Formulation, Characterization, And Antibacterial Evaluation Of A Novel Drug Delivery System Incorporating Selected Medicinal Plant Extracts

Abstract

The growing challenge of antimicrobial resistance necessitates the development of alternative therapeutic approaches. Although Holoptelea integrifolia and Withania somnifera have been extensively utilized in traditional medicine for their therapeutic properties, the antibacterial potential of their combined extracts has not yet been systematically investigated.

Plant extracts were obtained through successive solvent extraction and subjected to preliminary phytochemical screening. The antibacterial efficacy of individual extracts and their combinations (1:1, 1:2, and 2:1) was assessed against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae using the agar well diffusion method, minimum inhibitory concentration (MIC) determination, and checkerboard assay. The most effective synergistic combination was subsequently incorporated into chitosan-based microparticles using the ionotropic gelation technique and optimized employing a 3² factorial design. The optimized microparticles were further characterized and evaluated for their in vitro drug release profile and antibacterial performance.

Among the prepared extracts, the ethanolic extracts exhibited the highest extraction yield along with the greatest diversity of phytochemical constituents. The 1:2 extract combination demonstrated synergistic antibacterial activity, with fractional inhibitory concentration index (FICI) values ranging from 0.5 to 0.75, while the most pronounced synergistic effect was observed against P. aeruginosa (FICI = 0.5). The optimized microparticle formulation, containing 1.5% chitosan and 1.0% tripolyphosphate (TPP), exhibited a mean particle size of 42.36 μm, an encapsulation efficiency of 78.42%, and a sustained drug release profile extending over 24 hours. Furthermore, the developed formulation significantly enhanced antibacterial efficacy, producing a 2–4-fold reduction in MIC values and achieving complete eradication of S. aureus within 24 hours. Stability studies confirmed that the formulation remained stable for six months under accelerated storage conditions.

To the best of our knowledge, this study represents the first report demonstrating the synergistic antibacterial interaction between H. integrifolia and W. somnifera. The developed sustained-release chitosan microparticle formulation exhibited enhanced antibacterial efficacy against clinically significant bacterial pathogens, with particularly promising activity against P. aeruginosa.