TABLE 2

Ability of sulfa drugs to inhibit sepiapterin reduction and redox cycling by SPR

InhibitorSepiapterin ReductionaRedox Cycling
Inhibition TypeIC50Inhibition TypeIC50
nMμM
Antibacterial
 SulfasalazineNoncompetitive31Noncompetitive0.53
 SulfathiazoleNoncompetitive62Noncompetitive8.02
 SulfapyridineNoncompetitive141Noncompetitive19.41
 SulfamethoxazoleNoncompetitive180Noncompetitive10.97
Antidiabetic
 ChlorpropamideNoncompetitive120Noncompetitive0.37
 GlibenclamideNoncompetitive340Noncompetitive1.11
 TolbutamideNoncompetitive510Noncompetitive4.58
  • a Sepiapterin reduction and redox cycling were measured as described in Materials and Methods. For redox cycling assays, 200 μM menadione was used.