Novel Oxidized Sorbicillin Dimers with 1,1-Diphenyl-2-picrylhydrazyl-Radical Scavenging Activity from a Fungus.

Abstract

Three yellowish compounds with 1,1-diphenyl-2-picrylhydrazyl-radical scavenging activity were newly isolated from the fermentation broth of Trichoderma sp. USF-2690 strain that had been isolated from a soil sample: two were novel oxidized sorbicillin dimers designated as bisorbibutenolide (1) and bisorbicillinolide (2), and one was sorbicillin (3) itself. The structures of 1 and 2 were determined from spectroscopic evidence. In the DPPH-radical scavenging assay, α-tocopherol gave an ED50 value of 17.0 μM after standing for 30 min, while continuing observation showed that the ED50 values for bisorbibutenolide, bisorbicillinolide, and sorbicillin slowly reached 80.8, 88.8 and 152.3 μM over 24 hr.