From Usnea aciculifera, a new depside aciculiferin A (1) was isolated, together with eleven known compounds, (+)-(12 R)-usnic acid (2), methyl haematommate (3), methyl β-orsellinate (4), methyl orsellinate (5), atranol (6), 7-hydroxy-5-methoxy-6-methylphthalide (7), norstictic acid (8), stictic acid (9), atranorin (10), barbatinic acid (11) and diffractaic acid (12). Their chemical structures were elucidated by 1D and 2D NMR spectroscopic as well as HR-ESI-MS analysis. Usnic acid (2) and depside diffractaic acid (12) presented in high yield of around 1.5% of the dried material. Some lichen substances inhibited the growth of some cancer cell lines. Three depsides, 1, 11 and 12, were evaluated for their cytotoxic activity against HeLa (human epithelial carcinoma), NCI-H460 (human lung cancer) and MCF-7 (human breast cancer) cell lines at the concentration of 100 μg/mL. Depside 1 showed good and depside 12 strong cytotoxic activity against three surveyed cancer cell lines.

Introduction: Usnic acid isolated from lichen was a potential bioactivity compound. It has a broad spectrum bioactivity, including antiviral, anti-inflammatory, anticancer… However, low solubility in water limited its application. Many researchs have done to overcome the restriction. Recent results showed that usnic acid derivatives bearing triazole, enamine, pyrazole and benzylidene groups had strong antiviral and anticancer activities. Thus, investigation of usnic acid derivatives synthesis was an attractive aspect due to the diversity of bioactivities of usnic acid derivatives. Methods: Usnic acid was isolated from lichen, six ester derivatives of usnic acid were synthesized from usnic acid with acetyl chloride and benzoyl chloride under stirring at room temperature. The products were evaluated α-glucosidase and tyrosinase inhibitory activities. Results: All the ester derivatives were created with good yields. All derivatives exhibited the same or higher activity comparing with usnic acid. Ester of usnic acid bearing benzoyl group showed excellent α-glucosidase activity with IC50 26.7±0.57 and 68.8±0.15 µM. Conclusion: Among the ester derivatives, UE1 and UE6 were reported as as new compounds. Interestingly, all products displayed the same or higher biological activity than the starting material, usnic acid when evaluated against α-glucosidase and tyrosinase.

Chemical investigation of the ethyl acetate extract of Ficus consociata leaves, collected at Bien Hoa city, Dong Nai province, led to the isolation and structural elucidation of seven compounds, including luteolin (1), cirsiliol (2), isoquercetin (3), quercetin 3-O-α-L-arabinopyranoside (4), nikotoflorin (5), hesperidin (6) and (2E,4E,1'S,2'R,4'S,6'R)dihydrophaseic acid (7). Their chemical structures were elucidated by a combination of electronic circular dichroism (ECD) experiments and spectroscopic data (HR-MS, 1D, 2D NMR) analysis, and comparison with those reported in the literature. Although, these compounds were already known in other species, but this is the first report on chemical constituents of F. consociata.

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Introduction: R occella montagnei is widely distributed in subtropical regions. As the continuous study on the hexane extract of Roccella montagnei lichen, the isolation and structural determination of five compounds were addressed. Method: The crude extract was obtained from the dried lichen powder's extraction at room temperature. The n-hexane, n-hexane-ethyl acetate, and ethyl acetate extracts were obtained by the liquid-liquid partition method. The organic compounds were isolated from n-hexane extract by silica gel and Sephadex LH-20 column chromatography. Their chemical structures were identified by the NMR and HR-ESI-MS data analysis and the comparison of their NMR data with the published data. Results: Five compounds were isolated and chemically structural identified, consisting of 3b -hydroxy-7a-methoxystigmast-5-ene (1), sekikaic acid (2), lichenxanthone (3), (+)-6,8-dihydroxy-3-propyl-3,4-dihydroisocoumarin (4), and ar-turmerone (5). Conclusion: To the best of our knowledge, except 3 which was reported from this species for the first time, four isolated compounds left did not known to be present in Roccella genus before.