Parmoferone A, a new depsidone from the lichen Parmotrema cristiferum .

A new depsidone, parmoferone A ( 1 ), together with three known compounds, parmosidone K ( 2 ), albifolione ( 3 ), and 4-chloroorcinol ( 4 ) were isolated from the lichen Parmotrema cristiferum (Taylor) Hale (Parmeliaceae). The structures of isolated compounds were identified from its spectroscopic data and by comparison with the literature. Compounds 1-4 were evaluated for alpha-glucosidase inhibition. Compound 1 was determined to be a potent non-competitive inhibitor against alpha-glucosidase with an IC ₅₀ value of 18.1 μM.