Innovative encapsulation for enhanced drug delivery using stingless bee propolis and honey Tetragonisca angustula (Hymenoptera: Meliponini), and their antimicrobial activity

Propolis, known for its immunological and therapeutic properties due to flavonoids and phenolic acids, has been used in alternative medicine for many years. In Ecuador, the commercialization of stingless bee honey has been increasing recently, although the physical-chemical and biological characteristics of honey from each species are unknown due to their different behaviors and diets. The objective of this research was to synthesize chitosan nanoparticles by encapsulating commercial honey (NPMC), honey (NPMA), and propolis (NPP) from Tetragonisca angustula by ionic gelation and glutaraldehyde cross-linking. The polymeric nanoparticles were structurally characterized (TGA and FT-IR), and their antimicrobial activity against E. coli and S. aureus, cytotoxicity, and controlled release were evaluated in two phases at different pH levels, one gastric (pH 1.8) and intestinal (pH 7.4). FT-IR analysis of the polymeric nanoparticles revealed the presence of hydroxyl and alkyl groups. NPMA and NPP showed characteristic vibrations of flavonoids and C=O, regardless of the molecular weight of chitosan. In the TGA, the NPMC had decomposition efficiencies of 97.22% (LMW) and 92.10% (HMW). Propolis nanoparticles achieved encapsulation efficiencies of 94.31% and 89.21%. NPPA (HMW-chitosan-based nanoparticles encapsulating propolis from stingless bees) was the most effective against S. aureus. NPPB (LMW-chitosan-based nanoparticles encapsulating propolis from stingless bees) at 10 μg/mL showed higher cytotoxicity than NPMAA (HMW-chitosan-based nanoparticles encapsulating honey from stingless bees). In summary, propolis nanoparticles maintained efficiencies above 76%, while NPMC and NPMA exhibited loading capacities greater than 27%. In contrast, formulations with high molecular weight chitosan showed slightly lower values, although these differences were not statistically significant.