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. • Eighteen compounds (1–18) were isolated from Lichen Lethariella cladonioides. • The structure of a new phenolic acid 3,5-dihydroxy-4-methylbenzaldehyde (1) was established. • It is the first report of isolation of (−)-hydroxypropan-2′,3′-diol-orsellinate (10) from the Lichens. • It is the first report of isolation of compounds 6–7, 9, 12, 14, 16 and 18 from the genus Lethariella (Motyka) Krog. • Chemotaxonomic significance of these compounds was described.