Synthesis, spectral characterization and larvicidal activity of acridin-1(2H)-one analogues

Article abstract of DOI:10.1016/j.saa.2012.04.015

Acridin-1(2H)-one analogue of 7-chloro-3,4-dihydro-9-phenyl-2-[(pyridine- 2yl) methylene] acridin-1(2H)-one, 5 was prepared by using 7-chloro-3,4-dihydro- 9-phenylacridin-1(2H)-one, 3 and picolinaldehyde, 4 in the presence of KOH at room temperature. Thes

Full text of DOI:10.1016/j.saa.2012.04.015

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 442–445
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis, spectral characterization and larvicidal activity
of acridin-1(2H)-one analogues
b
b,
R. Subashini a, A. Bharathi a, Selvaraj Mohana Roopan a, , G. Rajakumar , A. Abdul Rahuman
⇑
⇑
,
Pavan Kumar Gullanki a
a Chemistry Research Laboratory, Organic Chemistry Division, School of Advanced Sciences, VIT University, Vellore 632 014, Tamil Nadu, India
b Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C. Abdul Hakeem College,
Melvisharam 632 509, Vellore District, Tamil Nadu, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Acridin-1(2H)-one analogue of 7-chloro-3,4-dihydro-9-phenyl-2-[(pyridine-2yl) methylene] acridin-
1(2H)-one, 5 was prepared by using 7-chloro-3,4-dihydro-9-phenylacridin-1(2H)-one, 3 and picolinalde-
hyde, 4 in the presence of KOH at room temperature. These compounds were characterized by analytical
and spectral analyses. The purpose of the present study was to assess the efficacy of larvicidal and repel-
lent activity of synthesized 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues such as com-
pounds 3 and 5 against the early fourth instar larvae of filariasis vector, Culex quinquefasciatus and
Japanese encephalitis vector, Culex gelidus (Diptera: Culicidae). The compound exhibited high larvicidal
effects at 50 mg/L against both the mosquitoes with LC50 values of 25.02 mg/L (r2 = 0.998) and
26.40 mg/L (r2 = 0.988) against C. quinquefasciatus and C. gelidus, respectively. The 7-chloro-3,4-dihy-
dro-9-phenyl-acridin-1(2H)-one analogues that are reported for the first time to our best of knowledge
can be better explored for the control of mosquito population. This is an ideal ecofriendly approach for
the control of Japanese encephalitis vectors, C. quinquefasciatus and C. gelidus.
Received 13 February 2012
Received in revised form 13 March 2012
Accepted 3 April 2012
Available online 23 April 2012
Keywords:
Synthesis
Acridin-1(2H)-one
NMR
Mass
Vector
Ó 2012 Elsevier B.V. All rights reserved.
Introduction
activity against larval stages of C. tritaeniorhynchus [5]. Despite
variation in geographic distribution of the virus, mosquito vector
The Culex quinquefasciatus is the most widely distributed mos-
quito in India, mainly found in urban and suburban areas.
Synthetic chemical larvicides continue to be applied for controlling
mosquitoes in most parts of the world. But many of these chemi-
cals are toxic to human, plant and animal life and resistance can
be problematic in maintaining control, especially with organo-
phosphate and pyrethroid larvicides [1]. The C. quinquefasciatus, a
vector of lymphatic filariasis, India, is endemic for lymphatic filari-
asis caused by Wuchereria bancrofti [2]. Lymphatic filariasis is a
widely distributed tropical disease with around 120 million people
infected worldwide. Japanese encephalitis (JE) is a disease caused
by an arbovirus that is mainly transmitted by the bite of infected
Culex tritaeniorhynchus mosquitoes. The annual incidence and
mortality estimates for JE are 30,000 to 50,000 and 10,000,
respectively, [3]. The methanol extracts of dried root powder
of Rhinacanthus nasutus was tested against A. aegypti and
C.quinquefasciatus larvae [4]. The petroleum ether (60–80 °C) ex-
tracts of the leaves of Vitex negundo were evaluated for larvicidal
species is relatively constant. The most important mosquito vector
in Asia is C. tritaeniorhynchus, which breeds in stagnant waters like
paddy fields or drainage ditches [6]. Other species are Culex vishnui
(India), C. gelidus and Culex fuscocephala [7] (India, Malaysia and
Thailand). The adults are mainly exophilic and often stay indoors
before and after feeding on blood [8]. They are mainly zoophagous
but also feed on man. C. tritaeniorhynchus can also act as a vector of
filariasis.
Insecticide resistance is increasingly becoming a problem for
malaria vector control programmes. Widespread use of the same
insecticides in the agricultural sector has made the situation
worse. Resistance may develop due to changes in the mosquito’s
enzyme systems, resulting in more rapid detoxification or seques-
tration of the insecticide, or due to mutations in the target site pre-
venting the insecticide–target site interaction [9]. Insecticides that
can be used in malaria control are increasingly becoming limited.
C. tritaeniorhynchus was found susceptible to permethrin and resis-
tant to DDT, dieldrin, fenitrothion and propoxur [10] and resistant
to organophosphorous insecticides [11]. The aphid control mea-
sures have largely been depending on the use of chemical pesti-
cides, including chlorinated hydrocarbons, organophosphates and
carbamates [12], which cause resistant development in the target
population [13].
⇑
Corresponding authors. Tel.: +91 98656 10356, +91 04162 202831, +91 94423
10155, +91 04172 269009.
E-mail addresses: mohanaroopan.s@gmail.com (S.M. Roopan), abdulrahu-
man6@hotmail.com (A. Abdul Rahuman).
1386-1425/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2012.04.015

