ORIGINAL RESEARCH

Synthesis of new olefin chalcone derivatives as antitumor,antioxidant and antimicrobial agents

Babasaheb P. Bandgar • Shivkumar S. Jalde • Laxman K. Adsul •

Sadanand N. Shringare • Shrikant V. Lonikar • Rajesh N. Gacche •

Nagesh A. Dhole • Shivraj H. Nile • Amol L. Shirfule

Received: 11 September 2011 / Accepted: 17 January 2012 / Published online: 24 February 2012

� Springer Science+Business Media, LLC 2012

Abstract Chalcone is a unique template that is associated

with several biological activities. Claisen–Schmidt con-

densation of olefin aldehyde 3 and various mono, disub-

stituted and heterocyclic acetophenones afforded novel

olefin chalcones. Synthesized compounds were subjected

for ADME prediction by computational method which

revealed that these molecules can be considered as a

potential drug. Out of the 21 compounds screened, com-

pounds 5u, 5g, 5c and 5e have shown significant cytotox-

icity against Hep 3BPN 7, compounds 5j, 5i, 5n and 5o

showed good cytotoxicity against HL 60 P 58. Compounds

5f, 5c, 5e and 5b showed potent cytotoxicity against Hela B

75. Antioxidant activity was assessed using three methods,

namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl

radical scavenging and ferric reducing antioxidant power

(FRAP). The result shows that all these compounds possess

significant antioxidant activity. Compounds 5k, 5s, 5a and

5c showed promising antibacterial activity. Compounds 5k,

5u and 5f could be considered as chemopreventive agents.

Keywords Chalcones � Cytotoxicity � Antimicrobial �Lipinski rule � Antioxidant

Introduction

Chalcones are a family of bicyclic flavonoids, defined by

the presence of two aromatic rings joined by a three carbon

unit containing an a,b-unsaturated carbonyl group. They are

also a precursor to many flavonoids. The chalcones display

wide range of biological activities. In fact, not many

structural templates can claim association with a diverse

range of pharmacological activities such as cytotoxicity,

antitumor, anti-inflammatory, antiplasmodial, immunosu-

pression and antioxidant (Dimmock et al., 1999). The

tumour inhibiting properties of chalcone are of special

interest and have been found to arise from their effects on

malignant cell proliferation through tumour angiogenesis

(Nam et al., 2003), interference with p53–MDM2 interac-

tion (Stoll et al., 2001), induction of apoptosis (Reddy et al.,

2011), disruption of cell cycle by inhibiting cell cycle check

points such as cyclin-dependent kinases (CDKs) (Liu et al.,

2007), or binding with tubulin and inhibiting the tubulin

polymerization (Lawrence et al., 2000), or inhibiting

depolymerization of microtubules (Tu et al., 2010). Chal-

cones have a preferential reactivity towards thiols in con-

trast to amino and hydroxyl groups. Thus, interactions with

nucleic acids may be absent which could eliminate the

problems of mutagenicity and carcinogenicity common in

various chemotherapeutics (Dimmock et al., 1999). Poly-

methoxylated chalcones have potent antimitotic activity

(Lawrence et al., 2000) as they possess a methoxylation

pharmacophore similar to known tubulin polymerization

inhibitors, such as combretastatin A4, colchicine and pod-

ophyllotoxin. Liu and Go (2006) described the synthesis of

B. P. Bandgar � L. K. Adsul � S. N. Shringare � S. V. Lonikar

Medicinal Chemistry Research Laboratory, School of Chemical

Sciences, Solapur University, Solapur 413255, Maharashtra,

India

B. P. Bandgar (&) � S. S. Jalde

Organic Chemistry Research Laboratory, School of Chemical

Sciences, SRTM University, Nanded 431606, Maharashtra, India

e-mail: bandgar_bp@yahoo.com

R. N. Gacche � N. A. Dhole � S. H. Nile

Biochemistry Research Laboratory, School of Life Sciences,

SRTM University, Nanded 431606, Maharashtra, India

A. L. Shirfule

Food and Drug Toxicology Research Centre, National Institute

of Nutrition, Hyderabad 500007, India

123

Med Chem Res (2012) 21:4512–4522

DOI 10.1007/s00044-012-9979-z

MEDICINALCHEMISTRYRESEARCH

methoxylated chalcones bearing N-methylpiperidine sub-

stituent to improve the aqueous solubility and drug like

character and have been shown to possess good antiprolif-

erative activity with an IC50 \ 5 lM. The presence of

piperidinyl substituent gives specificity to the mechanism of

antiproliferative activity. In another report, same research

group synthesized the chalcones with different basic func-

tionalities and evaluated for antiproliferative activity and

found that chalcones with single basic functionality had

better antiproliferative activity than those with more than

one basic group (Liu and Go, 2007).

The population of Staphylococcus aureus resistant to

traditional antibiotics such as methicillin, oxacillin or

nafcillin continues to rise and is now more than 50% in

intensive care units in United States (NNIS, 1999). It has

been reported that Vancomycin was the last resort for the

treatment of multiple drug resistant S. aureus (Sievert

et al., 2002). Liquorice (root and rhizome of Glycyrrrhiza

spp.) is currently used in tobacco, confectionary and

pharmaceutical industries. Among the retrochalcone

(chalcones which do not have an oxygen function at the

2-position) isolated from Glycyrrhiza inflata licochalcone

A (IV, Fig. 1) showed potent antibacterial activity espe-

cially to Bacillus subtilis, Staphylococcus aureus and

Micrococcus luteus (Tsukiyama et al., 2002). Nielson et al.

(2005) has synthesized cationic chalcones (V) which pos-

sess basic functionalities at both rings A and B. They

designed these compounds based on membrane active

cationic peptide antibiotics. They postulated that chalcones

with basic functionalities are protonated at physiological

pH. Bacterial membranes are rich in negatively charged

phospholipids and thus would attract positively charged

molecules, following initial electrostatic attraction. The

agents would then permeate and insert itself into bacterial

membrane to exert its lethal disruptive effect. Tomar et al.

(2007) has synthesized chalcones containing piperazine or

2,5-dichlorothiophene and some of the compounds to show

good antibacterial activity. Liu et al. (2008) has synthe-

sized chalcones containing basic functionalities (VI) and

evaluated these for antibacterial activity against drug-sen-

sitive Staphylococcus aureus. The SAR study indicate that

the presence of 1-methyl-4-piperidine and 2-hydroxy group

is necessary for antibacterial activity with IC50 6.3 lM for

the most active compound. In continuation of our studies in

synthesizing various biologically active compounds

(Bandgar et al., 2011), in the present study we have syn-

thesized and characterized several novel olefin chalcones

and subjected these for prediction of ADME by computa-

tional tools and evaluated for cytotoxicity, antioxidant and

antimicrobial activities.

