A new naphthoquinone from Polygonum aviculare

Polygonum aviculare (Polygonaceae) is abundant in Taif region of Saudi Arabia. Only little work on the phytochemical screening of this plant [1] was reported, although systematic studies have been carried out on a number of other species of Polygonum genus. The characteristic secondary metabolites in this genus are mostly flavonoids [1-4], stilbenes and chalcones [5,6]. In continuation of our interest in phytochemical studies on plants grown in Saudi Arabia, we now examined the acetone extract of Polygonum aviculare and this paper deals with the structure elucidation of a new naphthoquinone, 6-methoxyplumbagin (1) which was isolated along with 5,6,7,4'-tetramethoxyflavanone (5), sitosterol and oleanolic acid (Figure 1).