Fibroblast growth stimulation by extracts and compounds of Onosma argentatum roots

The roots of Onosma argentatum are used traditionally in Turkey for wound healing and burns. The n-hexane–dichloromethane extract of the roots, and four shikonin derivatives (deoxyshikonin, acetyl shikonin, 3-hydroxy-isovaleryl shikonin and 5,8-O-dimethyl acetyl shikonin) isolated from the n-hexane–dichloromethane extract were investigated for their ability to stimulate the growth of human amnion fibroblasts. A range of concentrations was studied and the extract found to stimulate the growth of human amnion fibroblasts in vitro at 0.1 μg/mL whilst 5,8-O-dimethyl acetyl shikonin had the same effect at 0.05–5 μg/mL, although cytotoxicity was observed at 50 μg/mL for all samples. The extract and all the other isolated compounds showed cytotoxicity at 10 μg/mL with the extract and 3-hydroxy-isovaleryl shikonin showing cytotoxicity at 5 μg/mL. It is suggested that any wound healing effect of the roots of Onosma argentatum might be partly due to an additive effect of the shikonin derivatives present.