Antimicrobial Activity and Phytochemical Composition of Allium sativum Bulb Extracts against Selected Gram-Negative Bacteria

Abstract

As a result of increasing antibiotics resistance due to multidrug resistance leads to the use of the medicinal plants as alternative antimicrobial agents. The study aimed to investigate the antimicrobial and phytochemical properties of Allium sativum bulb extracts against some selected gram-negative bacteria isolates. Allium sativum oil was extracted using Soxhlet extraction procedures; Clinical bacterial isolates were collected from pathology department of General Hospital Potiskum in Yobe state. Isolates were identified using standard methods. Antibacterial activity of different concentrations (20, 40, 60, 80 and 100) % of oil extract of Allium sativum bulb were investigated against five clinical bacterial isolates including, Proteus vulgaris, Pseudomonas aeruginosa, Escherichia coli, Shigella boydii and Klebsiella oxytoca.. The oil extract of the bulbs showed antimicrobial activity against all five clinical isolates. MICs and MBCs were evaluated by broth dilution method. The minimum inhibitory concentration (MIC) values for all the three oil extracts ranged between 0.5 and 1.0%, while the minimum bacterial concentration (MBC) values ranged between 1.0 and 1.5%. Important bioactive constituents were present in the different oil extraction method; alkaloids (for ethanol extracts, 19.04±0.04, for hexane extracts, 20.04±0.14 and for chloroform extracts, 20.04±0.07) and 0.51±0.01were detected for sterols in all the three oil extraction methods while others such as flavonoids, saponins, tannins and phenols were not detected. The yield extracts of the oil extract of the bulbs, for hexane were 12.6%, chloroform, 15.2% and ethanol, 16.2%, indicating that ethanol was the better of the three solvents used. The potential applications of Allium sativum oil extracts as natural antimicrobial agents call for the importance of further investigation into their nutritional potential.