RESUMO
OBJECTIVE: To screen Vietnamese medicinal plants for xanthine oxidase (XO) inhibitory activity and to isolate XO inhibitor(s) from the most active plant. METHODS: The plants materials were extracted by methanol. The active plant materials were fractionated using different organic solvents, including n-hexane, ethyl acetate, and n-butanol. Bioassay-guided fractionation and column chromatography were used to isolate compounds. The compounds structures were elucidated by analysis of spectroscopic data, including IR, MS, and NMR. RESULTS: Three hundreds and eleven methanol extracts (CME) belonging to 301 Vietnamese herbs were screened for XO inhibitory activity. Among these plants, 57 extracts displayed XO inhibitory activity at 100 µg/mL with inhibition rates of over 50%. The extracts of Archidendron clypearia (A. clypearia), Smilax poilanei, Linociera ramiflora and Passiflora foetida exhibited the greatest potency with IC50 values below 30 µg/mL. Chemical study performed on the extract of A. clypearia resulted in the isolation of six compounds, including 1-octacosanol, docosenoic acid, daucosterol, methyl gallate, quercitrin and (-)-7-O-galloyltricetiflavan. The compound (-)-7-O-galloyltricetiflavan showed the most potent XO inhibitory activity with an IC50 value of 25.5 µmol/L. CONCLUSIONS: From this investigation, four Vietnamese medicinal plants were identified to have XO inhibitory effects with IC50 values of the methanol extracts below 30 µg/mL. Compound (-)-7-O- galloyltricetiflavan was identified as an XO inhibitor from A. clypearia with IC50 value of 25.5 µmol/L.
