Novel indole S,O-bisdesmoside, calanthoside, the precursor glycoside of tryptanthrin, indirubin, and isatin, with increasing skin blood flow promoting effects, from two Calanthe species (Orchidaceae).

The methanolic extracts from Calanthe discolor LINDL. and C. liukiuensis SCHLTR. were found to exhibit hair restoring and skin blood flow promoting activities. Through bioassay-guided separation using the skin blood flow increasing effect, a novel indole S,O-bisdesmoside, calanthoside, was isolated together with three new components, glucoindican, calaliukiuenoside, and calaphenanthrenol, and known compounds such as tryptanthrin, indirubin, isatin, and indican. The structures of the new compounds were determined on the basis of physicochemical and chemical evidence and they showed an activating effect on skin blood flow. In addition, it was found that enzymatic hydrolysis of calanthoside with beta-glucosidase furnished tryptanthrin together with a small amount of indirubin and isatin, whereas indirubin and isatin were obtained from calanthoside by acid hydrolysis. Based on their contents in the fresh and dried plant, calanthoside may be a common genuine glycoside of tryptanthrin, indirubin, and isatin in the plant.