Preparation and photodynamic bactericidal effects of curcumin-β-cyclodextrin complex

Area of Science:

• Biomaterials Science
• Photochemistry
• Microbiology

Background:

• Curcumin, a natural compound, suffers from poor water solubility, limiting its therapeutic applications.
• Developing water-soluble curcumin derivatives is crucial for enhancing its bioavailability and efficacy.
• Photosensitizers are vital for photodynamic applications, requiring efficient reactive oxygen species (ROS) generation.

Purpose of the Study:

• To synthesize and characterize a curcumin-β-cyclodextrin (Cur-β-CD) complex as a novel photosensitizer.
• To evaluate the ROS generation capacity and photodynamic antibacterial activity of the Cur-β-CD complex.
• To elucidate the mechanisms underlying the photodynamic inactivation of food-borne pathogens by Cur-β-CD.

Main Methods:

• Formation of Cur-β-CD complex verified using Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD).
• Reactive oxygen species (ROS) generation measured upon blue-light irradiation.
• Photodynamic antibacterial efficacy assessed against Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli using plate count assays.
• Bacterial cell morphology changes observed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
• Mechanisms of inactivation investigated through agarose gel electrophoresis and SDS-PAGE.

Main Results:

• The Cur-β-CD complex was successfully synthesized and confirmed by spectroscopic and thermal analyses.
• Cur-β-CD effectively generated ROS under blue-light irradiation, indicating retained photodynamic activity.
• Significant photodynamic antibacterial effects were observed against tested food-borne pathogens.
• SEM and TEM revealed Cur-β-CD induced bacterial cell deformation, surface collapse, and structural damage, leading to cytoplasmic leakage.
• Agarose gel electrophoresis and SDS-PAGE confirmed bacterial DNA damage and protein degradation as inactivation mechanisms.

Conclusions:

• The Cur-β-CD complex is a promising photosensitizer with enhanced water solubility and retained photodynamic activity.
• Cur-β-CD exhibits potent photodynamic antibacterial effects against common food-borne pathogens.
• The inactivation mechanism involves ROS-mediated bacterial DNA and protein damage, offering a novel strategy for food safety.