Chemical constituents from the roots of Pteroxygonum giraldii Damme et Diels

Twenty-four compounds were obtained from Pteroxygonum giraldii and were classified as five triterpenes (1–5), two sterols (6 and 7), two quinones (8 and 11), three stilbenes (9, 10 and 18) and twelve flavonoids (12–17, 19–24). Seventeen of these compounds were obtained from the genus Pteroxygonum for the first time. The chemotaxonomic significance of this plant was also discussed. Compounds 10, 12 and 23 can serve as the fingerprints for P. giraldii, and compounds 12, 13, 17 and 22–24 are recognized as typical metabolites of P. giraldii. Both Pteroxygonum and Polygonum might have the same origin and could be classified into the same tribe among Polygonaceae. Furthermore, due to the presence of stilbenes, Pteroxygonum may have some taxonomic relationships with Fallopia, Rumex and Reynoutria.