Geranylgeraniol-type diterpenoids, boletinins A-J, from Boletinus cavipes as inhibitors of superoxide anion generation in macrophage cells

In addition to 16-hydroxygeranylgeraniol (1) and cavipetin B (2), 10 new geranylgeraniol-type diterpenoids, named boletinins A-J (3-12), were isolated from the fruiting bodies of Boletinus cavipes. Compounds 1-9 and 11 exhibited inhibitory activities of less than 10% at 25-125 muM in the xanthine oxidase test. A bioassay on superoxide anion (O-2(.-)) generation in macrophage cells revealed that 1 and 4-12 suppressed the generation by more than 20% at 25 muM. Compounds 4 and 5 showed inhibitory activities against O-2(.-) generation of more than 50% at 50 muM and exhibited no or low cytotoxicities against macrophage cells at 25-50 muM, suggesting that 4 and 5 are the most promising candidates for O-2(.-) generation inhibitors. O-Acyl geranylgeraniol derivatives, 2 and 7-12, showed cytotoxicities at 25 muM.