Enhanced delivery of Melittin via PEGylated PLGA nanoparticles: formulation, characterization, and in vitro evaluation

Abstract

Melittin (MEL), a major component of honeybee venom, possesses potent anti-inflammatory, antibacterial and anticancer properties. However, its clinical use is limited by its non-specific toxicity. This study investigates the nano-encapsulation of MEL into polyethylene glycol (PEG)-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (PNPs) to mitigate these effects and improve its therapeutic efficacy. MEL-loaded PLGA NPs (MEL-PNPs) were successfully prepared by the double-emulsion solvent evaporation method, and PEG-4000 was employed as a coating agent. The MEL-PNPs and MEL-PNPs coated with PEG, had an optimal size of 165 ± 9 and 221 ± 7 nm, respectively with a high EE% of 79.1 % and 70.4 % and LC% of 7.7 ± 0.6 %, respectively. In vitro release studies demonstrated a slow and sustained release of MEL from both PNPs of >85 % after eight days at two different pH conditions. Cytotoxicity study indicated that MEL-PNPs-PEG reduced the cytotoxicity against the normal cell line (HFF-1), maintaining a high cell viability after 72 h. In HepG2 cells, MEL-PNPs and MEL-PNPs-PEG showed enhanced anticancer activity, particularly after 48 h, with significant reductions in cell viability at higher concentrations. Also, B-PNPs and B-PNPs-PEG maintained the viability of HFF-1 and HepG2 cells at all concentrations till 72 h, indicating their safety. Antibacterial testing of MEL-loaded PNPs demonstrated significant inhibition of Gram–positive and Gram–negative pathogens. MEL-PNPs inhibited S. aureus and MRSA at 1.56 μg/mL, E. coli (ATCC 25922), and P. aeruginosa at 6.25 and 12 μg/mL, respectively, while MDR clinical isolates E. coli and P. aeruginosa both at 25 μg/mL. MEL-PNPs-PEG showed MICs of 0.78 and 1.56 μg/mL for S. aureus and MRSA, respectively, while for E. coli (ATCC 25922), P. aeruginosa (ATCC 27853), and MDR isolates of E. coli and P. aeruginosa, the MIC was in the range of 3.12–12.5 μg/mL. These findings suggest that the PEG-coated MEL-PNPs offer improved biocompatibility and more effective anticancer and antibacterial effects, making them a promising delivery system for MEL in cancer and infection therapy. An in vivo study is required to assess the performance of the developed MEL-loaded PNPs.