Synthesis and Antimicrobial Evaluation of
Some Novel Derivatives of Coumarin Moiety
Abhishek Kumar*, Prerana
Shetty, Amrutha C. L, Derin Reona Vaz, Ashlin Baby
Department of Pharmaceutical Chemistry,
NGSM Institute of Pharmaceutical Sciences, NITTE University, Paneer,
Deralakatte-575018, Mangalore, Karnataka.
*Corresponding Author E-mail: abhi12bunty@gmail.com
Received on 09.03.2016
Modified on 15.03.2016
Accepted on 02.04.2016 ©
RJPT All right reserved
Research J. Pharm. and Tech. 2016; 9(5): 545-548.
DOI: 10.5958/0974-360X.2016.00103.7
ABSTRACT:
A
series of novel substituted 3-(2-hydroxy-6-phenylpyrimidin-4-yl)-2-H-chromen-2-one and 3-(2-mercapto-6-phenylpyrimidin-4-yl)-2-H-chromen-2-one (APY1-APY8) were synthesized upon refluxing ethanolic
solution of 3-(3-phenylacryloyl)-2-H-chromen-2-one with urea/thiourea in presence of 20% KOH. The structures of the final synthesized compounds were
characterized by IR, mass and 1H NMR spectra. The synthesized
compounds were screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus,
Escherichia coli and Pseudomonas
aeruginosa by
cup plate method. Most of the compounds exhibited promising antibacterial
activity.
KEYWORDS: Chalcones, pyrimidines, 3-acetyl coumarin, antibacterial
activity.
INTRODUCTION:
Coumarins are group of secondary plant
metabolites found to exhibit important pharmacological activities. Some of
their 3-substituted derivatives such as novobiocin, coumaromycin and chartencin
are known to exhibit antibacterial activity. Coumarin derivatives have been reported to possess
anticoagulant, antibacterial1, anti-inflammatory2,
antioxidant3, anthelmintic and anticancer4 activities. Nitrogen containing heterocycles such as pyrimidine is
a promising structural moiety for drug designing. Pyrimidine derivatives are
known to be biologically active compounds and substituted pyrimidines have
shown wide range of biological activities like antitubercular5,
antibacterial6, antioxidant7 and anti-inflammatory8
activity.
The incorporation of two moieties
increases biological activity of both and thus it was of value to synthesize
some new heterocyclic derivatives having two moiety in the same molecule. By considering the above facts it was
contemplated to synthesize a new series of pyrimidine derivatives incorporating
the coumarin moiety and evaluate their antimicrobial activities.
MATERIALS AND METHODS:
All the chemicals
were of analytical grade: substituted salicylaldehyde, ethylacetoacetate,
absolute ethanol, piperidine, urea, thiourea and substituted benzaldehyde. Melting
points were determined by open capillary method and are uncorrected. The purity of the compounds was monitored
by thin layer chromatography (TLC) using silica gel G plates. The spots were
visualized under UV light and by the exposure to iodine vapors. The homogeneity of the compounds were checked on silica
gel-G coated plate by using Ethylacetate: Chloroform (9:1) as solvent. IR
spectra were recorded in Alpha Bruker using ATR method. 1H NMR
spectra were recorded on Bruker spectrophotometer (400 MHz) in DMSO-d6
solvent using tetra methyl silane (TMS) as an
internal standard. Mass spectra was recorded by LCMS method.
General
Procedure:
Synthesis
of Substituted 3-(3-phenylacryloyl)-2-H-chromen-2-one9
A mixture of substituted 3-acetyl-coumarin
(0.01 mol) and different substituted benzaldehyde (0.01 mol) in 20 ml absolute
ethanol was stirred together at room temperature for 24 hours in the presence
of 20% KOH. The completion of the reaction was monitored by TLC. The reaction
mixture was then poured into crushed ice and acidified with 2N HCl with
stirring. The product obtained was filtered, washed with water and
recrystallised from ethanol.
Synthesis of Substituted 3-(2-hydroxy-6-phenylpyrimidin-4-yl)-2-H-chromen-2-one and 3-(2-mercapto-6-phenylpyrimidin-4-yl)-2-H-chromen-2-one10 (APY1-
APY8)
A mixture of substituted 3-(3-phenylacryloyl)-2-H-chromen-2-one (0.01 mol) and urea/thiourea (0.01 mol) was dissolved
in 20 ml absolute ethanol in the presence of 20% KOH. The reaction mixture was
refluxed for about 6 hours. After the completion of the reaction, the reaction
mixture was poured into crushed ice. The precipitated solid was filtered,
washed with cold water and recrystallised from ethanol.
Figure 1: Reaction scheme for
Pyrimidine derivatives
Spectral data
3-(2-hydroxy-6-(3,4,5-trimethoxyphenyl)pyrimidin-4-yl)-2H-chromen-one (APY1)
IR KBr (cm-1): 1512 (Ar C=C str), 835 (Ar C-H bend), 3056
(Ar C-H str), 1692 (C=N str), 1268 (C-O str), 1698 (C=O str), 3482 (O-H str).
1H NMR (400 MHz, DMSO-d6): δ 7.31-8.12 (m, 10H,
Ar-H), 9.82 (s, 1H, OH), 3.26
(s, 3H, OCH3).
MS (M+): m/z 421.
3-(2-mercapto-6-(3,4,5-trimethoxyphenyl)pyrimidin-4-yl)-2H-chromen-one (APY2)
IR KBr (cm-1): 1516 (Ar C=C str), 832 (Ar C-H bend), 3050
(Ar C-H str), 1690 (C=N str), 1272 (C-O str), 1692 (C=O str), 2052 (S-H str).
