抄録
The biological activity of floccosin, which is characterized by a semiquinone structure with epoxide rings, was compared with that of xanthomegnin which had been demonstrated to exhibit strong uncoupling effect and to produce an electron transport shunt to the respiratory system in mitochondria. Floccosin was found to exhibit a similarily strong uncoupling effect on isolated mitochondria to that of xanthomegnin. Xanthomegnin markedly enhanced the letent ATPase activity of mitochondria, whereas floccosin showed biphasic effect on the ATPase activity : a weak stimulation at concentrations lower than about 80 μM, producing a maximum activity at around 40 μM, and a progressive inhibition at the higher concentrations than that. Xanthomegnin did not influence the ATPase activity of submitochondrial particles, whereas floccosin strongly inhibited the ATPase activity. Xanthomegnin induced mitochodrial swelling in KCl isotonic solution, whereas floccosin showed only faint effect on it. These results indicate that floccosin has different biological activities from those of xan-thomegnin.
