The antibacterial properties of Ampelocissus latifolia root extract against Bacillus anthracis.

Background: Bacillus anthracis a spore-forming Gram-positive bacterium, is the causative agent of anthrax in both animals and humans. The potential emergence of antibiotic-resistant strains of B. anthracis further poses a significant concern. The present study aims to evaluate the antibacterial activity of the methanolic root extract (MRE) of Ampelocissus latifolia against B. anthracis.

Methods: The anti-B. anthracis activity of the MRE was evaluated using the agar well diffusion assay (AWDA), while the minimum inhibitory concentration (MIC) was determined by the broth dilution method. MRE-induced bacterial cell death was further assessed through fluorescence microscopy and flow cytometry. Disruption of the bacterial cell wall by MRE was visualized using Gram staining and scanning electron microscopy (SEM). The thermal stability of MRE activity was examined by AWDA across different temperatures. Additionally, the interaction between MRE and antibiotics approved for anthrax treatment was investigated using the checkerboard assay. The in vitro cytotoxicity of MRE was assessed using the MTT assay.

Results: Our findings demonstrate that MRE exhibits potent antibacterial activity against B. anthracis, with a MIC of 0.078 mg/mL. The antibacterial effect of MRE is mediated through disruption of the bacterial cell wall integrity, resulting in leakage of intracellular contents and subsequent cell death. Notably, MRE retains its antibacterial activity even after prolonged exposure to elevated temperatures, indicating good thermal stability. Interaction studies revealed that MRE does not exhibit any antagonistic effects when combined with antibiotics approved for anthrax treatment; moreover, it shows a synergistic enhancement of streptomycin efficacy. Importantly, MRE demonstrated low cytotoxicity, highlighting its potential as a safe antibacterial agent. Additionally, it exhibits broad-spectrum efficacy against Gram-positive and acid-fast bacteria, while showing limited or no activity against Gram-negative bacteria.

Conclusion: Overall, MRE demonstrates potent antibacterial activity against B. anthracis. It could be particularly useful in treating cutaneous anthrax, where topical application of the extract might be effective. Moreover, MRE could serve as a natural disinfectant for B. anthracis-contaminated sites. Further research into the bioactive compounds present in the extract may lead to the development of new therapeutic agents for anthrax treatment.