Tocopherols as bioactive compounds in different cultivars of Gomphrena globosa L.
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resumo
Tocopherols are lipid-soluble molecules that belong to the group of the Vitamin E compounds,
playing an essential role on human nutrition and health [1]. The term "Vitamin E" was first
introduced as an important dietary factor for animal reproduction and, more than 40 years later,
it was associated to antioxidant properties. Nowadays, most of the researches focus on the
fundamental chemistry that explains their antioxidant properties, specific location, role in
biological membranes, and particularity on the benefits of these compounds for human health
[1]. The antioxidant activity of tocopherols can be explained by two main mechanisms: first as
scavengers of lipid peroxyl radicals, produced from polyunsaturated fatty adds of the
membrane phospholipids and lipoproteins, through the transfer of a hydrogen atom; and second
as a singlet molecular oxygen quencher, which can oxidize membrane lipids, proteins, amino
acids, and nucleic acids, among others [2, 3]. In this context, our study focused on the
identification and quantification of tocopherols in three different Gomphrena globosa L. cultivars
(red, white and pink globe amaranth). The analysis was performed by HPLC and the
quantification was based on their fluorescence signal response. White and pink globe amaranth
revealed similar amounts of Υ-tocopherol (1. 04 and 1.09 mg/100 g of dry weight) and total
tocopherols (1. 37 and 1.38 mg/100 g, respectively). α-Tocopherol was found in higher
concentrations in red globe amaranth (0.55 mg/100 g), that also presented Υ-tocopherol (0. 50
mg/100 g), but this was the only sample where α-tocopherol was not detected. This latter
isoform was found in low amounts in the other two cultivars in concentrations ranging from 0. 05
to 0.06 mg/100 g (for white and pink globe amaranth, respectively). The results obtained offer
prospects for the use of these less studied cultivars of G. globosa as antioxidants, making them
suitable to be included in the human diet.
