Protection of Mitochondrial Functions against Oxidative Stresses by Isoflavans from Glycyrrhiza glabra

Abstract

Isoflavan derivatives, glabridin (1), hispaglabridin A (2), hispaglabridin B (3), 4′-O-methylglabridin (4) and 3′-hydroxy-4′-O-methylglabridin (5), isolated from Glycyrrhiza glabra, were investigated for their ability to protect liver mitochondria against oxidative stresses.Mitochondrial lipid peroxidation linked to respiratory electron transport and that induced non-enzymatically were inhibited by these isoflavans. Hispaglabridin A (2) strongly inhibited both peroxidations and 3′-hydroxy-4′-O-methylglabridin (5) was the most effective at preventing NADH-dependent peroxidation. 3′-Hydroxy-4′-O-methylglabridin (5) protected mitochondrial respiratory enzyme activities against NADPH-dependent peroxidation injury. Dihydroxyfumarate-induced mitochondrial peroxidation was also prevented by this isoflavan.Isoflavans from G. glabra were shown to be effective in protecting mitochondrial function against oxidative stresses.