Toxicity of Vernonia anthelmintica Linn. (Asteracea) seeds against mosquitoes vectors

The Toxicological activity (larvicidal, adulticidal and repellent toxicity) of Vernonia anthelmintica seeds fraction was tested against different species of mosquito vectors viz, malaria (Anopheles culicifacies and Anopheles stephensi), filaria (Culex quinquefasciatus) and dengue (Aedes aegypti). The larvicidal toxicity of Vernonia anthelmintica seeds fraction was evaluated against the early 4th instars larvae of different mosquitoes species. Mean LC50 value of the column fraction KAL-4 from seeds of V. anthelmintica against the larvae of An. culicifacies, An. stephensi, Culex quinquifaciatus and Aedes aegpyti were found to be 64 ppm, 70 ppm, 143 ppm and 166 ppm respectively. The larvicidal toxicity was more against An. culicifacies, An. stephensi than Culex quinquifaciatus and Aedes aegypti. The seed extracts did not show any adulticidal toxicity and repellent toxicity even at 10% concentrated impregnated paper and 5% on human hand, respectively

Isolation of Bacillus producing Chitinase from Soil: Production and Purification of Chito-oligosaccharides from Chitin Extracted from Fresh Water Crustaceans and Antimicrobial Activity of Chitinase

In the present investigation Bacillus sp. strain was isolated and screened from the red soil collected from Doiwala region of Dehradun (U.K), India. Serial dilution technique was adopted to isolate the organism and was screened for its chitinolytic activity. The biochemical tests were performed to prove its validity. The microorganism was also screened by inoculating a loop full of the isolated strain in basic cresol red dye and incubated for about 18- 24 h. The conversion of colour of the red dye into purple (pH, 6.5- 8.8) was taken as an indication for the presence of Bacillus sp. Amylase production by the organism was also screened by introduction of iodine in the broth/agar culture having starch. The broth/agar medium having starch but no bacterial strain was used as the control. The disappearance of color confirmed the presence of Bacillus strain producing amylase which degrades the starch. The chitinous wastes were collected from fresh water crustaceans viz. fresh water crab (Potamon sp.) and fresh water prawn (Palaemon sp.) and the chitin extracted was used as the substrate for chitinase. The yield of chitin extracted from fresh water prawn (Palaemon sp.) was found to be comparatively higher than that of chitin extracted from fresh water crab (Potamon sp.). Standard colloidal chitin was used as the reference control. The enzyme activity of chitinase for degradation of chitin extracted from crab and prawn was compared. The results confirmed that chitinase activity for degradation of crab chitin was comparatively higher than that of degradation of prawn chitin. The enzyme activities were found to be 0.11 µg/ml/minute and 0.09 µg/ml/minute for degradation of crab and prawn chitin respectively. The antimicrobial activity of chitinase extracted was determined against the bacterial and fungal cultures. Potent antibacterial activity of chitinase was observed against the bacterial cultures but no antifungal activity was observed. The chitinase produced by the species was able to degrade the chitin and chito-oligosaccharides produced was separated by TLC and purified by HPLC

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