Phytochemical Profiling and Bactericidal Mechanism of Crinum wattii Extracts

Crinum wattii Baker, a perennial herb from the Amaryllidaceae family, was studied for its phytochemical content and antibacterial activity. Aqueous (AQE), ethanol (ETE), ethyl acetate (EAE), and chloroform (CFE) extracts from bulb samples were analyzed using colorimetric assays and high-performance liquid chromatography (HPLC). The ETE contained 47.93 mg/g of lycorine, suggesting its use as a quality control marker. AQE, EAE, and ETE showed high levels of tannins, flavonoids, and phenolics, respectively. Antibacterial activity was evaluated via disc diffusion method, revealing ETE as the most potent, especially against Bacillus cereus and Bacillus subtilis. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed ETE-induced bacterial lysis and abnormal elongation, while Fourier Transform Infrared (FT-IR) spectroscopy indicated reductions in protein amides, polysaccharides, ester lipids, and nucleic acids, alongside an increase in phospholipids. These findings suggest that ETE disrupts bacterial protein, DNA, and cell wall synthesis in Bacillus subtilis, as evidenced by FT-IR analysis and ultrastructural changes. However, further molecular-level studies are required to identify the specific targets and mechanisms involved. In summary, C. wattii ETE, rich in lycorine and phenolics, exerts bactericidal effects through a lysis-based mechanism. HIGHLIGHTS Crinum wattii extracts demonstrate strong potential as natural antibacterial agents against resistant bacterial strains. The ethanolic extract (ETE) contained 47.93 mg/g of lycorine, supporting its use as a quality control marker. ETE exhibited the highest antibacterial activity, notably against Bacillus cereus and Bacillus subtilis. SEM and TEM analyses confirmed ETE-induced bacterial lysis and abnormal elongation of bacterial cells. FT-IR analysis revealed that ETE disrupts bacterial proteins, DNA, cell wall integrity, and membrane components. GRAPHICAL ABSTRACT