Characterization of Antioxidant Capacity from Fruits with Distinct Anthocyanin Biosynthetic Pathways

Elham Hosseini -Beheshti,Steven Lund,David D Kitts

doi:10.4172/2155-9600.1000122

Abstract

The antioxidant capacity of individual anthocyanins is well established. Less information is available however, about the relative contribution to which specific anthocyanins in a complex mixture affect total antioxidant capacity in different soft fruit sources; especially those that share a similar pathway for anthocyanin synthesis. The objectives of this work were to compare the antioxidant capacity of two different soft fruits, blackcurrant and grape, which share similarities in anthocyanin biosynthetic pathways but are composed of distinctly different anthocyanin profiles. Anthocyanin composition profiles of grape and blackcurrant were characterized by High Performance Liquid Chromatography/Mass Spectrometry (HPLC). ORAC (Oxygen Radical Absorbance Capacity) and ABTS (2,2’-azinobis 3-ethylbenzothiazoline- 6-sulfonic acid) assays were used for antioxidant activity quantification. An anthocyanin antioxidant capacity index (AACI) was derived from the product of antioxidant (ORAC) activity for each of major anthocyanins present in blackcurrant and grape, and the sum of anthocyanins recovered from purified fruit extracts to determine the extent that the total antioxidant activity derived from different anthocyanin combinations. Blackcurrant contained four predominant anthocyanins, cyanidin3-glucoside (Cy3G), delphinidin3-glucoside (Dp3G), cyanidin3-rutinoside (Cy3R), and delphinidin3- rutinoside (Dp3R). Major anthocyanins found in grape were malvidin3-glucoside (Mv3G), Dp3G, Cy3G, petunidin3-glucoside (Pt3G), and peonidin3-glucoside (Pn3G). A greater (p<0.05) total antioxidant capacity existed for blackcurrant compared to grape when measured by ORAC and ABTS methods. An antioxidant synergy was confirmed for blackcurrant and wind grape thus indicating that this phenomenon is a factor for characterizing total antioxidant activity in both blackcurrant and wine grape.

Highlights

Anthocyanins are a diverse group of over 600 naturally occurring flavonoid compounds conferring hues of blue, purple, or deep red to several plants, including fruits of several commercially important species
Regression analyses showed that ABTS antioxidant activity was highly correlated with total anthocyanin and total phenolic contents in blackcurrant
Chemical characterization of blackcurrant anthocyanins using High Performance Liquid Chromatography/Mass Spectrometry (HPLC)/UV-MS disclosed that 3-rutinoside anthocyanins were the major anthocyanins, comprising more than 60% of the anthocyanin profile

Summary

Introduction

Anthocyanins are a diverse group of over 600 naturally occurring flavonoid compounds conferring hues of blue, purple, or deep red to several plants, including fruits of several commercially important species. Structure-antioxidant activity relationships, such as the presence of free hydroxyl groups located at the 3’ and 4’ positions of the B-ring of anthocyanidins have been shown to be important for Trolox equivalent antioxidant capacity (TEAC) and radical scavenging activity in low density lipoprotein oxidation assays [12,13,14]. This activity may in part be attributed to the enhanced stabilization of the radical state during electron transfer when assayed relative to compounds that lacked the orthodiphenolic structure [2,1214]. The addition of a glycoside residue (e.g. rutinose, glucose) at position 3 on the C-ring or methylation of the 3’ and/or 5’ hydroxyl group on the anthocyanidin B-ring has been shown to reduce Trolox equivalent antioxidant capacity and radical scavenging activity [2,8,1214]

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