Abstract
Effects of naturally occurring benzoquinone derivatives on rat liver mitochondrial respiration were examined manometrically and polarographically comparing with ubiquinone-0. Dihydroxythymoquinone, helicobasidin, and dihydroperezone were found to show significant effect on the respiration. At the concentration of 1.0×10-5M, dihydroxythymoquinone eliminated the State-3 respiration completely and the for 50% inhibition of the State-3 respiration it required the concentration of 3.2×10-6M. Helicobasidin was an uncoupler and dihydroperezone showed both an uncoupling action on State-4 respiration and an inhibitory action of State-3 respiration. The other benzoquinone derivatives examined did not show any significant effects on mitochondrial respiration.
