A new meroterpenoid pigment from the basidiomycete Albatrellus confluens.

A new farnesyl phenol named (+)-(R)-grifolinone C (1) has been isolated from the fruiting bodies of the basidiomycete Albatrellus confluens. (+)-(R)-Grifolinone C (1), a dimeric meroterpenoid, is accompanied by albatrellin (2), grifolinone B (3), grifolin (4), and grifolinone A (5). Albatrellin (2) exhibited cytotoxic activity against HepG2 human lung carcinoma cells with IC(50) value of 1.55 mug ml(-1). The structures were established on the basis of spectral evidence (IR, 1D- and 2D-NMR, and MS analyses).