Anjali Rawani

Mosquito larvicidal and antimicrobial activity of synthesized nano-crystalline silver particles using leaves and green berry extract of Solanum nigrum L. (Solanaceae: Solanales).

Silver nanoparticles (AgNPs) that are synthesized by using aqueous extracts of Solanum nigrum L., is a simple, non-toxic and ecofriendly green material. The present study is based on assessments of the larvicidal and antimicrobial activities of the synthesized AgNPs from fresh leaves, dry leaves and green berries of S. nigrum against larvae of Culex quinquefasciatus and Anopheles stephensi and four human pathogenic and five fish pathogenic bacteria respectively. The synthesized nanoparticles are characterized with UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM) analysis. The nanoparticles are spherical to polyhedral in shape with size of 50-100nm (average size of 56.6nm). In larvicidal bioassay with synthesized AgNPs, highest mortality are observed at 10ppm against An. stephensi with LC50 values of 1.33, 1.59, 1.56ppm and LC90 values of 3.97, 7.31, 4.76ppm for dry leaves, fresh leaves and berries respectively. Antibacterial activity test reveals better results against fish pathogenic bacteria than human pathogenic bacteria. Non target organism like Toxorhynchites larvae (mosquito predator), Diplonychus annulatum (predatory water-bug) and Chironomus circumdatus larvae (chironomid) are also exposed to respective lethal concentrations (to mosquito larvae) of dry nanoparticles and no abnormality in the non target organisms are recorded. These results suggest that the synthesized AgNPs of S. nigrum have the potential to be used as an ideal eco-friendly compound for the control of the mosquito larvae and harmful bacteria.

Larvicidal activity of Dregea volubilis and Bombax malabaricum leaf extracts against the filarial vector Culex quinquefasciatus.

OBJECTIVE To analyze the larvicidal activity of two plant leaf powder and leaf-extracts, Dregea volubilis and Bombax malabaricum against Culex quinquefasciatus. METHODS The larvicidal bioassay was done for powdered leaves of Dregea volubilis and Bombax malabaricum individually and their methanol extracts against first-, second-, third- and fourth-instar larval forms of Culex quinquefasciatus. Mortality rate was recorded after 24, 48 and 72 h of post-exposure. LC(50) and LC(90) values were calculated at different time intervals for third instar larvae. RESULTS All the graded concentration (0.1%, 0.2%, 0.3%, 0.4%, 0.5%) of powdered leaves showed significant (P <0.05) larval mortality. The mortality rate was higher in 50 ppm doses of methanolic extracts of both the plants against Culex quinquefaciatus. The corresponding LC(50) values were 56.97 ppm and 48.85 ppm, respectively after 24 h of exposure. There is no mortality of non-target organism such as Chironomous circumdatus, Oreochromis niloticus niloticus and Diplonichus annulatum within 72 h of post exposure to 0.1%, 0.2%, 0.3% crude powdered leaves and methanolic extracts of both the two individual plants under the laboratory condition. The results of preliminary qualitative phytochemical analysis of both the plants revealed the presence of many bioactive principles such as steroids, tannins, flavonoids, triterpenoids, saponins, etc. that may be responsible for their bio-control potentiality. CONCLUSIONS The results have shown potential and eco-friendly use of both plant extracts against larva of Culex quinquefasciatus for the first time.

Evaluation of antimicrobial properties of four plant extracts against human pathogens

Abstract Objective To investigate the antibacterial activity of the extracts of Alternanthera philoxeroides (A. philoxeroides), Plumeria obtusa (P. obtusa), Polyalthia cerasoides (P. cerasoides) and Ixora acuminate (I. acuminate) against human pathogens. Methods Aqueous and chloroform: methanol (1:1) extracts of the dried leaf of A. philoxeroides, flowers of P. obtusa, fruits of P. cerasoides and flowers of I. acuminate were tested in vitro by the disk diffusion method against four bacterial strains, namely, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Susceptibility of four reference bacterial strains to some antibiotics in nutrient agar was also tested. Minimal inhibitory concentration (MIC) values were determined and qualitative phytochemical analysis of the crude extract of the tested plant parts was done. Results Both the aqueous and the chloroform: methanol (1:1) extracts of P. cerasoides showed the strongest activity, followed by flowers of P. obtusa, leaves of A. philoxeroides and flowers of I. acuminate. Aqueous extracts of all the plant parts appeared to have less antibacterial activity than the chloroform: methanol (1:1) extracts. The result of phytochemical analysis of the crude extract of the tested plants showed that flavonoid was absent from all plant parts whereas steroid was present in all tested plant parts. Conclusions The results support that these plant extracts can be used for the treatment of bacterial diseases.

