Chemical constituents of chloroform extract from the lichen Ramalina peruviana Arch (Ramalinaceae)

Abstract From the chloroform extract of the lichen Ramalina peruviana Ach. (Ramalinaceae), collected at Cau Dat farm, Lam Dong province, Vietnam, eight organic compounds had been isolated: nonadecan‐1‐ol ( 1 ); nonadecenoic acid ( 2 ); (+)‐( 12R )‐usnic acid ( 3 ); three monophenolic compounds‐ rhizonic acid ( 4 ), divarinolmonomethylether ( 5 ) and divaricatinic acid ( 6 ); and two depsides‐ decarboxy‐2'‐ O ‐methyldivaricatic acid ( 7 ) and sekikaic acid ( 8 ). The chemical structure of these compounds was elucidated by spectroscopic analysis as well as high resolution ESI–MS analysis and comparison with those reported in the literature. Among these compounds, ( 1 ), ( 2 ), ( 4 ), ( 5 ) and ( 7 ) were the first time known in the Ramalina genus. Although compound ( 7 ) was detected in the lichen Neofuscelia depsidella by chromatographic comparisons with authentic material that was synthesized by condensation of the benzoic acid and 3‐methoxyl‐5‐propylphenol but it is isolated in the nature for the first time. The results of determining the α ‐glucosidase inhibitory activity of four isolated compounds show that the α ‐glucosidase inhibitory effect of ( 8 ) was the best with IC 50 values in 136.62 μg/mL (compared with the control acarbose IC 50 93.63 μg/mL).