Chemical Profile, Quantification of Phenolic Compounds, and DPPH Test of Nelsonia canescens (Lam.) Spreng (Acanthaceae), a Plant Harvested in Mali

Nelsonia canescens (Lam.) Spreng. (Acanthaceae) is used in traditional medicine, but information on the phytochemical composition and antioxidant properties of plants collected in Mali remains limited. This study aimed to characterise the chemical groups present in the whole plant, determine its total phenolic and flavonoid contents, and assess its free-radical-scavenging activity. Whole plants were harvested in July 2025 from Manankoro, Koulikoro Region, Mali, and processed to obtain an aqueous extract. Phytochemical screening was performed using colour and precipitation reactions, supplemented by thin-layer chromatography. Total phenolic content was determined by the Folin–Ciocalteu assay, and total flavonoid content was measured by a colourimetric method. Antioxidant activity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with ascorbic acid as the positive control. Screening identified alkaloids, tannins, flavonoids, sterols and triterpenes, free quinones, reducing sugars, amines, mucilage and cardiac glycosides. Chromatographic observations also indicated alkaloids, tannins, flavonoids and anthocyanins. The aqueous extract contained 16.250 ± 0.899 mg gallic acid equivalents per gram of extract of total phenolics and 1.280 ± 0.014 mg catechin equivalents per gram of extract of total flavonoids. Its DPPH inhibitory concentration (IC₅₀) was 192.95 ± 3.91 µg/mL, compared with 9.85 ± 0.85 µg/mL for ascorbic acid. These findings establish a preliminary phytochemical profile and indicate measurable but comparatively weak DPPH radical-scavenging activity under the conditions studied.