Flavopiridol (I, Fig. 1), a pioneering benchmark CDKs

inhibitor, induces cell cycle arrest at both G1 and G2

phases, and is a potent inhibitor of CDK1, 2, 4 and 6 in a

competitive manner with respect to ATP (Senderowicz,

2003). Structure–activity relationship (SAR) study of

flavopiridol analogue by Murthi et al. (2000) revealed that

a simpler analogue, olefin (II) shows good CDKs inhibitory

activity. Schoepfer et al. (2002) has designed and synthe-

sized 2-benzylidene-benzofurano-3-one (III) as flavopiridol

mimics. These compounds have 1-methyl piperidine sub-

stituent without hydroxyl group on the piperidine ring.

They reasoned that hydroxyl group is not very much crit-

ical for CDK inhibitory activity. These compounds show

significant inhibition of CDKs 1, 2 and 4 enzymatic

activities and have selectivity against CDK4. Hampson

et al. (2006) has synthesized olefin analogues of flavopir-

idol and found that they are potent inhibitors of glyocogen

phosphorylase (II). Keeping in view of above-mentioned

OH

HO O

N

R

OH

O

R= 2-Cl Phenyl

OH

HO O

N

R

O

R= 2-Cl Phenyl

R= 3-Cl Phenyl

R= 4-Cl Phenyl

R= Phenyl

OH

HO O

N

R2

R1

O

1 R1= NO2, R2 =H2 R1= SO2NH2, R2= H

HO O OH

O

Licochalcone A

NH

N

N

HN

O

Cationic Chalcone

O

O

N

OH

R2

R1

O

1 R1 = 4-Me, R2 = H2 R1 = H, R2 = 3-Cl

Antibacterial Basicchalcones

I IIIII

IV IVV

Fig. 1 Flavopiridol and its

analogues, synthetic and

naturally occuring chalcones

Med Chem Res (2012) 21:4512–4522 4513

123

activity of flavopiridol and its olefin analogues, we have

synthesized chalcones containing olefin moiety. The title

compounds were prepared as shown in Scheme 1. Com-

pound 2 (olefin) was prepared by reacting 1,3,5-trimethoxy

benzene with 1-methyl-4-piperidone in presence of

hydrogen chloride gas in glacial acetic acid (Hampson

et al., 2006). Compound 2 on Vilsmeier–Hack formylation

gave 2,4,6-trimethoxy-3-(1-methyl-1,2,3,6-tetrahydropyri-

din-4-yl)benzaldehyde (olefin aldehyde) 3. Compound 3 on

Claisen–Schmidt condensation with various mono, disub-

stituted and heteroaromatic acetophenones under basic

media afforded a product, which on purification by re-

crystalization with suitable solvent gave title compounds in

good to excellent yields (Table 1). All the synthesized

novel olefin chalcones were characterized by IR, 1H NMR

and mass spectral analyses and evaluated for cytotoxicity,

antioxidant and antimicrobial activities.

Materials and method

Chemistry

All the chemicals were purchased from Aldrich Chemical

Co., USA. All the solvents were purchased from S. D. Fine

chemicals. Thin layer chromatography plates were pur-

chased from Merks kiesegel 60F254, 0.2 mm thickness

sheet and media for antimicrobial study was purchased

from HiMedia Chemicals Pvt. Ltd., Mumbai (MS), India.

Melting points were recorded in open capillaries with

electrical melting point apparatus and were uncorrected. IR

spectra (KBr disks) were recorded using a Perkin–Elmer

237 spectrophotometer. 1H NMR spectra were recorded on

Bruker Advance (300 and 400 MHz) spectrometer using

DMSO-d6 as solvent, with TMS as an internal reference.

Mass spectra were recorded on a Shimadzu LCMS-QP

1000 EX. TLC was performed on silica gel coated plates

for monitoring the reactions. The spots could be visualized

easily under UV light.

O

O O

O

O O

N

O

O O

CHO

N

O

O O

CHO

N

+R

OR

O

OO

N

O

1 2 3

3 4a-u 5a-u

a b

c

Scheme 1 Synthesis of novel

olefin chalcones. Reagents and

conditions: (a) N-methyl

piperidone, HCl, AcOH,

85–90 �C, 3.5 h; (b) DMF,

POCl3, rt, 2 h; (c) NaOH, EtOH,

rt, 24 h

Table 1 Synthesis of novel olefin chalcones

O

OO

N

O

B AR

Entry R Product Yielda (%) MP (�C)

1 C6H5 5a 92 151–153

2 4-BrC6H4 5b 89 175–177

3 4-FC6H4 5c 95 139–141

4 3,4-OmeC6H3 5d 91 99–101

5 C4H3S 5e 81 140–142

6 3,4-ClC6H3 5f 78 98–100

7 4-NO2C6H4 5g 96 168–170

8 4-ClC6H4 5h 93 162–164

9 3,4-FC6H3 5i 90 169–171

10 2,4-OCH3C6H3 5j 83 142–144

11 3-NH2C6H4 5k 85 216–218

12 4-NH2C6H4 5l 78 194–196

13 2,5 OmeC6H3 5m 75 122–124

14 4-Me C6H4 5n 84 175–177

15 2-OmeC6H4 5o 81 126–128

16 4-OmeC6H4 5p 87 162–164

17 4,6-Ome,2-OHC6H1 5q 85 68–70

18 2,4,-ClC6H3 5r 71 140–142

19 2,4,6-OmeC6H1 5s 77 145–147

20 2,5,-ClC6H3 5t 69 110–112

21 C4H4N 5u 61 220–222

a Isolated yield

4514 Med Chem Res (2012) 21:4512–4522

123

Synthesis of 2,4,6-trimethoxy-3-(1-methyl-1,2,3,6-

tetrahydropyridin-4-yl)benzaldehyde 3

Olefin 2 (1.0 g, 4 mmol) was dissolved in dry DMF

(13.3 ml) under anhydrous condition. It was cooled to 0�C,

POCl3 (7.2 ml) was added dropwise for 30 min and stirring

continued for 2 h at 25�C. After completion of reaction

(TLC) reaction mass was poured over crushed ice (50 g),

basified with Na2CO3, extracted with chloroform, dried

over anhydrous Na2SO4 and purified through silica gel

column using 0.5–1% methanol ? 1% liquor ammonia in

chloroform as eluting solvent afforded product 3 in 51%

yield.

Synthesis of novel olefin chalcones (5a–5u)

A mixture of substituted acetophenones (2 mmol) was

dissolved in 15 ml of ethanol under stirring, to this 4 ml

(20%) aqueous NaOH was added and stirred for 10 min.

To this reaction mixture 3-(1,2,3,6-tetrahydro-1-methyl-

pyridin-4-yl)-2,4,5-trimethoxybenzaldehyde (291 mg,

1 mmol, 2) was added and stirring continued for 24 h at

room temperature. After completion of reaction (TLC), the

reaction mixture was poured over crushed ice and stirred.

The light yellow solid obtained was filtered, washed with

water and dried. The crude yellow solid products were

purified by recrystalization using methanol to afford pure

compounds 5a–5u (Scheme 1).

