Formulation, Physico-Chemical Characterization, and Evaluation of the In Vitro Release Capacity of the Ruta graveolens L. Phytocomplex from Biodegradable Chitosan and Alginate Microspheres

The objective of this study was to develop microspheres (Ms) from natural materials, chitosan (Ch) and sodium alginate (Na-Alg), that protect Ruta graveolens L. (RG) extract against temperature, pH, and the oxidative impact of degradation. The microspheres also masked the unpleasant taste by enclosing them in a biodegradable polymeric matrix. First, the total polyphenols, total flavonoid content, and antioxidant activity were quantified spectrophotometrically. Individual polyphenol contents were identified and quantified by high-performance liquid chromatography (HPLC) with UV detection. The RG extract was encapsulated in microspheres of chitosan–sodium alginate–Ruta graveolens L. extract (CARG-Ms) using two distinct procedures (method 1, in which the RG extract was added to the Ch solution and the Na-Alg solution was dripped into this mixture, and method 2, in which the RG extract was added to the Na-Alg solution and then dripped into the Ch solution) to determine which method was more advantageous. All microspheres were evaluated and characterized by confocal laser-scanning microscopy (CLSM), scanning electron microscopy (SEM), optical scanning, entrapping efficiency (EE%), swelling index (SWL%), and in vitro release (RGrel%), and all results underwent univariate and multivariate analysis using a regression model. Following these tests, it was observed that the extract had an appreciable flavonoid content of 37.98%, with antioxidant properties evidenced by the 54.25% inhibition of DPPH. Of the polyphenolic compounds identified in the extract by using the HPLC method, rutin was present in the highest amount, at 745.17 μg/mL. The microspheres prepared by method 2, which contained the highest concentration of chitosan, had several desirable properties, including a high degree of roughness, high entrapping efficiency (75%), a wrinkled appearance, a better in vitro release capacity, and a lower SWL%. On the other hand, CARG-Ms prepared by method 1, which contained a smaller concentration of Ch, had faster swelling and slower release of the extract due to the lower entrapping efficiency (35%). These results suggest that the concentration of wall material and the preparation method play important roles in the encapsulation process and final particle characteristics. According to the obtained results, after the multivariate statistical analysis, it can be observed that the microspheres prepared via method 2 of the complex coacervation process were the most effic