Kitchen phytochemicals from Allium cepa - their role in multidrug resistance

Bacterial resistance to antibiotics is increasingly becoming a concern to public health. Current antibiotics have failed to bring desirable results to many bacterial infections due to multi-resistant strains. So, concerted efforts are being made to curve this with the help of dietary phytohemicals. A number of dietary phytochemical are being put to trials for antimicrobial activity; however it is worthwhile to search such a part of diet that is very frequently used by major population. Keeping this view in mind an effort has been made to evaluate the antimicrobial activity of most common vegetable component Allium cepa. Methanolic and aqueous extracts were prepared from Allium cepa and antibacterial activity was tested on four pathogenic bacteria (Gram-positive and Gram negative) Staphylococcus aureus, Bacillus Subtilis, Escherichia coli and Pseudomonas aeruginosa using Disc diffusion method and Minimum inhibitory concentration by the Microtitre well plate method. Conventional antibiotic discs of Tetracycline and Gentamycin were used as positive control. Among the two extracts, methanolic extract exhibited a significant antimicrobial activity on the test organisms Ps. aeruginosa (17.5mm) and B. subtilis (11.3mm). The minimum inhibitory concentration value for Ps. aeruginosa was 500μl and for B. subtilis was 250μl for methanolic extract. The growth of other two bacteria i.e. E. coli and S. aureus were not inhibited by methanolic as well as aqueous extract that indicates non susceptibility to aqueous and methanol extract of Allium cepa. From the study, it was concluded that the commonly used Allium cepa possess potent antibacterial property against Bacillus Subtilis and Pseudomonas aeruginosa.