Phytochemical and chemotaxonomic study on the Lichen Lethariella cladonioides

The comprehensive phytochemical research of Lethariella cladonioides (Nyl.) Krog, (Parmeliaceae), a lichen in southwest China, resulted in isolation of eighteen compounds (1–18), including a new phenolic acid 3,5-dihydroxy-4-methylbenzaldehyde (1) and seventeen known compounds, nine phenolic acids (2–10), one dibenzofuran (11), two depsides (12 and 13), one alkane (14), one glucoside (15), two polyols (16 and 17), and one fatty acid (18). The structures of these compounds were assigned by detailed interpretations of spectroscopic data (1D and 2D NMR, HR-ESI-MS) and comparisons with the published data. Among them, 3,5-dihydroxy-4-methylbenzaldehyde (1) is a new one. (−)-hydroxypropan-2′,3′-diol-orsellinate (10) have not been reported from any species in the lichens. Compounds 6, 7, 9, 12, 14, 16 and 18 were firstly isolated from the genus Lethariella (Motyka) Krog. Compounds 2, 6, 7, 9, 10, 12, 14, 16 and 18 were reported from L. cladonioides firstly. The chemotaxonomic significance of these compounds was also discussed.