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 mu M in the ABTS and DPPH radical scavenging activities, respectively.