Adamantyl and homoadamantyl derivatives from Garcinia multiflora fruits

Nine undescribed caged polycyclic polyprenylated acylphloroglucinols (PPAPs), including adamantane type PPAPs (1-2), and homoadamantane type PPAPs (3-9), were isolated from the fruits of Garcinia multiflora, along with three known analogues. A new epimeric pair of isohypersampsonone B (5) and epi-isohypersampsonone B (6), featuring an unusual hexahydrofuro[2,3-b]furan-diepoxy ring system fused in a homoadamantane skeleton, was not separated due to the rapid equilibration between the two isomeric forms. All new caged PPAPs (1-9), sharing a common isogeranyl group, were determined on the basis of comprehensive NMR and MS spectroscopic data. Their cytotoxicity against three human tumor cell lines (SGC-7901, HepG2, HCT-116) and the nitric oxide production inhibitory activity of lipopolysaccharides-stimulated RAW 264.7 cells were tested. Compounds 8 and 12 displayed mild cytotoxicity against three human cancer cell lines with IC₅₀ values of 10-20 μM. Furthermore, compounds 8 and 12 also exhibited NO production inhibitory effect with an IC₅₀ value of 18.24 and 12.50 μM respectively.