1-Phenyl-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,6-tetrahy-

dro-pyridin-4yl)-phenyl]-propenone (5a) IR (KBr) cm-1:

2925, 1640, 1580, 1464, 1105. 1H NMR (DMSO,

400 MHz) d: 8.03 (m, 3H), 7.89 (d, 1H, J = 16 Hz), 7.60

(m, 3H), 6.55 (s, 1H), 5.55 (s, 1H), 3.96 (s, 3H), 3.82 (s,

3H), 3.63 (s, 3H), 2.96 (s, 2H), 2.50 (s, 2H), 2.26 (m, 5H).

MS: m/z 394 [M??1].

1-(4-Bromo-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,

6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5b) IR

(KBr) cm-1: 2925, 1650, 1580, 1146, 1108, 765, 635. 1H

NMR (DMSO, 400 MHz) d: 7.86 (d, 1H, J = 16 Hz), 7.76

(d, 1H, J = 16 Hz), 7.58 (d, 2H, J = 8 Hz), 7.42 (d, 2H,

J = 8 Hz), 6.52 (s, 1H), 5.46 (s, 1H), 3.94 (s, 3H), 3.88 (s,

3H), 3.72 (s, 3H), 2.97 (s, 2H), 2.48 (s, 2H), 2.27 (m, 5H).

MS: m/z 474 [M??2].

1-(4-Fluoro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,

6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5c) IR

(KBr) cm-1: 2935, 1646, 1598, 1554, 1455,1393, 1240,

1102, 1012, 765, 635. 1H NMR (DMSO, 400 MHz) d: 8.09

(d, 2H, J = 8 Hz), 7.96 (d, 1H, J = 16 Hz), 7.89 (d, 1H,

J = 16 Hz), 7.39 (d, 2H, J = 8 Hz), 6.55 (s, 1H), 5.55 (s,

1H), 3.93 (s, 3H), 3.84 (s, 3H), 3.68 (s, 3H), 2.90 (s, 2H),

2.50 (s, 2H), 2.26 (m, 5H). MS: m/z 412 [M??1].

1-(3,4-Dimethoxy-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-

1,2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5d) IR

(KBr) cm-1: 2935, 1640, 1595, 1556, 1460, 1393, 1240,

1105, 777. 1H NMR (DMSO, 400 MHz) d: 7.60 (d, 1H,

J = 16 Hz), 7.50 (d, 1H, J = 16 Hz), 7.32 (m, 2H), 7.00

(s, 1H), 6.55 (s, 1H), 5.49 (s, 1H), 3.93 (s, 3H), 3.83 (s,

3H), 3.72 (s, 3H), 3.56 (s, 3H), 3.30 (s, 3H,), 2.89 (s, 2H),

2.53 (s, 2H), 2.25 (m, 5H). MS: m/z 454 [M? ?1].

1-Thiophene-2yl-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,6-

tetrahydro-pyridin-4yl)-phenyl]-propenone (5e) IR (KBr)

cm-1: 2926, 1639, 1580, 1553, 1464, 1393, 1240, 1103. 1H

NMR (DMSO, 400 MHz) d: 7.89 (d, 1H, J = 16 Hz), 7.76

(d, 1H, J = 16 Hz), 7.50 (s, 2H), 6.84 (s, 1H), 6.54 (s, 1H),

5.47 (s, 1H), 3.96 (s, 3H), 3.84 (s, 3H), 3.75 (s, 3H), 2.96 (s,

2H), 2.45 (s, 2H), 2.27 (m, 5H). MS: m/z 400 [M??1].

1-(3,4-Dichloro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,

2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5f) IR

(KBr) cm-1: 2925, 1634, 1560, 1464, 1323, 1203, 1108,

936, 744, 648. 1H NMR (DMSO, 400 MHz) d: 8.01 (s,

1H), 7.82 (m, 2H), 7.76 (m, 2H), 6.55 (s, 1H), 5.55 (s, 1H),

3.98 (s, 3H), 3.83 (s, 3H), 3.76 (s, 3H), 2.90 (s, 2H), 2.50 (s,

2H), 2.25 (m, 5H). MS: m/z 462 [M?].

1-(4-Nitro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,

6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5g) IR

(KBr) cm-1: 2934, 1650, 1594, 1551, 1456, 1394, 1240,

1104, 852, 718. 1H NMR (DMSO, 400 MHz) d: 8.20 (d,

2H, J = 8 Hz), 8.12 (d, 1H, J = 16 Hz), 7.95 (d, 2H,

J = 8 Hz), 7.79 (d, 1H, J = 16 Hz), 6.55 (s, 1H), 5.50 (s,

1H), 3.93 (s, 3H), 3.84 (s, 3H), 3.65 (s, 3H), 2.90 (s, 2H),

2.55 (s, 2H), 2.26 (m, 5H). MS: m/z 439 [M??1].

1-(4-Chloro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,

6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5h) IR

(KBr) cm-1: 2925, 1634, 1560, 1464, 1323, 1203, 1108,

805, 740. 1H NMR (DMSO, 400 MHz) d: 7.95 (d, 1H,

J = 16 Hz), 7.84 (d, 1H, J = 16 Hz), 7.68 (d, 2H,

J = 8 Hz), 7.45 (d, 2H, J = 8 Hz), 6.54 (s, 1H), 5.55 (s,

1H), 3.92 (s, 3H), 3.78 (s, 3H), 3.68 (s, 3H), 2.90 (s, 2H),

2.48 (s, 2H), 2.27 (m, 5H). MS: m/z 428 [M??1].

1-(3,4-Difluoro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,

2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5i) IR

(KBr) cm-1: 2925, 1634, 1560, 1464, 1325, 1203, 1108,

936, 744, 648. 1H NMR (DMSO, 400 MHz) d: 7.94 (d, 1H,

J = 16 Hz), 7.87 (d, 1H, J = 16 Hz), 7.82 (s, 1H), 7.76 (s,

1H), 7.32 (s, 1H), 6.55 (s, 1H), 5.53 (s, 1H), 3.94 (s, 3H),

Med Chem Res (2012) 21:4512–4522 4515

123

3.84 (s, 3H), 3.64 (s, 3H), 2.96 (s, 2H), 2.50 (s, 2H), 2.27

(m, 5H). MS: m/z 430 [M??1].

1-(2,4-Dimethoxy-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-

1,2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5j) IR

(KBr) cm-1: 2935, 1646, 1595, 1556, 1460, 1393, 1240,

1105, 777. 1H NMR (DMSO, 400 MHz) d: 7.79 (d, 1H,

J = 16 Hz), 7.74 (d, 1H, J = 16 Hz), 7.55 (d, 1H,

J = 8.8 Hz), 6.63 (m, 2H), 6.52 (s, 1H), 5.50 (s, 1H), 3.93 (s,

3H), 3.83 (s, 3H), 3.82 (s, 3H), 3.60 (s, 3H), 3.32 (s, 3H), 2.95

(s, 2H), 2.50 (s, 2H), 2.26 (m, 5H). MS: m/z 454 [M??1].

