Nandita Chowdhury

Mosquito larvicidal activities of Solanum villosum berry extract against the dengue vector Stegomyia aegypti.

BackgroundVector control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. Although several plants have been reported for mosquitocidal activity, only a few botanicals have moved from the laboratory to field use, because they are poorly characterized, in most cases active principals are not determined and most of the works are restricted to preliminary screening. Solanum villosum is a common weed distributed in many parts of India with medicinal properties, but the larvicidal activity of this plant has not been reported so far.MethodsAqueous and polar/non-polar solvent extract of fresh, mature, green berries of S. villosum was tested against Stegomyia aegypti, a common vector of dengue fever. A phytochemical analysis of chloroform:methanol extract was performed to search for the active toxic ingredient. The lethal concentration was determined (log probit analysis) and compared with Malathion. The chemical nature of the active substance was also evaluated following ultraviolet-visual (UV-Vis) and infrared (IR) analysis.ResultsIn a 72 hour bioassay experiment with the aqueous extract, the highest mortality was recorded in 0.5% extract. When the mortality of different solvent extracts was compared, the maximum (p < 0.05) mortality was recorded at a concentration of 50 ppm of chloroform:methanol extract (1:1, v/v). The larvicidal activity was lower when compared with the chemical insecticide, Malathion (p < 0.05). Results of regression analysis revealed that the mortality rate (Y) was positively correlated with the period of exposure (X) and the log probit analysis (95% confidence level) recorded lowest value (5.97 ppm) at 72 hours of exposure. Phytochemical analysis of the chlororm:methanol extract reported the presence of many bioactive phytochemicals. Two toxic compounds were detected having Rf = 0.82 (70% and 73.33% mortality in 24 and 48 hours, respectively) and Rf = 0.95 (40% and 50% mortality in 24 and 48 hours, respectively). IR analysis provided preliminary information about the steroidal nature of the active ingredient.ConclusionS. villosum offers promise as potential bio control agent against S. aegypti particularly in its markedly larvicidal effect. The extract or isolated bioactive phytochemical could be used in stagnant water bodies for the control of mosquitoes acting as vector for many communicable diseases.

Mosquito larvicidal and antimicrobial activity of protein of Solanum villosum leaves

BackgroundMosquitoes are associated with the transmission of malaria, dengue, Japanese encephalitis, filariasis and other viral diseases throughout the globe, apart from being a nuisance pest. Biological control alone or as a part of integrated vector management stands to be a better alternative to the chemical controls aimed against pest mosquitoes. At the same time it is necessary to control bacteria by synthetic or natural means (plant products). Hence the present study was designed to screen the effect of mosquito larvicidal and antimicrobial activitiy of protein isolated from matured leaves of Solanum villosum against mosquito immatures and some pathogenic bacteria.MethodsAqueous solvent extract of fresh mature leaves of S. villosum was tested against 3rd instar larvae of Anopheles stephensi, Culex quinquefasciatus and Stegomyia aegypti mosquitoes and against four pathogenic bacteria. The protein fraction was isolated and tested for mosquitocidal and antibacterial activities. Amino acid analysis was performed on isolated protein using PICO.TAG amino acid system. SDS-PAGE was also done to detect the bands of amino acid on the basis of their molecular weights.ResultsProteins isolated from mature leaves of S. villosum were found to have larvicidal and antimicrobial properties. Analysis of the isolated protein identified fifteen amino acids of which eight were essential amino acids. SDS-PAGE detected seven bands corresponding to different molecular weights in the range of 69–109 KDa.ConclusionProteins of mature leaves of S. villosum exhibited moderate larvicidal and antimicrobial activities. The study provides considerable scope in exploiting local indigenous resources for isolation of antimicrobial and mosquito larvicidal proteins.

Determination of the n-alkane profile of epicuticular wax extracted from mature leaves of Cestrum nocturnum (Solanaceae: Solanales)

An n-hexane extract of fresh, mature leaves of Cestrum nocturnum (Solanales: Solanaceae) containing thin layer epicuticular waxes was analysed by thin-layer chromatography, infrared and gas liquid chromatography using standard hydrocarbons. Seventeen long chain alkanes (n-C18 to n-C34) were identified and quantified. Hentriacontane (n-C31) was established as the major n-alkane, while nonadecane (n-C19) was the least abundant component of the extracted wax fraction. The carbon preference index calculated for the sample was 1.30, showing an odd to even carbon number predominance.

n-alkane profile of Argemone mexicana leaves.

An n-hexane extract of fresh, mature leaves of Argemone mexicana (Papaveraceae), containing thin-layer epicuticular waxes, has been analysed for the first time by TLC, IR and GLC using standard hydrocarbons. Seventeen long-chain alkanes (n-C18 to n-C34) were identified and quantified. Nonacosane (n-C29) was established as the n-alkane with the highest amount, whilst octadecane (n-C18) was the least abundant component of the extracted wax fraction. The carbon preference index (CPI) calculated for the hydrocarbon sample with the chain lengths between C18 and C34 was 1.2469, showing an odd to even carbon number predominance.

Fatty Acid Analysis of Leaf and Berry of Solanum villosum Mill. and its Prospect as Diet and Bactericide

Abstract Unsaturated fatty acids (FA) are required for various biological processes of animals including human. They are used as supplementary diet in treating many diseases and have large-scale industrial uses. In the present study, oils from leaves and berries of Solanum villosum Mill. (Solanaceae:Solanales) were extracted with petroleum ether (60-80°C) and subjected to Gas Liquid Chromatography (GLC) to identify the available FA. The antibacterial potential of the petroleum ether extract against some pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) was demonstrated by disc diffusion method and Minimum Inhibitory Concentrations (MIC) was also determined. In the extracted oil, major unsaturated FA components were identified as lenoleic acid and oleic acid and saturated FA were palmitic acid and stearic acid. Tested bacteria showed high to moderate sensitivity to the extracts, except B. subtilis exhibited resistance to the extract of leaves, whereas E. coli and P. aeruginosa to the extract of berry. So, oils from S. villosum leaf and berry can be considered as an important source of unsaturated FA, specially the linoleic acid and can be used as a healthier alternative to commonly used oils opening good prospects in many industries. Moderate antibacterial property may provide an added advantage.