Botany, ethnomedicine, phytochemistry and pharmacology of Amaranthus spp.- a review

Abstract

Amaranthus, a plant of Amaranthaceae family is cultivated worldwide for its nutritious grains and leaves. This fast-growing crop thrives well even in challenging conditions such as high temperatures, low moisture, diseases, and pests. The genus has 70–74 species, 17 of which are edible, with most being diploid and only one species being tetraploid. Further, about 55 species are native to the Americas, with the rest found in Asia, Africa, Europe, and Oceania. Amaranthus's leaves, shoots, tender stems, and grains are versatile ingredients used in sauces, soups, and various recipes. It is a nutrient-rich plant, providing essential carbohydrates, vitamins, calcium, iron, beta-carotene, dietary fiber, and amino acids like lysine and sulfur. Further, the nutritional composition of plants varies with species and plant parts. With over 50 identified nutritional compounds, Amaranthus exhibits numerous pharmacological benefits, including antioxidant, anti-inflammatory, antimicrobial, antidepressant, antihyperglycemic, antihyperlipidemic, hepatoprotective, antiviral, antibacterial, hypocholesterolemic, and neuroprotective effects. In Ayurveda, it is traditionally used to treat conditions such as menorrhagia, leucorrhoea, dysentery, diarrhea, hemorrhagic colitis, asthma, bronchitis, piles, blood disorders, bladder discomfort, toothache, and as a diuretic. This review provides an in-depth examination of Amaranthus spp., covering their historical context, distribution, linguistic diversity, cyto-taxonomy, origin, and genetic diversity. It emphasizes the plant's diverse applications in agriculture, health, and nutrition, particularly in addressing global food security and nutrition challenges. Further research is needed to isolate active components, optimize extraction, and explore Amaranthus's therapeutic potential in functional foods, supplements, and natural colorants. Sustainable farming and breeding can enhance Amaranthus yields, betalain content, and reduce anti-nutritional compounds, benefiting farmers especially in developing countries.