Many naturally occurring and synthetic compounds containing dihydrocyanopyridine and cyanopyran moiety show pharmacological properties. The aim of this study is to investigate the larvicidal and antioxidant potential of dihydrophenanthroline-3-carbonitrile derivatives
The special scopes of natural products are discovery of potential drugs with novel structures and varying biological activity. Compounds containing heterocyclic ring systems are of much importance in medicinal chemistry [
Biologically important 1,4-DHP heterocycles.
Vector control is facing a threat due to the emergence of resistance to synthetic insecticides. Nowadays researchers are focusing their research on a synthetic compound that kills the larvae at initial stage itself [
Taking these facts into account, our research group have been involved actively to synthesis a drug against larvae. Due to effect of synthetic compounds on larvicidal activity, our research group mainly focused on killing the larvae at initial stage itself. Earlier we reported the 7-chloro-3,4-dihydro-9-phenylacridin-1(2
Nowadays, antioxidants that exhibit DPPH radical scavenging activity are increasingly receiving attention (Figure
In the present study, the efforts have been laid down to synthesis of 2-amino-10-chloro-4,12-diphenyl-1,4,5,6-tetrahydrobenzo[
Melting points were measured on Elchem Microprocessor based DT apparatus using an open capillary tube and are corrected with standard benzoic acid. IR spectrum was recorded on a Perkin-Elmer spectrum RXI FT-IR spectrometer (400–4000 cm−1; resolution: 1 cm−1) using KBr pellets. 1H and 13C NMR spectra were obtained on a Bruker Avance 400 MHz spectrometer. Chemical shifts were reported on the scale relative to TMS. Exact mass measurements of the molecular ions were obtained on ESI-MS Thermo Fleet.
(
Summary of synthesized dihydropyridine derivatives (
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S. no. | Compounds | R | M. Pt. |
Yield |
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1 |
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144–146 | 79 |
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2 |
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230–232 | 80 |
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3 |
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238–240 | 76 |
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4 |
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140–142 | 80 |
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5 |
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210–212 | 75 |
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6 |
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255–257 | 71 |
Synthesis of 2-amino-10-chloro-4,12-diphenyl-1,4,5,6-tetrahydrobenzo[
During preliminary screening with the laboratory trial, the larvae of
From the stock solution, different concentrations ranging from 3.12 to 50 ppm were prepared for larvicidal activity. Based on the preliminary screening results, synthetic compounds,
The average larval mortality data were subjected to probit analysis for calculating LC50, LC90, and other statistics at 95% fiducial limits of upper confidence limit and lower confidence limit, and chi-square values were calculated using the software [
All the synthesized compounds,
DPPH antiradical scavenging activity was also time dependent. The radical scavenging activity of the tested samples, expressed as percentage inhibition of DPPH, was calculated according to the following formula:
DPPH antiradical scavenging activity with time-dependent antiradical scavenging activity.
Percentage radical scavenging activity at various concentrations.
Pale yellow solid; M.F: C29H21ClN4; Yield 79%; M.P: 144–146°C; FT-IR (KBr)
Yellow solid; M.F: C31H25ClN4O2; Yield 80%; M.P: 230–232°C; FT-IR (KBr)
White solid; M.F: C31H25ClN4O2; Yield 76%; M.P: 238–240°C; FT-IR (KBr)
White solid; M.F: C30H23ClN4O; Yield 80%; M.P: 140–142°C; FT-IR (KBr)
Orange solid; M.F: C29H20Cl2N4; Yield 75%; M.P: 210–212°C; FT-IR (KBr)
White solid; M.F: C29H20Cl2N4; Yield 71%; M.P: 255–257°C; FT-IR (KBr)
Results on the larvicidal activities of
Larvicidal activity, mean efficacy (percentage ± S.D) of synthetic compounds against fourth instar larvae of
Compound |
Concentration |
% Mortality a(ppm) ± SD | |
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50 |
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25 |
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12.5 |
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6.25 |
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3.12 |
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50 |
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25 |
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12.5 |
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6.25 |
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3.12 |
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50 |
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25 |
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12.5 |
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6.25 |
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3.12 |
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50 |
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25 |
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12.5 |
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6.25 |
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3.12 |
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50 |
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25 |
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12.5 |
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6.25 |
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3.12 |
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50 |
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25 |
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12.5 |
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6.25 |
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3.12 |
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LC50, LC90, and other statistical analysis of synthetic compounds against fourth instar larvae of
Sample code | Species | LC50 ± SE (ppm) | UCL–LCL | LC90 ± SE (ppm) | UCL–LCL |
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128.48–82.30 |
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660.92–464.35 | 10.64 |
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198.02–124.16 |
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840.26–629.06 | 12.88 | |
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48.89–35.07 |
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214.73–147.66 | 10.56 |
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64.77–46.81 |
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238.03–166.62 | 12.80 | |
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124.89–115.07 |
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273.78–227.64 | 10.24 |
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87.73–46.82 |
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248.03–186.12 | 8.82 |
Control: nil mortality; LC50: lethal concentration that kills 50% of the exposed larvae; LC90: lethal concentration that kills 90% of the exposed larvae; UCL: upper confidence limit; LCL: lower confidence limit;
The entire synthesized compounds scavenged DPPH radical significantly in a concentration-dependent manner. Their comparable scavenging activities were expressed in IC50 (concentration required for 50% inhibition of l M DPPH concentration) value. As presented in Table
50% inhibition of scavenging activity for compounds
Compounds | aIC50 × 10−3 |
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38 |
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53 |
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54 |
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41 |
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68 |
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71 |
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80 |
9-Amino-acridine-propranolol | 13.6 |
The difference in activity amongst compounds
Our study demonstrated the novel 2-amino-10-chloro-4,12-diphenyl-1,4,5,6-tetrahydrobenzo[
The authors declare that there is no conflict of interests regarding the publication of this paper.
The study was supported by DST-SERB Fast Track (Sanction no. SR/FT/CS-264/2012), Government of India, New Delhi. The authors gratefully acknowledge DST-FIST for providing NMR facilities to the school. They acknowledge the support extended by VIT-SIF for GC-MS and NMR analysis.