1-(3-Amino-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,

6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5k) IR (KBr)

cm-1: 3407, 3334, 2933, 1645, 1591, 1458, 1390, 1312,

1099. 1H NMR (DMSO, 400 MHz) d: 7.92 (d, 1H, J =

16 Hz), 7.82 (d, 1H, J = 16 Hz), 7.16 (m, 2H), 7.10 (d, 1H,

J = 8 Hz), 6.79 (d, 1H, J = 8 Hz), 6.55 (s, 1H), 5.52 (s, 1H),

5.38 (s, 2H, –NH2), 3.97 (s, 3H), 3.83 (s, 3H), 3.63 (s, 3H),

2.96 (s, 2H), 2.50 (s, 2H), 2.27 (m, 5H). MS: m/z 409 [M??1].

1-(4-Amino-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,

6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5l) IR (KBr)

cm-1: 3407, 3334, 2933, 1645, 1591, 1458, 1390, 1312,

1099. 1H NMR (DMSO, 400 MHz) d: 7.92 (d, 1H, J =

16 Hz), 7.82 (d, 1H, J = 16 Hz), 7.75 (d, 2H, J = 8.4 Hz),

6.61 (d, 2H, J = 8.4 Hz), 6.55 (s, 1H), 6.07 (s, 2H, –NH2),

5.52 (s, 1H), 3.96 (s, 3H), 3.82 (s, 3H), 3.62 (s, 3H), 2.96 (s,

2H), 2.50 (s, 2H), 2.27 (m, 5H). MS: m/z 409 [M??1].

1-(2,5-Dimethoxy-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-

1,2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5m) IR

(KBr) cm-1: 2935, 1646, 1595, 1556, 1460, 1393, 1240,

1105, 777. 1H NMR (DMSO, 400 MHz) d: 7.72 (d, 1H,

J = 16 Hz), 7.56 (d, 1H, J = 16 Hz), 7.09 (m, 2H), 6.98

(s, 1H), 6.52 (s, 1H), 5.49 (s, 1H), 3.93 (s, 3H), 3.82 (s,

3H), 3.79 (s, 3H), 3.73 (s, 3H), 3.56 (s, 3H), 2.94 (s, 2H),

2.50 (s, 2H), 2.26 (m, 5H). MS: m/z 454 [M??1].

1-p-Tolyl-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,6-tetrahy-

dro-pyridin-4yl)-phenyl]-propenone (5n) IR (KBr)

cm-1: IR (KBr) cm-1: 2935, 1646, 1595, 1556, 1460,

1393, 1240, 1105. 1H NMR (DMSO, 400 MHz) d: 8.01 (d,

1H, J = 16 Hz), 7.89 (m, 3H), 7.20 (d, 2H, J = 8 Hz),

6.55 (s, 1H), 5.55 (s, 1H), 3.93 (s, 3H), 3.83 (s, 3H), 3.68 (s,

3H), 2.96 (s, 2H), 2.50 (s, 2H), 2.39 (s, 3H), 2.26 (m, 5H).

MS: m/z 408 [M??1].

1-(2-Methoxy-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,

3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5o) IR

(KBr) cm-1: 2935, 1646, 1598, 1554, 1455, 1393, 1240,

1102, 765, 635. 1H NMR (DMSO, 400 MHz) d: 7.70 (d,

1H, J = 16 Hz), 7.54 (d, 1H, J = 16 Hz), 7.49 (d, 1H,

J = 7.6 Hz), 7.42 (m, 1H), 7.16 (d, 1H, J = 8 Hz), 7.03

(ddd, 1H, J = 7.6, 6.8, 1.3), 6.52 (s, 1H), 5.49 (s, 1H), 3.92

(s, 3H), 3.84 (s, 3H), 3.82 (s, 3H), 3.56 (s, 3H), 2.94 (s,

2H), 2.50 (s, 2H), 2.26 (m, 5H). MS: m/z 424 [M??1].

1-(4-Methoxy-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,

3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5p) IR

(KBr) cm-1: 2935, 1646, 1598, 1555, 1460, 1393, 1242,

1103, 777, 648. 1H NMR (DMSO, 400 MHz) d: 7.90 (d, 1H,

J = 16 Hz), 7.78 (d, 1H, J = 16 Hz), 7.65 (d, 2H,

J = 8 Hz), 6.84 (d, 2H, J = 8 Hz), 6.50 (s, 1H), 5.50 (s, 1H),

3.93 (s, 3H), 3.82 (s, 3H), 3.70 (s, 3H), 3.65 (s, 3H), 2.96 (s,

2H), 2.50 (s, 2H), 2.26 (m, 5H). MS: m/z 424 [M??1].

1-(2-Hydroxy-4,6-dimethoxy-phenyl)-3-[2,4,6-trimethoxy-

3-(1-methyl-1,2,3,6-tetrahydro-pyridin-4yl)-phenyl]-prope-

none (5q) IR (KBr) cm-1: 3450, 2935, 1646, 1595, 1556,

1460, 1393, 1240, 1105, 777. 1H NMR (DMSO, 400 MHz)

d: 14.22 (s, 1H), 7.79 (d, 1H, J = 16 Hz), 7.74 (d, 1H,

J = 16 Hz), 6.63 (m, 2H), 6.52 (s, 1H), 5.50 (s, 1H), 3.93 (s,

3H), 3.83 (s, 3H), 3.82 (s, 3H), 3.60 (s, 3H), 3.32 (s, 3H), 2.95

(s, 2H), 2.50 (s, 2H), 2.26 (m, 5H). MS: m/z 470 [M??1].

1-(2,4-Dichloro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-

1,2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone (5r) IR

(KBr) cm-1: 2925, 1634, 1560, 1464, 1323, 1203, 1108,

936, 744, 648. 1H NMR (DMSO, 400 MHz) d: 7.98 (s,

1H), 7.82 (m, 2H), 7.57 (m, 2H), 6.47 (s, 1H), 5.47 (s, 1H),

3.89 (s, 3H), 3.78 (s, 3H), 3.72 (s, 3H), 2.89 (s, 2H), 2.50 (s,

2H), 2.24 (m, 5H). MS: m/z 462 [M?].

3-[2,4,6-Trimethoxy-3-(1-methyl-1,2,3,6-tetrahydro-pyridin-

4-yl)-phenyl]-1-(2,4,6-trimethoxy-phenyl)-proenone (5s) IR

(KBr) cm-1: 2935, 1646, 1595, 1556, 1460, 1393, 1240,

1105, 777. 1H NMR (DMSO, 400 MHz) d: 7.80 (d, 1H,

J = 16 Hz), 7.56 (d, 1H, J = 16 Hz), 6.70 (s, 2H), 6.50 (s,

1H), 5.57 (s, 1H), 3.93 (s, 3H), 3.82 (s, 3H), 3.79 (s, 3H),

3.73 (s, 3H), 3.56 (s, 3H), 3.40 (s, 3H), 2.96 (s, 2H), 2.50 (s,

2H), 2.26 (m, 5H). MS: m/z 484 [M??1].

