New acetylated flavonol glucuronides isolated from Polygoni avicularis herba and their influence on some neutrophiles' functions

Polygoni avicularis herba is a pharmacopoeial medical material used for upper respiratory tract disorders and as diuretic agent. It contains flavonoids as a dominating group of compounds. Previous studies have shown that besides some well-known compounds such as avicularin, isoquercitrin and hyperoside, extracts from Polygoni avicularis herba contain significant quantities of several flavonol glucuronides which presence have not been confirmed before in this plant material (1).

The extract for isolation of chosen compounds was prepared by heating dry plant material with 70% methanol on water bath. After evaporation of methanol extract was partionated between CHCl₃, AcOEt and n-butanol to obtain fraction of different polarity. Main constituents were isolated by column chromatography on Diaion HP-20 and Toyopaerl HW-40F followed by preparative HPLC. 10 flavonol glucuronides were isolated and their structure was determined by 1D and 2D NMR experiments. Compounds P7, P8 and P9 were isolated for the first time form any plant material. The presence of the rest of compounds was confirmed for the first time in Polygoni avicularis herba.

The bioactivity of isolated compounds were evaluated in human neutrophil model. All the compounds were able to scavenge reactive oxygen species in f-MLP and PMA stimulated neutrophils. Isolated constituents were also able to inhibit the elastase release from stimulated neutrophils. The bioactivity of investigated compounds was correlated with differences in their chemical structure.

Reference:

[1] Granica, S.; Piwowarski J. P.; Popławska M.; Jakubowska M.; Borzym J.; Kiss A. K. Novel insight into qualitative standardization of Polygoni avicularis herba (Ph. Eur.). Journal of Pharmaceutical and Biomedical Analysis 2013, 72, 216 – 222.