Structural features and antioxidant activity of tannin from persimmon pulp

• Published in: Food research international Vol. 41; no. 2; pp. 208 - 217
• Main Authors: Gu, Hai-Feng, Li, Chun-Mei, Xu, Yu-juan, Hu, Wan-feng, Chen, Mei-hong, Wan, Qiong-hong
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2008; Elsevier
• Subjects: Antioxidant activity; antioxidants; Biological and medical sciences; Condensed tannin; Diospyros kaki; epicatechin; epigallocatechin; Food industries; fractionation; free radical scavengers; free radicals; fruit extracts; fruit pulp; fruits (food); Fundamental and applied biological sciences. Psychology; gallic acid; molecular weight; peroxide value; Persimmon ( Diospyros kaki L.) pulp; persimmons; phenolic compounds; Structural features; tannins; thiols; ultrafiltration; Persimmon ( Diospyros kaki L.) pulp; Structural features; Condensed tannin; Antioxidant activity; Diospyros kaki; Antioxidant; Flavonoid; Persimmon (Diospyros kaki L.) pulp; Pulp; Polyphenol; Tannin; Ebenaceae; Dicotyledones; Angiospermae; Spermatophyta
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2007.11.011

Phenolic compounds from persimmon pulp were extracted with methanol acidified with 1% HCl, and then purified on AB-8 macroporous resin. The tannic extracts obtained were fractionated by polysulfone ultrafiltration membrane with molecular weight cutoff of 10,000 Da into two fractions: low molecular weight tannin (LMWT) and high molecular weight tannin (HMWT). HPLC–MS analysis showed that gallic acid was one of the main components of LMWT fraction. The molecular weight distribution of HMWT was determined to be in the range of 1.16 × 10 4 Da to 1.54 × 10 4 Da, with the molecular weight of 1.28 × 10 4 Da in M n ¯ and 1.39 × 10 4 Da in M w ¯ by GPC method. HPLC–MS showed that the thiolysis degradation products of HMWT consist of (epi) gallocatechin, epigallocatechin-3- O-gallate, epicatechin-3- O-gallate and an unknown monomer with the ratio of 1:7:3:1 by estimation of the peak area on HPLC. The antioxidant properties of persimmon tannins were evaluated using the hydroxyl radical scavenging activities by 2-deoxyribose oxidation system and salicylic acid system, superoxide anion scavenging activity, and linoleic acid lipid peroxidation inhibition activity, respectively. HMWT exhibited excellent antioxidant activities in all tested systems in a dose-dependent manner. The antioxidant activity of HMWT was significantly stronger than that of LMWT and grape seeds proanthocyanidins (GSP), suggesting that high molecular weight condensed tannins are the major antioxidant composition in persimmon pulp.