**Table 3.**

*Mineral (ash) composition of* Amaranthus *L. seeds, mass %, X (2020–2021).*

of P is 1.5 times higher than that in the seeds of *A. tricolor* L. The macroelement K is responsible for regulating the majority of metabolic reactions occurring in living organisms. It controls osmotic pressure, transmembrane potential, charge equilibrium, cathode-anion balance, pH—everything that makes up the homeostasis of cells and tissues [37]. In the human body, P is a part of DNA and RNA, phospholipids, phosphate esters, nucleoside phosphates—ATP, ADP, NATP, where it performs a structural and metabolic function [38].

The content of Mg and Mo in the seeds of *A. tricolor* L. (7.33 and 2.54 mass %) differs slightly from the content in the seeds of *A. cruentus* L. (5.76 and 3.43 mass %). In the human body, Mg is necessary for the processes of regeneration and renewal of cells, tissues, and organs. It activates a large number of enzymes involved in the assimilation of CO2 and nitrogen. In cytosol, Mg balances organic compounds (groups of sugars, nucleotides, organic and amino acids). Mg is necessary to maintain cathodic-anionic balance and regulate pH [39]. Mo is an important element in the diet, catalyzes the reactions of oxygen transfer from substrates or to substrates, using water as a donor or acceptor of oxygen, is a part of enzymes [40]. The content of trace elements S, Mn, Fe, and Zn in amaranth seeds of the studied cultivars differs slightly (**Table 2**).

S is a biogenic element in the composition of proteins and glutathione, has antioxidant activity, provides the process of energy transfer in the cell by transferring electrons, participates in the transfer and fixation of methyl groups, the formation of covalent, hydrogen, and mercaptide bonds, provides the transfer of genetic information. Mn is a cofactor and activator of many enzymes (pyruvate kinase, decarboxylase, siperoxide dismutase), participates in the synthesis of glycoproteins and proteoglycans, has antioxidant activity.

In active centers (hemoproteins and iron-sulfur proteins), Fe determines the structure and activity of space and participates in redox reactions. Organic Fe is a necessary compound for the human body. This element is part of catalytic centers of many redox enzymes. Zn stabilizes the structure of molecules, plays an important role in the metabolism of DNA and RNA, in protein synthesis and cell division, in the processes of signaling within the cell [41–43].

Si is not only the basis of the framework element of tissues, but also controls a number of biological and chemical processes in a living organism, increases the resistance of a living organism to the effects of biogenic and abiogenic stressors, is a necessary trace element that is part of active centers in the form of selenocysteine animoacystide [44]. The concentration of Si in *A. tricolor* L. seeds is two times more than that in the seeds of *A. cruentus* L.

The minerals found in amaranth seeds are important for meeting human dietary needs and can make a significant contribution to recommended diets.

#### **2.7 Biologically active components of the studied cultivars of** *Amaranthus L.*

The previous studies of the extracts from cv. Valentina fresh leaves detected the following physiologically active substances with antioxidant activity: Amarantin— 1.5 mg/g, Ascorbic acid—150–170 mg/100 g, simple phenols and phenolcarboxylic acids, Chlorogenic, Ferulic, Gallic acids, and Arbutin—2.05, 0.01, 1.51, and 473 mg/g, respectively. All metabolites are biologically active substances [45]. Phenolic acids and Betacyanin (Amarantin) are characterized by antibacterial [46–48], antimycotic, antiinflammatory, and wound-healing properties. Ferulic acid has radioprotective properties, glycosylated hydroquinone Arbutin exhibits antioxidant activity [48]. The

*Metabolite Profile of* Amaranthus tricolor *L. and* Amaranthus cruentus *L.… DOI: http://dx.doi.org/10.5772/intechopen.102375*

pigment Amarantin is a multifunctional pigment of red-colored amaranth leaves. Amarantin is a nitrogenous heterocyclic compound that has a strong physiological effect on living organisms. The study of the biochemical properties of Amarantin extracted from the leaves of the red-colored cv. Valentina revealed the following physiological activities: antibacterial, antimycotic, antioxidant, antitumor. The extracts from fresh and dried leaves of cv. Valentina stimulated the growing activity of vegetable seeds, which allows its extracts to be used in phytobiology for stimulation of seeds and sprouts (in the concentration of 10-4, 10-5 M) [49]. The mechanism of antioxidant activity of Amarantin is associated with its ability to neutralize the superoxide radical and inhibit lipid peroxidation. This allows the leaves to be used to obtain Amarantin extract as a dietary supplement and a phytopreparation.

