Lichen substances. V. Methylated derivatives of orsellinic acid, lecanoric acid, and gyrophoric acid from Pseudocyphellaria crocata

Abstract

Two tridepsides (tenuiorin and methyl gyrophorate) have been identified as major constituents of Pseudocyphellaria crocata. Two similarly substituted didepsides (methyl evernate and methyl lecanorate) and the monomer methyl orsellinate have been isolated as new natural products. A number of additional orsellinic acid derivatives occur in the same lichen as identified by cochromatography with reference compounds, which reveals a biosynthetical fingerprint pattern based on methyl ester formation, 4-O-methylation, and condensation.