Polyphenols from aerial parts of Polygonum bellardii and their biological activities.

CONTEXT

Polygonum species have been used in the treatment of several types of inflammatory disorders and cancer. Nevertheless, there are no reports related to the anti-inflammatory and anti-proliferative activities of Polygonum bellardii All. (Polygonaceae).

OBJECTIVE

This study investigated the chemical composition of the methanol extract of P. bellardii. The anti-inflammatory and cytotoxic activities of methanol, n-butanol, ethyl acetate extracts and isolated polyphenols were determined.

MATERIALS AND METHODS

The chemical structure of the isolated compounds was elucidated using different spectral techniques. MTT assay was used to evaluate the anti-proliferative activity in HeLa, MCF-7 and HepG-2 cells. Inhibition of 5-lipoxygenase (5-LOX) activity and prostaglandin E2 (PGE2) production in stimulated HepG-2 cells were used to assess the anti-inflammatory activity.

RESULTS

The present study resulted in isolation of five compounds (new for the species). They were identified as gallic acid (1), quercetin (2), myricetin (3), quercetin-3-O-β-D-glucopyranoside (5) and myricetin-3-O-α-arabinofuranoside (7). Additionally, a couple of previously isolated compounds such as quercetin-3-O-(5″-acetyl-α-arabinofuranoside) (4) and myricetin-3-O-(5″-acetyl-α-arabinofuranoside) (6) were detected. The n-butanol extract has the highest cytotoxicity in HeLa, MCF-7 and HepG-2 cells, with IC₅₀ values of 15.26, 50.66 and 30.09 µg/ml, respectively. Compound 6 exhibited a marked cytotoxicity in HeLa (IC₅₀ 75.04 µg/ml) and HepG-2 (IC₅₀ 41.03 µg/ml) cells. Crude extracts and pure compounds inhibited the 5-LOX activity and PGE2 production in a dose-dependent manner (0.1-250 µg/ml).

DISCUSSION AND CONCLUSION

These results explain the traditional uses of P. bellardii and indicate that polyphenols, despite structural similarity, have different cytotoxic and anti-inflammatory effects.