摘要Objective:To synthesize and isolate silver and gold nanoparticles from Litchi chinensis leaf methanolic extract,and to evaluate its comparative biological activities including muscles relaxant,analgesic,anti-inflammatory and antidiarrheal.Methods:The gold and silver nanoparticles were synthesized by dissolving methanolic extract in gold chloride and silver nitrate solution separately which were confirmed by colour change and UV-Vis spectroscopy,and pellets were collected through centrifugation.Biological activities of the extract were conducted on BALB/c mice through various standard methods and the data were subjected to One-way ANOVA.Results:The colorless gold chloride solution changed to purple soon after the addition of plant extract,demonstrating that the reaction took place and gold ions were reduced to gold nanoparticles,while colorless silver nitrate solution changed to light and dark brown that was indicative of silver nanoparticles.The muscles relaxant activity showed that silver nanoparticles were more effective than gold nanoparticles and methanolic extract in traction test.The analgesic activity showed that silver and gold nanoparticles showed highest percentage decrease in acetic acid induced writhing at the doses of 50,100 and 150 mg/kg b.w.The highest anti-inflammatory activity was produced by gold nanoparticles followed by silver nanoparticles,while low activity was observed in methanolic leaf extract.Only the crude methanolic extract showed significant antidiarrheal activity as compared to the standard drug atropine sulphate,while antidiarrheal activities of gold and silver nanoparticles were non-significant.Contusions:The present work concludes that isolated silver and gold nanoparticles from leaf methanolic extract shows strong muscles relaxant,analgesic and antiinflammatory activities while crude methanolic extract possesses good antidiarrheal activity.