Oregonensins A and B, new meroterpenoids from the culture broth of Ganoderma oregonense and their antioxidant activity

Two new meroterpene derivatives (1 and 2), together with three known compounds (3–5) were isolated from the culture broth of fungus Ganoderma oregonense. Chemical structures of compounds 1–5 were determined using spectroscopic methods. All compounds were tested for 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging efficacy. Compound 1 exhibited significant antioxidant activities with IC50 values of 31.2 and 65.4 μM in the ABTS and DPPH radical scavenging activities, respectively.