**2.4 Effects of drought on influence on antioxidant activity and phenol compounds sum accumulation**

The ability of amaranth leaf extracts to absorb DPPH + free radicals, which is used as a measure of total antioxidant activity (TAA), and total phenol content (TPC) are shown in **Table 1**. The antioxidant activity of the water extracts of *A. tricolor* L. leaves was significantly higher than that of *A. cruentus* L. leaves. The antioxidant activity of the alcohol solution differed slightly between the types of amaranth. In the conditions


#### **Table 1.**

*The effect of drought stress on the antioxidant activity of water (ААА) and methanol (ААМ) extracts, expressed in %, and the total content of polyphenols (TРС), expressed in mg equivalent of gallic acid (mg/g TW) in the leaves of Amaranthus species.*

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

of water deficiency in the leaves of both types of amaranth, the antioxidant activity of water and alcohol extracts increases by 1.5**–**2.5 times. Antioxidant activity plays a crucial role in maintaining the balance between free radical synthesis and capture [30–32]. With a lack of water, the total content of phenols in the leaves of both types of amaranth increases by three times. The variation coefficient of the antioxidant activity and the total amount of phenolic compounds was low, which indicates the relative homogeneity of the data obtained. A high correlation was established between the antioxidant activity of water and alcohol extracts and the TPC content in the leaves of both amaranth species (r = 0.77, r = 0.91), respectively.

Hence, the leaf mass of *A. tricolor* L. can be considered as a source of plant antioxidants that can normalize the ability of the human body to counteract free radicals caused by stress.

#### **2.5 The influence of drought on the contents of metabolites in the leaves of A. tricolor L. (cv. Valentina) и A. cruentus L. (cv. Krepysh)**

Forty-three secondary metabolites were totally determined in ethanol extracts of amaranth leaves. Forty-two substances were identified in the leaves of *A. tricolor* L. (cv. Valentina) and 35 metabolites in the leaves of *A. cruentus* L. (cv. Krepysh) (**Table 2**). Among nine compounds that possess antimicrobial characteristics, five belong to organic acids—Lactic acid, Pyruvic acid, Glyoxylic acid, Acetamide, Malic acid, and Tartaric acid; one to sugar alcohol—Glycerol; one to amide—Acetamide; and one to phenolic compounds—Benzoic acid. The content of Lactic acid, Benzoic acid, Malic acid, and Mannonic acid is 40, 6, 2, and 1.5 times higher in the leaves of cv. Valentina, than in the leaves of cv. Krepysh, respectively. Glyoxylic acid is found only in the leaves of green-colored amaranth; Acetamide is only in the leaves of red amaranth. Other organic acids are represented by the following compounds: Butanoic scid, Clycolic acid, Oxalic acid, 2-Butanedioic acid, Monoethyl malonic acid, Succinic acid, Glyceric acid, 2-Oxopentanoic acid, Malonic acid, 2.3.4.-Trihydroxybutiric acid, Arabinoic acid, Ketosuccinic acid, Fumaric acid, 2-Propenoic acid, and Citric acid. The phenolic compounds are presented by Caffeic acid, Vanillic acid, and Cinnamic acid. The following compounds were also detected: glycoside Apigenin, keto-acid—1.2- Ketoglutaric acid, sugar acid—Myo-inositol; 4 aminoacids—Lauric acid, Myristic acid, Palmitic acid, and Stearic acid (only in the leaves of cv. Valentina). Under drought conditions, the following compounds were synthesized in a significantly larger amount in the leaves of A. tricolor L. cv. Valentina: Mannonic acid—by 70 times; Myo-inositol—by 40 times; Caffeic acid—by 23 times; Tartaric acid—by 15 times; Clycerol—by 7 times; L-Proline and Serine—by 4 times; and Glycolic acid, Oxalic acid, and Lactic acid—by 2**–**3 times. The differences in the synthesis of these compounds were less obvious in the leaves of *A. cruentus* L. (cv. Krepysh). Our results are consistent with earlier findings that the accumulation of Proline and other amino acids increases with water potential decrease in the leaves [33, 34]. Myo-inositol is necessary for absolutely everyone for the synthesis of the substances involved in the transmission of intracellular signals from receptors. It is a vitamin-like substance that affects metabolism and normalizes the levels of sugar and insulin in the blood. It increases the sensitivity of body cells to hormones, supports hormonal balance, and stimulates the proper functioning of the hormone insulin and the stabilization of carbohydrate metabolism [35]. The present study confirmed that the leaves of cv. Valentina and Krepysh are the sources of biologically active compounds and have an enriched antioxidant profile.


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


#### **Table 2.**

*Metabolites discovered in ethanol extracts of* Amaranthus *L. leaves.*

## **2.6 The ash residue comparative composition of** *A. tricolor* **L. (Valentina cultivar) and** *A. cruentus* **L. (Krepysh cultivar) amaranth seeds**

The content (in mass %) of 11 main elements that make up the mineral part of amaranth seeds was studied (**Table 3**). The ash composition of the seeds varies significantly. The descending series of the elements accumulation is the following:

*A. tricolor* L. – Ca > P > K > Mg > Mo > S > Si > Se > Fe > Zn > Mn.

*A. cruentus* L. – K > P > Ca > Mg > Mo > S > Se > Zn > Fe > Si > Mn.

At the same time, the main proportion of ash elements in the seeds of *A. tricolor* L. is Ca, and in the seeds of *A. cruentus* L.—K.

Ca is the main ash element in the seeds of *A. tricolor* L., and its portion is 17.83 mass %. The proportion of Ca in the seeds of *A. cruentus* L. is less, and its portion is 11.54 mass %. Ca is a part of coenzymes and cell nuclei, it is involved in the most important processes for human organisms, such as metabolism, immunity, regeneration, and others [36]. The proportion of K in the seeds of *A. cruentus* L. is 1.8, and the proportion

