Toxicological Evaluation and Isolation of Antibacterial Compounds from Hexane Extract of Uritica dioica Leaves

The present study describes the antibacterial activity, toxicological evaluation and phytochemical profile of Urtica dioica. U. dioica leaves were subjected to solvent extraction by hexane, ethyl acetate, chloroform, methanol and water and all the extracts were tested for antibacterial activity against five clinical isolates of gram negative and gram positive bacteria. The antibacterial activity was assessed by disc diffusion method. Hexane extract showed good antibacterial activity against all the five bacterial strains, hence it was further purified using silica column chromatography and MIC of the semi purified fraction F_B of hexane extract was determined by broth dilution method. The F_B showed MIC value of 31.25, 250, 7.81, 31.25 and 125µg/ml against Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Klebsiella pneumoniae and Shigella flexneri respectively. F_B was subjected to GC-MS analysis in search of potent antibacterial compound(s). Neophytadiene (26.97%), butyl tetradecyl ester (9.53%), Dibutyl phthalate (7.45%), Bis(2-ethyl hexyl) maleate (8.80%) and 1,2- benzenedicarboxylic acid (9.89%) were the major constituents which may be responsible for the antibacterial activity of hexane extract of U. dioica. Sub-acute toxicity studies of F_B were carried in wistar rats at doses of 100, 200, 400 and 800mg/kg bw to assess index of safety. Hematological parameters from blood and other biochemical parameters (Liver Function Tests and Lipid Profile) from serum showed that the F_B was safe at tested concentrations.