MECHANISM OF CATECHIN CHEMILUMINESCENCE IN THE PRESENCE OF ACTIVE OXYGEN

The photon emission (chemiluminescence; CL) of catechin in the presenc e of active oxygen species (hydrogen peroxide, hydroxyl radical tert-b utyl hydroperoxide and tert-butyl oxyl radical) and acetaldehyde was c onfirmed to occur non-enzymatically at room temperature in aqueous neu tral conditions. The CL intensity [P] in the presence of active oxygen species (X), catalytic species (Y) and receptors (Z) is predicted by [P] = k [X] [Y] [Z]. The calculated photon constants (k) of 8 catechin s and gallic acid were 8.23 x 10(6) M(-2)s(-1) counts ((-)-epigallocat echin). 2.78 x 10(6) ((-)-epigallocatechin gallate), 4.66 x 10(5) ((-) -gallocatechin gallate), 4.36 x 10(5) ((-)-gallocatechin). 2.70 x 10(5 ) ((-)-epicatechin), 6.44 x 10(4) ((-)-catechin). 5.85 x 10(4) ((-)-ep icatechin gallate), 4.78 x 10(4) (gallic acid) and 3.54 x 10(4) ((-)-c atechin gallate), respectively. The system of active oxygen species, c atalytic species and receptors is proposed to be a scavenging mechanis m for active oxygen species. In the presence of acetaldehyde. (-)-epig allocatechin (maximum k value among catechins tested) reacted with ter t-BuOOH to form tert-BuOH as determined by HPLC analysis.