Proanthocyanidins (OPC)

Proanthocyanidins are oligomeric flavonoids built from catechin and epicatechin units and their gallic acid esters, joined head-to-tail by interflavan bonds. Grape seed material is predominantly B-type linked, in contrast to the A-type oligomers that characterise cranberry and peanut skin. Strictly speaking, "OPC" denotes the dimer and trimer fraction; longer chains are the condensed tannins. Thovek supplies Vitis vinifera L. seed extract standardised on total proanthocyanidins by the acid-butanol (Bate-Smith) UV assay, with HPLC-UV/MS used to confirm the monomer and dimer fingerprint against (+)-catechin (CAS 154-23-4), (-)-epicatechin (CAS 490-46-0) and procyanidin B2 (C30H26O12, MW 578.5, CAS 29106-49-8). Grape seed is one of the densest dietary sources of this class, reported at roughly 3,532 mg per 100 g of seed. In formulation the powder is red-brown to purple-brown, freely soluble in water and aqueous ethanol, and distinctly astringent. That combination makes it straightforward in two-piece capsules, direct-compression tablets, stick packs and low-pH beverage concentrates, but formulators should plan for colour carry-over into white tablet coats and for the polyphenol-protein binding that can dull mouthfeel in dairy or collagen matrices. It is routinely co-formulated with ascorbic acid and other polyphenols. French maritime pine bark is the other commercially significant OPC botanical and can be quoted as an alternative feedstock; note that the best-known pine bark article on the market is a registered trademark of a third party, and Thovek offers only generic pine bark proanthocyanidins with no implied equivalence. Commercially this is a clean allergen profile: grape-derived, vegan and vegetarian, non-GMO, and free of milk, egg, soy, fish, crustacean, gluten and tree nut. The one item worth a buyer's attention is sulphur dioxide, because seed feedstock recovered from winery pomace can carry residues from sulphited musts; Thovek reports SO2 on every batch so the buyer can judge the 10 mg/kg labelling threshold. Each shipment travels with CoA, MSDS, allergen, GMO and BSE/TSE statements, heavy metals, pesticide residue, residual solvent and microbiology data, and origin documentation. Thovek makes no therapeutic or disease claim for this ingredient; substantiation of any on-pack claim, and confirmation of regulatory status in the destination market, rest with the brand owner.