Abstract

Vernonia amygdalina Delile, commonly known as bitter leaf, is a widely recognized medicinal plant in Africa but remains largely underexplored in Yemen. This study aimed to investigate the phytochemical profile, antioxidant capacity, and antibacterial activity of the methanolic leaf extract of V. amygdalina collected from Socotra Island. Preliminary phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, saponins, terpenoids, cardiac glycosides, phenols, and steroids. Quantitative estimation demonstrated a high total flavonoid content (238.4 ± 4.2 mg QE/g) and substantial total phenolic content (122.6 ± 3.1 mg GAE/g). Antioxidant evaluation using the DPPH radical scavenging assay showed strong free radical inhibition, with 84.7% activity at 400 µg/mL and an IC₅₀ value of 96.4 µg/mL, while the ferric reducing antioxidant power assay indicated strong electron-donating potential (OD₇₀₀ = 0.732). Antibacterial testing against clinical isolates showed concentration-dependent inhibition. MIC values were 50 mg/mL for Staphylococcus aureus and S. epidermidis, while Gram-negative bacteria (E. coli, K. pneumoniae, and P. aeruginosa) exhibited higher MIC values (100 mg/mL) with MBCs exceeding 200 mg/mL. These findings support the traditional use of V. amygdalina and highlight the Socotra accession as a promising, locally accessible source of bioactive compounds with antioxidant and antibacterial potential. Further work should isolate active constituents and assess in vivo efficacy and safety.