Chemical Constituents of the Epiphytic and Lithophilic Lichens of the Genus Collema.

Biodiversity of secondary lichen metabolites by the epiphytic and lithophilic lichens of the genus Collema is reported. The most abundant fatty acids were α-linolenic acid (18:3n-3), oleic acid (18:1n-9), and palmitic acid (16:0), but a great variation of the ester composition from one to another was found. A comparison of neutral lipids, glycolipids, polar lipids and fatty acid composition of four species was done. DGTS, DGTA, PC, and PI were found as major components among polar lipids. Chemical constituents were characterized by GC-MS, HPLC, HR-TLC, and other chemical methods. Biological activity of isolated compounds from Collema species is also discusses. Several indole alkaloids and other nitrogen-containing metabolites have been isolated from the genus Collema: C. cristatum, C. callopismum, C. fuscovirens and C. flaccidum. [ABSTRACT FROM AUTHOR]