Garcinol, a polyisoprenylated benzophenone derivative, was purified from Garcinia indica fruit rind, and its antioxidative activity, chelating activity, free radical scavenging activity, and anti-glycation activity were studied. Garcinol exhibited moderate antioxidative activity in the micellar linoleic acid peroxidation system and also exhibited chelating activity at almost the same level as citrate. It also showed nearly 3 times greater DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical scavenging activity than DL-alpha-tocopherol by weight in aqueous ethanol solution. In a phenazine methosulfate/NADH-nitroblue tetrazolium system, garcinol exhibited superoxide anion scavenging activity and suppressed protein glycation in a bovine serum albumin/fructose system. Thus, garcinol might be beneficial as a potent antioxidant and a glycation inhibitor under specified conditions.

No abstract

It is known that procyanidins, which are contained in grape seeds, are antioxidative and have certain biological effects. Antiulcer activities of grape seed extracts (GSE-I and GSE-II) and procyanidins were investigated using rats. GSE-I (with low flavanol content), GSE-II (with high flavanol content), and procyanidins at a dose of 200 mg/kg strongly inhibited the stomach mucosal injury induced by 60% ethanol containing 150 mM hydrochloride. This suppressive effect seems dependent on the content of procyanidin oligomers. Procyanidin oligomers (dimers to hexamers) were prepared and studied for their antiulcer activities at a dose of 200 mg/kg. The gastric protective activity of a series of procyanidins increased with the increasing polymerization of catechin units. Oligomers longer than tetramers showed a strong protective effect against gastric mucosal damage. The binding ability of procyanidin oligomers to bovine serum albumin in the acidified solution was strengthened with the increase of molecules. The mechanism of antiulcer activity may be the protection by radical scavenging activity on the stomach surface against radical injury induced by HCl/EtOH solution and the defense action of procyanidins covering the stomach surface by their strong ability to bind protein. Keywords: Grape seed extract; antiulcer activity; procyanidin; oligomer; radical scavenging activity; HCl/EtOH-induced ulcer