Bernthsen synthesis, antimicrobial activities and cytotoxicity of acridine derivatives

Article abstract of DOI:10.1016/j.bmcl.2010.06.001

The condensation reaction of diphenylamine with 2-oxo-2H-(substituted chromen)-4-yl acetic acid in presence of anhydrous zinc chloride afford 4-(acridine-9-ylmethyl)-2H-(substituted chromen)-2-one. The synthesized compounds were characterized by spectral studies and elemental analysis and screened for their in vitro antibacterial activity against Staphylococcus aureus, Staphylococcus pyogenes (gram +ve), Escherichia coli, Pseudomonas aeruginosa (gram -ve) and antifungal activity against Aspergillus niger and anticancer activity (HL-60, Hep-2 & HEK293T) by MTT assay. Chloro substituted compounds showed antimicrobial and anticancer activity with IC ₅₀ values in the low micromolar range.

Full text of DOI:10.1016/j.bmcl.2010.06.001

Bioorganic & Medicinal Chemistry Letters 20 (2010) 6324–6326
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Bernthsen synthesis, antimicrobial activities and cytotoxicity of acridine
derivatives
⇑
Mehul M. Patel, Mimansha D. Mali, Saurabh K. Patel
Chemistry Research laboratory, Department of Chemistry, Veer Narmad South Gujarat University, Surat 395 007, Gujarat, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The condensation reaction of diphenylamine with 2-oxo-2H-(substituted chromen)-4-yl acetic acid in
presence of anhydrous zinc chloride afford 4-(acridine-9-ylmethyl)-2H-(substituted chromen)-2-one.
The synthesized compounds were characterized by spectral studies and elemental analysis and screened
for their in vitro antibacterial activity against Staphylococcus aureus, Staphylococcus pyogenes (gram +ve),
Escherichia coli, Pseudomonas aeruginosa (gram Àve) and antifungal activity against Aspergillus niger and
anticancer activity (HL-60, Hep-2 & HEK293T) by MTT assay. Chloro substituted compounds showed anti-
microbial and anticancer activity with IC50 values in the low micromolar range.
Received 5 February 2010
Revised 14 May 2010
Accepted 1 June 2010
Available online 4 June 2010
Keywords:
4-(Acridin-9-ylmethyl)-2H-(substituted
chromen)-2-one
Ó 2010 Published by Elsevier Ltd.
Antibacterial activity
Antifungal activity
Anticancer activity
Acridine-based pharmacophores have wide applications in anti-
microbial and anticancer therapy. The discovery of acridines as
antimalarial and antitumor agents have attracted the attention of
organic chemists and thus led to intensive interest in the synthesis
of several drugs based on acridine.1,2 Acridines are known to be
biologically versatile compounds possessing several biological
activities.3,4 Some of the acridine derivatives bearing a heterocy-
clic/aromatic ring system as one of the substituents have been
found to be associated with biological activities. Nitrogen-contain-
ing heterocycles are indispensable structural units for medicinal
chemists. Many compounds containing the acridine chromophore
were synthesized and tested, and the aminoacridines found wide
use,5,6 both as antibacterial agents and as antimalarial. Acridines
show a wide spectrum of biological activities such as DNA interca-
lating agents, anticancer,7 antitumor,8 analgesic,9 anticonvulsant,10
hypertensive and anti-inflammatory.11
The Benzopyrones are a group of compounds whose members
include coumarins and flavonoids. Dietary exposure to benzopyro-
nes is quite significant, as these compounds are found in vegeta-
bles, fruits, seeds, nuts, coffee, tea and wine. Coumarins have
multiple biological activities including disease prevention, growth
modulation and anti-oxidant properties.12 Coumarin is a natural
substance that has shown anti-tumor activity in vivo, with the ef-
fect believed to be due to its metabolites (e.g., 7-hydroxycouma-
rin). Based on the survey of recent studies on acridines and
coumarins, the focus of our work is synthesis of relevant com-
pounds and their therapeutic importance.
The synthesis of the compounds was carried as outlined in
Scheme 1. The compound, (2-oxo-2H-(substituted chromen)-4-
yl)acetic acid 2(a–h) was synthesized by pechmann condensation
using various derivative of phenol 1(a–h) and obtained as white
needle crystals with good 68% yield.13,14 We report a simple and
an efficient one pot synthesis of a few acridine derivatives through
the condensation reaction of diphenylamine (3) with various (2-
oxo-2H (substituted chromen)-4-yl)acetic acid 2(a–h). Synthesis
of 4-(acridin-9-ylmethyl)-2H-(substituted chromen)-2-one 4(a–h)
as a first approach, the reactants (diphenylamine, zinc chloride
and (2-oxo-2H-(substituted chromen)-4-yl)acetic acid) were
mixed in the stoichiometry ratio (1:5:3) used in literature for the
conventional heating, by acid-catalyzed Bernthsen synthesis.15
Molecular formula and structures of the compounds were in accor-
dance with by spectral data and elements analytical data.16
All the synthesized compounds were evaluated for their in vitro
antibacterial activity against Staphylococcus aureus, Staphylococcus
pyogenes (gram +ve), Escherichia coli, Pseudomonas aeruginosa (gram
Àve) and for their antifungal activity against Aspergillus niger by
agar plate disk diffusion method and compared with standard
drugs. The results are given in Table 1. The synthesized compounds
are tested against bacterial species with MIC values ranging from
25 to 1000 l
g/mL.17 While considering all the newly synthesized
compounds of this series together, we may conclude that: ampicil-
lin, chloramphenicol, ciprofloxacin, norfloxacin, nystatin, and gre-
seofulvin were use as standard drugs. From the screening results,
molecule 4g (R = H, R1 = Cl) showed outstanding activity against
⇑
Corresponding author. Tel.: +91 9825121977.
E-mail address: saurabh@vnsgu.ac.in (S.K. Patel).
0960-894X/$ - see front matter Ó 2010 Published by Elsevier Ltd.
doi:10.1016/j.bmcl.2010.06.001

