Phytochemical constituents, antioxidant and antibacterial activity of the Philippine Sampa-sampalukan (Phyllanthus niruri) leaf extract against selected human bacterial pathogens

The Philippine sampa-sampalukan (Phyllanthus niruri) is an underexplored plant with significant ethnopharmacological potential. This study examined the phytochemical constituents, antioxidant, and antimicrobial activity of its leaf ethanolic extract, collected from the botanical garden of Central Philippine University, Iloilo, Philippines. Qualitative analysis identified various bioactive compounds, including alkaloids, tannins, saponins, proteins, phenols, flavonoids, glycosides, carbohydrates, and terpenoids. Quantitatively, the extract contained 258.07±4.13 mg gallic acid equivalent (GAE)/g of total phenolics and 76.10±0.47 mg quercetin equivalent (QE)/g of flavonoids. The 1,1-diphenyl-1-picrylhydrazyl (DPPH) assay confirmed concentration-dependent antioxidant activity. The extract also exhibited strong antibacterial effects against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Streptococcus agalactiae, Edwardsiella tarda, Salmonella typhi, Escherichia coli, and Pseudomonas aeruginosa, with significant inhibition at 100 mg/mL. This study underscores P. niruri’s potent bioactive compounds and their potential for therapeutic applications.