1H NMR (400 MHz, DMSO-d6): δ 7.27-8.16 (m, 10H,
Ar-H), 9.85 (s, 1H, OH), 3.36
(s, 3H, OCH3).
MS (M+): m/z 437.
6-chloro-3-(2-hydroxy-6-(4-nitrophenyl)- pyrimidin-4-yl)-2H-chromen-one (APY5)
IR KBr (cm-1): 1508 (Ar C=C str), 830 (Ar C-H bend), 3054
(Ar C-H str), 1688 (C=N str), 1696 (C=O str), 1342 (Ar-NO2 str), 732
(C-Cl str), 3476 (O-H str).
1H NMR (400 MHz, DMSO-d6): δ 7.12-8.16 (m, 10H,
Ar-H), 12.19 (s, 1H, SH)
MS (M+): m/z 395.
6-chloro-3-(2-mercapto-6-(4-nitrophenyl)- pyrimidin-4-yl)-2H-chromen-one (APY6)
IR KBr (cm-1): 1518 (Ar C=C str), 836 (Ar C-H bend), 3058
(Ar C-H str), 1680(C=N str), 1696 (C=O str), 1340 (Ar-NO2 str), 736
(C-Cl str), 2048 (S-H str).
1H NMR (400 MHz, DMSO-d6): δ 7.15-8.19 (m, 10H,
Ar-H), 12.13 (s, 1H, SH)
MS (M+): m/z 411.
Antimicrobial
Activity:
All the synthesized compounds were evaluated for their antibacterial
activity against Staphylococcus aureus,
Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis using cup plate method11. The
synthesized test compounds were tested at a concentration of 100 µg/50µl and the standard compound i.e.
Ciprofloxacin were tested at 25 µg/50µl. Dimethyl formamide (DMF) was used as
control. In this technique, melted agar inoculated with microorganisms is
poured into petridishes. Wells are made in the agar plate and a specific volume
of the antimicrobial substances are placed in them, plates were incubated at a
temperature of 37oC for 24 hrs. The antimicrobial substance diffuses
through agar around its well and produces a clear zone of inhibition. The diameter
of this zone (mm) gives an estimation of the degree of activity of the
antimicrobial substance.
RESULTS AND DISCUSSION:
Table 1: Physicochemical
data of 2-Hydroxy Pyrimidines
|
Comp. code |
R |
R1 |
Mol. formula |
Mol. wt |
M.P oC |
Rf Value |
% Yield |
|
APY1 |
H |
3,4,5-OCH3 |
C23H21N2O6 |
421 |
198-200 |
0.70 |
78 |
|
APY3 |
H |
3-NO2 |
C19H11N3O5 |
361 |
210-212 |
0.68 |
69 |
|
APY5 |
5-Cl |
4-NO2 |
C19H10ClN3O5 |
395 |
226-228 |
0.64 |
58 |
|
APY7 |
3,5-Br |
3-NO2 |
C19H9Br2N3O5 |
519 |
240-242 |
0.72 |
59 |
Table 2: Physicochemical
data of 2-Mercapto Pyrimidines
|
Comp. code |
R |
R1 |
Mol. formula |
Mol. wt |
M.P oC |
Rf Value |
% Yield |
|
APY2 |
H |
3,4,5-OCH3 |
C23H21N2O5S |
437 |
206-208 |
0.76 |
75 |
|
APY4 |
H |
3-NO2 |
C19H11N3O4S |
377 |
216-218 |
0.60 |
76 |
|
APY6 |
5-Cl |
4-NO2 |
C19H10ClN3O4S |
411 |
230-232 |
0.66 |
60 |
|
APY8 |
3,5-Br |
3-NO2 |
C19H9Br2N3O4S |
535 |
234-238 |
0.62 |
62 |
Table 3: Antimicrobial
activity of the compounds (RPY1-RPY8) by cup plate method
|
Compd |
Diameter of zone of
inhibition (mm) |
|||
|
S.aureus |
B.subtilis |
E.coli |
P.aureginosa |
|
|
APY1 |
15 |
18 |
13 |
12 |
|
APY2 |
19 |
16 |
14 |
13 |
|
APY3 |
10 |
12 |
11 |
09 |
|
APY4 |
08 |
10 |
09 |
08 |
|
APY5 |
18 |
19 |
17 |
16 |
|
APY6 |
17 |
16 |
13 |
15 |
|
Ciprofloxacin |
26 |
26 |
22 |
23 |
|
Control |
- |
- |
- |
- |
Antimicrobial
activity
The in vitro antibacterial and antifungal
activity of the synthesized compounds were determined by using cup-plate
method. The results of antibacterial and antifungal activity of newly
synthesized compounds are reported
against Bacillus subtilis, Staphylococcus aureus, Escherichia
coli and Pseudomonas aeruginosa. Compounds
APY1, APY2, APY5 and APY6 showed good antibacterial activity compared to the standard drug
ciprofloxacin. The results of the antimicrobial activity are summarized in
Table 3.
CONCLUSION:
This study reports the successful synthesis of
substituted pyrimidine derivatives with moderate yields and most of the
synthesized compounds showed promising antibacterial activity.
ACKNOWLEDGEMENTS:
The authors are thankful to Nitte
University for providing the necessary facilities to carry out this research.
The authors are grateful to Sequent Research Ltd, Mangalore and Central
Instrumentation Facility, MIT Manipal for providing spectroscopic data
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