1-(2,5-Dichloro-phenyl)-3-[2,4,6-trimethoxy-3-(1-methyl-

1,2,3,6-tetrahydro-pyridin-4yl)-phenyl]-propenone

(5t) IR (KBr) cm-1: 2925, 1634, 1560, 1464, 1323, 1203,

1108, 936, 744, 648. 1H NMR (DMSO, 400 MHz) d: 8.02

(s, 1H), 7.89 (m, 2H), 7.78 (m, 2H), 6.45 (s, 1H), 5.55 (s,

1H), 3.93 (s, 3H), 3.87 (s, 3H), 3.75 (s, 3H), 2.90 (s, 2H),

2.54 (s, 2H), 2.25 (m, 5H). MS: m/z 462 [M?].

1-(1H-Pyrrol-2yl)-3-[2,4,6-trimethoxy-3-(1-methyl-1,2,3,6-

tetrahydro-pyridin-4yl)-phenyl]-propenone (5u) IR (KBr)

cm-1: 3338, 2915, 1672, 1580, 1464, 1389, 1105, 801, 675.

4516 Med Chem Res (2012) 21:4512–4522

123

1H NMR (DMSO, 400 MHz) d: 11.88 (s, 1H), 7.88 (d, 1H,

J = 16 Hz), 7.69 (d, 1H, J = 16 Hz), 7.11 (s, 1H), 7.01 (s,

1H), 6.53 (s, 1H), 6.23 (s, 1H), 5.52 (s, 1H), 3.97 (s, 3H),

3.82 (s, 3H), 3.63 (s, 3H), 2.96 (s, 2H), 2.50 (s, 2H), 2.26

(m, 5H). MS: m/z 383 [M??1].

Biological activities

Cytotoxic activity

The cytotoxicity assay was performed as per the earlier

reported method with slight modification (Wahab et al.,

2009). The cells were harvested (2.5–3 9 104 cells/well)

and inoculated in 96-well microtitre plate. The cells were

washed with phosphate buffer saline (PBS) and the cul-

tured cells were then incubated in with and without test

compound (100 lg). After 72 h incubation, the medium is

aspirated. 10 ll of MTT solution (5 mg/ml in PBS, pH 7.2)

is added to each well and the plates are incubated for 4 h at

37�C. After incubation 100 ll of DMSO (\0.5%) was

added to the wells followed by gentle shaking to solublize

the formation of dye for 15 min. Absorbance was read at

540 nm and surviving cell fraction was calculated. Meth-

otrexate was used as a reference drug. All the measure-

ments were taken in triplicate and the mean values were

calculated. The inhibition of cell viability was calculated as

follows

% Inhibition ¼ 1� T

C� 100

where T is absorbance of treated cells and C is absorbance

of untreated cells.

DPPH radical scavenging activity

The DPPH radical scavenging activity of chalcones was

measured according to the procedure of Blois (1958) with

minor modification (Bandgar et al., 2010a). The reaction

mixture contained test compound (100 lg) with equal

volume of DPPH radical (10-4 M in absolute ethanol)

solution. After 20 min reaction time, the absorbance was

recorded at 517 nm using UV–Visible spectrophotometer.

Ascorbic acid was used as a standard antioxidant agent. All

the measurements were taken in triplicate and the mean

values were calculated.

Hydroxyl radical scavenging activity

Hydroxyl radical scavenging activity was determined by

using the earlier reported method (Gacche et al., 2008)

with slight modification. The reaction mixture contained

60 ll of (1 mM) FeCl3, 90 ll of (1 mM) 1,10-phenan-

throline, 2.4 ml of (0.2 M) phosphate buffer (pH 7.8),

150 ll of (0.17 M) H2O2 and 1.5 ml of test compound

(100 lg which is dissolved in 0.05% DMSO). The reaction

mixture was kept at room temperature for 5 min incubation

and absorbance was measured at 560 nm using the UV–

Visible spectrophotometer. Ascorbic acid was used as a

reference compound. All the measurements were taken in

triplicate and the mean values were calculated.

% Activity ¼ 1� Absorbance of test compound

Absorbance of control� 100

Ferric reducing antioxidant power (FRAP) assay

In the ferric to ferrous reduction assay, the electron dona-

tion capacity (reflecting the electron transfer ability) of the

compounds was assessed. The ferric reducing power of

synthesized novel olefin chalcones was determined by

using previously published protocol of Queiroz (Queiroz

et al., 2007). The reaction mixture contained 2.5 ml of

individual compounds (100 lg), sodium phosphate buffer

(200 lM, pH 6.6) and 2.5 ml of 1% potassium ferricya-

nide. The mixture was incubated at 50�C for 20 min. The

reaction was quenched by the addition of 2.5 ml trichlo-

roacetic acid (10% w/v). Finally the reaction mixture was

centrifuged at 650 rpm for 10 min. 5 ml of supernatant was

mixed with equal volume of distilled water and 1 ml ferric

chloride (0.1%) was added. The absorbance was measured

at 700 nm using UV–Visible spectrophotometer. Increase

in the absorbance of the reaction mixture indicates higher

reducing power. Ascorbic acid was used as a standard. All

the measurements were taken in triplicate and the mean

values were calculated.

% Activity ¼ 1� Absorbance of test compound

Absorbance of control� 100

Antimicrobial activity (agar diffusion method)

The antimicrobial activity was tested through agar diffu-

sion method (Bandgar et al., 2010a, b). All the bacterial

strains such as Escherichia coli (DH5-a), Proteus vulgaris

(MTCC 1751), Staphylococcus aureus (MTCC 96) and

fungal strain Candida albicans (MTCC 3017) used were

procured from Institute of Microbial Type Culture Col-

lection (IMTCC), Chandigarh, India and National Collec-

tion of Industrial Microorganisms (NCIM), Pune (MS),

India. All the synthesized compounds were dissolved to

prepare a stock solution of 1 mg/ml using DMSO (0.05%).

Stock solution was aseptically transferred and suitably

diluted to have solutions of concentration ranging

50–100 lg. For antifungal activity, Candida albicans spore

suspension in sterile distilled water was adjusted to give a

final concentration of 106 cfu/ml. Inoculum of 0.1 ml

spore suspension of selected fungus was spread on Sab-

ouraud’s Dextrose agar plates. For antibacterial activity,

Med Chem Res (2012) 21:4512–4522 4517

123

Muller Hinton agar was seeded with 0.1 ml of respective

bacterial strains suspension prepared in sterile saline

(0.85%) of 105 cfu/ml dilution. The wells of 6 mm diam-

eter were filled with 0.1 ml each test compound separately

for fungus and bacterial strain. The DMSO (0.05%) alone

was used as a controller. The antibiotics streptomycin and

flucanozole were used as a reference for antibacterial and

antifungal, respectively. Inoculated plates in duplicate were

then incubated at 37 ± 0.5�C for antibacterial activity for

24 h and at 28 ± 0.2�C for antifungal activity for 48 h.