Mosquito larvicidal and biting deterrency activity of bud of Polianthes tuberosa plants extract against Anopheles stephensi and Culex quinquefasciatus.

Abstract Objective To evaluate the larvicide and biting deterrency activity of bud of Polianthes tuberosa (P. tuberosa) against Culex quinquefasciatus (Cx. quinquefasciatus) and Anopheles stephensi (An. stephensi). Methods Crude and solvent extract [ethyl acetate, chloroform: methanol (1:1, v/v), acetone] of fresh, mature, bud of P. tuberosa was tested against Cx. quinquefasciatus and An. stephensi. The repellent activity tested by chloroform: methanol (1:1, v/v) solvent extract against both mosquito species. The appropriate lethal concentrations at 24 h for chloroform: methanol (1:1, v/v) extract was also studied on non target organisms such as Toxorhynchites larvae, Diplonychus annulatum and Chironomus circumdatus. Results In a 72 h bioassay experiment, 0.5 % crude extract showed the highest mortality and chloroform: methanol (1:1, v/v) solvent extract showed the highest mortality, the maximum (P Conclusions Both crude and chloroform: methanol (1:1, v/v) extract showed efficient activity against Cx. quinquefasciatus, so it could be used as a mosquito larvicide agent. There is no change in the activity of non-target organism so, it is safe to use.

Evaluation of mosquito larvicidal activity of fruit extracts of Acacia auriculiformis against the Japanese encephalitis vector Culex vishnui

Abstract The larvicidal potentiality of crude and ethyl acetate extracts of fruits of Acacia auriculiformis was investigated against all the larval instars of JE vector Culex vishnui. The crude extracts showed good results against all the larval instars with highest mortality at 0.09%. Highest mortality was found at 300 ppm of ethyl acetate extract. Lowest LC50 value was obtained at 72 h for third instar larvae. Non target organisms tested, showed no to very less mortality to ethyl acetate solvent extract. Presence of N–H stretching, a C=O stretching, C=C and C–N stretching vibrations of secondary amide or amine group were confirmed from IR analysis. GC-MS analysis revealed the presence of three compounds namely Ethane 2-chloro-1,1-dimethoxy, Acetic acid, 1-methyl ether ester and [4-[1-[3,5-Dimethyl-4[(trimethylsilyl)oxy)phenyl]-1,3-dimethylbutyl)-2,6dimethylphenoxy)(trimethyl) silane, responsible for mosquito larval death.

Phytochemical Analyses and Larvicidal Potentiality of Fruit Peel Extracts of Citrus limetta against Filarial Vector Culex quinquefasciatus

Different concentrations of crude and different solvents viz., n-hexane, ethyl acetate, and methanol fruit peel extracts of Citrus limetta Risso ( C. limetta ) were taken for investigation for larvicidal activity against Culex quinquefasciatus Say, 1823 ( Cx. quinquefasciatus ) mosquito species. Crude extract showed good larvicidal activity with very low concentrations against 1 st - 4 th instars larvae. Only 3 rd instar larvae were taken for larvicidal bioassay experiments for each solvent extract. LC 50 values of n-hexane, ethyl acetate, and methanol fruit peel extracts of C. limetta were 661.27, 1268, and 939.43 ppm respectively after 24 h of exposure. No mortality was observed on control treatments. Log probit analyses, regression equations, and R 2 values of larvicidal bioassay experiments with crude and different solvent extracts were determined. Statistical justification was done through ANOVA analyses. Qualitative phytochemical analyses were carried out and detected different secondary metabolites. No mortality was observed on tested non target organisms.