Isolation, characterization and antibacterial evaluation of bioactive compounds from Senna against human pathogenic bacteria

Compounds obtained from Senna (Cassia angustifolia) leaves, a medicinal plant traditionally used for its therapeutic properties. Phytochemical screening revealed a rich composition of secondary metabolites including flavonoids, glycosides, alkaloids, tannins, saponins, and phenolic acids. Advanced spectroscopic and chromatographic techniques, such as FTIR, UV-Vis, and GC-MS, were employed to characterize these constituents, confirming the presence of structurally diverse compounds such as oleic acid, squalene, heptanoic acid, and various flavonoids and glycosides. These compounds are known for their antioxidant, antimicrobial, and pharmacological potential. The antibacterial activity of Senna leaf extracts was assessed using both agar well diffusion and broth microdilution methods against selected human pathogenic bacteria, including Staphylococcus aureus (Gram-positive), as well as Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi (Gram-negative). Results demonstrated that the alcoholic extract exhibited notable antibacterial efficacy, with inhibition zones reaching up to 25 mm against Staphylococcus aureus at 200 mg/mL. Activity against Gram-negative bacteria was also observed, though generally with smaller inhibition zones, reflecting inherent differences in bacterial cell wall permeability. GC-MS analysis identified 17 major compounds spanning several chemical classes, highlighting the complexity and therapeutic potential of Senna. Isolated flavonoids such as epicatechin, kaempferol derivatives, and vidalenolone further support the observed antimicrobial effects. The results confirm that antibacterial activity correlates with the identified phytoconstituents, especially flavonoids and glycosides, which are known to disrupt microbial cell walls and interfere with essential metabolic pathways. Overall, this research provides scientific evidence that Senna leaves represent a promising source of natural antibacterial agents with potential applications in the development of plant-derived pharmaceuticals. By offering safer, eco-friendly alternatives to conventional antibiotics, these findings contribute to ongoing efforts to address the global challenge of antibiotic resistance. Further investigations involving purification, structural elucidation, mechanistic studies, and in vivo evaluation are strongly recommended to advance the therapeutic application of these natural compounds.