Flavonoid glucuronides with anti-leukaemic activity from Polygonum amphibium L

Introduction –  The chemical and pharmaceutical studies carried out on species from Polygonum L. genus showed biological activity both of the extracts and the components isolated from them. These results were the impulse to examine Polygonum amphibium L. Objective –  The aim of this study was the isolation of active components from methanol extract and the determination of their cytotoxic effect on human leukaemic cell lines. Methodology  – Three flavonoid components from butanol soluble fractions of methanol extract by CC and PC preparative chromatography were isolated. Their structures were established on the basis of ¹H, ¹³C and correlation (DEPT, H‐H, COSY, HMQC, HMBC) NMR, UV and FAB‐MS spectroscopic techniques. The evaluation of the anti‐leukaemic activities of 1 and 2 against Jurkat and HL60 cell lines was carried out in vitro using annexin V fluorescence assay. Results  – Two new flavonoid glucuronides, quercetin‐3‐O‐β‐glucuronide ( 1 ) and quercetin‐3‐O‐α‐rhamnosyl‐(1 → 2)‐β‐glucuronide ( 2 ), and kaempferol‐3‐O‐α‐rhamnosyl‐(1 → 2)‐β‐glucuronide ( 3 ), were isolated from Polygonum amphibium L. It was demonstrated that the glucuronides of quercetin are able to induce apoptosis in the tested human leukaemic cells. These compounds penetrate through cytoplasm to the cellular nucleus of the cultured cells, and give intensive apoptotic responses in the stimulated leukaemic cells. The number of apoptotic cells increased with the concentration (1 nm to 10 µm ) of 1 or 2 and periods of exposure (1–3 days). Conclusion  – Compounds 1 and 2 may be considered good candidates for leukaemia chemotherapeutic agents. Copyright © 2008 John Wiley & Sons, Ltd.