Chemical profiling of lithophytic holobiont depside of hammered shield lichen

Abstract

Background: Lithophytic holobionts survive harsh environments by synthesizing specialized secondary metabolites. This study outlines the distinct chemotype of the rock-associated, extremophilic hammered shield lichen, i.e., Parmelia sulcata. Methods: Crude ethanolic extract was obtained by cold maceration of the hammered shield lichen and fractionated using silica-gel column chromatography. Nonpolar fractions were profiled by GC-MS, with compound annotations based on NIST library matching and relative peak-area normalization. Results: GC-MS profiling of P. sulcata fraction L10-L13 revealed a dominant orcinol-pathway chemotype, comprising primarily orcinol (43.39%) and atraric acid (20.92%). Conclusion: Chromatography-assisted approach successfully separated bioactive depsides. The isolated lichen depsides (P. sulcata) represent favorable structural scaffolds for treating several chronic diseases.