Chemical Characterization and Biological Activities of Leaves Extracts from Tragia furialis Bojer (EUPHORBIACEAE)

Abstract

Background: Tragia furialis Bojer is a medicinal plant from northern Madagascar, is traditionally used to treat coughs, asthma, and skin infections. This study evaluated its antioxidant and antimicrobial potential and identified its active phytochemical constituents. Study Design: Leaves were dried, powdered, and sequentially extracted with hexane, ethyl acetate, and methanol. The extracts were analyzed for total polyphenol content (Folin–Ciocalteu method) and antioxidant activity (DPPH assay). Antimicrobial activity was assessed via disk diffusion against ten bacterial strains. Bioactive compounds were isolated through chromatography and identified using NMR spectroscopy and literature comparison. Results: Phytochemical screening of brut ethanolic extract revealed the presence of flavonoids, tannins, triterpenoids, steroids, and coumarins. The methanol extract showed the highest yield (4.38%) and exceptionally high polyphenol content (48.1 ± 0.1 mg GAE/g). It exhibited potent antioxidant activity, surpassing ascorbic acid (IC₅₀ = 10.0 µg/mL vs. 12.18 µg/mL). This extract demonstrated strong, broad-spectrum antimicrobial activity, with inhibition zones ranging from 13.33 ± 0.88 mm to 18 ± 0.66 mm and showed strong antibacterial activity against nine out of ten strains. The minimal inhibitory concentrations (MICs) for active strains ranged from 3.125 to 50 mg/mL. Fractionation led to the isolation of three known phenolic compounds: velutin, quercetin, and 1,2,3,4-tetragalloylglucoside. Conclusion: The methanol extract of Tragia furialis leaves is rich in phenolic compounds and possesses significant antioxidant and antimicrobial properties. These results scientifically validate its traditional uses and highlight its potential as a valuable source of bioactive compounds for phytomedicine.