Biological Activities of Lichen-Derived Monoaromatic Compounds

Abstract

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 (1), 3,5-dihydroxybenzoate methyl (2), 3,5-dihydroxy-4-methylbenzoic acid (3), 3,5-dihydroxy-4-methoxylbenzoic acid (4), 3-hydroxyorcinol (5), atranol (6), and methyl hematommate (7). To obtain more derivatives, available compounds from the previous reports such as methyl β-orsellinate (8), methyl orsellinate (9), and D-montagnetol (10) were selected for bromination. Electrophilic bromination was applied to 8–10 using NaBr/H2O2 reagents to yield products methyl 5-bromo-β-orsellinate (8a), methyl 3,5-dibromo-orsellinate (9a), 3-bromo-D-montagnetol (10a), and 3,5-dibromo-D-montagnetol (10b). Compounds were evaluated for alpha-glucosidase inhibition and antimicrobial activity against antibiotic-resistant, pathogenic bacteria Enterococcus faecium, Staphylococcus aureus, and Acinetobacter baumannii. Compound 4 showed stronger alpha-glucosidase inhibition than others with an IC50 value of 24.0 µg/mL. Synthetic compound 9a exhibited remarkable activity against Staphylococcus aureus with a MIC value of 4 µg/mL. Molecular docking studies were performed to confirm the consistency between in vitro and in silico studies.

UHPLC-MS Metabolomic Fingerprinting, Antioxidant, and Enzyme Inhibition Activities of Himantormia lugubris from Antarctica

“…Moreover, usnic acid in U. longissima is found in high concentrations and is evidenced with a significant effect on different cancer cell lines [37]. As for other chemical compounds, atranol was reported as a biologically active constituent of several lichens [38] including Stereocaulon azoreum and Stereocaulon vesubianum [39,40], and in Antarctic lichens in Everniopsis trulla [41], while barbatolic acid reported in Bryoria lichens [42] was reported to be active against breast cancer [43], showed antiangiogenic effects [44], and was previously reported in H. lugubris [45] while the compound 5,7-dihydroxy-6-methylphthalide was only reported to occur in Usnea florida [46] and Usnea antarctica [41]; the concentration of both compounds was 85.833 and 49.374 per gram of lichen, respectively (Table 2).…”

α‐Glucosidase Inhibitory Cycloartanes from the Vietnamese Combretum quadrangulare

“…From the extract EA, five fractions EA1-EA5 were prepared and fraction EA2 was chemically investigated in the previous report. [10] In this article, fraction EA5 (3.1 g) was applied to silica gel CC using a gradient system of hexane-ethyl acetate 3450, 1709, 1426, 1366, 1227, 1088, 1050 cm À 1 ; The 1 H and 13 C-NMR spectroscopic data are provided in Table 1.…”

“…The activity of 1 and 2 was evaluated following the procedure reported previously by Do et and coworkers. [10] Inhibitory Type Assay of 1 on α-Glucosidase α-Glucosidase inhibition type of 1 was determined by Lineweaver-Burk plots, using previous methods similar to those reported in the literature. [6] Different concentrations of pNPG substrate (1 mM, 2 mM, and 4 mM) in the presence of various concentrations of 1 (0, 1.48, 2.96, 5.92 and 11.84 μM).…”

“…[8][9] The Vietnamese native plant had much attention of phytochemists. [1,[8][9][10] Dao and co-workers indicated that the extracts of the plant growing in Vietnam showed potent α-glucosidase inhibition. The previous reports focused on the bioactive fractions (so-called P9 and EA2) to find the bioactive compounds.…”

“…Combretic acids and combretanones are potential anticancer compounds against several cell lines [8–9] . The Vietnamese native plant had much attention of phytochemists [1,8–10] . Dao and co‐workers indicated that the extracts of the plant growing in Vietnam showed potent α‐glucosidase inhibition.…”