Effects of Astilbe thunbergii rhizomes on wound healing Part 1. Isolation of promotional effectors from Astilbe thunbergii rhizomes on burn wound healing

The dried rhizomes of Astilbe thunbergii (Sieb. et Zucc) Miq (Saxifragaceae) have been traditionally used for the treatments of a sword cut, wound bitten by animals, frost-bite, burn, suppurative dermatitis or skin inflammatory diseases from the Tang period (about 8th century) in China. The physiological actions, especially the wound-healing effects of this drug are not yet well understood. In this study, we examined the effects of an ethanol extract of Astilbe thunbergii rhizomes on burn wound healing in mice. The topical application at a dose of 100mg ointment per wound of 70% ethanol extract (0.5 or 1.0% (w/w) ointment) of this drug promoted the burn wound healing. The ethanol extract was divided into two fractions (ethyl acetate-soluble and -insoluble fractions), and it was found that the topical application at a dose of 100mg ointment per wound of the ethyl acetate-soluble fraction (0.5 and 1.0% ointment) promoted the burn wound healing. Based on this finding, we attempted to isolate the active substance(s) from the ethyl acetate-soluble fraction. Three active substances 1, 2 and 3, were obtained from A. thunbergii rhizomes as promotional effectors of burn wound healing in mice. Based on the analysis of (1)H and (13)C NMR spectra, compounds 1, 2 and 3 were identified as eucryphin (1), bergenin (2) and astilbin (3), respectively. The effective dose (ED(50)) of compounds 1, 2 and 3 on burn wound healing were 4, 190 and 64 microg/wound, respectively. Among these three compounds, eucryphin (1) promoted the burn wound healing most strongly.