The constituents of Urtica cannabina used in Uighur medicine.

Urtica cannabina L. (Urticaceae) is a perennial herb that grows in Xinjiang Uighur Autonomous Region (northwest China). Two megastigmanes (1, 2) and five flavonoid glycosides (3-7) were isolated from its fruit. Compound 1 was determined by spectroscopic analysis to be (+)-blumenol A, and its absolute stereochemistry was determined in detail using chemical conversion and a modification of Mosher's method. Other compounds were identified as (+)-dehydrovomifoliol (2), isovitexin (3), isoquercitrin (4), astragalin (5), afzelin (6), and quercitrin (7) using spectroscopic (NMR, HMBC, MS) and physical methods (melting point and optical rotation). Compounds 1-7 were isolated from this plant for the first time, while this is the first report of megastigmanes in the Urticaceae family. The chemotaxonomic significance of the isolation of these megastigmanes and flavonoid glycosides from Urtica species is discussed.