Abstract
Current in vitro methodologies neglect or subestimate the contribution of betalains to antioxidant capacity in foods because they do not reflect their in vivo biological mechanisms. In this study, we assessed the sensibility of the lipoxygenase-fluorescein (LOX-FL) method towards betalains, phenolic compounds and ascorbic acid from Opuntia spp. fruits; and (ii) the antioxidant capacity of peel and pulp extracts from Opuntia ficus-indica L. Mill (var. Fresa, Colorada and Blanco) and Opuntia stricta var. Dillenii; by comparing the LOX-FL method to traditional antioxidant methods (ORAC and TEAC). The spectrophotometric monitoring of the LOX-FL reaction avoided interference caused by betalain pigments. Indicaxanthin and betanin showed high antiperoxidative and radical scavenging mechanisms in the LOX-FL assay. O. stricta var. Dillenii tissues the highest antioxidant capacity which correlated with betanin content. ORAC and TEAC antioxidant methods were less sensible towards betalain antioxidant activity. To our knowledge, this is the first time the LOX-FL antioxidant method has been used on betalains and betalain-rich foods.Graphical
Highlights
Dietary antioxidants are of interest from biological, medical, and nutritional perspectives because they contribute to the reduction of risk of diseases derived from metabolic syndrome
Dillenii, is native to Central America and may be found in the Mediterranean region, China, and North Africa. They are referred to as sweet- or wild prickly pear fruits and have recently been characterized in terms of betalains and phenolic compounds [5, 6]
Dillenii peels and pulps were characterized in terms of betalains, phenolic compounds and ascorbic acid (Supplementary Table S2)
Summary
Dietary antioxidants are of interest from biological, medical, and nutritional perspectives because they contribute to the reduction of risk of diseases derived from metabolic syndrome. Betalains are water soluble natural colorants composed of a nitrogenous core structure called betalamic acid They are classified in two groups, betacyanins (red-violet colors) and betaxanthins (yellow-orange colors) depending on the nature of the added residue. Pear fruits are juicy, colored, fruits rich in betalains (betanin, indicaxanthin, portulacaxanthin, vulgaxanthin, betanidin) and phenolic compounds (piscidic acid, Plant Foods for Human Nutrition (2021) 76:354–362 isorhamnetin glycosides, quercetin glycosides and kaempferol glycosides) [3, 4]. Dillenii, is native to Central America and may be found in the Mediterranean region, China, and North Africa They are referred to as sweet- or wild prickly pear fruits and have recently been characterized in terms of betalains (betanin, phyllocactin, betanidin, and neobetanin) and phenolic compounds (piscidic acid, eucomic acid, and isorhamnetin glycosides) [5, 6]
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