THE PHYSICOCHEMICAL STABILITY, BIOACCESSIBILITY AND CYTOTOXICITY OF PITANGA LEAF EXTRACT INTO W/O AND W/O/W EMULSIONS BY IN VITRO DIGESTION

Substances rich in polyphenols, as plant extracts, may have high biological activity. However, they are highly unstable when exposed to environmental and gastrointestinal conditions, and then, they may lose their activity, which limits their application. The encapsulation of active substances in emulsions can enhance their biological stability. The objective of this study was to perform an in vitro digestion (IVD) of a single W/O (SE) and double W/O/W (DE) emulsions encapsulating Pitanga leaf extract (PLE), and to analyze physiochemically the digested samples and for their cytotoxicity. The SE and DE emulsions were prepared in two stages. Firstly, the SE was produced by dispersing the PLE in a lipid phase. And then, the DE was produced by dispersing the SE in an external aqueous phase. The PLE, SE and DE were submitted to in vitro digestion using a static model that simulates gastrointestinal condition. Digested and undigested samples were analyzed for microstructure, droplet size (DZ) and ζ-potential, free fatty acids release (FFA), bioavailability and cytotoxicity. For SE, DZ increased from ~0.200 µm in the initial, oral and gastric phases, to 2.336±0.516 µm in the intestinal phase. For DE, DZ increased from ~1.200 µm in the initial and oral phases, to 2.034±0.291 µm in the gastric phase, decreasing to 0.631±0.038 µm in the intestinal phase. The FFA for SE (44.9±4.6%) was lower than for DE (88.1±2.8%). Overall, DE presented the highest values of bioavailability parameters (>80%). The undigested samples were non-cytotoxic to Caco-2 cells, with cell viability above 93%. After IVD, SE showed cytotoxicity at all concentrations studied, and DE was only cytotoxic at the highest concentration. PLE was non-toxic at all concentrations. These results suggest that the DE presented high digestibility and improved the stability of PLE after IVD, showing cytotoxicity only at the highest concentration studied.