Trans-Resveratrol 98% (Polygonum cuspidatum Extract)

Trans-Resveratrol 98% is the purified stilbenoid concentrate obtained from the dried root and rhizome of Polygonum cuspidatum Sieb. et Zucc. — the accepted botanical name is Reynoutria japonica Houtt., family Polygonaceae, and the plant is traded as Japanese knotweed or hu zhang. The milled root is extracted with food-grade alcohol or ethyl acetate, passed over adsorbent resin, crystallised and dried, which lifts the stilbene fraction from roughly 0.4% in the raw root to NLT 98% in the finished powder. Thovek also supplies the unpurified 20% and 50% knotweed extract grades; they are a different article commercially and, as set out below, a different tariff article as well. The active molecule is trans-resveratrol, 5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-1,3-diol, CAS 501-36-0, C14H12O3, MW 228.24, PubChem CID 445154. It is an off-white to pale beige crystalline powder melting at 253–255 °C, practically insoluble in water at about 3 mg per 100 mL, and freely soluble in ethanol, DMSO and dimethylformamide at roughly 65 mg/mL. The trans isomer is the one buyers specify and the one Thovek assays; ultraviolet light isomerises it to cis-resveratrol, so the material is crystallised, dried and packed under exclusion of light and shipped in opaque liners. Assay is by HPLC against a trans-resveratrol reference standard, and the certificate states the isomer measured rather than reporting total resveratrol. The knotweed root also carries polydatin (piceid, resveratrol-3-O-β-D-glucoside, CAS 27208-80-6), the anthraquinone emodin (CAS 518-82-1) and quercetin. Purification to 98% removes almost all of these, and Thovek reports residual emodin and total anthraquinones on the certificate of analysis because several buyers set an internal ceiling on them. The powder is plant-derived and therefore vegan and vegetarian, non-GMO, and free of milk, egg, soy, fish, crustacean, mollusc, peanut, tree nut, sesame, mustard, celery, lupin and gluten; none of the permitted extraction solvents introduces an allergen. Halal and kosher certification is available. Material is supplied against heavy-metal, pesticide-residue, residual-solvent and microbiological limits, with a synthetic-origin declaration on request for buyers who must distinguish plant-derived resveratrol from the fermentation-derived and chemically synthesised articles.