Application of the INFOGEST Protocol to Evaluate the Effects of Simulated <i>In Vitro</i> Gastrointestinal Digestion on Polyphenols and Antioxidant Potential of Four Native Amazonian Fruits

Brazil's native fruits, such as buriti, bacaba, guapeva, and taturubá, are rich in bioactive compounds with antioxidant and therapeutic potential. This study assessed their phenolic profile, bioaccessibility, antioxidant potential, and <i>in vitro</i> biological properties before and after simulated <i>in vitro</i> gastrointestinal digestion. The results obtained indicated that the 70% ethanolic extracts before <i>in vitro</i> digestion presented gallic acid as the major compound in the pulps of buriti, bacaba, and guapeva, with concentrations of 3284.04, 421.98, and 425.63 μg g^-1, respectively. In contrast, the taturubá pulp revealed a higher gallic acid content in the aqueous extract (3376.48 μg g^-1). In addition, gallic acid demonstrated high bioaccessibility, especially in the pulps of buriti (87.89%) and bacaba (77.25%). However, all the phenolic compounds tested showed significant reductions between the undigested sample and the intestinal phase (<i>p</i> < 0.05), indicating degradation processes or the creation of new unidentified compounds. Significant decreases in antioxidant potential were observed (<i>p</i> < 0.05), particularly in the oral and gastric phases: bacaba had a 95.85% reduction in DPPH inhibition (from 88.30% to 3.66%), and taturubá had a 79.10% reduction in FRAP (from 1585.51 to 331.35 mg of AAE 100 g^-1). The reduction in antioxidant potential after digestion is relevant for functional foods, as it indicates possible degradation or modification of bioactive compounds, which can compromise their bioavailability and reduce the physiological effectiveness of antioxidant effects in the body. However, guapeva showed an 8.20% increase in antioxidant activity in the intestinal phase (from 359.57 to 389.36 mg of AAE 100 g^-1). The fruit pulps also inhibited α-amylase activity, with the most significant inhibition in the intestinal phase: buriti (72.24%), bacaba (78.23%), guapeva (58.65%), and taturubá (47.53%). These findings suggest the potential of these fruits for the development of functional foods, although the evidence is based on <i>in vitro</i> assays and should be further validated through <i>in vivo</i> studies to confirm their physiological relevance.