Percentage yield: 90.25 %; Rf: 0.73.

STEP-III: Synthesis of Mannich bases

A mixture of 1,1'-(4-(2-chloro-6-methylquinolin-3-yl)-2,6-dimethyl-1,4-dihydropyridine-

3,5-diyl)diethanone (0.01 mol), different bases (0.01 mol) and paraformaldehyde (0.02

mol) was taken in methanol and heated under reflux for 4 hours. The reaction mixture

was cooled and poured into crushed ice. The product was filtered and recrystallized from

aqueous ethanol.



Scheme: Synthesis of Mannich bases of 1,4-dihydropyridine:

Different substitutents (R) are introduced through phthalimide, p-aminobenzoic acid,

morpholine, sulphanilamide, benzimidazole, benzotriazole.



TABLE 1: PHYSICAL CONSTANT DATA TABLE OF MANNICH BASES

DERIVATIVES

No. Name (R) Molecular formula

Melting Point (°C)

Yield %

Rf Value

1 Phthalimide C30H26N3O4Cl 200-206 43.65%

0.26 Hexane:Ethyl acetate ::8:2

2 p-Amino benzoic acid

C29H28N3O4Cl 136-140 45.52%


3 Morpholine C26H30N3O3Cl 152-156 43.70% 0.38 Acetone:Benzene ::9:1

4 Sulphanilamide C28H29N4O4SCl 236-242 50.24%


5 Benzimidazole C29H27N4O2Cl 122-128 42.46% 0.53 Acetone:Benzene ::9:1

6 Benzotriazole C28H26N5O2Cl 136-140 52.97% 0.60 Acetone:Benzene ::9:1

(1a) 2-((3,5-Diacetyl-4-(2-chloro-6-methylquinolin-3-yl)-2,6-dimethylpyridin-1(4H)-

yl) methyl) isoindoline-1,3-dione

IR (KBr, cm-1): 1307 (C-N str), 1743 (C=O str in amide), 3248 (N-H str), 752 (C-Cl str),

1423 (-CH3 str), 1600, 1527, 1491 (Aromatic); 1H NMR (δ ppm, DMSO): 2.27 (s, 6H,

COCH3), 2.40 (s, 9H, -CH3), 4.74 (s, 1H,-CH-), 5.01 (s, 2H,-CH2); Mass: (m/e) 528 (M+),

301.2(100).

(1b) 4-(((3,5-Diacetyl-4-(2-chloro-6-methylquinolin-3-yl)-2,6-dimethylpyridin-1(4H)-

yl) methyl)amino)benzoic acid

IR (KBr, cm-1): 3215 (N-H str), 1718(-COOH str), 1672(-C=O str), 752(C-Cl str), 1423(-

CH3 str), 1491(C=N str), 1600,1527,1491(Aromatic); 1H NMR (δ ppm, DMSO): 2.27 (s,



9H, -CH3), 4.0 (s, 2H, -CH2), 4.15 (t, 1H, -NH), 6.2-8.23 (m, 10H, Ar-H), 4.74 (s, 1H, -

CH); Mass: (m/e) 516.5(M-1), 367.2(100).

(1c) 4-(((3,5-Diacetyl-4-(2-chloro-6-methylquinolin-3-yl)-2,6-dimethylpyridin-1(4H)-

yl) methyl)amino)benzenesulfonamide

IR (KBr, cm-1): 1155 & 1330 (SO2NH2 str), 665 (C-S str), 1215 (S=O str), 3228 (-NH

str).

(1d) 1,1'-(4-(2-Chloro-6-methylquinolin-3-yl)-2,6-dimethyl-1-(morpholine- methyl)-

1,4-dihydropyridine-3,5-diyl)diethanone

IR (KBr, cm-1): 1334(C-N str), 1222(C-O-C str), 3220 (N-H str), 740(C-Cl str), 1420(-

CH3 str), 1596, 1530, 1490(Aromatic); 1H NMR (δ ppm, DMSO): 3.64(t, 4H, O-CH2),

2.5(t, 4H, N-CH2), 3.70 (s, 2H,-CH2); Mass: (m/e) 466.3(M-1), 367.2(100).

(1e) 1,1'-(1-((1H-benzo[d]imidazol-1-yl)methyl)-4-(2-chloro-6-methylquinolin-3-yl)-

2,6-dimethyl-1,4-dihydropyridine-3,5-diyl)diethanone

IR (KBr, cm-1): 3218 (N-H str), 1330 (C=N str), 735(C-Cl str), 1425(-CH3 str), 1604,

1527, 1470(Aromatic); Mass: (m/e) 503.3(M+), 301.2(100).

(1f) 1,1'-(1-((1H-benzo[d][1,2,3]triazol-1-yl)methyl)-4-(2-chloro-6-methylquinolin-3-

yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-diyl)diethanone

IR (KBr, cm-1): 1610 (N=N str), 1220 (Azide), 3220 (N-H str), 740(C-Cl str), 1420(-CH3

str), 1596, 1530, 1490(Aromatic); Mass: (m/e) 499.7 (M+), 301.2(100).

RESULTS AND DISCUSSION

Biological Evaluations

Microbial Screening:

The synthesized compounds were screened for their anti-microbial activity by Agar

diffusion method and Disc diffusion method using medium F and Sabouraud’s agar

medium for bacteria and fungi respectively. Anti microbial activity was evaluated by

measuring the diameter of zone of inhibition against test organisms. Based on the results

it is refered that synthesis of some 1,4-dihydropyridine derivatives have significant

inhibition effect on the growth of bacteria like Bacillus cereus, Staphylococus aureus,

Bacillus subtillus and Escherichia coli and fungi like Candida albicans. The results were

tabulated in table. The results showed that the compound Ib, Ic and If showed very good



activity when compare to that the standard (Streptomycin, Tetracycline and Miconazole).

