Abstract
The nineteen isothiocyanate compounds with five kinds of functional groups, alkyl, ω-alkenyl, aryl, -methylthioalkyl, and ω-methylsulfinylalkyl, were tested for minimum inhibitory concentration against growth of four species of bacteria and two species of fungi. In general, the isothiocyanate (ITC) analogues showed antimicrobial activities according to the following order : aryl ITC > ω-methylthioalkyl ITC> ω-alkenyl ITC> ω-methylsulfinylalkyl ITC > alkyl ITC. They also had different antimicrobial spectra. The aryl and ω-mithylthioalkyl ITCs indicated higher antimicrobial activity against gram-positive becteria and fungi than gram-negative bacteria, whereas ω-alkenyl ITCs were more effective against gram-negative bacteria and fungi than gram-positive bacteria. Gram-positive bacteria and A. niger were more sensitive to the ω-methylsulfinylalkyl ITCs than gram-negative bacteria and C. albicans. The antimicrobial activity was increased by a combination of ITCs having different antimicrobial spectra. The ITCs other than alkyl ITC inhibited the growth of methicillin resistant Staphylococcus aureus and methicillin sensitive S. aureus at the same concentration. The antimicrobial activity of ITC analogues other than alkyl ITC is about 5 to 10 times those of preservatives generally used in foods.
