Sanguinones A and B, Blue Pyrroloquinoline Alkaloids from the Fruiting Bodies of the Mushroom Mycena sanguinolenta

Two previously unknown blue alkaloid pigments, sanguinone A (1) and sanguinone B (2), and one new red indoloquinone alkaloid, sanguinolentaquinone (3), have been isolated from Mycena sanguinolenta fruiting bodies. In addition, decarboxydehydrosanguinone A (4) was identified as an oxidative decarboxylation artifact of 1. The structures of these alkaloids have been established by 2D NMR and ESIMS methods. The absolute configurations of 1 and 2 were determined by comparison of their CD spectra with the CD spectrum of mycenarubin A (5), which we isolated recently from fruiting bodies of the mushroom Mycena rosea. The sanguinones are structurally related not only to the mycenarubins A (5) and B but also to a large number of marine alkaloids such as the discorhabdins.