Research on microencapsulation of polyphenols obtained from Pseuderanthemum palatiferum leaves as promising delivery systems for antioxidant and antibacterial applications

Abstract

This research aimed to prepare microcapsules of polyphenols from Pseuderanthemum palatiferum (P. palatiferum) using sodium alginate and chitosan as wall materials, with P. palatiferum extract as the core material via ionic gelation. Ionic gelation parameters were investigated to achieve optimal encapsulation efficiency of the polyphenol content. Independent factors, including sodium alginate, chitosan, and calcium chloride concentration, were designed and optimized using the Box–Behnken design of response surface methodology. The physical and chemical features of microcapsules were characterized using SEM, FTIR, and TGA. The antioxidant activity of the microcapsules was tested using DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) scavenging assay, while antibacterial activity against Escherichia coli and Staphylococcus aureus was examined. The results showed that the optimal encapsulation efficiency reached 72.53% under conditions of 1.77% sodium alginate, 0.5% chitosan, and 0.5% calcium chloride concentration. Compared with the blank microcapsules, extract-loaded microcapsules exhibited higher water content and solubility, and a swelling ratio that was reduced by more than 4.5 times. The microcapsules had a dense and compact structure with spherical forms and an average size of 1.9 mm. The bioactive compounds from the extract can be preserved under different environmental conditions due to the protection of microcapsules. Extract-loaded microcapsules, exhibiting notable antioxidant and antibacterial capacities, have considerable potential for applications in the food and pharmaceutical fields.