R. Subashini et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 442–445
443
There are numerous biologically active fused heterocyclic rings.
Among these acridone and its analogues are one such scaffold
known to associate with several biological activities [14] such as
amsacrine (cytotoxic and antiviral agents) [15], clomacran (tran-
quilizer), monometacrine (antidepressant), acridine carboxamide
(antitumour) [16] and in natural products such as plakinidine A
and B (anthelmintic) [17], dercitin (anticancer) [18]. Among the
naturally occurring compounds, chalcones and their synthetic ana-
logues possess good biological properties. They are also effective
in vivo as cell proliferating inhibitors, anti-tumour promoting and
chemo preventing agents. Since a number of clinically useful anti-
cancer drugs have genotoxic effects due to interaction with the
amino groups of nucleic acids, chalcones may be devoid of this
important side effect [19]. Some chalcones are a very important
class of compounds from a biological point of view, particularly
as anti-oxidants, anti-inflammatory, pulmonary carcinogens inhib-
itors, antimalarial and anti-leishmanials [20]. Chalcones are key
precursors in the synthesis of a large array of biologically impor-
tant heterocycles. Thus, the synthesis of chalcones has generated
a vast interest to organic/medicinal chemists.
performed by using silica gel (60ꢀ120 mesh). Melting points were
measured on Elchem Microprocessor based DT apparatus using an
open capillary tube and are corrected with standard benzoic acid.
The NMR spectra were recorded on a Bruker Advance III –
500 MHz spectrometer using TMS as internal standard (chemical
shifts d in ppm). Mass was recorded on Finnigan Mat 8230 Mass
Spectrometer.
Chemistry
The synthetic strategy leading to the key precursor 1 and 2 and
the target compounds 3 and 5 are illustrated in Fig. 1. The key
intermediates, 7-chloro-3,4-dihydro-9-phenylacridin-1(2H)-one,
3 was prepared by using 2-amino-5-chlorobenzophenone, 1 with
cyclohexane-1,3-dione, 2 in the presence of glacial CH3COOH and
Conc. H2SO4 at 150 °C for 6 h. The compound 5 was prepared by
the reaction of compound 3 with picolinaldehyde, 4 in the pres-
ence of KOH.
General procedure for the synthesis of 7-chloro-3,4-dihydro-9-phenyl-
Among the various methods solvent-free chemical reactions are
gaining importance due to the advantages and environmentally
friendly processes they offer, as compared to conventional reac-
tions [21]. In recent years organic reactions in the solid state have
been attracting the synthetic organic chemists because of their
simplicity and synthetic value [22,23]. Therefore, these facts led
us to investigate the neat reaction [24]. It has many advantages
including, reduced pollution, low costs and simplicity in process
and handling. In this report we have achieved 7-chloro-3,4-dihy-
dro-9-phenyl-2-[(pyridine-2yl) methylene] acridin-1(2H)-one, 5
using green chemical approach. The efficacy of larvicidal and repel-
lent activity of synthesized compounds 3 and 5 against the early
fourth instar larvae of filariasis vector that is, C. quinquefasciatus,
Japanese encephalitis vector, that is, C. gelidus is reported here.
acridin-1(2H)-one analogues, 3, 5
7-Chloro-3,4-dihydro-9-phenylacridin-1(2H)-one, 3
In a round bottom flask, a mixture of 2-Amino-5-chloro benzo-
phenone, 1 (0.01 mol), 1, 3-hexanedione, 2 (0.012 mol), glacial ace-
tic acid (10 mL) and conc.H2SO4 (3–4 drops) were heated at 150 °C
for 6 h. The completion of the reaction was monitored by TLC.
Then the reaction mixture was cooled at room temperature fol-
lowed by this mixture was added to the crushed ice with drop by
drop addition. The solid formed was allowed to stand for 30 min
and filtered off to dryness. Then the compound was recrystallized
using ethanol. The structure of the recrystallized compound 3 was
confirmed by 1H NMR 1H NMR, 13C NMR and Mass analysis.
7-Chloro-3,4-dihydro-9-phenyl-2-[(pyridine-2yl) methylene]
Materials and methods
acridin-1(2H)-one, 5
About
7-chloro-3,4-dihydro-9-phenylacridin-1(2H)-one,
3
Chemicals and instruments
(0.001 mol) and picolinaldehyde, 4 (0.001 mol) were taken in a
mortar. KOH (5 pellet) was added to the mortar and grind well
and leave it for 5 h at room temperature to get compound 5. The
completion of the reaction was monitored by checking TLC. Then
the reaction mixture was cooled at room temperature followed
by this mixture was added to the crushed ice with drop by drop
Solvents and reagents were commercially sourced and used
without further purification. Thin layered chromatography (TLC)
was performed on preparative plates of silica gel. Visualization
was made with iodine chamber. Column chromatography was
O
O
Cl
Cl
gla. CH3COOH
O
+
H
H2SO4
N
H2
N
O
150 0C/ 6 hrs
O
N
1
3
2
4
KOH, RT, 5 hr
O
Cl
N
N
5
Fig. 1. Synthesis of 7-chloro-3,4-dihydro-9-phenyl-2-pyridine2yl)methylene]acridin-1(2H)-one, 5.

