Phytochemical Characterization and Antioxidant Mechanisms of Amazonian Tucumã (Astrocaryum vulgare) and Uxi (Endopleura uchi) Pulps Support Their Potential as Natural Food Preservatives.

The growing demand for clean-label foods has intensified the search for natural alternatives to synthetic preservatives. Amazonian fruits are promising sources of bioactive compounds with antioxidant properties that may improve food preservation. This study evaluated the phytochemical composition, fatty acid profile, and antioxidant potential of pulps from tucumã (Astrocaryum vulgare) and uxi (Endopleura uchi) to assess their suitability as natural food preservatives. Pulp extracts were characterized by total phenolic and flavonoid contents, fatty acid composition, and high-performance liquid chromatography coupled with diode-array detection (HPLC-DAD). Antioxidant activity was evaluated using ferric reducing antioxidant power (FRAP), total antioxidant capacity (TAC), DPPH radical scavenging, and thiobarbituric acid reactive substances (TBARS) assays. Tucumã contained significantly higher levels of total phenolics (36.21 ± 1.99 mg GAE/g extract) and flavonoids (16.16 ± 0.21 mg QE/g extract) than uxi (31.56 ± 0.85 mg GAE/g extract and 5.68 ± 0.45 mg QE/g extract, respectively). Fatty acid analysis revealed distinct lipid profiles, with tucumã predominated by linoleic acid and uxi by oleic acid. HPLC-DAD identified gallic acid as the major phenolic compound in uxi, whereas tucumã exhibited a more diverse phytochemical profile, including citric acid and quercetin derivatives. Despite its lower phenolic content, uxi showed significantly higher FRAP values and greater DPPH radical scavenging activity at concentrations ≥ 100 mg/L, whereas TAC and EC50 values did not differ significantly between the extracts. Both fruits effectively inhibited lipid peroxidation. These findings demonstrate that antioxidant performance depends on phytochemical composition rather than solely on total phenolic content, highlighting tucumã and uxi as promising natural antioxidants for food preservation and functional food applications.