Effects of the garlic compounds diallyl sulphide and diallyl disulphide on arylamine N‐acetyltransferase activity in Klebsiella pneumoniae

Arylamine N ‐acetyltransferase (NAT) activities with 2‐aminofluorene (2‐AF) were determined in the bacterium Klebsiella pneumoniae . Cytosols or suspensions of K. pneumoniae with or without specific concentrations of diallyl sulphide (DAS) or diallyl disulphide (DADS) as co‐treatment showed different percentages of 2‐AF acetylation. The data indicated that there was decreased NAT activity associated with increased levels of DAS or DADS in K. pneumoniae . In growth studies on K. pneumoniae it was demonstrated that DAS or DADS elicited a dose‐dependent bacteriocide effect on K. pneumoniae . For the cytosol examinations, the apparent values of K m and V max were 0.96 ± 0.09 mM and 7.87 ± 0.79 nmol min −1 mg −1 protein, respectively, for 2‐AF. However, when DAS or DADS was added to the reaction mixtures, the apparent values of K m and V max were 0.16 ± 0.04 mM and 0.99 ± 0.16 nmol min −1 mg −1 protein with DAS, respectively, and 0.14 ± 0.18 mM and 0.85 ± 0.10 nmol min −1 mg −1 protein with DADS, respectively, for 2‐AF. For the intact bacteria examination, the apparent values of K m and V max were 0.57 ± 0.06 mM and 2.00 ± 0.14 nmol min −1 per 10 × 10 10 CFU, respectively, for 2‐AF. However, when DAS or DADS was added to the reaction mixtures, the apparent of values of K m and V max were 0.41 ± 0.04 mM and 1.30 ± 0.10 nmol min −1 per 10 × 10 10 CFU with DAS, respectively, and 0.34 ± 0.04 mM and 1.08 ± 0.08 nmol min −1 per 10 × 10 10 CFU with DADS, respectively, for 2‐AF. This report is the first demonstration to show that the garlic components DAS and DADS would affect K. pneumoniae growth and NAT activity. Copyright © 1999 John Wiley & Sons, Ltd.