Efficient Extraction of Phenolic Compounds From Cariniana rubra Gardener Ex Miers From the Legal Amazon: Ultrasound-Assisted Optimization, Chemical Characterization, and Antioxidant Potential.

Cariniana rubra, native to the Brazilian Cerrado and the Amazon-Cerrado ecotone, is traditionally used in folk medicine but remains underexplored. This study optimized extraction yield and bioactive compound content using ultrasound-assisted extraction (UAE) and Soxhlet extraction. A central composite rotational design (CCRD) assessed ethanol concentration and extraction time, with response surface modeling (RSM) determining optimal conditions. UAE yielded 49.60% (50% ethanol, 132 min) and Soxhlet 25.25% (78% ethanol, 300 min). Maximum phenolic compound contents were 382.62 mg GAE g-1 (UAE; 48 min) and 385.95 mg GAE g-1 (Soxhlet; 480 min). Flavonoid contents were 137.83 mg QE g-1 (UAE; 90 min) and 73.66 mg QE g-1 (Soxhlet; 120 min). Antioxidant activity was confirmed by DPPH•, with IC50 values of 37.73 µg mL-1 (UAE) and 36.20 µg mL-1 (Soxhlet), surpassing Trolox (23.64 µg mL-1), and equivalent to Trolox in ABTS assays (53.67 and 38.67 µM Trolox g-1) and FRAP (453.44 and 558.44 µM Fe2+ g-1). FT-IR analysis confirmed phenolic compound indicators, while LC-DAD identified epicatechin, rutin, and myricetin. These optimized methods produced extracts with high antioxidant activity, suggesting potential for further applications.