Molluscicidal effect of Achyranthes aspera L.(Amaranthaceae)aqueous extract on adult snails of Biomphalaria pfeifferi and Lymnaea natalensis

Background:Intestinal schistosomiasis caused by Schistosoma mansoni is a wide spread disease in most parts of Ethiopian highlands.Snail control is one major strategy in schistosomiasis control.The use of molluscicidal plant products is becoming interesting due to their environmental friendliness,accessibility and easy application.This research is aimed to evaluate the molluscicidal effect of Achyranthes aspera on Biomphalaria pfeifferi and Lymnaea natalensis snails,which are of great medical and veterinary importance in Ethiopia.Methods:Adult B.pfeifferi snails were exposed to the various concentrations of A.aspera aqueous leaf extract for 24,48 and 72 h.Similarly,adult L.natalensis snails were exposed to the extract for 24 h.Mortality data were analyzed using probit regression model.Phytochemical content of the plant was analyzed using standard screening methods.Results:The plant’s molluscicidal effect on the two snail species was demonstrated.The 24 h LC50 and LC90 values against L.natalensis were 69.5 and 93.9 ppm respectively.In the 24,48 and 72 h exposure of B.pfeifferi,the LC50 values were 72.4,69.9,64.7 ppm and the LC90 were 96.5,93.8,92.8 ppm,respectively.The phytochemical screening tests indicated presence of saponins.Conclusion:From the findings of this study,A.aspera has a molluscicidal potential.The result provides a useful foundation for further in-depth studies to ensure its wider applicability in different water bodies and evaluate its toxic effects on non-target species.

Antibacterial potential of Thevetia peruviana leaf extracts against food associated bacterial pathogens

Objective:To isolate and characterize the food associated bacterial strains,and to evaluate the antibacterial activity and minimum inhibitory concentration of various solvents(acetone,chloroform,methanol and petroleum ether)leaf extracts of Thevetia peruviana(T.peruviana)against their respective isolated and standard bacterial strains and also to investigate the presence of various phytochemical constituents in the leaf extracts of test plant.Methods:The food associated bacterial strains were isolated from students'lunch boxes in Tesfa Tewahido Primary School.The antimicrobial activity and minimum inhibitory concentrations were determined by the disc diffusion and serial dilution methods,respectively and phytochemical constituents were also detected in various solvent leaf extracts of T.peruviana.Results:The result showed that all the tested solvent leaf extracts of T.peruviana exhibited antibacterial activity against the tested standard and isolated bacterial strains with zones of inhibition ranged from 10.0 to 17.0 mm.Amongst the tested food borne bacterial pathogens,Salmonella typhimurium was most sensitive towards petroleum ether leaf extracts of T.peruviana while,methanol leaf extracts was relatively least effective against all the tested standard and isolated bacterial strains.Minimum inhibitory concentration of various solvent leaf extracts of T.peruviana ranged from 16.67 to 50.00 mg/mL for all the tested standard and isolated bacterial strains.The phytochemical constituents screening on the leaf extracts of T.peruviana showed the presence of alkaloids,cardiac glycosides,flavonoids,polyphenols,saponins and tannins.Conclusions:The present study suggests that T.peruviana could be used as prospective aspirants against the common food borne bacterial pathogens and also provide a wide array in the development of drugs against common food borne bacterial pathogens.