The activity was due to the presence of carboxylic acid group in compound Ib,

sulphonamide group in compound Ic and triazole ring in compound If.

TABLE 2: ANTIBACTERIAL ACTIVITY (ZONES OF INHIBITION) OF

SYNTHESISED COMPOUNDS

Compound code

Conc. (µg/ml)

Zone of inhibition(mm)

Gram +ve Gram –ve

B.cereus S.aureus B.subtillus E.coli

Ia

64 8 7 7 7 80 - - - - 100 9 8 9 9 125 10 11 11 10 156 12 12 12 12

Ib

64 10 10 11 11 80 - - 12 12 100 13 12 15 14 125 14 14 16 15 156 15 16 16 17

Ic

64 11 11 - - 80 13 12 11 12 100 14 13 13 13 125 15 14 15 15 156 16 17 17 16

Id

64 - 8 8 - 80 9 - - 10 100 10 10 10 10 125 12 11 11 11 156 13 14 13 13

Ie

64 9 8 9 9 80 11 10 11 10 100 12 11 12 11 125 14 13 13 12 156 15 15 15 14

If

64 10 9 11 10 80 11 10 12 12 100 12 12 13 12 125 15 14 14 14 156 16 15 15 15

Streptomycin

25 10 8 - - 50 12 10 - - 75 18 14 - - 100 24 20 - -

Tetracycline

25 - - - 11 50 - - - 14 75 - - - 20 100 - - - 22



Degree of activity was measured by the zone of inhibition (mm), (--) No inhibition

Figure 1 Antibacterial activity chart of B.cereus Gram +ve bacteria of synthesized test compounds (Note: Concentration of streptomycin and tetracycline were considered at 25, 50, 75 and

100 μg/ml instead of 64, 80, 100, 125 and 156 μg/ml respectively).

Figure 2 Antibacterial activity chart of S.aureus Gram +ve bacteria of synthesized test compounds (Note: Concentration of streptomycin and tetracycline were considered at 25, 50, 75 and

100 μg/ml instead of 64, 80, 100, 125 and 156 μg/ml respectively).



Figure 3 Antibacterial activity chart of B.subtillus Gram +ve bacteria of synthesized test

compounds (Note: Concentration of streptomycin and tetracycline were considered at 25, 50, 75 and 100 μg/ml instead of 64, 80, 100, 125 and 156 μg/ml respectively).

Figure 4 Antibacterial activity chart of E.coli Gram -ve bacteria of synthesized test compounds

(Note: Concentration of streptomycin and tetracycline were considered at 25, 50, 75 and 100 μg/ml instead of 64, 80, 100, 125 and 156 μg/ml respectively)



TABLE 3: ANTIFUNGAL ACTIVITY (ZONES OF INHIBITION) OF

SYNTHESISED COMPOUNDS

Compound code

Conc. (µg/ml)


Compound code

Conc. (µg/ml)


C. albicans C. albicans

Ia

50 -

Id

50 - 100 - 100 - 150 8 150 10 200 10 200 14

Ib

50 8

Ie

50 8 100 10 100 9 150 16 150 10 200 18 200 14

Ic

50 8

If

50 8 100 13 100 12 150 16 150 14 200 17 200 15

Degree of activity was measured by the zone of inhibition (mm), (--) No inhibition

Figure 5 Antifungal activity chart of C. albicans fungi of synthesized test compounds.

CONCLUSION

In summary, most of the synthesized compounds showed significant antibacterial activity

and antifungal activity within the series against both of Gram +ve and Gram –ve bacteria



at 156 and 125 μg/ml concentrations and antifungal activity of fungi at 150 and 200

μg/ml concentrations.

ACKNOWLEDGEMENT

The authors are thankful to L.J.Institute of Pharmacy for providing facilities for synthesis

and biological screening.

REFERENCES

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multifunctional molecule – A review. International Journal of ChemTech

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2. Prakash, Hussain K, Kumar R, Wadhwa D, Sharma C and Aneja KR: Synthesis

and antimicrobial evaluation of new 1,4-dihydro-4-pyrazolylpyridines and 4-

pyrazolylpyridines. Organic and Medicinal Chemistry Letters 2011; 1-6.

3. Velazquez AMa, Torres LA, Diaz G and Ramirez A: A novel one pot, solvent-

free Mannich synthesis of methylpiperidinylphenols,

methylphenylmorpholinylphenols and methylthiophenylmorpholinylphenols

using infrared light irradiation. Arkivoc 2006; 2: 150-161.

4. Shah TB, Gupte A, Patel MR, Chaudhari VS, Patel H and Patel VC: Synthesis

and in vitro study of biological activity of heterocyclic N-Mannich Bases. Indian

Journal of Chemistry 2009; 48B: 88-96.

5. Khan FN, Subashini R, Roopan SM, Hathwar VR and Ng SW: 2-Chloro-6-

methylquinoline-3-carbaldehyde. Acta Crystallography 2009; E65: o2686.

For Correspondence: Kinjal A. Anand Email: [email protected]

synthesis of some novel mannich bases of … · antianginal, vasodilator ... spectrophotometer...

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