Novel DPPH Radical Scavengers, Bisorbicillinol and Demethyltrichodimerol, from a Fungus.

In our screening program for antioxidants with DPPH radical scavenging activity, we isolated four yellowish compounds from the fermentation broth of Trichoderma sp. USF-2690 strain isolated from a soil sample: two were novel compounds designated bisorbicillinol (1) and demethyltrichodimerol (2), and two were known compounds bisvertinolone (3) and trichodimerol (4). The structures of 1 and 2 were elucidated by spectroscopic evidence and chemical modification. Two compounds seemed to be the oxidized dimers of sorbicillin. In the evaluation of DPPH radical scavenging activity, bisorbicillinol gave the lowest ED50 value (31.4 μM) among the four compounds, equal to that of BHT (27.0 μM).