Biological Activities of Lichen-Derived Monoaromatic Compounds.

Lichen-derived monoaromatic compounds are bioactive compounds, associated with various pharmacological properties: antioxidant, antifungal, antiviral, cytotoxicity, and enzyme inhibition. However, little is known about data regarding alpha-glucosidase inhibition and antimicrobial activity. Very few compounds were reported to have these activities. In this paper, a series of monoaromatic compounds from a lichen source were isolated and structurally elucidated. They are 3,5-dihydroxybenzoic acid (), 3,5-dihydroxybenzoate methyl (), 3,5-dihydroxy-4-methylbenzoic acid (), 3,5-dihydroxy-4-methoxylbenzoic acid (), 3-hydroxyorcinol (), atranol (), and methyl hematommate (). To obtain more derivatives, available compounds from the previous reports such as methyl β-orsellinate (), methyl orsellinate (), and D-montagnetol () were selected for bromination. Electrophilic bromination was applied to - using NaBr/HO reagents to yield products methyl 5-bromo-β-orsellinate (), methyl 3,5-dibromo-orsellinate (), 3-bromo-D-montagnetol (), and 3,5-dibromo-D-montagnetol (). Compounds were evaluated for alpha-glucosidase inhibition and antimicrobial activity against antibiotic-resistant, pathogenic bacteria , , and . Compound showed stronger alpha-glucosidase inhibition than others with an IC value of 24.0 µg/mL. Synthetic compound exhibited remarkable activity against with a MIC value of 4 µg/mL. Molecular docking studies were performed to confirm the consistency between in vitro and in silico studies.