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.

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-5propylphenol 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 IC50 values in 136.62 μg/mL (compared with the control acarbose IC50 93.63 μg/mL).

Placolobium vietnamense N.D.Khoi & Yakovlev (Fabaceae) is an indigenous plant of Vietnam. Up to now, this plant has not yet been chemically and biologically studied. In this paper, six isoflavones including afrormosin (1), cladrastin (2), 8‐O‐methylretusin (3), millesianin C (4), barbigerone (5), and durallone (6) were isolated from the ethyl acetate extract of the stem bark of Placolobium vietnamense. Their structures were established by means of physical data (ESI MS, 1D and 2D NMR) and evaluated for the cytotoxic activities against liver hepatocellular carcinoma (HepG2), human lung cancer (NCI‐H460), human epithelial carcinoma (HeLa) and human breast cancer (MCF‐7) cell lines. This is the first report on phytochemical studies of this plant.