Phenolic compounds from the lichen Parmotrema tinctorum

Abstract

Introduction: The metabolites of lichens concentrated depsidones, depsides, and diphenyl ethers were possessed antibiotic, antifungal, antiviral, antitumor, and anticancer activities. Parmotrema tinctorum (Despr. ex Nyl.) Hale, a species of foliose lichen, is widely distributed in Lam Dong province, Vietnam. Herein, this paper describes the isolation and structure elucidation of seven compounds isolated from this lichen. Methods: Phytochemical investigations of the ethyl acetate extract of the lichen P. tinctorum led to the isolation of seven pure compounds. Their chemical structures were elucidated by extensive HR-ESI-MS and NMR spectroscopic analysis and comparison with previously published data. Results: Seven compounds, namely orcinol (1), orsellinic acid (2), methyl orsellinate (3), methyl heamatomate (4), lecanorin (5), lecanoric acid (6), and gyrophoric acid (7). These compounds were determined the α-glucosidase inhibitory activity. Conclusions: Compound 7 was determined for the first time in P. tinctorum, and this was also the first time these compounds were determined the α-glucosidase inhibitory activity.