Analysis of A‐Type and B‐Type Highly Polymeric Proanthocyanidins and Their Biological Activities as Nutraceuticals

Kazushige Yokota,Hideto Kimura,Takashi Akihiro,Satoshi Ogawa

doi:10.1155/2013/352042

Abstract

Proanthocyanidins have a series of heteroflavan‐3‐ols, (+)‐catechin/(−)‐epicatechin units, which are linked through a single B‐type linkage and a doubly linked A‐type linkage. Recently, we have performed the structural characterization of seed shells of the Japanese horse chestnut and fruits of blueberry and cranberry. The molecular sizes of them were higher in the order of blueberry > cranberry > seed shells of the Japanese horse chestnut between the respective fractions. For the analysis of terminal and extension units in those proanthocyanidins, the isolated fractions were subjected to the thiolytic cleavage of the B‐type linkages using 1‐dodecanethiol, and the resulting degradation products were identified by ultraperformance liquid chromatography coupled with electrospray‐ionization mass spectrometry. These analyses provided fast and good resolution of the degradation products and revealed higher proportions of A‐type linkages compared with B‐type linkages in both isolated fractions in the order of the seed shells > cranberry > blueberry. Moreover, the isolated fractions with higher molecular sizes and those more abundant in the proportions of A‐type linkages were found to be more effective in the inhibition of pancreatic lipase activity. The results suggest that A‐type highly polymeric proanthocyanidins are promising for the attenuation of lipid digestion as dietary supplements.

Highlights

Proanthocyanidins are well known to be a subclass of polyphenolic compounds that can be detectable in a wide variety of food sources, such as fruits, nuts, beans, apples, and red wine [1]. ese compounds are regarded as healthy food supplements due to their activities serving as potent antioxidants to suppress the generation of reactive oxygen species under the oxidative stress in the body [2]
Seeds of the Japanese horse chestnut were collected from the forest of northern Hyogo Prefecture in Japan, and frozen fruits of blueberry and cranberry were purchased from the commercial sources [2]. ese food sources were used for crude extraction of total polyphenolic compounds with 70% acetone as described in our reports [2, 11]. ese crude extracts from each food source were fractionated sequentially by column chromatography on Diaion HP-20 and Chromatorex ODS1024T to obtain total fraction of polyphenolic compounds. e resulting fractions were separated by column chromatography with Sephadex LH20 into three fractions corresponding to F1, F2, and F3 by eluting with ethanol, methanol, and 70% acetone, respectively. ese fractions can be separated on the basis of varied sizes of proanthocyanidins
Our analysis provided the evidence that seed shells of the Japanese horse chestnut contained apparently higher proportions of doubly liked A-type linkages with variations in the binding mode than fruits of blueberry and cranberry

Summary

Introduction

Proanthocyanidins are well known to be a subclass of polyphenolic compounds that can be detectable in a wide variety of food sources, such as fruits, nuts, beans, apples, and red wine [1]. ese compounds are regarded as healthy food supplements due to their activities serving as potent antioxidants to suppress the generation of reactive oxygen species under the oxidative stress in the body [2]. F 1: iolytic cleavage of highly polymeric proanthocyanidins having a series of heteropoly avan-3-ols, ( )-catechin (−)-epicatechins, with doubly linked A-type inter avan linkages and single B-type bonds. No detailed studies have been described to determine the proportions of terminal and extension units of A-type and B-type highly polymeric proanthocyanidins as well as their polymer sizes. We attempted to perform structural characterization of highly polymeric proanthocyanidins from seed shells of the Japanese horse chestnut (Aesculus turbinata BLUME) and cranberry (Vaccinium macrocarpon Aiton) fruit as rich sources of A-type highly polymeric proanthocyanidins by thiolytic degradation with 1-dodecanethiol. Using chromatographic and instrumental analyses we have obtained structural information on the proportion of A-type linkages relative to Btype linkages and the molecular sizes of highly polymeric proanthocyanidins isolated differently from three types of food sources. We discuss the implication of different preparations of them as nutraceuticals on the basis of our recent data regarding the inhibitory effects on the digestion of carbohydrates and lipids [6, 7, 11]

Preparation and Isolation of Highly Polymeric Proanthocyanidins

Biological Activities of A-Type and B-Type as Neutraceuticals

Conclusions