SETOSOL, A BIOLOGICALLY-ACTIVE HEPTAKETIDE-LIKE METABOLITE FROM THE PLEIOCHAETA-SETOSA PHYTOPATHOGEN

Setosol, a biologically active natural product, was extracted from Ple iochaeta setosa, an organism isolated from volcanic rock in the Canari es. With molecular formula C15H16O5 and a melting point of 139 degrees C, this pale yellow and amorphous compound inhibited the growth of Py ricularia oryzae, Drechslera oryzae, and Gerlachia oryzae. Isolation o f the new compound was performed by repeated centrifugal TLC on silica gel, and its structure was established as dimethyl-4-methoxy-6,10,11- trihydroxy-benzooxaonin by detailed spectral studies, including COSY, 2D H-1-C-13 direct chemical shift correlation (XHCORR), 2D H-1-C-13 co rrelation via long-range coupling (COLOC), heteronuclear-gated decoupl ing (GATEDEC), and single-frequency heteronuclear-gated decoupling (SF DEC) NMR techniques, as well as UV, IR, and MS.