In Vitro Gingival Wound Healing Activity of Extracts from Reynoutria japonica Houtt Rhizomes

Rhizomes of Reynoutria japonica Houtt. are a traditional Chinese medicinal herb (Polygoni cuspidati rhizoma, hu zhang) used for treatment of numerous diseases including wound healing support. The aim of this study was to provide evidence for the value of this herbal drug’s traditional use as a gingival healing treatment as well as to obtain the most active extract. In vitro studies were performed using primary human gingival fibroblasts (HGFs) with determination of viability (MTT assay), cell proliferation (the confocal laser scanning microscope (CLSM) was used to visualize histone 3 expression), cell migration (wound healing assay), and evaluation of the expression of collagen type III (immunocytochemical staining) after incubation with extracts from R. japonica rhizomes (25% or 40% ethanol or 60% acetone). In addition to these extracts, commercial dental rinse (containing chlorhexidine digluconate 0.2%) was tested as the gold standard of choice for gum healing in dental practice. The studied extracts were qualitatively and quantitatively characterized using the validated HPLC/DAD/ESI-HR-QTOF-MS method. Total phenols and tannins content were determined using the Folin–Ciocalteu assay. Low concentration of all extracts after 24 h incubation caused significant increase in HGF viability. This effect was most pronounced at a concentration of 50 µg/mL, which was selected for further experiments. All extracts (at 50 µg/mL) stimulated HGF to proliferate, migrate, and increase collagen III synthesis, but with different strength. The highest stimulated proliferation and migration activity was observed after incubation with 25% EtOH, which according to phytochemical analysis may be related to the highest content of resveratrol and an appropriate composition of procyanidins. The 25% EtOH extract from R. japonica rhizomes appears to be a promising gingival wound healing agent worthy of animal and clinical trials.