Concentricol, a taxonomically significant triterpenoid from Daldinia concentrica

In the course of a chemotaxonomic study of xylariaceous Ascomycetes, a major metabolite was isolated and identified from the ascostromata of Daldinia concentrica. The compound, for which the name concentricol is proposed, constitutes a highly oxidised squalene derivative. A survey of several Daldinia spp. from around the world (including several type materials), employing analytical HPLC-UV/Vis (with diode array detection) and positive electrospray HPLC-MS of stromatal MeOH extracts revealed that concentricol was omnipresent in the stromata of D. concentrica, as well as in those of several collections of the pantropical Daldinia eschscholzii. All other investigated Daldinia spp. were found devoid of concentricol but contained binaphthalenes, benzophenones and/or azaphilones as further taxonomically relevant main metabolites.