ES-242-2

Verticillium sp. SPC-15898 was found to produce novel metabolites, designated ES-242-2-(-)8, which were structurally related to ES-242-1. These compounds were isolated from the culture broth and the physico-chemical and biochemical properties were examined. ES-242-2-(-)8 inhibited [3H]thienyl cyclohexypiperidine ([3H]TCP) binding to rat crude synaptic membranes (CSM) with IC50 values of 0.116, 2.9, ca. 2.9, 25.3, 1.0, 59, 24, and 13 microM, respectively. None of these compounds showed inhibitory effects against the binding of [3H]kainate to its receptor, which is another subtype of the excitatory amino acid receptor.

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.