Biochemistry of Amaranthus polyphenols and their potential benefits on gut ecosystem: A comprehensive review of the literature

The complete plastome of Amaranthus roxburghianus (Amaranthaceae)

Amaranthus roxburghianus H.W. Kung 1935, belonging to the Amaranthaceae family, is recognized for its significant medicinal properties. However, molecular research on this species has been limited. This study represents the inaugural documentation of the sequencing and assembly of the complete plastome of A. roxburghianus. The genome spans a total length of 149,969 base pairs (bp), exhibiting a conventional quadripartite structure. This structure comprises a large single-copy (LSC) region of 83,917 bp, a small single-copy (SSC) region of 18,124 bp, and two inverted repeat (IR) regions, each extending to 23,964 bp. In its entirety, the A. roxburghianus plastome encompasses 128 genes, of which 107 are unique, encompassing 77 individual protein-coding genes, 26 unique tRNA genes, and four unique rRNA genes. Phylogenetic analysis has shown a close resemblance between A. roxburghianus and A. polygonoides, both part of the subgenus Albersia. Although the genus Amaranthus is roughly divided into three subgenera, additional plastid genomic data are required for a more accurate assignment of A. albus and A. blitoides. The sequencing of this plastome is a significant step forward, likely to expedite the development of molecular markers and significantly contribute to genetic assays involving this distinctive species.

Chenopodium quinoa Willd. and Amaranthus hybridus L.: Ancestral Andean Food Security and Modern Anticancer and Antimicrobial Activity

The species Chenopodium quinoa Willd. and Amaranthus hybridus L. are Andean staples, part of the traditional diet and gastronomy of the people of the highlands of Colombia, Ecuador, Peru, Bolivia, northern Argentina and Chile, with several ethnopharmacological uses, among them anticancer applications. This review aims to present updated information on the nutritional composition, phytochemistry, and antimicrobial and anticancer activity of Quinoa and Amaranth. Both species contribute to food security due to their essential amino acid contents, which are higher than those of most staples. It is highlighted that the biological activity, especially the antimicrobial activity in C. quinoa, and the anticancer activity in both species is related to the presence of phytochemicals present mostly in leaves and seeds. The biological activity of both species is consistent with their phytochemical composition, with phenolic acids, flavonoids, carotenoids, alkaloids, terpenoids, saponins and peptides being the main compound families of interest. Extracts of different plant organs of both species and peptide fractions have shown in vitro and, to a lesser degree, in vivo activity against a variety of bacteria and cancer cell lines. These findings confirm the antimicrobial and anticancer activity of both species, C. quinoa having more reported activity than A. hybridus through different compounds and mechanisms.

Phytochemical profiling of three Amaranthus species using LC-MS/MS metabolomic approach and chemometric tools

Several Amaranthus vegetables (Amaranthaceae) have been recognized as valuable sources of minerals, vitamins, proteins, and phytonutrients, with health-promoting characteristics. In this study, three edible Amaranthus species, namely A. hybridus (AH), A. blitum (AB), and A. caudatus (AC), were chemically characterized using non-targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. Further, multivariate chemometric analyses were conducted, including principal component analysis (PCA) and correlation-covariance plot (C-C plot). As a result, forty-one diverse compounds were identified, which varied in distribution and abundance across the investigated species. Amino acids and flavonoid glycosides were the most prevalent metabolites. Other identified compounds comprised nucleoside, chlorogenic acids, hydroxy cinnamoyl amides, and triterpenoid saponins. The most discriminant metabolites were flavonoid glycosides and hydroxy cinnamoyl amides, giving each species a chemotaxonomic identity. Advancing the chemotaxonomy of Amaranthaceae, adenosine nucleoside and N-coumaroyl-ʟ-tryptophan were first reported from this family. Isorhamnetin and tricin glycosides were uniquely identified in AC, offering useful chemotaxonomic markers for this species. Notably, AB and AH profiles shared most metabolites, yet with varying abundance. These include adenosine, nicotiflorin, dicaffeoylquinic acids, and N-trans-feruloyl-4-O-methyldopamine. However, N-coumaroyl-ʟ-tryptophan and kaempferol dirhamnoside were exclusively found in AB, separating it from AH. In conclusion, the applied analytical techniques established molecular fingerprints for the included species, identified specific biomarkers, and investigated their interconnections.

Effect of Foliar Application of Hydrogen Peroxide Macroconcentrations on Growth Parameters, Phenolic Compounds and Antioxidant Capacity in the Leaves and Seeds of Amaranthus hypochondriacus L

Amaranth has many interesting features, both nutritional and otherwise, that make it attractive as a food crop. Plants grown in greenhouses have higher yields but lower nutritional value compared to those grown in open fields. This prompted an interest in studying viable elicitors for the production of amaranth. Small hydrogen peroxide (H₂O₂) concentrations for foliar spraying from 0 to 18 mM have been used in greenhouse amaranth cultivation. The objective of this work was to evaluate the effect of foliar application of H₂O₂ megadoses on growth parameters, total phenolic compounds, condensed tannins, anthocyanins, and the antioxidant capacity of leaves and seeds of amaranth grown in a greenhouse setting. The seed of the Amaranthus hypochondriacus L. species was used. The concentrations of H₂O₂ analyzed were 0, 125, 250 and 400 mM, with 11 applications throughout the growing cycle. The variable data were subjected to an analysis of variance (ANOVA), followed by a Tukey's post hoc test (95% CI, p < 0.05). The results on chlorophyll, growth parameters and proximal chemical analysis showed no statistical difference between the control group versus the treatment groups. A greater number of favorable changes in the different variables studied were observed with the 125 mM H₂O₂ treatment, including the increase in antioxidant capacity measured by FRAP. The seed showed a considerable increase in TFC with all treatments and responded better to the 250 mM H₂O₂ treatment in the case of DPPH (an increase of 30%) and TPC (an increase of 44%). A 28% increase in anthocyanin content was observed with the treatment of 400 mM H₂O₂. The use of H₂O₂ may be an appropriate strategy to enhance the production of antioxidant compounds in amaranth without affecting growth or its basic proximal chemical composition. More studies are required in this regard.