444
R. Subashini et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 442–445
addition. The solution was neutralized by the addition of dil. HCl.
Then the precipitate was allowed to settle down and filtered off
and dried. The product so obtained was purified by performing col-
umn chromatography using petroleum ether and ethylacetate in
the ratio of 9:1. Purified compound was confirmed by 1H NMR,
13C NMR and Mass analysis.
concentration. The numbers of dead larvae were counted after
24 h of exposure C. quinquefasciatus and C. gelidus, the percentage
mortality was reported from the average of five replicates.
However, at the end of 24 h the selected test samples turned out
to be equal in their toxic potential.
Statistical analysis
Mosquito larvicidal assay
The average larval mortality data were subjected to probit anal-
ysis for calculating LC50 and other statistics at 95% fiducial limits of
upper confidence limit and lower confidence limit were calculated
[26]. Results with p < 0.05 were considered to be statistically
significant.
Insect rearing
The C. quinquefasciatus and C. gelidus larvae were collected from
rice field and stagnant water area of Melvisharam (12° 5602300 N,
79°1402300 E) and identified in Zonal Entomological Research
Centre, Vellore (12°5504800 N, 79°704800 E), Tamil Nadu, to start the
colony, and larvae were kept in plastic and enamel trays containing
tap water. They were maintained and reared in the laboratory as
per the reported method [25].
Results
Spectral data of compounds 3 and 5
Larvicidal bioassay
The nature of the compound 3 is yellow in colour with 81%
yield, and the melting point is 185 °C. The spectral data of com-
pound 3 as 1H NMR (CDCl3): d (ppm) 2.24–2.31 (q, 2H, –CH2),
2.72 (t, 2H, –CH2), 3.38 (t, 2H, –CH2), 7.16–7.19 (m, 2H), 7.43–7.44
(d, 1H), 7.52–7.54 (q, 3H), 7.69–7.72 (q, 1H), 8.01 (t, 1H); 13C NMR
(CDCl3): d (ppm) 21.2, 34.4, 40.5, 124.4, 126.7, 127.9, 128.3, 130.0,
132.4, 132.6, 136.8, 146.9, 162.5, 197.6. HRMS is the further sup-
ported data for finding the formation of expected compound 3,
and we have observed the molecular ion peak around 307.0764.
The fragmentation as follows 307.0764 (5%), 281.0728 (17%),
219.2697 (10%), 155.2955 (21%), 143.2400 (100%), 128.2381
(100%), 112.3339 (30%), 100.3460 (75%), 80.3947 (100%), 74.4690
(80%), 61.2416 (100%).
During preliminary screening with the laboratory trial, the
larvae of C. quinquefasciatus and C. gelidus were collected from
the insect-rearing cage and identified in the Zonal Entomological
Research Centre, Vellore. For the bioassay test, mosquito larvae
were taken in five batches of 20 in 250 mL of water and Physico-
chemical data of synthesized compounds 3 and 5. The control
was set up with dechlorinated tap water. The number of dead
larvae was counted after 24 h of exposure, and the percentage of
mortality was reported from the average of five replicates. The
experimental media in which 100% mortality of larvae occurs alone
were selected for dose response bioassay.
Dose response bioassay
The melting point that we have observed for compound 5 is
191 °C with 92% yield. The NMR report of compound 5 is supported
for the compound confirmation. 1H NMR (CDCl3): d (ppm) 2.24–2.31
(q, 2H, –CH2), 2.72 (t, 2H, –CH2), 3.38 (t, 2H, –CH2), 7.16–7.19 (m,
2H), 7.43–7.44 (d, 1H), 7.52–7.54 (q, 3H), 7.69–7.72 (q, 1H), 8.01
(t, 1H); 13C NMR (CDCl3): d (ppm) 25.4, 33.2, 122.9, 126.6, 127.5,
128.4, 132.4, 134.3, 136.4, 136.6, 139.1, 146.9, 149.5, 150.7, 155.0,
161.9, 187.9. Further this target molecule has been confirmed by
The synthesized compounds 3 and 5 toxicity test was per-
formed by placing 20 mosquito larvae into 200 mL of sterilized
double-distilled water with nanoparticles into a 250-mL beaker
(Borosil). The synthesized compound solutions were diluted using
double-distilled water as a solvent according to the desired
concentrations (50 and 10 mg/L). Each test included a set of control
group (distilled water) with five replicates for each individual
Table 1
Mosquito larvicidal activity of compounds 3 and 5 against the early fourth instar larvae of C. quinquefasciatus and C. gelidus.
Compounds
Species
Concentrations
(mg/L)
% Mortality
(mg/L) SD
95% Confidence
Slope
r2
interval for
LC50 (LCL–UCL)a
(mg/L)
C. quinquefasciatus
50
40
30
20
10
50
40
30
20
10
50
40
30
20
10
50
40
30
20
10
62
44
31
16
07
59
38
26
14
04
100
83
52
34
17
100
79
56
31
20
3
42.78
37.5–48.78
31
14
34
56
0.989
0.978
0.998
0.988
C. gelidus
45.44
42.1–48.95
C. quinquefasciatus
C. gelidus
5
25.02
22.5–27.76
26.40
23.7–28.59
a
LCL, lower confidence level; UCL, upper confidence level.

