Cytotoxic Terphenyl Neolignans from Fungus <i>Terana coerulea:</i> New Natural Corticins D and E, and Revised Structure for Corticin A

The cobalt crust fungus Terana coerulea (Phanerochaetaceae family) was selected for a bio-guided study after an ethnobotanical survey at the Irati's Forest (Navarra, Spain) for its local use as antibiotic. Six extracts of increasing polarity, from hexane to hot water, were obtained from powdered dry fungi and tested for cytotoxicity against four human tumour cell lines and one non-tumour primary cell culture. From the most cytotoxic, EtOAc extract, we isolated and identified three terphenyl neolignans: two of them new natural products, named corticins D and E, and one previously described as corticin A, whose earlier structure has been revised. Their structural elucidation and biological evaluation as cytotoxic agents are described.