International Journal of ChemTech Research
CODEN (USA): IJCRGG ISSN: 0974-4290
Vol.2, No.1, pp 504-508, Jan-Mar 2010
B.S. Vatkar* 1 , A.S. Pratapwar 2 , A.R. Tapas 2 , S.R. Butle 1 and Balkrishna Tiwari 1
1 School of Pharmacy, S.R.T.M. University, Nanded - 431606, (M.S.), India.
2 S.N. Institute of pharmacy, Pusad- 445204 (M.S.), India.
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, 1 H 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 anti-
Tuberculosis, 8 antifungal, 9 antiarrhythmic, 10 antiviral, 11 antihypertensive, 12 Antioxidant, 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, 1 H-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 CDCl
3
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
R
1
R
2
OH
CH
3
+
H
O
Substituted acetophenone
(I a-f )
R
3
O
Substituted aromatic aldehyde
(II a-f )
Base
R
1
OH
O
Substituted chalcone
( Intermediate )
( III a-f )
R
2
R
3
R
1
KOH / EtOH
R
2
R
3
O
Compound code
IVa
IVb
IVc
IVd
IVe
IVf
R
1
H
H
H
OH
OH
OH
R
2
NO
2
H
H
OH
NO
2
H
O
Substituted flavanone
( final )
( IV a-f)
R
3
H
F
CH
3
H
H
CH
3

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
IVa
IVb
IVc
IVd
IVe
IVf
Mol. formula
M.P.

C Rf value
C
15
H
11
NO
4
174-176

C 0.65
C
15
H
11
FO
2
168-170

C 0.82
C
16
H
14
O
2
182-184

C 0.78
C
15
H
12
O
4
192-194

C 0.76
C
15
H
11
NO
5
202-204

C 0.80
C
16
H
14
O
3
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-NO
2
),
1706(C=O),
1589(CH=CH),
1103(C-O-C).
3070(OH),
3004(C-CH
3
),
1739(C=O),
1512(CH=CH),
1141(C-O-C).
1 H NMR (CDCl3/

(ppm)
3.8(d,2H,O=C-CH
2
),
5.8(t,1H,O-CH),7-8.1
(m,4H,5,6,7,8 -Ar-H), 8.2-
8.6(m,4H,2’,4’,5’,
6’-Ar-H)
3.7(d,2H,O=C-CH
2
),
5.6(t,1H,O-CH),6.5-
7.4(m,4H, 5,6,7,8-Ar-
H),7.58.0(m,4H,2’,3’,5’,
6’-Ar-H)
2.4(S,3H,CH
3
)3.7(d,2H,O
=CCH
2
),5.6(t, 1H,O-
CH),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-CH
2
),
5(s,2H,3’,7-OH),
5.4(t,1H,O-CH),
6.8-7.5(m,3H,5,6,8-Ar-
H),7.67.9(m,4H,2’,3’,5’,
6’-Ar-H)
3.6(d,2H,O=C-CH
2
),
4.9(s,1H,7-OH),
5.8(t,1H,O-CH),
6.3-6.6(m,3H,5,6,8-Ar-
H),6.8-7.1(m,4H,
2’,4’,5’,6’-Ar-H)
2.4(s,3H,CH
3
),3.7(d,2H,
O=C-CH
2
), 5.6 (t; 1H, O-
CH) 5(s,1H, 7-OH) 6.9-7.3
(m,3H, 5,6,8-Ar-H),7.4-
8.0 (m, 4H,2’,4’, 5’,6’-Ar-
H)
Table No. 2 Antimicrobial Activity of derivatives
Compounds
E. c.
Antibacterial*
P. a.
Antifungal*
A. n. A. f.
IV a
IV b
IV c
IV d
IV e
IV f
Streptomycin
Fluconazole
08
09
07
08
07
07
18
--
13
08
08
10
11
09
15
--
09
12
11
10
08
09
--
13
10
08
09
10
08
12
--
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) 507
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, 1 H 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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