Phytochemical Analysis of Garlic Hydro-alcoholic Extract and Evaluation of its Anti-bacterial Effect on Enterohemorrhagic Escherichia coli in Vitro and ex Vivo

Garlic is a medicinal plant with various health promoting properties including antimicrobial effects. In this study, we investigated in vitro antibacterial effects of garlic hydro-alcoholic extract against enterohemorrhagic Escherichia coli (EHEC).

Garlic hydro-alcoholic extract was prepared by maceration method.  Phytochemical analysis of the extract was carried out using gas chromatography-mass spectrometry. Minimum inhibitory concentration (MIC) of the extract against EHEC was determined by micro-dilution assay. Cytotoxic effect of the garlic extract on human colon adenocarcinoma cell line (SW480) was assessed using MTT assay. Micro-dilution assay was also used to determine the MIC of the extract against EHEC when co-cultured with SW480 cells.

The amount of organosulfur in garlic extract was 70.91% and the most common organosulfur compounds were trisulfide, di-2-propenyl (34.8%) and diallyl disulfide (14.83%). The MIC of garlic hydro-alcoholic extract on EHEC alone and when co-cultured with SW480 was 12.5 mg/ml. Concentrations of 12.5 mg/ml and 25 mg/ml of the extract significantly reduced the viability of SW480 cells compared to control and concentration of 6.25 mg/ml of garlic extract (p <0.0001).

The garlic hydro-alcoholic extract has inhibitory effects on EHEC in vitro. Therefore, it can be considered a suitable candidate for controlling infections caused by EHEC.