Abstract
Background: The global escalation of antimicrobial resistance (AMR) and oxidative stress–mediated infections has intensified the demand for safe, cost-effective, and plant-derived therapeutic agents, particularly in veterinary and ethnomedicinal healthcare systems. Euphorbia hirta, a widely distributed traditional medicinal plant, is known for its pharmacological relevance but remains insufficiently explored in terms of comparative bioactivity across different plant parts and extraction solvents. This study was therefore undertaken to systematically evaluate the phytochemical composition, antioxidant potential, and antimicrobial activity of aqueous and methanolic extracts derived from the leaves, roots, and stems of E. hirta.
Methods: Leaves, roots, and stems of Euphorbia hirta were subjected to extraction using aqueous and methanolic solvents. The resulting extracts were evaluated for qualitative and quantitative phytochemical constituents, including phenolics, flavonoids, tannins, saponins, alkaloids, and steroids. Antioxidant activity was assessed using the DPPH radical scavenging assay, with IC₅₀ determination. Antimicrobial activity was evaluated using the agar well diffusion method against clinically relevant bacterial strains, including Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus, Klebsiella pneumoniae, and Clostridium spp. Zones of inhibition were measured and compared across plant parts and solvent systems.
Results: Phytochemical analysis revealed that leaves contained the highest concentration of bioactive compounds, including phenolics (206.17 ± 3.21 mg GAE/g), flavonoids (37.97 ± 1.05 mg GAE/g), tannins (89.62 ± 2.13 mg GAE/g), saponins (3.25 ± 0.18%), alkaloids (6.15 ± 0.22%), and steroids (12.84 ± 0.56 mg/g), indicating strong biochemical richness. Antioxidant evaluation showed potent activity in leaf extracts, with DPPH radical scavenging of 72.96% and an IC₅₀ value of 0.803 mg/mL. Antimicrobial screening demonstrated that methanolic leaf extracts exhibited superior activity, particularly against Escherichia coli (18 mm) and Salmonella typhi (17 mm), compared to aqueous extracts (12–14 mm). Root extracts showed moderate antibacterial effects, with inhibition zones of 16 mm against Pseudomonas aeruginosa and 14 mm against both Staphylococcus aureus and Salmonella typhi. In contrast, stem extracts exhibited minimal to negligible activity, with no inhibition observed against E. coli, K. pneumoniae, and Clostridium spp., and only weak activity against S. aureus (4 mm) and P. aeruginosa (6 mm). A strong correlation was observed between phenolic/flavonoid content, antioxidant potential, and antimicrobial efficacy, with methanolic extracts consistently outperforming aqueous extracts.
Conclusion: The study demonstrates that Euphorbia hirta, particularly its leaf fraction, possesses significant antioxidant and antimicrobial properties attributed to its rich phenolic and flavonoid content. Methanolic extraction proved more efficient in recovering bioactive compounds, resulting in enhanced biological activity. These findings validate the ethnomedicinal relevance of E. hirta and highlight its potential as a promising phytopharmaceutical candidate for managing oxidative stress–related infections. The study further supports sustainable natural drug discovery aligned with SDG-3 (Good Health and Well-Being), promoting the development of affordable plant-based therapeutic alternatives.

Key words: Antimicrobial activity, antioxidant assay, Euphobia hirta, SDG-3, Vetrinary microbes