Polyphenol Composition of Traditional Decoctions from Polygoni Cuspidati Rhizoma et Radix of Different Origin and Their Impact on Human Gingival Fibroblasts

Polygoni cuspidati rhizoma et radix (rhizomes of Reynoutria japonica Houtt.) have a long tradition of use in traditional Chinese medicine confirmed by numerous contemporary studies. Our earlier results implied the potential use of decoction of this raw material in oral wound improvement. In this study, we investigated Polygoni cuspidati rhizoma et radix traditionally prepared decoctions from European wildly growing plant (SC decoction; self-collected decoction) and from a pharmacopeial raw material (PH decoction) purchase from a certified pharmacy in Europe. We performed qualitative and quantitative phytochemical analysis and examined the effect of the decoctions and their major constituents on the viability of the human gingival fibroblast (HGF-1) cell line. The SC decoction caused a higher increase in cell viability in a wide range of concentrations 2.5–2000 µg/mL (from 100 µg/mL an increase of 35% and more, compared to control, at p ≤ 0.0001), while the decoction PH showed a statistically significant increase only at a concentration of 100 µg/mL (an increase of 24% compared to control, at p ≤ 0.001). Moreover, the PH decoction showed cytotoxic activity towards HGF-1 at higher concentrations (≥500 μg/mL), which was not observed in the SC decoction. Substantial differences in the chemical composition between the two decoctions were also observed. The SC decoction contained significantly more flavan-3-ols and procyanidin dimers and less stilbenes and anthraquinones than the PH decoction. For example, SC contained about 9 times more epicatechin and 3 times more catechin, as well as 4.5 times more procyanidin B1 and 9 times more procyanidin B2 and B4 than the PH decoction but about 7.5 times less resveratrol and 4 times less emodin. We concluded that the high content of flavan-3-ols and procyanidins with low cytotoxic potential towards HGF-1, as well as the correspondingly low content of some anthraquinones, had a beneficial effect on the activity of the SC decoction.