Novel Sorbicillin Analogues from the Marine Fungus Trichoderma sp. Associated with the Seastar Acanthaster Planci

Two novel sorbicillinoid analogues, (4'Z)-sorbicillin (1) and (2S)-2,3-dihydro-7-hydroxy-6-methyl-2-[(E)-prop-1-enyl]-chroman-4-one (2), together with three known compounds, (2S)-2,3-dihydro-7-hydroxy-6,8-dimethyl-2-[(E)-prop-1-enyl]-chroman-4-one (3), sorbicillin (4), and 2',3'-dihydrosorbicillin (5), were isolated from the culture broth of the fungus Trichoderma sp. associated with the seastar Acanthaster planci. Their structures were determined by analysis of the NMR and MS data. Compound 1 was the first example with a Z-configuration of the C-4'/C-5’ double bond in the sorbyl side chain. Compounds 2 and 3 were uncommon monomeric sorbicillinoids with a cyclic sorbyl chain. 2, 3 and 5 showed moderate cytotoxic activities against various cancer cell lines.