IBUPROFEN INHIBITS ARYLAMINE N-ACETYLTRANSFERASE ACTIVITY IN THE BACTERIA KLEBSIELLA-PNEUMONIAE

Ibuprofen, one of the nonsteroidal anti-inflammatory drugs, inhibited arylamine N-acetyltransferase activity of Klebsiella pneumoniae both i n vitro and in vivo. The NAT activities of Klebsiella pneumoniae were inhibited by ibuprofen in a dose-dependent manner both in vitro and in vivo. In vitro, the NAT activity was 0.675 +/- 0.028 nmol/min/mg of p rotein for the acetylation of 2-aminofluorene. In the presence of 8 mM ibuprofen, the NAT activity was 0.506 +/- 0.002 nmol/min/mg of protei n for the acetylation of 2-aminofluorene. In vivo, the NAT activity wa s 0.279 +/- 0.016 nmol/min/10(10) colony forming units (CFU) for the a cetylation of 2-aminofluorene. In the presence of 8 mM ibuprofen, the NAT activity was 0.228 +/- 0.008 nmol/min/10(10) CFU for the acetylati on of 2-aminofluorene. The inhibition of NAT activity by ibuprofen was shown to persist for at least 4 h. For in vitro examination, the valu es of apparent K-m and V-max were 1.08 +/- 0.05 mM and 9.17 +/- 0.11 n mol/min/mg of protein, respectively, for 2-aminofluorene. However, whe n 8 mM of ibuprofen was added to the reaction mixtures, the values of apparent K-m and V-max were 1.19 +/- 0.01 mM and 6.67 +/- 0.11 nmol/mi n/mg of protein, respectively, for 2-aminofluorene. For in vivo examin ation, the values of apparent K-m and V-max were 1.24 +/- 0.48 mM and 4.18 +/- 1.06 nmol/min/10 x 10(10) CFU, respectively, for 2-aminofluor ene, However, when 8 mM of ibuprofen was added to the culture, the val ues of apparent K-m and V-max were 0.95 +/- 0.29 mM and 2.77 +/- 0.37 nmol/min/mg protein, respectively, for 2-aminofluorene, respectively. This report is the first finding of ibuprofen inhibition of arylamine N-acetyltransferase activity in a strain of Klebsiella pneumoniae.