Kinetic Study of In Vitro Release of Neem from Chitosan Biopolymer and Assessment of Its Biological Effectiveness

The study examined the sustained release of neem from the polymeric carrier system chitosan by varying the drug content, ionic strength of the release medium, and pH. Six different kinetic models, i.e., Korsmeyer-Peppas (KP), Peppas-Sahlin (PS), Higuchi, Hixson-Crowell, Zero order, and First order were used to investigate the drug release kinetics. Based on the R² values, the KP and PS models were chosen from the examined models to study the drug release mechanism from the chitosan biopolymer. The values found for model parameters <i>n</i> and <i>m</i> in the KP and PS models differ noticeably, suggesting that Fickian diffusion and Case II relaxation are important components of the neem release mechanism from chitosan. At lower ionic strengths and lower pH values, neem is released from the composite mostly by Fickian diffusion. The diphenyl-2-picrylhydrazyl assay served to assess the composite's antioxidant properties. The composite's antioxidant properties ranged from 3.56 ± 1.89% at 10 μg/mL to 51.28 ± 1.14% at 70 μg/mL. The ability of the composite to inhibit the denaturation of egg albumin was also tested and it ranged from 59.68 ± 0.93% at 25 μg/mL to 187.63 ± 3.53% at 1600 μg/mL. The drug composite has exhibited antibacterial activity against <i>Klebsiella pneumoniae</i>, <i>Pseudomonas aeruginosa</i>, <i>Escherichia coli</i>, and <i>Staphylococcus aureus</i>, and proved to be highly effective against <i>P. aeruginosa</i> at lower concentrations and against <i>S. aureus</i> at higher concentrations. The resulting inhibition zones for <i>P. aeruginosa</i> at 5 and 10 mg/mL concentrations were 16.5 ± 2.25 mm, and 14.83 ± 0.6 mm, respectively, whereas for <i>S. aureus,</i> it was 16.67 ± 0.33 mm at 20 mg/mL. The neem-chitosan composite's minimum inhibitory concentration/minimum bactericidal concentration ratio for <i>K. pneumoniae</i>, <i>P. aeruginosa</i>, and <i>S. aureus</i> was greater than 4, suggesting that they trigger bacteriostatic outcomes, whereas for <i>E. coli,</i> it was 4, which means that bactericidal effects were evident.