Three new lactarane sesquiterpenoids from the mushroom Russula sanguinea

The family Russulaceae is one of the largest in the subdivision Basidiomycotina in Whittaker's Kingdom of Fungi [1] and comprises hundreds of species, worldwide distributed, belonging to the genera Lactarius and Russula. While secondary metabolites occurring in the fruiting bodies of Lactarius species have been well investigated [2], the Russula mushrooms have received less attention, notwithstanding the larger number of existing species [3]. In a previous paper, we reported the isolation and structural elucidation of sterols from the fruiting bodies of Russula sanguinea (Bull.) Fr. [4]. In the course of further studies on the constituents of the above mushroom, three new lactarane sesquiterpenoids, sangusulactones A-C (1-3), along with two known compounds have been isolated (Figure 1). This paper deals with the structural elucidation of the new compounds. The known compounds 4 and 5 were identified as blennin A (4) [5] and 15-hydroxyblennin A (5) [6], respectively, by comparison of their spectral data with those reported in the literature.