Inhibition of Bacterial Growth by Allyl Isothiocyanate and its Derivatives

Abstract

Growth inhibition of six species of bacteria by allyl isothiocyanate (AIT) and its some derivatives was studied at 30°C on shaking culture to elucidate the relationship between chemical structure of AIT and the inhibitory action. Among allyl derivatives tested, 0.8mM allyl alcohol inhibited the growth on stationary phase of Proteus vulgaris and Bacillus cereus, and 0.8mM diallyl disulfide extended the lag phase of Staphylococcus aureus, Pro. vulgaris, Pseudomonas aeruginosa and B. cereus.However, allyl chloride, allyl cyanide and diallyl sulfide did not exhibit any inhibition. Comparison of the inhibitory activity of alkyl isothiocyanates showed that methyl isothiocyanate was most effective, followed by ethyl isothiocyanate, and n-propyl as well as nbutyl isothiocyanate was less effective. AIT, an alkenyl isothiocyanate was more effective than ethyl isothiocyanate. From these results, it was concluded that isothiocyanate radical is essential for the inhibition, whereas allyl radical is not. Generally, alkyl isothiocyanate of low molecular weight is more active than that of high molecular weight. Alkenyl isothiocyanate is more active than corresponding alkyl isothiocyanate.