Nanobactericides Derived from Cinnamon Bark Extract: Phytochemical Profiling and Antibacterial Efficacy Against Bacterial Panicle Blight in Rice

Bacterial panicle blight (BPB), caused by the Gram-negative aerobic bacterium Burkholderia glumae (B.glumae), poses a significant threat to global rice production. Cinnamon bark extract (CBE) has demonstrated potent antioxidant and antimicrobial properties due to its high concentration of bioactive compounds, including eugenol and cinnamaldehyde. To enhance the efficacy and stability of these volatile compounds, this study employed nanotechnology and encapsulation techniques. The objective was to develop a CBE-based nanoformulation to inhibit B. glumae and control BPB in rice. CBE-chitosan (CBE-CS) nanoformulations were synthesized using ionic cross-linking between chitosan and trisodium phosphate (TPP) at various concentrations (0%, 0.5%, 1%, 2%, and 4% TPP). More than 15 active compounds were identified in CBE, including (Z)-3-Phenylacrylaldehyde, 2-Propenoic acid, 3-(2-hydroxyphenyl), cinnamaldehyde dimethyl acetal, and hexadecanoic acid. Bacterial membrane damage was significantly greater in treatments with CBE compared to untreated controls. The synthesized nanoparticles ranged in size from 43.66 nm to 106.1 nm, with encapsulation efficiencies between 48.65% and 48.78%, and loading capacities between 25.65% and 33.9%. Scanning electron microscopy (SEM) revealed spherical and homogeneous nanoparticles, while FTIR and XRD analysis confirmed the successful encapsulation of CBE in the chitosan nanoparticles. The antibacterial activity of the nanoformulations showed inhibition zones ranging from 7.5 to 11.8 mm, with the CBE-CS formulation containing 0.5% TPP demonstrating the highest efficacy (MIC = 15.6 mol/ml; MBC = 31.25 mol/ml).