International Journal of ChemTech Research
CODEN (USA): IJCRGG
ISSN: 0974-4290
Vol.2, No.1, pp 504-508,
Jan-Mar 2010
Synthesis and Antimicrobial Activity of Some
Flavanone Derivatives
B.S. Vatkar*1, A.S. Pratapwar2, A.R. Tapas2, S.R. Butle1
and Balkrishna Tiwari1
1School
of Pharmacy, S.R.T.M. University, Nanded - 431606, (M.S.), India.
2S.N.
Institute of pharmacy, Pusad- 445204 (M.S.), India.
*Corresponding author:[email protected]
Mobile No: 919403389262
ABSTRACT: Flavanone has been used widely for their antimicrobial and antifungal property. The Chalcones were
reported by Claisen-Schmidt condensation of substituted acetophenone with substituted aromatic aldehydes. Various
analogs of flavanone were synthesized from by oxidative cyclization of chalcones with satisfactory yield and purity. All
the title compounds characterized on the basis of their IR, 1H NMR, Mass spectroscopic data. All analogues of 2,3dihydro-2-phenylchromen-4-one have shown moderate to good antimicrobial and antifungal property by the Filter paper
disc method.
KEY WORDS: Synthesis, Flavanone, Benzopyran, Antimicrobial activity.
INTRODUCTION
Due to the rapid development of bacterial
resistance to antibacterial agents, it is vital to discover
novel scaffold for the design and synthesis of the new
antibacterial agents to help in the battle against
pathogenic microorganisms. Much research has been
carried out with the aim to discover the therapeutic
values of flavanone derivatives.
Flavones which are also known as
anthoxanthins, are widely distributed as yellow
coloured plant pigment (flavus, latin meaning yellow)
and occur either in the free state or as glycosides
associated with tannins. The derivatives of phenol
present as glycosidal form and chemically they are
derivatives of phenyl benzo-Y-pyrone (chromone)
ring. The basic flavanoid structure is a flavone
nucleus, In nature, they are available as flavone,
flavonol, flavanone, isoflavone, chalcone and their
derivatives.1 Natural and synthetic flavanoids and
flavanones have attracted considerable attention
because of their interesting biological activity
including antimycobacterial,2 antimicrobial,3,4 anti-lung
cancer,5
antibacterial,6
antiproliferative,7
anti8
9
Tuberculosis, antifungal, antiarrhythmic,10 antiviral,11
antihypertensive,12Antioxidant,12 Anti-inflammatory.12
Flavonoids have created a more attention of researcher
with the discovery of the French Paradox, i.e.decrease
incidence of cadio-vascular disease observed in
Mediterranean population, in association with red
wine consumption and a greater amount of saturated
fat than average diet in other countries.12,13 In the
present work we report the reaction of various
substituted acetophenone with different substituted
aromatic aldehyde to form Chalcones. Various analogs
of flavanone were reported by oxidative cyclization of
Chalcones. The structures of the various synthesized
compounds were assigned on the basis of IR, 1H-NMR
spectral data. These compounds were also screened for
their antimicrobial activity.
EXPERIMENTAL
Melting points were determined on SUPERFIT
melting point apparatus in open capillary tubes and are
uncorrected. The IR spectra were recorded in KBr on
SHIMADZU FT-IR – 8400 spectrophotometer. The
1H-NMR were recorded in CDCl3 on a Varian
mercury YH-300 NMR Spectrometer using TMS as an
B.S. Vatkar et al /Int.J. ChemTech Res.2010,2(1)
505
internal standard. The purity of the compounds was
checked by TLC-using Silicagel-G (Merck). Column
chromatography was performed on Silica gel (Merck,
60-120 mesh).
General procedure for the preparation of chalcone
(IIIa-f)
A mixture of substituted acetophenones (0.01 mole)
and aryl aldehydes (0.01 mole) was stirred in ethanol
(30 mL) and then an aqueous solution of potassium
hydroxide (15 mL) was added to it. The mixture was
kept over night at room temperature and then it was
poured into crushed ice and acidified with dilute
hydrochloric acid. The chalcone derivative precipitates
out as solid. Then it was filtered and crystallized from
ethanol.14
General procedure for the synthesis of flavanones
from chalcone ( IVa-f)
Substituted chalcones (0.001 mol) dissolved in
methanol (50 ml) in a 200 ml beaker. The resulting
solution was made alkaline (pH 10.0) with potassium
hydroxide pellets and was allowed to react for 2—3 h
at room temperature (the reaction time for different
chalcones vary from 1—3 h). The reaction mixture
was then acidified (using 10% aqueous hydrochloric
acid: ice-cold) to precipitate the flavanones. The
product was filtered with suction on a Buchner funnel,
washed with cold water until the washings were
neutral to litmus and then with 5 ml of ice-cold
rectified spirit. The dried product was recrystallised
from 95% ethanol.1
SCHEME OF SYNTHESIS
R2
R2
R1
OH
CH3
O
Substituted
acetophenone
(I a-f )
R3
+
R3
Base
R1
H
O
Substituted
aromatic aldehyde
(II a-f )
OH
O
Substituted chalcone
( Intermediate )
( III a-f )
KOH / EtOH
R2
R3
R1
O
O
Substituted flavanone
( final )
( IV a-f)
Compound code
R1
R2
R3
IVa
H
NO2
H
IVb
H
H
F
IVc
H
H
CH3
IVd
OH
OH
H
IVe
OH
NO2
H
IVf
OH
H
CH3
B.S. Vatkar et al /Int.J. ChemTech Res.2010,2(1)
506
Table 1. Characterization and Spectral data of compounds IVa-f
Compoun
d code
Mol.
