Antimicrobial, proximate and phytochemical evaluation of garlic (Allium sativum l) (ex-lugu cultivars)

Abstract

Due to the increasing rates of the evolution of resistant microorganisms to conventional antibiotics, the development of novel antimicrobials remains an area of intensive research in the field of Microbiology. The aqueous methanol and ethyl acetate extracts of Allium sativum var. Ex-Lugu were analysed for their proximate, phytochemical and antimicrobial properties. Gas chromatography-Mass spectrometry (GC-MS) was employed for the quantitative analysis of the extracts. Proximate analysis revealed the ex-lugu variety to be 12% richer in protein compared to the West African Food and Agricultural Organization (FAO) standard reference for composition of foods. Results of phytochemical and GC-MS analyses showed the presence of tannins, caryophyllene oxide and heptadecane-9-hexyl in the methanol extract (ME) but not in the aqueous (AE) and ethyl acetate (EE) extracts. ME (100 mg/mL) showed superior activity with zone of inhibition (ZOI) of 24 mm against Pseudomonas aeruginosa and Salmonella typhimurium. ME had a minimum inhibitory concentration (MIC) of 6.25 mg/mL against Enterococcus faecium and Escherichia coli which surpasses the other extracts while the minimum fungicidal concentration (MFC) was 25 mg/mL against C. albicans which was less than that of miconazole (50 mg/mL). EE had lesser MIC value (25 mg/mL) against P. aeruginosa compared to 50 mg/mL for ampicillin. There was significant difference (P < 0.05) in the antimicrobial effect of ME compared to the other extracts. This study has revealed the major and active phytochemical compounds in Allium sativum Ex-Lugu cultivar which might be of potential chemotherapeutic effect against infections caused by the test microorganisms.