Objective To investigate the chemical constituents and biological activities of Wikstroemia micrantha(Thymelaeaceae). Methods The chemical constituents were isolated and purified via multiple chromatographic techniques including normal-phase silica gel column chromatography, ODS reversed-phase column chromatography and Sephadex LH-20 gel permeation chromatography. The structures of isolated compounds were elucidated by physicochemical properties, 1D NMR, and ESI-MS spectroscopic analyses. The cytotoxic activities of all compounds against five human tumor cell lines (human breast cancer MCF-7 cells, human ovarian cancer SKOV3 cells, human colon cancer HCT-116 cells, human promyelocytic leukemia HL-60 cells, and human hepatocellular carcinoma HepG2 cells) were screened by the CCK-8 assay. Enzyme inhibition assays were performed to evaluate the inhibitory effects of the compounds on α-glucosidase, butyrylcholinesterase (BChE) and acetylcholinesterase (AChE). Results A total of ten compounds were isolated from the ethanol extract of the dried branches and leaves of W. micrantha, and their structures were identified as syzalterin (1), 2-(p-hydroxyphenoxy)-6,8-dimethyl-5,7-dihydroxychromone (2), genkwanin (3), luteolin (4), 7-hydroxycoumarin (5), daphnoretin (6), daphnetin (7), 2,2′-oxybis(1,4-di-tert-butylbenzene) (8), (+)-3-hhydroxy-1,5-diphenylpentan-1-one (9), 1,5-diphenylpentan-1-one (10). In vitro antitumor activity screening revealed that compounds 2 and4 exhibited weak cytotoxicity against various tumor cell lines, with their median inhibitory concentration (IC₅₀) values ranging from 18 to 50 μmol/L. In α-glucosidase inhibitory assay, compounds 1, 2 and 7 displayed moderate inhibitory activity, with IC₅₀ values of (15.51 ± 0.49), (15.99 ± 1.15) and (19.65 ± 1.71) μmol/L, respectively. Results from the in vitro BChE inhibitory assay indicated that compound7 exerted potent inhibitory activity with an IC₅₀ value of (5.63 ± 0.20) μmol/L, whereas compound 9 exhibited moderate inhibitory activity [IC₅₀ = (13.22 ± 0.84) μmol/L]. None of the isolated compounds 1—10 showed notable inhibitory activity against AChE. Conclusion Compounds 1—10 were isolated from W. micrantha for the first time. Bioactivity screening demonstrated that several isolates possessed favorable antitumor activity and selective BChE inhibitory effects. This study provides chemical material basis and experimental data support for further research and development of the medicinal material W. micrantha.

Wikstroemia Endl.  /  Wikstroemia micrantha Hemsl.  /  antitumor activity  /  in vitro enzyme inhibitory activity  /  genkwanin  /  luteolin  /  7-hydroxycoumarin  /  daphnetin