CAPSAICIN OXIDATION BY PEROXIDASE FROM CAPSICUM-ANNUUM (VAR ANNUUM) FRUITS

Capsaicin (8-methyl-N-vanillyl-6-nonenamide) oxidation by peroxidase (EC 1.11.1.7) from Capsicum annuum var. annuum fruits is studied. Capsaicin (Sigma) contains two components which are oxidized indistinctively by pepper peroxidase when capsaicin disappearance is monitored by HPLC. Spectrophotometric studies illustrated that capsaicin oxidation by pepper peroxidase showed maximal spectral changes at 262 nm. At this wavelength, epsilon262 = 5.3 x 10(3) M-1 cm-1 was calculated for the only absorbent oxidation product. The dependence of the capsaicin oxidation rate by pepper peroxidase on capsaicin and H2O2 concentrations reveals Michaelis-Menten-type kinetics with inhibition at high substrate concentrations and an acidic optimal pH. From these studies, it can be concluded that capsaicin is oxidized by pepper peroxidase and that a possible participation of peroxidase in capsaicin metabolism in the pepper fruit should be taken into account.