M. M. Patel et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6324–6326
6325
N
OH
H2C
C
COOH
O
R
O
(i)
(ii)
3
CH2
HO
COOH
COOH
+
R1
R
R1
H2C
R
CH2COOH
R1
O
O
2(a-h)
1(a-h)
4(a-h)
OH
OH
OH
OH
OH
OH
1c
OH
OH
OH
Cl
CH3
NO2
OH
1h
Cl
CH3
1d
1g
1f
1a
1e
1b
Scheme 1. Reagents and conditions: (i) concd H2SO4; (ii) ZnCl2, 230 °C, 20 h.
Table 1
Antimicrobial activity of synthesized compounds (4a–h)
Compound
Gram-positive bacteria
Gram-negative bacteria
P. aeruginosa
Fungal
S. aureus
S. pyogenes
E. coli
A. niger
4a
4b
4c
4d
4e
4f
4g
4h
250
250
500
125
50
500
250
500
250
50
250
500
50
100
250
500
75
250
100
50
250
100
150
125
50
200
75
50
100
50
25
10
—
250
200
62.5
125
500
250
25
100
100
50
500
500
1000
500
1000
>1000
1000
250
—
—
—
—
100
100
Amicillin
Chloramphenicol
Ciprofloxacin
Norfloxacin
Nystatin
Greseofulvin
50
10
—
—
50
10
—
—
25
10
—
—
—
Table 2
Gram-negative P. Aeruginosa, as compared with chloramphenicol
and ciprofloxacin (Table 1) whereas compounds 4e (R = Cl, R1 =
H) and 4h (R = H, R1 = OH) displayed brilliant activity against
Gram-negative bacteria E. coli. Compound 4e (R = Cl, R1 = H)
showed excellent antimicrobial activity against the gram-positive
bacteria S. Aureus as compared with ampicillin. Compound 4c
(R = CH3, R1 = H) exhibits exceptional activity against gram-posi-
tive bacteria S. Pyogenes whereas other compounds showed mod-
erate to poor activity against all bacterial strains compared with
the standard drugs. All the synthesized compounds showed only
moderate anti fungal activity.
In vitro cytotoxicity evaluation of substituted 4-(acridine-9-yl-
methyl)-2H-(substituted chromen)-2-one (4a–g) derivatives were
carried out against HL-60 (Human leukemia) and Hep-2 (Human
larynx carcinoma) and one normal cell line HEK293T (Human
embryonic kidney). The cytotoxicity assay was performed by
MTT in Table 2. The MTT Assay is a well-established colorimetric
assay, which can be used to detect the effects of agents on cellular
metabolism. Derivatives of acridine, compounds 4e and 4g showed
good cytotoxicity against HL-60 cells. None of the derivatives
showed cytotoxicity against Hep-2 cells and HEK293T cells in the
IC50 values (lM) of Acridine derivatives on three different cell lines
Sample code
IC50 values (
lM)
Hep-2
HL-60
HEK293T
4a
4b
4c
4d
4e
4f
4g
4h
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
27.53
>100
28.72
>100
8.79
>100
>100
>100
>100
>100
>100
>100
>100
>100
Cyclophosphamide
*
IC50 is the concentration of compound required to inhibit the cell growth by 50%.
mide (CP), a widely used anticancer and immunosuppressive
agent, is itself a prodrug, and IC50 value of standard anticancer drug
(Cyclophosphamide) was evaluated against same cell lines. Cyclo-
phosphamide was more potent against HL-60 (Human leukemia)
and compared to Hep-2 (Human larynx carcinoma) and HEK293T
(Human embryonic kidney) in vitro.
compound concentration range of 0.005–100 lM. Cyclophospha-

