Preparation and Antioxidant Activity of Cyanidin from Condensed Tannins Extracted from Calyx of Bruguiera gymnorrhiza

Type of structural units, degree of polymerization and mean molecular weight of condensed tannins extracted from calyx of large red mangrove (Bruguiera gymnorrhiza) were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Crude cyanidin products were prepared from condensed tannins of B. gymnorrhiza by means of butanol/HCl reaction. In addition, the free radical-scavenging activity and antioxidant ability of crude cyanidin products were determined by using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) and ferric reducing/antioxidant power (FRAP) model systems respectively. The results showed that catechin/epicatechin were the structural units occurring in condensed tannins of B. gymnorrhiza. Average degree of polymerization was 7.5, and mean molecular mass was 2081.60 u. Crude cyanidin products showed a very good DPPH radical scavenging activity (IC50 of 43.889 mg/L) and ferric reducing/antioxidant ability ((7.718±0.109)mmol/g).