Free radical scavenging activity of coenzyme Q measured by a chemiluminescent assay

Abstract

Involvement of coenzyme Q (CoQ) in anti-oxidant activities, in addition to its major redox role, has frequently been suggested in recent years. In order to elucidate if CoQ could really be engaged in scavenging free radicals produced endogenously in a biological system, an experimental system was developed in which beef heart mitochondria in the presence of a saturating NADH concentration and of rotenone produce free radicals. The presence of oxygen-reactive forms was easily detected by a luminol-dependent chemiluminescence process. The chemiluminescence assay showed that short-chain CoQ homologues can act as pro-oxidants, enhancing free radical effects, while exogenous coenzyme Q 10 could scavenge free radicals, especially at very low concentration. In this system, exogenous CoQ 10 was more effective than α-tocopherol at the same concentration in scavenging free radicals. The molecular mechanism that leads to this ability is still nuclear, but these results are of biochemical and biomedical importance because they indicate that CoQ may act as an anti-oxidant in situations mimicking physiopathological conditions. This direct chemiluminescent method is promising for studies of biochemical processes which involve active oxygen species.