R. Subashini et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 95 (2012) 442–445
445
High Resonance Mass Spectrometry. The calculated mass is
396.1029 but the actual mass that we have observed through HRMS
is 396.1028. The fragmentation is as follows 396.1028 (37%),
302.2106 (13%), 351.0925 (13), 292.9968 (25%), 229.0848 (40%),
209.0697 (100%), 79.1620 (55%), 190.0011 (15%), 135.1195 (20%).
of mosquito population by using compounds 3 and 5. This is an
ideal eco-friendly approach for the control of filariasis vector, C.
quinquefasciatus and Japanese encephalitis vector, C. gelidus.
Acknowledgements
Mosquito larvicidal activity of compounds 3 and 5
The authors are grateful to VIT University, Vellore and C. Abdul
Hakeem College, Melvisharam management for providing the
necessary research facility and their support.
In the present study, mosquito’s larvae were exposed to varying
concentrations of synthesized compounds 3 and 5 for 24 h. The
larval percent mortality observed in green synthesis of synthetic
compound 3 was 07, 16, 31, 44 and 62; 04, 14, 26, 38 and 59 at
50 mg/L against C. quinquefasciatus and C. gelidus respectively. Values
of the efficacy of compound 3 were against C. quinquefasciatus
(LC50 = 42.78 mg/L; r2 = 0.989) and C. gelidus (LC50 = 45.44 mg/L;
r2 = 0.978). The larval percent mortality observed in green synthe-
sis of synthetic compound 5 was 17, 34, 52, 83 and 100; 20, 31, 56,
79 and 100 at 50 mg/L against C. quinquefasciatus and C. gelidus,
respectively. The maximum efficacy was observed in compound
5 against the larvae of C. quinquefasciatus (LC50 = 25.02 mg/L;
r2 = 0.998) and C. gelidus (LC50 = 26.40 mg/L; r2 = 0.988), respec-
tively. In the present study, the larvicidal activity results showed
the highest mortality in compound 5 than 3. The control (distilled
water) showed nil mortality in the concurrent assay. The chi-
square value was significant at p 6 0.05 level. The complete
mortality was observed for compounds 3 and 5 for larvae of
C. quinquefasciatus and C. gelidus at 50 mg/L (Table 1).
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.saa.2012.04.015.
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All the compounds 3 and 5 were screened for the efficacy of lar-
vicidal and repellent activity against the early fourth instar larvae
of filariasis vector (C. quinquefasciatus) and Japans encephalitis vec-
tor (C. gelidus) at 10–50 mg/mL. The compounds exhibited high lar-
vicidal effects at 50 mg/L against both the mosquitoes with LC50
values of 25.02 mg/L (r2 = 0.998) and 26.40 mg/L (r2 = 0.998)
against C. quinquefasciatus and C. gelidus respectively. To our best
of knowledge there is no report in the literature for the control