Phytochemical Study and Evaluation of the Antioxidant Activity of Extracts of the Roots of Chrysopogon nigritanus

In this work, we were interested in a medicinal plant named Chrysopogon nigritanus, belonging to the Poaceae family. In order to carry out this study, we were interested first in the phytochemical screening test, after having carried out the extraction with two solvents (water and isopropanol), to characterize the different families of metabolites present in the extracts. Then, the assays of polyphenols and flavonoids were carried out in order to quantify the contents of these two compounds in each extract. Finally, the antioxidant activity of the extracts was evaluated by three methods: the CUPRAC method, the trapping of the 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH•) and the trapping of the ABTS•+ radical-cation (2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)). The best antioxidant activities were obtained with the ABTS•+ radical scavenging with IC50 of 0.13 mg/mL for the aqueous extract and 0.19 mg/mL for the isopropanol extract. Based on these first results, an in-depth study is underway for various biological tests and the isolation of bioactive molecules.