In-vitro antimicrobial activity of four diallyl sulphides occurring naturally in garlic and Chinese leek oils

The in-vitro antimicrobial activity of garlic oil, Chinese leek oil and four diallyl sulphides occurring naturally in these oils against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), three Candida spp. and three Aspergillus spp. (total of 276 clinical isolates) was studied. The magnitude of activity of the four diallyl sulphides followed the order diallyl tetrasulphide > diallyl trisulphide > diallyl disulphide > diallyl monosulphide. These results suggest that disulphide bonds are an important factor in determining the antimicrobial capabilities of these sulphides. The concentration of four diallyl sulphides in garlic and Chinese leek oils was in the range 41.7–52.7% of total sulphides. Garlic oil, with a higher concentration of four diallyl sulphides, showed greater antimicrobial activity than Chinese leek oil. Diallyl disulphide, diallyl trisulphide, diallyl tetrasulphide and the oils rich in these sulphides may have a role in the prevention or treatment of infections.