Preparation and Evaluation of the Antibacterial Effect of Chitosan Nanoparticles Containing Ginger Extract Tailored by Central Composite Design

Purpose: The ginger root extract has shown remarkable antimicrobial effects. Nanocarriers based on biodegradable polymers (like chitosan) are promising drug delivery vehicles for antibacterial compounds. In this study, aqueous and methanolic extracts of ginger root were prepared, loaded on chitosan nanoparticles (NPs), and their antimicrobial effects were investigated. Methods: The NPs were prepared using the ionic gelation technique. The central composite design model was employed to optimize the formulation variables and achieve the minimum particle size and maximum zeta potential. The total phenol content of the powdered extracts was determined. The antimicrobial activity of the NPs was evaluated by the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results: The optimum size of NPs containing methanolic or aqueous extract were 188.3 and 154.7 nm, with a zeta potential of 29.1 and 32.1 mv, and entrapment efficiency percent (E.E.%) of 61.57 +/- 3.12% and 44.26 +/- 2.57%, respectively. Transmission electronic microscopy images confirmed the spherical particles in the low nanometer range. The phenol content of methanol extract was higher than the aqueous one (60.216 +/- 1.83 and 39.835 +/- 1.72 mg gallic acid equivalent/100 g), respectively). According to the results of the MIC and MBC, methanol extract NPs showed more potent antimicrobial effects, which seems to be associated with higher concentrations of phenolic compounds. The FTIR spectrophotometry showed no chemical interaction between the extracts and other ingredients. Conclusion: The results demonstrated that current NPs significantly increased the antibacterial effects of ginger extracts and could be selected for further evaluation.