ES-242 Derivatives and Cycloheptapeptides from Cordyceps sp. Strains BCC 16173 and BCC 16176

Five new ES-242 analogues (1–5) were isolated together with nine known compounds (6–14) from the insect pathogenic fungus Cordyceps sp. BCC 16173. A closely related strain, BCC 16176, provided cordyheptapeptide A (15) and small amount of its new analogue, cordyheptapeptide B (16), along with known ES-242s. Structures of the new bioxanthracenes, 1–5, were determined to be 6′-O-desmethyl analogues of 6 (ES-242-4), 8, 9 (ES-242-2), 12, and 13, respectively, primarily by spectroscopic analyses. Cordyheptapeptide B (16) has an N-methyl-l-phenylalanine residue instead of the N-methyl-l-tyrosine in 15.