Design and Development of Curcumin-Derived Quinazoline Hybrid Molecules and their Polymeric Nanoparticles for Targeted Antibacterial Therapy: Physicochemical Characterization, HPLC/LC-MS Quantification, Drug-Release Kinetics, ROS-Mediated Mechanistic Studies, MIC/MBC, Biofilm Inhibition and In Vitro Pharmacological Evaluation

Abstract

Background: The increasing prevalence of multidrug-resistant (MDR) bacterial infections has become a major global health concern due to the declining efficacy of conventional antibiotics. Curcumin possesses broad-spectrum antibacterial and antioxidant activities but is limited by poor aqueous solubility, low bioavailability, and rapid metabolism. Quinazoline derivatives exhibit promising antimicrobial properties, while polymeric nanoparticles offer improved drug delivery through enhanced stability, sustained release, and targeted delivery. Therefore, the present study aimed to develop curcumin-derived quinazoline hybrid molecules encapsulated in polymeric nanoparticles as a novel antibacterial nanotherapeutic system.
Objective: To design and synthesize curcumin-derived quinazoline hybrid molecules, formulate them into polymeric nanoparticles, characterize their physicochemical properties, quantify the drug using HPLC/LC-MS, investigate drug-release kinetics and ROS-mediated antibacterial mechanisms, and evaluate their antibacterial and in vitro pharmacological activities.
Materials and Methods: Curcumin-derived quinazoline hybrid molecules were synthesized using a molecular hybridization approach and structurally characterized by FTIR, UV–Visible spectroscopy, ^1H/^13C NMR, and LC-MS. Polymeric nanoparticles were prepared by the solvent evaporation method using PLGA and characterized for particle size, polydispersity index (PDI), zeta potential, morphology (SEM/TEM), encapsulation efficiency, and drug loading. Drug quantification was performed using validated HPLC and LC-MS methods. In vitro drug-release studies were conducted using the dialysis bag diffusion technique, and release kinetics were analyzed using zero-order, first-order, Higuchi, and Korsmeyer–Peppas models. Antibacterial activity was evaluated through reactive oxygen species (ROS) generation, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill kinetics, biofilm inhibition assay, cytotoxicity, cell viability, and hemocompatibility studies.
Results: The synthesized curcumin–quinazoline hybrid was obtained with a yield of 81.6 ± 1.8% and purity of 98.7 ± 0.4%. Polymeric nanoparticles exhibited a mean particle size of 176.4 ± 8.2 nm, PDI of 0.183 ± 0.02, zeta potential of −29.8 ± 1.5 mV, encapsulation efficiency of 87.5 ± 2.4%, and drug loading of 13.8 ± 0.9%. HPLC analysis demonstrated excellent linearity (R² = 0.9995) with high analytical precision and accuracy. The nanoparticles displayed sustained drug release over 72 h, with the Korsmeyer–Peppas model providing the best kinetic fit (R² = 0.995). ROS production increased approximately 3.4-fold compared with untreated controls. The nanoformulation showed potent antibacterial activity with MIC values ranging from 4–8 µg/mL and MBC values from 8–16 µg/mL, achieving >99.9% bacterial killing within 24 h. Biofilm inhibition reached 86.3 ± 2.1%, while cell viability remained above 90%, cytotoxicity remained below 10%, and hemolysis was less than 2%, indicating good biocompatibility.
Conclusion: Curcumin-derived quinazoline hybrid-loaded polymeric nanoparticles demonstrated favorable physicochemical characteristics, accurate analytical quantification, sustained drug-release behavior, enhanced ROS-mediated antibacterial activity, significant inhibition of bacterial growth and biofilm formation, and excellent in vitro biocompatibility. These findings suggest that the developed nanoformulation is a promising targeted antibacterial drug-delivery system with potential application in the treatment of multidrug-resistant bacterial infections. Further in vivo pharmacokinetic, toxicological, and efficacy studies are warranted to facilitate clinical translation.