Bioassay guided phytochemistry of aerial part of Laportea Aestuans (l.) chew (urticaceae)

Abstract

There are evidences that free radicals mediated damages play important role in the aetiology of several diseases necessitating search for  antioxidants especially from natural origin. Free radical scavenging activities of Laportea aestuans (Urticaceae) is well documented, therefore this study aims at evaluating the safety of L. aestuans and isolating free radical scavenging compound(s) from the plant extract. The aerial (leaves, stem and inflorescence) parts of L. aestuans were collected together and extracted with 80% methanol. The toxicity of the plant extract was evaluated using brine shrimp lethality assay and acute toxicity study while Thin Layer Chromatography (TLC) bioautography with 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH•) radical as detection reagent was used to guide the isolation of compounds from the plant extract. The LC₅₀ of L. aestuans extract was 4276.87 µg/mL, suggesting that the extract is nontoxic. This was further confirmed by the healthiness of study rats following administration of the extract at 5000 mg/kg b.wt in the acute toxicity study. TLC bioautography showed that hexane fraction had the most pronounced radical scavenging activities. Three compounds identified as hexadecanoic acid butyl ester, heptadecanoic and octadecane were characterized using IR, ¹H, ¹³C NMR, ESI – MS and GC – MS analysis.