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

In addition to16-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 microM in the xanthine oxidase test. A bioassay on superoxide anion (O2*-) generation in macrophage cells revealed that 1 and 4-12 suppressed the generation by more than 20% at 25 microM. Compounds 4 and 5 showed inhibitory activities against O2*- generation of more than 50% at 50 microM and exhibited no or low cytotoxicities against macrophage cells at 25-50 microM, suggesting that 4 and 5 are the most promising candidates for O2*- generation inhibitors. O-Acyl geranylgeraniol derivatives, 2 and 7-12, showed cytotoxicities at 25 microM.