T. Murakami et al., Chemical constituents of two oriental orchids, Calanthe discolor and C-liukiuensis: Precursor indole glycoside of tryptanthrin and indirubin, HETEROCYCLE, 54(2), 2001, pp. 957
Two indole glycosides, calanthoside and glucoindican, were isolated from tw
o oriental orchids, Calanthe discolor LINDL. and C. liukiuensis SCHLTR., to
gether with calaphenanthreol, calaliukiuenoside, and bioactive known alkalo
ids, tryptanthrin, indirubin, and isatin. The structures of calanthoside, g
lucoindican, calaphenanthreol, and calaliukiuenoside were determined on the
basis of physicochemical and chemical evidence. Furthermore, it was found
that enzymatic hydrolysis of calanthoside furnished tryptanthrin as the mai
n product, whereas indirubin and isatin were obtained by acid hydrolysis of
calanthoside.