Evaluation Of Anti-Inflammatory and Anti-Bacterial Activity of Onion Peel (Allium Cepa. L) And Analysis of Its Bioactive Compounds

This study investigated the phytochemical composition and therapeutic potential of onion peel (Allium cepa L.) extract, focusing on its anti-inflammatory and antibacterial properties. The onion peel was subjected to extraction and fractionation using petroleum ether, diethyl ether, and ethyl acetate. The resultant extracts were analysed by thin-layer chromatography (TLC) and subsequently confirmed using infrared (IR) spectroscopy, mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy, leading to the identification of key bioactive compounds such as quercetin, isorhamnetin, and kaempferol. The anti-inflammatory activity of the extract was evaluated in a carrageenan-induced paw oedema model in Wistar albino rats. The ethanolic extract demonstrated a dose-dependent reduction in paw thickness, with significant effects observed at 200 mg/kg and 400 mg/kg doses, comparable to those of the standard drug indomethacin. The antibacterial potential was assessed against gram-positive (Staphylococcus aureus and Bacillus subtilis) and gram-negative (Proteus vulgaris and Escherichia coli) bacteria at concentrations ranging from 100 to 800 µg/µl, using ciprofloxacin as a reference. The maximum inhibition zone was observed at 800 µg/µl. These findings underscore the significant anti-inflammatory and antimicrobial properties of onion peel extract and confirm the presence of key flavonoids responsible for its bioactivity. These results suggest the potential of onion peel waste as a valuable source of natural therapeutic agents, warranting further pharmaceutical and biomedical research.