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M. M. Patel et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6324–6326
11. Sondhi, S. M.; Bhattacharjee, G. Cent. Eur. J. Chem. 2004, 2, 1.
In conclusion, acridine and coumarin related compounds have
12. Lacy, A.; Kennedy, O. R. Curr. Pharm. Des. 2004, 10, 3797.
13. Vinogradova, S. V.; Tur, D. R. Poly. Sci. USSR 1973, 15, 323.
14. Korshak, V. V.; Vinogradova, S. V.; Pankratov, V. A. Plast. Massy. 1967, 5, 21;
Chem. Abstr. 1967, 67, 54496.
proved for many years to have significant therapeutic potential.
They come from a wide variety of natural sources and new acridine
derivatives are being discovered or synthesised on a regular basis.
However, their vital role in plant and animal biology has not been
fully exploited. Series of 4-(acridine-9-ylmethyl)-2H-(substituted
chromen)-2-one have been prepared in one pot synthesis. It is evi-
dent from the research described that synthesized compounds are
a plentiful source of potential anti-cancer drugs deserving further
study.
15. Bernthsen, A. Justus Liebigs Ann. Chem. 1884, 224, 1.
16. Spectral data of compounds: 4-(acridin-9-ylmethyl)-2H-chromen-2-one (4a):
Yield 68%; mp 250–252 °C; IR (KBr) 2828, 1765, 1455, 1025 cmÀ1
;
1H
NMR(400 MHz, CDCl3)
23H15NO2 requires C, 81.88; H, 4.48; N, 4.15; founds C, 81.85; H, 4.45; N, 4.11.
4-(Acridin-9-ylmethyl)-7-nitro-2H-chromen-2-one (4b): Yield 72%; mp 280–
284 °C; IR (KBr) 2850, 1770, 1459, 1028 cmÀ1 1H NMR (400 MHz, CDCl3) d 2.60
d 2.57 (s, 2H, –CH2–), 7.00–7.69 (m, 15H, Ar-H);
C
;
(s, 2H, CH2–), 7.10–7.89 (m, 14H, Ar-H); C23H14N2O4 requires C, 2.00; H, 7.59;
N, 16.68; founds C, 72.25; H, 7.69; N, 16.74. 4-(Acridin-9-ylmethyl)-7-methyl-
2H-chromen-2-one (4c): Yield 72%; mp 267–270 °C; IR (KBr) 2885, 1768, 1458,
Acknowledgments
1027 cmÀ1 1H NMR (400 MHz, CDCl3) d 1.30 (s, 3H, CH3–), 2.65 (s, 2H, CH2–),
;
7.15–7.90 (m, 17H, Ar-H); C24H17NO2 requires C, 81.96; H, 4.78; N, 3.90; founds
C, 82.03; H, 4.88; N, 3.99. 4-(Acridin-9-ylmethyl)-6-methyl-2H-chromen-2-
The authors are thankful to SAIF, Chandigarh for providing spec-
tral and analytical data of the compounds. The author also grateful
to Department of Bioscience and Veer Narmad South Gujarat Uni-
versity, Surat for providing help in carrying out the antimicrobial
screening.
one (4d): Yield 72%; mp 250–254 °C; IR (KBr) 2860, 1758, 1460, 1022 cmÀ1 1H
;
NMR (400 MHz, CDCl3) d 1.22 (s, 3H, CH3–), 2.58 (s, 2H, CH2–), 7.13–7.80 (m,
17H, Ar-H); C24H17NO2 requires C, 82.00; H, 4.80; N, 3.91; founds C, 82.03; H,
4.88; N, 3.99. 4-(Acridin-9-ylmethyl)-7-chloro-2H-chromen-2-one (4e): Yield
69%; mp 255–259 °C; IR (KBr) 2838, 1740, 1462, 1015, 810 cmÀ1 1H NMR
;
(400 MHz, CDCl3) d 2.608 (s, 2H, CH2–), 7.00–7.75 (m, 14H, Ar-H); C23H14ClNO2
requires C,74.17; H, 3.79; N, 3.67; founds C,74.30; H, 3.80; N, 3.77. 4-(Acridin-
9-ylmethyl)-7-hydroxy-2H-chromen-2-one (4f): Yield 70%; mp 250–252 °C; IR
References and notes
(KBr) 3378, 2839, 1770, 1462, 1024 cmÀ1 1H NMR (400 MHz, CDCl3) d 8.89
;
(s,1H, –OH), 2.39 (s, 2H, CH2–), 7.03–7.81 (m, 15H, Ar-H); C23H15NO3 requires
C, 78.12; H, 4.22; N, 3.90; founds C, 78.17; H, 4.28; N, 3.96. 4-(Acridin-9-
ylmethyl)-7-chloro-2H-chromen-2-one (4g): Yield 69%; mp 277–280 °C; IR
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;
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