A novel sterol from Chinese truffles Tuber indicum

From the fruiting bodies of Ascomycetes Tuber indicum, a new steroidal glucoside with polyhydroxy ergosterol nucleus, tuberoside (2), has been isolated along with additional four known ergosterol derivatives, (22E, 24R)-ergosta-7, 22-dien-3beta, 5alpha, 6beta-triol (1), 5alpha, 8alpha-epidioxy-(22E, 24R)-ergosta-6, 22-dien-3beta-ol (3), (22E, 24R)-ergosta-5, 22-dien-3beta-ol (4), and (22E, 24R)-ergosta-4, 6, 8(14), 22-tetraen-3-one (5). The structure of new compound was established as 3-O-beta-D-glucopyranosyl-(22E, 24R)-ergosta-7, 22-dien-5alpha, 6beta-diol (2) on the basis of chemical and spectroscopic means ((1)H NMR, (13)C NMR, HMQC, HMBC, MS, and IR). This is the first example of isolation of a polyhydroxylated ergosterol glucoside from higher fungi in nature.