After incubation, the antimicrobial activity was measured

in terms of the zone of inhibition in millimetre.

Calculation of physicochemical properties

The physicochemical properties of the compounds such as

molecular weight, cLog P, HBA, HBD and Drug likeness

were studied from online Osiris property explorer for drug

bioavailability of chemical compounds (Miteva et al.,

2006). Quantum chemical descriptors such as energy of

highest occupied molecular orbital (EHOMO) and of lowest

unoccupied molecular orbital (ELUMO) of the synthesized

compounds were calculated using a BioMed CaChe 6.1

(Fujitsu Ltd.). Number of rotatable bonds and topological

polar surface area (TPSA) were calculated from online

Molinspiration chemoinformatics software. Aqueous solu-

bility of the synthesized compounds was studied from

online ALOGPS software.

Results and discussion

MTT microdilution assay was used for the evaluation of

cytotoxic properties of the novel olefin chalcones. The

growth inhibitory effect was assessed using three human

cancer cell lines, Hep 3BPN 7 (liver), HL 60 P 58 (leu-

kaemia), HeLa B 75 (cervix) and one normal cell line

PN-15C-12 (normal chang liver cell line). The results are

summarized in Table 2. All the tested compounds exhib-

ited cytotoxic effect on the cancer cell lines selected in this

study. Compounds 5u, 5g, 5c, 5e, 5f, 5b and 5a have shown

significant cytotoxicity against Hep BPN 7 (80.13–78.06%)

as compared to the standard methotrexate (64.60%,),

whereas, rest of the compounds have shown moderate

cytotoxicity. SAR study of these compounds with respect

to liver cancer cell line revealed that in general, compounds

with electron withdrawing groups on aromatic B ring are

more cytotoxic than their counterparts containing electron

donating groups. The bioisosteric replacement of phenyl

(5a) with pyrrole (5u) showed an increase in cytotoxicity.

Compounds 5j, 5i, 5n, 5o, 5k and 5u exhibited good

cytotoxicity against HL 60 P 58 (78.48–66.55%) as com-

pared to the standard methotrexate (54.08%,), while other

test compounds showed lower cytotoxicity. The SAR study

of these compounds with respect to human leukaemia cell

line revealed that compounds with electron donating

groups on aromatic ring B have higher cytotoxicity than

their counterpart containing electron withdrawing groups

with the exception of 5i. Introduction of one more methoxy

group on aromatic ring B (5j) (78.48%) resulted in

decrease in cytotoxicity (5s) (65.04). Position of methoxy

group is also important for cytotoxicity, changing it from

2,4-position on aromatic B ring (5j) to 2,5-position (5m)

lower the cytotoxicity.

Compounds 5f, 5c, 5e, 5b, 5d, 5a and 5h showed potent

cytotoxicity against Hela B 75 (85.93–83.67%) as com-

pared to the standard methotrexate (78.66%,), rest of the

compounds have shown moderate cytotoxicity. Com-

pounds containing electron withdrawing groups on aro-

matic ring B displayed higher cytotoxicity than their

counterpart containing electron donating groups on aro-

matic ring B with the exception of 5d. Changing the

position of chlorine from 3,4-position (5f) to 2,5-position

of aromatic ring B (5t) resulted in decrease in activity. All

the synthesized compounds under study presented good

cytotoxicity against tumour cell lines. However, they are

Table 2 Cytotoxicity profile of novel olefin chalcones

Compound Hep 3BPN7 HL60 P58 Hela B75 PN-5C-12

5a 78.06 ± 1.28 63.52 ± 1.33 84.15 ± 2.46 61.79 ± 1.48

5b 78.93 ± 1.8 62.68 ± 1.83 84.84 ± 1.76 66.40 ± 2.11

5c 79.86 ± 1.18 62.18 ± 2.93 85.04 ± 2.33 69.43 ± 1.53

5d 79.46 ± 3.01 62.77 ± 2.23 84.84 ± 1.08 65.21 ± 1.23

5e 79.8 ± 1.68 54.28 ± 2.75 84.91 ± 2.03 67.19 ± 1.28

5f 79.8 ± 243 65.04 ± 1.75 85.93 ± 2.44 67.19 ± 3.11

5g 80.13 ± 2.29 65.88 ± 1.43 83.67 ± 1.88 70.09 ± 1.21

5h 77.4 ± 2.48 65.04 ± 2.18 83.74 ± 1.16 67.98 ± 2.22

5i 76.93 ± 3.19 70.50 ± 1.65 82.85 ± 2.28 65.48 ± 1.93

5j 77 ± 2.42 78.48 ± 1.24 83.40 ± 1.57 47.82 ± 3.16

5k 76.33 ± 2.78 66.72 ± 1.73 82.64 ± 2.26 44.53 ± 1.88

5l 75.06 ± 1.84 61.17 ± 1.88 79.28 ± 2.67 49.67 ± 3.33

5m 73.40 ± 2.26 66.30 ± 1.46 82.09 ± 2.72 41.10 ± 1.38

5n 72.53 ± 1.86 69.49 ± 3.42 82.23 ± 2.51 44.26 ± 1.71

5o 71.33 ± 1.49 68.40 ± 1.85 81.13 ± 1.29 46.77 ± 1.50

5p 72.33 ± 1.81 56.97 ± 1.55 80.86 ± 1.18 46.11 ± 1.73

5q 71.40 ± 2.02 64.20 ± 1.24 79.69 ± 2.44 44.13 ± 1.82

5r 71.26 ± 3.09 58.99 ± 1.72 79.42 ± 2.59 50.98 ± 1.51

5s 70.53 ± 1.82 65.04 ± 1.27 78.73 ± 1.40 59.81 ± 1.48

5t 70.8 ± 1.27 65.63 ± 1.29 79.97 ± 2.33 60.47 ± 3.02

5u 80.13 ± 2.43 66.55 ± 1.50 77.77 ± 2.29 57.57 ± 1.88

Methotrexate 64.60 ± 1.29 54.08 ± 2.37 78.66 ± 1.87 53.85 ± 3.42

Hep 3BPN7: Liver, HL60 P58: Human leukaemia, Hela B75: Cervical,

PN-15C-12: Normal liver, the results are the mean values of n = 2, all the

compounds tested at 100 lg. Values are mean ± SEM of three parallel

measurements

4518 Med Chem Res (2012) 21:4512–4522

123

minimally cytotoxic to normal cell line as indicated by less

inhibition of growth of normal cell line under study.

