Grape skin is rich in resveratrol, a polyhydroxyphenol compound, which has the functions of reducing blood lipid, antithrombotic, preventing arteriosclerosis and enhancing immunity.
Tannin, another important substance in grape skin, has the functions of anti-allergy, delaying aging, enhancing immunity and preventing cardiovascular and cerebrovascular diseases.
Anthocyanins contained in grape skin have strong anti-oxidation, anti-mutation, relieving liver dysfunction and protecting cardiovascular system.
Grape skin also has anti-cancer effect. Researchers at Illinois Pharmaceutical University found that this substance exists in more than 70 kinds of plants such as peanuts and grapes, especially grape skins and red wine.
Grape seeds contain polyphenols (GPS), mainly catechins and procyanidins. Catechins, including catechins, epicatechin and its gallate, are the main monomers in grape seeds and the constituent units of oligomeric and polymeric proanthocyanidins. The proanthocyanidins (GSPE) in grape seeds are polymerized by different amounts of flavanols. At present, the most widely studied products are mainly polymerized from (+)-catechin (+)-catechin) and (-)-epicatechin (-) [1]. These substances can effectively remove harmful oxygen free radicals, inhibit lipid peroxidation and low density lipoprotein in erythrocyte membrane, promote the formation of relaxing factor NO in endothelial cells, prevent platelet aggregation and prevent cardiovascular and cerebrovascular diseases. Their ability to scavenge oxygen free radicals is much higher than that of vitamin E [2]. According to the latest literature, polyphenols can lower the blood pressure of patients with metabolic syndrome. Grape seed is rich in oil, accounting for about12% ~15% of its weight [3]. Oil contains a large number of unsaturated fatty acids, of which linoleic acid accounts for 58% ~ 78%. Linoleic acid is an essential fatty acid for human body, which can prevent atherosclerosis, hypertension and hypercholesterolemia. At the same time, linoleic acid is one of the main raw materials for human body to synthesize arachidonic acid, which is the main substance for human body to synthesize prostaglandin, and has the functions of dilating blood vessels and preventing thrombosis. Grape seed also contains a small amount of volatile components, mainly 2,6? Di-tert-butyl p-cresol, 2? Ethyl? 1? Ethanol, nonanal, α? Pinene, 3? Karin, d? Limonene and other compounds [4]. Most of these substances belong to alcohols, phenols and terpenoids, all of which have high biological activity [5]. Grape seed contains crude protein, amino acids, vitamins A, E, D, K, P and trace elements such as calcium, zinc, iron, magnesium, copper, potassium, sodium, manganese and cobalt.