Bioactive Potential of Dendrophthoe Falcate (L.F.) Ettingsh Parasitizing Senna Siamea: A Comprehensive Study on Antibacterial, Antibiofilm, And Time-Kill Dynamics Against Clinical Isolates

The present study evaluates the antibacterial, antibiofilm, and time-kill potential of Dendrophthoe falcata (D. falcate) leaf extracts parasitizing Senna siamea (S. siamea) against clinically relevant bacterial pathogens. Antibacterial activity assessed by the agar well diffusion method revealed that the ethyl acetate extract exhibited the most potent concentration-dependent inhibition, with maximum zones of inhibition recorded against Staphylococcus aureus, E. coli, P. aeruginosa, and K. pneumoniae (18.2 ± 0.5 mm to 17.0 ± 0.4 mm at 100 mg/mL). Methanol and acetone extracts showed moderate activity, while the toluene extract exhibited minimal effects. Minimum inhibitory concentration (MIC) assays supported these findings, with the ethyl acetate extract showing the lowest MIC values (2.9–5.2 µg/mL), indicating high potency, followed by methanol, acetone, and toluene extracts. Antibiofilm assays further demonstrated the efficacy of ethyl acetate extract, with low BIC₅₀% (1.2–1.9 mg/mL) and BIC₉₀% (2.3–2.9 mg/mL) values, outperforming the other extracts. Time-kill kinetics confirmed the bactericidal activity of the extracts, with ethyl acetate extract achieving complete bacterial eradication at 1× MIC within 4.5–5.5 h and at 2× MIC within 3.0–3.5 h. These results suggest that the ethyl acetate fraction of D. falcata leaves holds significant potential as a natural antimicrobial and antibiofilm agent against multidrug-resistant pathogens, warranting further bioactive compound isolation and mechanistic studies.