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Amaranth is an indispensable C4 agricultural crop with considerably reduced productivity under hypothermia loading. During seed ripening, chilling stress (1 °C–2 °C) can harm the photosynthetic organs in the plants and reduce the efficiency of low-molecular-weight defense systems. The studies on the content of low-molecular-weight antioxidants commenced in the leaves of the Amaranth cultivar Valentina cultivated in an open field in the post-stress period (after a chilling stress). After chilling at 2 °C in the post-stress period, older leaves of the main shoot displayed partial damage, while young leaves of the lateral shoots visually maintained a native appearance. The ascorbic acid (AA) content showed significant variations in the leaves. The content of possessing antioxidant properties revealed red-colored amaranthine decreased during this period, i.e., 1.5–1.9 times in young leaves, 3.5 times in leaves damaged by cold (DC), and non-damaged by cold (NDC) leaves showed a 1.1-times decrease. The decline in photosynthetic pigment content varied from 14% for carotenoids (Cars) to 60% for chlorophylls a (Chl a) and b (Chl b) in NDC leaves. The water and ethanol-soluble antioxidant contents improved with repeated cold stress (2 °C) in young leaves. The same pattern was also evident for the ascorbic acid and amaranthine content enhancement (20%–25% and 30%, respectively). The formation of hypothermia-induced tolerance in the leaves of different ages in autumn, which are the prime producers of low-molecular-weight antioxidants, signified a close relationship to the functioning of hydrophilic and hydrophobic antioxidants. [ABSTRACT FROM AUTHOR]

Amaranth (Amaranthus spp.) is an important food crop source of nutrients and bioactive compounds. Different species of amaranth showed considerable phenotypic variations and could possess diverse nutritional properties. The presented study strove to determine the diversity of amaranth collection for morphological and biochemical traits and their antioxidant potential for developing new cultivars adapted to the environmental conditions of Central Russia. The selected 16 amaranth accessions had high variability in morphological and biochemical traits. With red-colored leaves, amaranthine content ranged from 0.319a to 2.031f mg/g fresh weight (FW). The water-soluble antioxidant content ranged from 0.425a to 1.439h mg of gallic acid equivalent (GAE)/g FW. In amaranth accessions, the phenolic compound content in leaves varied from 2.700a to 4.825g mg GAE/g FW. In the amaranth collection, the total chlorophyll content ranged from 0.9946a to 3.5467j mg/g, and carotenoids from 0.2196a to 0.8289i mg/g. A strong positive correlation (P ≤ 0.05) was evident between total chlorophyll and carotenoid contents (r≈0.90), plant height and inflorescence length (r≈0.79), and inflorescence length and seed weight harvested per plant (r≈0.76). In summary, when evaluating the antioxidant levels in various samples, the Valentina cultivar, characterized by red leaves, appeared to have the highest amaranthine concentration. Both Valentina and Fakel cultivars exhibited the maximum overall antioxidant capacity. Additionally, the Valentina and Duimovochka cultivars emerged as the top accumulators of polyphenols. These findings highlight the significant antioxidant potential present in these specific cultivars. [ABSTRACT FROM AUTHOR]

Phytochemicals are plant-based bioactive compounds produced by plants for their protection. In Allium species, the principal bioactive phytochemicals include organosulfur compounds, polyphenols, and saponins. Most of them have also displayed antioxidant activities aside from other biological properties. Selection for productivity, disease resistance, and long shelf life has brought the biologically active substances out of control of selection. However, at the same time, enhancement of their contents could result from hybridization with some wild species of Allium. [ABSTRACT FROM AUTHOR]

The latest review discusses the chief metabolites of the genus Allium L., which characterize their nutritional qualities. The publications presented in the leading databases, such as Web of Science, Scopus, PubMed, Science Direct, and NCBI bore analysis. The vital active phytochemicals of Allium species include ascorbic acid, fatty acids, and carbohydrates. Many believe these biologically active compounds can prevent cancer development, coronary heart disease, and atherosclerosis. [ABSTRACT FROM AUTHOR]

Tomatoes are low in calories, however, they provide the precious content of vitamins, minerals, organic acids, carbohydrates, and, especially, carotenoids (β-carotene and lycopene), as essential requirements for the normal functioning of the human body. The latest study aimed to quantify the various compounds that exhibit antioxidant activities in different tomato cultivars. Tomato landraces with the supreme content of individual chemicals and complex of varied traits can serve as genetic sources in breeding for obtaining the tomato genotypes with the highest content of carotenoids, ascorbic acid, phenols, dry matter, and soluble sugars. Comparative analysis of tomato cultivars showed that to obtain genetic material with an enhanced content of secondary metabolites, the following tomato cultivars are recommendable for the desired hybridization to make possible cross combinations, i.e., Black Jack, Shirley, Bosare blue, and Christmas Blueberry and can suggest more precisely for high carotenoids content. Tomato cultivars VS169-19 and Paul Robeson can benefit as sources of soluble sugars and antioxidants, such as ascorbic acid and polyphenols. [ABSTRACT FROM AUTHOR]