Antioxidant and Starch-Hydrolyzing Enzymes Inhibitory Properties of Striga-Resistant Yellow-Orange Maize Hybrids.

Abdulazeez Olamilekan Elemosho,Abebe Menkir,Busie Maziya-Dixon,Emmanuel Anyachukwu Irondi,Emmanuel Oladipo Ajani,Emmanuel Oladeji Alamu

doi:10.3390/molecules26226874

Abstract

Most of the health benefits derived from cereals are attributed to their bioactive compounds. This study evaluated the levels of the bioactive compounds, and the antioxidant and starch-hydrolyzing enzymes inhibitory properties of six pipeline Striga-resistant yellow-orange maize hybrids (coded AS1828-1, 4, 6, 8, 9, 11) in vitro. The maize hybrids were grown at the International Institute of Tropical Agriculture (IITA), Nigeria. The bioactive compounds (total phenolics, tannins, flavonoids, and phytate) levels, antioxidant (DPPH• and ABTS•+ scavenging capacity and reducing power) and starch-hydrolyzing enzymes (α-amylase and α-glucosidase) inhibitory activities of the maize hybrids were determined by spectrophotometry. At the same time, carotenoids were quantified using a reverse-phase HPLC system. The ranges of the bioactive compounds were: 11.25–14.14 mg GAE/g (total phenolics), 3.62–4.67 mg QE/g (total flavonoids), 3.63–6.29 mg/g (tannins), 3.66–4.31% (phytate), 8.92–12.11 µg/g (total xanthophylls), 2.42–2.89 µg/g (total β-carotene), and 3.17–3.77 µg/g (total provitamin A carotenoids). Extracts of the maize hybrids scavenged DPPH• (SC50: 9.07–26.35 mg/mL) and ABTS•+ (2.65–7.68 TEAC mmol/g), reduced Fe3+ to Fe2+ (0.25 ± 0.64–0.43 ± 0.01 mg GAE/g), and inhibited α-amylase and α-glucosidase, with IC50 ranges of 26.28–52.55 mg/mL and 47.72–63.98 mg/mL, respectively. Among the six clones of the maize hybrids, AS1828-9 had the highest (p < 0.05) levels of tannins and phytate and the strongest antioxidant and starch-hydrolyzing enzymes inhibitory activities. Significant correlations were observed between total phenolics and the following: ABTS•+ (p < 0.01, r = 0.757), DPPH• SC50 (p < 0.01, r = −0.867), reducing power (p < 0.05, r = 0.633), α-amylase IC50 (p < 0.01, r = −0.836) and α-glucosidase IC50 (p < 0.05, r = −0.582). Hence, the Striga-resistant yellow-orange maize hybrids (especially AS1828-9) may be beneficial for alleviating oxidative stress and postprandial hyperglycemia.

Highlights

IntroductionThe provision of high-yielding, nutritious and healthy food crops is essential in order to address the challenges posed by malnutrition and the diseases associated with it
The bioactive components determined in the six pipeline Striga-resistant yelloworange maize hybrids (AS1828-1 (AS1), AS1828-4 (AS4), AS1828-6 (AS6), AS1828-8 (AS8), AS1828-9 (AS9), AS1828-11 (AS11)) in this study included total phenolics, flavonoids, tannins, carotenoids, and phytic acid
14.14 mg GAE/g in AS4 and AS9, respectively; total flavonoids ranged from 3.62 to 4.67 mg quercetin equivalent (QE)/g in AS11 and AS6, respectively; tannin content ranged from 3.64 to 6.29 mg/g in AS1 and AS9, respectively; and phytic acid content ranged from 3.66% in AS6 to 4.47% in AS1

Summary

Introduction

The provision of high-yielding, nutritious and healthy food crops is essential in order to address the challenges posed by malnutrition and the diseases associated with it. Different systematic approaches, such as breeding disease-resistant staples with improved nutritional quality, have been employed in plant breeding research programs to meet the dietary needs of the rapidly increasing global population. This has become more imperative considering the drastic reduction in the quantity and quality of global food supply occasioned by environmental pollution, global warming, and the development of novel biofuel sources [1]. In sub-Saharan Africa, maize (Zea mays L.) has been shown to contribute to food security and poverty reduction among low-income families [2]

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