Tagitinin C‐Rich Extract From Tithonia diversifolia (hemsl.) A. Gray Exerts Activity Against Pathogenic Bacteria and Biofilms

The increasing prevalence of persistent and difficult-to-treat infections has intensified interest in natural compounds able to act on both planktonic bacteria and biofilm structures. Tithonia diversifolia, a species rich in bioactive metabolites such as tagitinin C, has emerged as a promising source of antimicrobial agents. This study evaluated the antibacterial and antibiofilm activities of a tagitinin C-rich leaf extract and potential mechanisms of action. The extract was obtained by supercritical CO₂ extraction, chemically characterized by HPLC, and assessed against Staphylococcus aureus, Enterococcus faecalis, and Pseudomonas aeruginosa using disk diffusion, broth microdilution, and molecular docking assays. Antibiofilm activity was investigated against a biofilm-forming S. aureus strain using coverslip disruption assays, optical microscopy, and scanning electron microscopy. The extract showed strong antimicrobial activity against S. aureus (MIC/MBC: 0.039 mg/mL), intermediate inhibition of E. faecalis (1.25 mg/mL), and moderate effects on P. aeruginosa (5 mg/mL). It also promoted significant biofilm disruption (66.2% ± 4.1%), with microscopy revealing reduced bacterial density and altered structural organization. Docking results demonstrated favorable binding affinities with MurA, MurE, and MurG, suggesting stable interactions with essential enzymes involved in peptidoglycan synthesis. Overall, the findings highlight the therapeutic potential of T. diversifolia extract against resistant microorganisms and biofilm-associated infections.