Meroterpenoids from the fruiting body of Albatrellus dispansus with inhibitory activities against Candida albicans budded-to-hyphal-form transition and biofilm formation.

Six novel meroterpenoids, dispanoic acids A-C (1-3), 2'-hydroxydaurichromanic acid (4), albatrellutin A (5), and dispanolactone (6), along with four known meroterpenoids, grifolin (7), grifolic acid (8), grifolin methyl ether (9), and grifolic acid methyl ether (10), were obtained by bioactivity-guided isolation from the n-hexane, CHCl3 and MeOH extracts of the fruiting body of Albatrellus dispansus. The structures of 1-6 were elucidated from NMR and MS spectroscopic data. Although 5 was determined to have the same structure as albatrellutin, its 1H and 13C NMR data were inconsistent with published data. Therefore, we synthesized albatrellutin (reported original structure) and a positional isomer of albatrellutin (revised structure). The published NMR data for albatrellutin and the synthesized positional isomer of albatrellutin were in good agreement. Thus, we corrected the structure of albatrellutin to the positional isomer and renamed it albatrellutin A. Compound 5, which has the structure originally reported as albatrelutin, was named neoalbatrellutin. Isolated compounds (1-10) were evaluated for their inhibitory activity against Candida albicans budded-to-hyphal-form transition (BHT). A new compound 3 showed potent inhibitory activity against BHT and biofilm formation by C. albicans and also downregulated expression of the hyphal wall protein 1 (HWP1).