EFFECTS OF SIMULATED GASTROINTESTINAL DIGESTION ON POLYPHENOL STABILITY AND ANTIOXIDANT POTENTIAL OF FOUR NATIVE AMAZONIAN FRUITS

Native Brazilian fruits, including buriti, bacaba, guapeva, and taturubá, stand out as important sources of bioactive compounds with recognized antioxidant and therapeutic properties. In this research, the in vitro digestion process was conducted following the INFOGEST protocol, simulating the oral, gastric and intestinal phases to evaluate the bioaccessibility of bioactive compounds. The phenolic profile, bioaccessibility, antioxidant potential, and in vitro biological activities of these fruits were evaluated before and after simulated gastrointestinal digestion. For the 70% ethanolic extracts obtained prior to digestion, gallic acid was the compound the most abundant phenolic in the pulps of buriti, bacaba, and guapeva, with respective concentrations of 3284.04, 421.98, and 425.63 µg g⁻¹. Conversely, in taturubá pulp, the highest gallic acid concentration was detected in the aqueous extract (3376.48 µg g⁻¹). Bioaccessibility analysis revealed that gallic acid was particularly stable and potentially bioavailable, reaching 87.89% in buriti and 77.25% in bacaba. Despite this, all phenolic compounds exhibited significant declines (p < 0.05) from the undigested stage to the intestinal phase, suggesting degradation and/or transformation into other unidentified molecules. Antioxidant capacity also decreased significantly during digestion (p < 0.05), especially in the oral and gastric phases. Bacaba presented a 95.85% drop in DPPH radical inhibition (from 88.30% to 3.66%), while taturubá showed a 79.10% reduction in FRAP values (from 1585.51 to 331.35 mg AAE 100 g⁻¹). Interestingly, guapeva exhibited a positive response, with an 8.20% increase in antioxidant activity during the intestinal phase (from 359.57 to 389.36 mg AAE 100 g⁻¹), possibly due to the generation of neoantioxidant compounds. Regarding enzymatic inhibition, all fruit pulps were able to inhibit α-amylase, with more pronounced effects in the intestinal stage: buriti (72.24%), bacaba (78.23%), guapeva (58.65%), and taturubá (47.53%). Collectively, these results demonstrate that although gastrointestinal digestion can lead to considerable losses of phenolic compounds, some functional properties particularly antioxidant potential and α-amylase inhibitory activity are preserved or even improved in certain fruits. Such findings reinforce the functional relevance of these native species and their potential for incorporation into functional food products and nutraceuticals designed to support human health.