Studies on the Structure and Biosynthesis of Tridentoquinone and Related Meroterpenoids from the Mushroom Suillus tridentinus (Boletales)

Tridentoquinone ( 1 ), the main pigment of Suillus tridentinus , is accompanied by the known meroterpenoid bolegrevilol ( 3 ) and a dimer, tridentorubin ( 5 ). The absolute configuration of 1 was unambiguously established by a single‐crystal X‐ray analysis of the corresponding (–)‐camphanoate. The structure of 5 was elucidated by 2D NMR techniques including a 2D INADEQUATE experiment. Feeding experiments with [1‐ 13 C]‐labeled 4‐hydroxybenzoic acid ( 6* ) and 3,4‐dihydroxybenzoic acid ( 7* ) proved the incorporation of these precursors into all three metabolites. Tridentoquinone ( 1 ) was monolabeled at C‐1 suggesting the formation of the ansa ring by oxidative cyclisation of 2‐geranylgeranyl‐6‐hydroxybenzoquinone ( 10 ). This was supported by the isolation of the expected intermediate, deoxytridentoquinone ( 11 ), from the mushroom extract. Tridentorubin ( 5 ) may be formed by addition of precursor 10 to tridentoquinone ( 1 ). This hypothesis is backed up by the in vitro formation of an analogous product 13 from 1 and 1,4‐benzoquinone. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)