Phenolic composition and antioxidant activities of cladodes of the two varieties of cactus pear (Opuntia ficus-indica) grown in Ethiopia

K Haile,M Atlabachew,B Mehari,B S Chandravanshi

doi:10.4314/bcse.v30i3.3

Abstract

In this study, young cladodes corresponding to two (thorn-less and thorn-containing) varieties of cactus pear ( Opuntia ficus-indica ) from four different areas of Tigray region, Ethiopia, were investigated for their phenolic contents and antioxidant activities. Quantitative estimation of total phenolic contents and antioxidant activities in the cladodes was carried out using spectrophotometric methods. A 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay was used for the determination of the antioxidant activities, while Folin-Ciocalteau reagent, aluminum chloride and protein (albumin) precipitation methods were used for the determination of total polyphenol, flavonoid and tannin contents, respectively. The cladodes were found to be rich in polyphenols, with values in the range 18.0-71.4 mg gallic acid equivalent (GAE)/g of dry weight (DW). The predominant part of the polyphenols is represented by tannins, 9.00-41.2 mg GAE/g of DW, followed by flavonoids, 6.40-25.0 mg catchin equivalent (CE)/g of DW. The cladodes showed strong antioxidant activities, 59.3-85.8% inhibition compared to ascorbic acid. Application of paired t-test on the overall mean total polyphenol contents of samples collected from the different areas revealed the presence of significant variation between the thorn-less (31.6 GAE/g of DW) and thorn-containing (47.7 GAE/g of DW) varieties. One-way ANOVA also revealed that there are significant variations among samples from the same variety but collected from different areas. KEY WORDS : Opuntia ficus-indica , Flavonoids, Tannins, Polyphenols, Antioxidant activities, Ethiopia Bull. Chem. Soc. Ethiop. 2016 , 30(3), 347-356. DOI: http://dx.doi.org/10.4314/bcse.v30i3.3

Highlights

In recent decades, studies have been focused on foods rich in phytochemical and functional properties
The concentration of polyphenols found in Ethiopian cladodes is much higher than those (3.82 5.71 mg gallic acid equivalent (GAE)/g of dry weight (DW)) reported by Ramirez-Moreno et al [30] on the level of polyphenols in cladodes of the two varieties
We report the results of the analysis of the two varieties of Ethiopian cladodes of Opuntia ficus-indica for their total polyphenol, tannin and flavonoid contents and antioxidant activities for the first time

Summary

Introduction

Studies have been focused on foods rich in phytochemical and functional properties. Many studies have indicated a positive correlation between consumption of plant foods and reducing the risks of some diseases such as cancer, cardiovascular diseases, or diabetes [1]. This relation is in most cases attributed to high contents of phenolic compounds and their respective antioxidant activities [2]. Phenolic compounds are widely distributed in many fruits and vegetables Their type, concentration and their biological activity varied with plant species [1,2,3,4]. There are several species belonging to the genus Opuntia (Family Cactaceae)

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