Under the conditions of drought and high solar radiation, the content of Amarantin in the leaves of cv. Valentina decreases to 40%. The received data indicate that Amarantin performs an important protective function of the photosynthetic apparatus in the plant [50, 51]. The advantage of Amarantin as a water-soluble antioxidant is its rapid synthesis (within 4 hours) after the cessation of drought. The data obtained by us and investigated in the literature data indicate an important role of Amarantin in photosynthetic, metabolic, and protective reactions of an amaranth plant.

Consequently, the data found in literary sources and the results received by us prove that *A. tricolor* L. cv. Valentina is not only highly drought-tolerant, but is also a promising, reproducible source of antioxidants and can be used to create functional foods and phytobiological preparations. The presence of potential antinutrients may limit the use of amaranth in a human diet. To inactivate or reduce these antinutrients, various pretreatment methods are used, such as heat treatment, extrusion, etc. Therefore, further profiling of the metabolomic profile is necessary to improve the nutritional properties of the food product.

#### **3. Conclusions**

In the present study, the representatives of species C4 (amaranth) *A. tricolor* L. cv. Valentina and *A. cruentus* L. cv. Krepysh have observed several adaptive responses to drought stress under the conditions of water deficit. The features of specific changes in photosynthetic pigments, antioxidant activity, the amount of phenolic compounds, and the composition of metabolites in the leaves were revealed. The increase in the content of phenolic compounds, the total antioxidant activity allowed the plants to survive in adverse environmental conditions. The greatest adaptive potential to drought stress, taking into account the complex of studied physiological and biochemical parameters, was demonstrated by amaranth of cv. Valentina. *A. tricolor* L. cv. Valentina used in the present study can be further investigated as a promising cultivar that can accelerate the breeding for drought tolerance in amaranth.

The leaves of *A. tricolor* L. cv. Valentina contain a sufficient amount of nutraceuticals, phytopigments, and phytochemicals, and the seeds contain a set of macro- and microelements. The leaves of amaranth cv. Valentina can also be used to produce juice as a source of potential nutritional value, phytopigments, antioxidants, flavonoids, phenols, and ascorbic acid in the diet. The present study showed that the cultivars are the sources of biologically active compounds and have an enriched antioxidant profile. The leaves of amaranth A. tricolor cv. Valentina contain a sufficient amount of nutraceuticals, phytopigments, phytochemicals, and the seeds

contain a set of macro- and microelements. Valentine's amaranth leaves can also be used to produce juice as a source of potential nutritional value, phytopigments, antioxidants, flavonoids, phenols, and ascorbic acid in the diet. The increased level of the essential macro- and microelements such as Ca, K, P, Mg, Mo, S stipulates the perspective of the functional products creation on the base of the seeds of the studied amaranth (cv. Valentina and Krepysh). The mineral elements concentration in different organs of the plant and their influence on the human life activity are an actual (global) problem, as the deficit of macro- and microelements in the industrial food stuff is extremely huge and dangerous for the human health, because the major part of food stuff is depleted in mineral substances.

The present study showed that the *A. tricolor* L. cv. Valentina and *A. cruentus* L. cv. Krepysh are sources of biologically active compounds and have an enriched antioxidant profile. Recently, the demand for healthy food has increased substantially due to the fact that the link between the health and the consumed products has been shown. In addition to high nutritional value, pseudocereal plants, which include amaranth, contain a large amount of biologically active substances necessary for health. The high protein content of amaranth seeds is characterized by a well-balanced amino acid profile. Seeds are a good source of unsaturated fatty acids, dietary fiber, and essential trace elements. In addition, they contain a wide variety of biologically active compounds. Due to the lack of gluten, these pseudocereals are also interesting ingredients for gluten-free products. Currently, the gluten-free food market is expanding rapidly due to the increasing prevalence of gluten-related diseases such as celiac disease, i.e., gluten intolerance. Amaranth seeds can be used to produce new products, as well as to be an additive to enrich traditional food. Red-colored amaranth leaves can be used to make herbal teas and natural food dyes. The detailed fundamental knowledge of the composition and properties of amaranth seeds is crucial for their introduction into industrial production.
