## 4 Discussion
In our earlier study [10], ethanol extracts (25% EtOH and 40% EtOH) and an acetone extract (60% acetone) prepared from the same raw material that was used to prepare the SC decoction showed a narrower range of concentrations stimulating the viability of gingival fibroblasts than the SC decoction. After 24 h of incubation, these extracts stimulated fibroblast viability at a concentration of 50 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, but starting from 500 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, cytotoxic activity was observed. We included these extracts in the current study to examine the content of procyanidins and flavan-3-ols (Figure 6, Table 3). Ethanol and acetone extracts contained significantly higher epicatechin content than the decoction, but not catechin. The highest content of the procyanidins tested was observed in 60% acetone, which is consistent with the literature that it is a good solvent for procyanidin extraction [38]. A decrease in the content of these compounds was observed with a decrease in the amount of ethanol in the solvent: 40% EtOH > 25% EtOH > decoction. However, the amount of procyanidin B3 in the decoction was higher than in the ethanol extracts. It should be remembered that here we have only quantitatively examined flavan-3-ol monomers and procyanidins dimers. We know from previously performed tests that the total amount of tannins and, therefore, also the more polymerized procyanidins, is much higher in acetone and ethanol extracts than in a decoction [9; 10]. Despite the higher content of procyanidins and flavan-3-ols with proven fibroblast proliferation-stimulating activity in these ethanol and acetone extracts, these preparations did not give a more beneficial effect than decoctions. Similarly, in the case of the PH decoction, other compounds present in higher concentrations in these products, e.g., the previously mentioned resveratrol or emodin and its derivatives, could have a negative effect on the tested activity. According to a previous study [10], the content of emodin and resveratrol in ethanol and acetone extracts is significant higher than in the SC decoction. Emodin per gram of extract is 1.47 mg (25% EtOH), 3.68 mg (40% EtOH), and 9.63 mg (60% acetone), and for resveratrol it is 3.95 mg (25% EtOH), 3.05 mg (40% EtOH), and 1.47 mg (60% acetone) [10]. It appears that these compounds may be responsible for the cytotoxic effects of the extracts at high concentrations. Moreover, it is also possible that high concentration of procyanidins or flavan-3-ols in extracts may have a negative effect on fibroblasts. In summary, it should be stated that although the PH decoction showed stimulation of the viability of gingival fibroblasts, this activity was weaker than that of the SC decoction. The PH decoction showed cytotoxic activity at higher concentrations, which was not observed in the SC decoction. The differences in activity resulted from different chemical composition. The SC decoction contained significantly more flavan-3-ols and procyanidin dimers and less stilbenes and anthraquinones than the PH decoction, which probably had a positive effect on the observed activity. It is worth mentioning that decoctions usually have a high content of saccharides, which we have already observed in the rhizomes of _Polygonum cuspidatum_[9], and they can also interact synergistically with other compounds, influencing the final activity. We are currently testing the activity of this group of compounds. The major differences in the composition of decoctions may be due to environmental factors but may also result from genetic variation resulting from a possible crossing and repeated uncontrolled backcrossing with related species. In Europe, _Reynoutria \(\times\) bohemica_ [PERSON]. [PERSON] \(\&\) [PERSON], a hybrid of _Reynoutria japonicus_ and _Reynoutria sachalinensis_, is common, and the genetic structure of hybrid populations is unresolved. These hybridshave often a varied spectrum of morphological traits that may lead to unintended admixture to the material collected from wild habitats.