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Purification and Characterization of Polyphenols from Chestnut Astringent Skin

Tsujita, Takahiro, Yamada, Misato, Takaku, Takeshi, Shintani, Tomoyoshi, Teramoto, Kanae, Sato, Takafumi
Journal of agricultural and food chemistry 2011 v.59 no.16 pp. 8646-8654
Castanea, alpha-amylase, antioxidant activity, blood glucose, corn starch, dialysis, ellagic acid, gallic acid, oral administration, proanthocyanidins, procyanidins, rats, tannins
Polyphenolic compounds from chestnut astringent skin (CAS) were purified by dialysis, using Diaion HP-20 and Sephadex LH-20 columns. During purification, specific alpha-amylase inhibitory activities were increased about 3.4-fold, and the 50% inhibition value was 5.71 micrograms/mL in the Sephadex LH-20 fraction (SE-fraction). The SE-fraction contained about 67% of the total polyphenols, 57.3% of the flavanol-type tannins, and 51.3% of the procyanidins. Strong antioxidant activity was observed in the SE-fraction. Oral administration of the SE-fraction in rats fed corn starch significantly suppressed an increase in blood glucose levels. The SE-fraction contained gallic acid and ellagic acid. The MALDI-TOF spectrum showed a peak series exhibiting a mass increment of 288 Da, reflecting the variation in the number of catechin/epicatechin units. Our results suggest CAS contains polyphenols with strong α-amylase inhibitory activity. The data also suggest CAS polyphenols might be oligomeric proanthocyanidins with gallic acid and ellagic acid.