ABSTRACT
Allium cepa L. (Onions) have been consumed in many parts of the world for both nutritional and medicinal purposes. The great flavour it impacts on food and its ability to be consumed raw makes it stand out amongst other vegetables. Bioactive components of plants, antioxidant capacity and antimicrobial efficacy are important factors to consider in choice of vegetables to be consumed. The plant has been reported to be effective in treatment of common cold, heart disease, coughs and sore throats. This study was aimed at evaluating and comparing the phytochemical, antioxidant and antimicrobial properties of red and white Allium cepa . White and red onion bulbs were obtained from trader in Uselu market, Egor Local Government Area, Edo State, Nigeria. They were identified and authenticated at the Department of Plant Biology and Biotechnology, University of Benin, Benin City, Nigeria. Quantitative and qualitative phytochemical analysis was carried out using standard methods. Four assays were employed for antioxidant evaluation of the onion bulbs which were FRAP (Ferric Reducing Antioxidant Power), TAC (Total Antioxidant Capacity), reducing power and DPPH (2,2, Diphenyl-1-picryl-hydrazyl-hydrate). Six (6) test isolates (Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus sp. and Candida sp.) were obtained from University of Benin Teaching Hospital (UBTH), Benin City, Nigeria and were reidentified at the Department of Pharmaceutical Microbiology, University of Benin, Benin City, Nigeria. The isolates were used in determining the MIC (Minimum Inhibitory Concentration), MBC (Minimum Bacteriocidal Concentration) and zones of inhibition which were recorded in millimeters (mm). Antimicrobial susceptibility of bacterial isolates was determined using Kirby-Bauer disc diffusion method.