The involvement of reactive oxygen species (ROS) and

the free radical-mediated oxidative damage of cell mem-

branes, DNA and proteins in degenerative process related

to ageing, cancer, inflammation, atherosclerosis, is a cause

of concern. Therefore, there is increasing interest in the

protective and preventative functions of foods and their

constituents against oxidative damage caused by ROS and

free radicals (Glucin, 2010). We have evaluated antioxi-

dant activity of novel olefin chalcones against DPPH stable

free radical. Free radical scavenging activity was measured

in terms of DPPH reduction and the results are presented in

Table 3. All the synthesized compounds showed good to

moderate free radical scavenging activity. Compounds 5k

(94.50%), 5l (89.60%) exhibited similar radical scavenging

activity as the standard ascorbic acid (95.76%), whereas

compounds 5u, 5j, 5i and 5n showed moderate radical

scavenging activity and rest of the compounds showed

minimum activity. Amino functionality and heterocyclic

aromatic ring seem to favour the antioxidant activity.

Substantial evidence exists to support the role of both

oxygen and organic-free radical intermediates in the bio-

molecular interactions which contribute to the initiation,

promotion and/or progression stages of chemical carcino-

genesis (Trush and Kensler, 1991). Chemoprevention was

described as the use of natural or synthetic chemicals

allowing suppression, retardation or inversion of carcino-

genesis. Curcumin is a well-known chemopreventive agent

which has good antioxidant and potent cytotoxicity against

various human cancer cell lines (Duvoix et al., 2005). In

the present study, compounds 5k, 5u and 5f have shown

good antioxidant activity and significant cytotoxicity and

hence these compounds could be considered as chemo-

preventive agents.

Hydroxyl radical is known to react with all components

of DNA molecule, damaging both the purine and pyrimi-

dine bases and also deoxyribose backbone (Halliwell and

Gutteridge, 1999). Hydroxyl radicals are among the most

hyper ROS and are considered to be responsible for some

tissue damage occurring in inflammation. Results of

hydroxyl radical (HO•) scavenging activity of synthesized

chalcones are given in Table 3. These results revealed that

the synthesized compounds have shown moderate to min-

imum HO• scavenging activity. Compounds 5u, 5n, 5o, 5f,

5j and 5p showed moderate HO• radical scavenging

activity (63.15–57.89%) as compared to the standard

ascorbic acid (88.54%), whereas rest of the compounds

have minimum activity. Compounds containing electron

donating groups on aromatic ring B revealed higher HO•

scavenging activity as compared to their counterparts

containing electron withdrawing groups, with the exception

of 5f. Heteroaromatic compound (5u) has higher HO•

radical scavenging activity than its aromatic counterpart

(5a).

FRAP assay measures the ability of a compound to

reduce the Fe[(CN)6]3- to Fe[(CN)6]2-. The reducing

power associated with antioxidant activity reflects the

electron donating capacity of bioactive compounds (Xing

et al., 2005). The results of the reducing power of novel

olefin chalcones are presented in Table 3. These results

revealed that the compounds under study have promising

reducing ability. Compounds 5q, 5n, 5p, 5m and 5k

(69.27–64.83%) exhibited good reducing power as com-

pared to standard ascorbic acid (78.17), whereas com-

pounds 5r, 5t, 5u, 5o, 5e and 5s have shown moderate

activity and rest of compounds showed very low activity.

The SAR study revealed that compounds containing elec-

tron donating groups on aromatic ring B have higher

reducing power than their counterpart containing elec-

tronwithdrawing groups with the exception of the com-

pounds 5r and 5t. The presence of hydroxyl group imparts

the reduing power (5q), methylation of hydroxyl group (5s)

resulted in decreases activity. The bioisosteric replacement

Table 3 Antioxidant activity of novel olefin chalcones

Compound % DPPH

inhibition

% •OH

inhibition

Reducing

powerb

5a 27.88 ± 2.20 41.35 ± 1.35 58.38 ± 1.87

5b 23.26 ± 1.73 44.36 ± 2.66 50.32 ± 2.09

5c 22.88 ± 3.09 38.72 ± 1.83 48.30 ± 2.29

5d 22.30 ± 2.38 34.96 ± 1.51 50.72 ± 2.37

5e 22.69 ± 1.62 36.46 ± 1.43 59.59 ± 1.05

5f 56.92 ± 3.11 59.77 ± 1.71 46.69 ± 2.46

5g 25 ± 2.83 51.50 ± 1.27 46.29 ± 1.37

5h 20.38 ± 1.87 16.91 ± 1.30 41.85 ± 1.83

5i 58.84 ± 1.99 52.25 ± 2.28 43.87 ± 2.19

5j 60.57 ± 1.76 59.02 ± 3.01 53.15 ± 2.56

5k 94.50 ± 3.12 55.63 ± 2.88 64.83 ± 2.10

5l 89.60 ± 3.35 54.13 ± 3.06 48.30 ± 2.92

5m 57.69 ± 1.60 54.88 ± 1.80 66.45 ± 1.37

5n 58.46 ± 1.26 59.77 ± 1.11 68.06 ± 1.55

5o 60.00 ± 2.38 59.77 ± 1.92 60.80 ± 2.37

5p 55.57 ± 3.25 57.89 ± 3.44 67.66 ± 2.92

5q 57.30 ± 2.09 51.12 ± 1.85 69.27 ± 1.44

5r 56.73 ± 2.62 48.12 ± 1.61 63.62 ± 3.20

5s 56.15 ± 2.19 46.61 ± 173 58.79 ± 1.46

5t 55.38 ± 2.84 48.49 ± 3.22 62.41 ± 1.37

5u 68.65 ± 2.46 63.15 ± 1.27 61.20 ± 1.05

AAa 95.76 ± 3.31 88.34 ± 1.96 78.17 ± 1.88

Values are mean ± S.E.M. of three parallel measurementsa Standard, Ascorbic acid at 1 mMb Ferric reducing antioxidant power (FRAP) assay, all the compounds

tested at 100 lg

Med Chem Res (2012) 21:4512–4522 4519

123

of phenyl group (5a) by heterocyclic ring resulted in

increase in the reducing power (5u and 5e).

All the synthesized compounds were subjected to anti-

microbial activity by disk diffusion method against Esch-

erichia coli (DH5-a), Proteus vulgaris (MTCC 1751),

Staphylococcus aureus (MTCC 96) and Candida albicans

(MTCC 3017). Streptomycin and flucanazole are used as

standard drugs against bacteria and fungus, respectively.

The results of antimicrobial activity of novel olefin chal-

cones are presented in Table 4. Compounds 5k, 5s, 5a, 5c,

5n, 5m, 5p, 5o and 5j have shown good antibacterial

activity and inhibited the growth of both gram positive and

gram negative bacteria under study. The SAR study of

these compounds have shown that compounds containing

electron donating groups on aromatic ring B have higher

antibacterial activity than the compounds containing elec-

tron withdrawing groups with the exception of 5c. Com-

pounds with heteroaromatic ring 5u and 5e have lower

antibacterial activity than their aromatic counterpart (5a).

Compounds with methoxy group on aromatic ring B have

higher antibacterial activity (5s, 5m, 5p, 5o and 5j).