formula
M.P. C
Rf
value
IVa
C15H11NO4
174-176C
0.65
IVb
C15 H11 FO2
168-170C
0.82
IVc
C16 H14O2
182-184C
0.78
IVd
C15 H12O4
192-194C
0.76
IVe
C15H11NO5
202-204C
0.80
IVf
C16 H14O3
168-170C
0.71
IR (Cm-1, KBr)
1492 (CNO2),
1720 (C=O),
1527 (CH=CH),
1197 ( C-O-C).
840 (C-F),
1710(C=O),
1595 CH=CH),
1105(C-O-C).
1677(C=O),
1566(CH=CH),
1157(C-O-C).
3068(OH),
3089(OH),
1708(C=O),
1587(CH=CH),
1103(C-O-C).
3043(OH),
3066(C-NO2),
1706(C=O),
1589(CH=CH),
1103(C-O-C).
3070(OH),
3004(C-CH3),
1739(C=O),
1512(CH=CH),
1141(C-O-C).
H NMR (CDCl3/ 
(ppm)
3.8(d,2H,O=C-CH2),
5.8(t,1H,O-CH),7-8.1
(m,4H,5,6,7,8 -Ar-H), 8.28.6(m,4H,2’,4’,5’,
6’-Ar-H)
3.7(d,2H,O=C-CH2),
5.6(t,1H,O-CH),6.57.4(m,4H, 5,6,7,8-ArH),7.58.0(m,4H,2’,3’,5’,
6’-Ar-H)
2.4(S,3H,CH3)3.7(d,2H,O
=CCH2),5.6(t, 1H,OCH),6.8-7.4(m,4H,5,6,7,
8-Ar-H),7.5-8.0(m,4H,
2’,3’,5’,6’-Ar-H)
3.2(d,2H,O=C-CH2),
5(s,2H,3’,7-OH),
5.4(t,1H,O-CH),
6.8-7.5(m,3H,5,6,8-ArH),7.67.9(m,4H,2’,3’,5’,
6’-Ar-H)
3.6(d,2H,O=C-CH2),
4.9(s,1H,7-OH),
5.8(t,1H,O-CH),
6.3-6.6(m,3H,5,6,8-ArH),6.8-7.1(m,4H,
2’,4’,5’,6’-Ar-H)
2.4(s,3H,CH3),3.7(d,2H,
O=C-CH2), 5.6 (t; 1H, OCH) 5(s,1H, 7-OH) 6.9-7.3
(m,3H, 5,6,8-Ar-H),7.48.0 (m, 4H,2’,4’, 5’,6’-ArH)
1
Table No. 2 Antimicrobial Activity of derivatives
Compounds
Antibacterial*
Antifungal*
E. c.
P. a.
A. n.
A. f.
IV a
08
13
09
10
IV b
09
08
12
08
IV c
07
08
11
09
IV d
08
10
10
10
IV e
07
11
08
08
IV f
07
09
09
12
Streptomycin
18
15
--Fluconazole
--13
15
*Zone of inhibition was measured in mm. Escherichia coli (E.c.), Pseudomonas aeruginosa (P.a), Aspergillus
niger (A.n.), Aspergillus flavus (A.f.).
B.S. Vatkar et al /Int.J. ChemTech Res.2010,2(1)
ANTIMICROBIAL ACTIVITY:
The synthesised compounds (IVa-IVf) were screened
for their in vitro antimicrobial activity against
Escherichia coli, Pseudomonas aeruginosa and
antifungal activity against Aspergillus niger,
Aspergillus flavus, by measuring the zone of inhibition
in mm. The antimicrobial activity was performed by
filter paper disc plate method at concentration 100
µg/mL and reported in Table-2. Muller Hinton agar &
Sabouroud Dextrose agar were employed as culture
medium and DMSO was used as solvent control for
antimicrobial activity.Streptomycin and Fluconazole
were used as standard for antibacterial and antifungal
activities respectively.
CONCLUSION
The structure of the synthesized substituted flavanones
were confirmed from their respective spectral data
such as IR,1H NMR Studies,From the antimicrobial
screening it was observed that all the compounds
exhibited activity against all the organisms employed.
The Antibacterial activity of all compounds against
tested microorganism have been found that compound
No.IVa,IVb,IVd,IVe possessed good antibacterial
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