In Vitro Cell-Mediated Antioxidant Protection of Human Erythrocytes by Some Common Tropical Fruits

E González,F Vaillant,A Pérez

doi:10.4172/2155-9600.1000139

Abstract

The semi-automated erythrocyte cellular antioxidant activity (ERYCA) method and Hydrophilic Oxygen Radical Absorbance Capacity (H-ORAC) assay were used to assess the ability of aqueous acetone extracts from 34 common tropical fruits to delay hemolysis of human erythrocytes and loss of fluorescein fluorescence respectively, when exposed to free peroxyl radicals induced by 2,2'-azobis (2-amidinopropane hydrochloride) (AAPH). The ERYCA assay quantifies both direct scavenging of free radicals and cell-mediated antioxidant protection (Cell-MAP). Because the H-ORAC method only analyzes the direct scavenging of free radicals in the reaction medium, Cell-MAP was deduced from the results of both assays. The results showed that Cell-MAP of fruit extracts on erythrocytes is, on average 3 to 4 times more than protection from direct scavenging of free radicals in the surrounding medium. The Cell-MAP of fruit extracts ranged from 0 to almost 4500 ?mol quercetin equivalents (QE) per 100 g on fresh weight basis, with tropical highland berries, cashew apple, mamey and 3 guavas species scoring the highest. Correlation coefficients among ERYCA, H-ORAC, Cell-MAP and total polyphenolic (TPP) content (assessed using a modified method excluding non-phenolics interference) were very high (r2>0.88 for all correlations), even though numerous discrepancies existed between the results of different methods. The analysis of Cell-MAP sheds new light on antioxidant rich food. (Resume d'auteur)

Highlights

Oxygen is essential for aerobic life forms, the high prooxidant activity of its metabolites can cause cell injury
Most oxidant/antioxidant reactions occur within organ cells, pro-oxidants and antioxidants along with all byproducts are transported through the bloodstream in which erythrocytes are directly exposed to free radicals
The erythrocyte cellular antioxidant activity (ERYCA) and Hydrophilic Oxygen Radical Absorbance Capacity (H-ORAC) methods are very similar except that in the first assay, human erythrocyte cells were used instead of the fluorescein used in the H-ORAC assay

Summary

Introduction

Oxygen is essential for aerobic life forms, the high prooxidant activity of its metabolites can cause cell injury. Mitochondria which consume more than 90% of the oxygen received by an organism are the primary source of free radicals [1]. Other sources of free radicals include pro-oxidative enzymes liberated during stress, inflammation or immune activity, [1] and environmental factors such as air pollution, sun radiation and chemicals [2]. The efficiency of such mechanisms tends to deteriorate for diverse reasons including aging, disease or poor nutritional habits. In these specific situations, dietary antioxidant compounds could play a significant role in keeping free radicals at or under a normal physiological level [2,3,4,5,6]

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Results

Conclusion