Polygonum cuspidatum anthraquinone emodin from

Emodin (l,6,8-trihydroxy-3-methylanthraquinone), the active principle of Polygonum cuspidatum (Polygonaceae), was reported to be an inhibitor of the p56 -PTK activity from bovine thymus, with an IC50 of 18.5 pM. When the hydroxyl functions at C-6 or C-8 were blocked by methylation or glycosylation, respectively, the effect disappeared. The inhibition was competitive with respect to ATP and non competitive with respect to the substrate [64]. In a bioassay-guided separation of the anthraquinones found in rhizomes of another Polygonaceae species, rhubarb Rheum... 

The action of three anthraquinones (emodin, physcion and emodin-O-(3-D-glucoside), isolated from the root of Polygonum cuspidatum, on protein tyrosine kinase was investigated by Jayasuriya et al. [11] (see Table 5). 

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