Identifying secondary metabolite content and antioxidant potential in selected commercially available medicinal plants

Abstract

Medicinal plants are the most valuable source of biomedicine used in traditional systems of medicine and they also it supplies the chemical entities for the synthetic drugs [1]. Plant secondary metabolites are various chemical compounds produced by the plant cell through primary metabolic pathways. At present, traditional medicine, which comprises mostly of herbal components is preferred globally [2]. There are some secondary metabolites abundantly used in traditional medicine. Among these, tannins which are phenolic compounds possessing high molecular weight ranging from 500-3000 Dalton are abundant in vacuole tissues of leaves, wood, roots, fruit, and bark of plants [3]. Up to the present, exceeding 4500 varying flavonoids have been found. They are a larger category of phenolic compounds. Flavonoids have been discovered in a lot of plant tissues including plant cell vacuoles. Flavonoids are available as monomers and dimers of oligomers [4]. Antioxidants are important phytoconstituents in medicinal plants. An antioxidant is “any substance that, when present at low concentrations compared with those of an oxidizable substrate, significantly delays or prevents oxidation of that substrate” [5, 6]. Free radicals denote the highly reactive species capable of widespread, indiscriminate oxidation and peroxidation of proteins, lipids , and DNA [7]. Rapid production of free radicals leads to oxidative damage to biomolecules and causes serious diseases like degenerative disorders, cancer, diabetes, neural disorders, and aging. Hence antioxidants play a vital role to block free radical production [8, 9]. Antioxidants are known to fulfill their task through several mechanisms including retarding, avoiding, or eliminating the oxidative damage to the susceptible molecules [10]. Many research has investigated almost all the fresh herbal medicinal plants and different parts of them to test their phytochemical content, antioxidant potential etc., but the above qualities of commercially available medicinal plants are not that much touched by researchers although it is important. Therefore, the current study was conducted to investigate the secondary metabolite content and in vitro antioxidant activities of six selected commercially available dried medicinal plant parts namely stems of Coscinium fenestratum, flowers of Aegle Marmelos, roots of Vetiveria Zizanioides, stems of Tinospora cordifolia , rhizomes of Acorus calamus and fruits of Terminalia Chebula which are commonly employed in herbal medicine to treat digestive system associated ailments, apart from their medicinal value in the treatment of many other diseases. The plant parts were assessed qualitatively and quantitatively during the current experiment. These plants are widely used in the traditional medicine system of Sri Lanka, due to their vast medicinal properties that immensely contribute to treating diseases.