Compounds 5k and 5f showed good activity against Can-

dida albicans, while, compounds 5a and 5c have moderate

antifungal activity. Interestingly, compound 5l has mod-

erate antifungal activity, however, changing the position of

amino group on aromatic ring B from meta (5k) to para

postion (5l) there is a significant decrease in the activity. It

seems that the meta substitution in the compounds is nec-

essary for antifungal activity. In general most of the chal-

cones under study are inactive against Candida albicans.

About 30% of oral drugs fail in development due to

poor pharmacokinetics (Waterbeemd and Gifford, 2003).

Among the pharmacokinetic properties, a low and highly

variable bioavailability is indeed the main reason for

stopping further development of the drugs. An in silico

model for predicting oral bioavailability is very important,

both in the early stage of drug discovery to select the most

promising compounds for further optimization and in the

later stage to identify candidates for further clinical

development. In silico prediction of oral bioavailability is

pioneered by Lipinski et al. (1997) who put forwarded the

rule of five to determine the oral bioavailability of com-

pounds. The rule of five defines four simple physico-

chemical parameters for poor drug absorption and

permeation which are molecular weight [ 500,

cLogP [ 5, hydrogen bond acceptor [ 10 and hydrogen

bond donor [ 5. Results of physicochemical properties of

synthesized novel olefin chalcones are presented in

Table 5. These results revealed that all the compounds

obey the Lipinski rule of five. In addition to the molecular

properties discussed by Lipinski, Navia and Chaturvedi

(1996) has discussed other properties in regard to oral

bioavailability. They postulated the desirability of

molecular flexibility for membrane permeation which is

measured by the number of rotatable bonds. Compounds

with 10 or fewer rotatable bonds will have probability of

good oral bioavailability. The compounds under study have

the number of rotatable bonds less than 10 with the

exception of compound 5s which has 10 rotatable bonds.

Polar surface area (PSA) of a molecule encodes more

hydrogen bonding information, it refers to surface area of

the oxygen, nitrogen, sulphur and attached hydrogen atom,

and it has been shown to correlate well with drug transport

properties (Veber et al., 2002). A new and fast methodol-

ogy has been developed to calculate the PSA from frag-

ment contribution which is termed as TPSA. The TPSA

equal to or less than 140 A2 will have high probability of

good oral bioavailability. Results from Table 5 showed

that compounds under study have TPSA in the range

48.01–93.83. Drug likeness can be defined as a delicate

balance among the molecular properties of compound that

Table 4 Antimicrobial activity of novel olefin chalcones

Compound Zone of inhibition (mm)

EC SA PV CA

5a 5.5 ± 1.10 5 ± 1.47 2.5 ± 1.34 3.5 ± 1.70

5b 2 ± 2.29 0.5 ± 1.28 NR 0.5 ± 2.61

5c 4.5 ± 1.76 2 ± 1.21 7.5 ± 1.41 3.5 ± 1.58

5d 2 ± 1.39 0.5 ± 2.16 5.5 ± 1.36 1.5 ± 1.34

5e 1.1 ± 1.83 2.5 ± 1.30 6.5 ± 1.20 1.5 ± 2.29

5f 1.5 ± 1.77 5 ± 1.52 9.1 ± 1.16 5.5 ± 1.03

5g 2 ± 2.38 5 ± 1.38 4 ± 1.48 2 ± 1.56

5h 3 ± 1.51 2.5 ± 1.43 3 ± 2.27 ND

5i 2 ± 1.19 2.5 ± 2.37 4 ± 1.15 1.1 ± 2.12

5j 3.15 ± 1.72 2.5 ± 1.35 3.5 ± 1.23 ND

5k 3.5 ± 1.41 3.5 ± 1.66 7 ± 1.05 6.30 ± 1.30

5l 6.5 ± 1.04 1.5 ± 2.76 5 ± 2.61 2.9 ± 1.19

5m 2.5 ± 2.24 5 ± 1.62 5 ± 1.82 ND

5n 2.5 ± 1.20 5 ± 2.18 10.2 ± 1.11 0.1 ± 2.12

5o 3.5 ± 1.63 2.5 ± 1.20 3 ± 1.08 ND

5p 3.5 ± 1.25 2.5 ± 1.52 7 ± 1.45 ND

5q 2 ± 1.37 1.5 ± 1.80 9.5 ± 1.55 ND

5r 2.5 ± 2.64 1.1 ± 2.16 5.5 ± 1.72 1.1 ± 1.02

5s 3.5 ± 1.61 3.5 ± 1.27 3.5 ± 2.61 ND

5t 1.5 ± 1.43 1.5 ± 2.61 6.5 ± 1.35 1.5 ± 1.42

5u 6.25 ± 1.01 1.1 ± 1.11 3 ± 1.23 1.5 ± 1.20

Streptomycina 2.5 ± 1.45 2 ± 1.57 2.4 ± 1.4 –

Flucanozoleb – – – 6.5 ± 1.29

Values are mean ± SEM of three parallel measurements

ND not determined, data represent mean of two replicates; ECEscherichia coli; SA Staphylococcus aureus; PV Proteus vulgaris; CACandida albicansa Standard at 20 lg, b standard at 10 lg, all the compound tested at

100 lg

4520 Med Chem Res (2012) 21:4512–4522

123

influence its pharmacodynamics and pharmacokinetics and

ultimately affect their absorption, distribution, metabolism

and excretion in human body (Vistolli et al., 2008).

Compounds under study showed good drug likeness score

in the range 0.20–5.85. The importance of aqueous solu-

bility for drug design can be recognized at all stages of

drug development. The solubility is extremely important as

it determines uptake, movement and elimination of the

substances from the body (Balakin et al., 2006). We have

calculated the aqueous solubility of synthesized com-

pounds as ALOGPS and all compounds possess good water

solubility in the range 0.90–85.77 mg/l. Overall, all the

synthesized compounds comply with the rules of Lipinski

and other parameter such as number of rotatable bonds,

TPSA and aqueous solubility. Hence in principle, all of

these compounds could be considered as good oral

candidates.

Conclusion

In this study, we have synthesized a series of novel olefin

chalcones and screened for ADME and drug likeness, all

the compounds have shown good ADME and drug likeness

profile could be considered as good oral drug candidates.

Synthesized compounds were evaluated for cytotoxicity,

antioxidant and antimicrobial activities. Compounds 5u,

5g, 5c and 5e have shown significant cytotoxicity against

Hep 3BPN 7, electron withdrawing groups on aromatic

ring B had higher cytotoxicity. Compounds 5j, 5i, 5n and

5o showed good cytotoxicity against HL 60 P 58, electron

donating groups on aromatic ring B enhance the cytotox-

icity. Compounds 5f, 5c, 5e and 5b showed potent cyto-

toxicity against Hela B 75. The present study revealed that

these chalcones were potent cytotoxic agents against

tumour cell lines without being more toxic to normal cells.

Compounds 5k and 5l have shown good free radical

scavenging activity. Compounds 5k, 5s, 5a and 5c showed

promising antibacterial activity. Compounds 5k, 5u and 5f

could be considered as chemopreventive agents.

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