Green extraction of Kamut® wheat bran polyphenols: Chemical characterization, plasma and cellular antioxidant activity, antimalarial activity, encapsulation, and in vitro digestion

Kamut® wheat bran (KWB) is a valuable source of polyphenols, yet its potential as a natural antioxidant remains underexplored. This study investigated the environmentally sustainable extraction of antioxidants from KWB using ultrasound-assisted extraction (UAE) and evaluated the extracts' chemical composition, antioxidant activity, and bioaccessibility after in vitro digestion. Using response surface methodology, a statistical approach for optimizing experimental conditions, the optimal extract obtained at 500 W ultrasonic power with 100 % ethanol, contained 103 mg GAE/100 g DW total phenols and 117 mg QE/100 g DW total flavonoids. Higher ethanol concentrations improved the recovery of lipophilic polyphenols, enhancing their antioxidant activities as measured by CUPRAC and DPPH assays, and also protected against lipid peroxidation in human plasma. HPLC-HRMS identified tocopherols such as α-, β-, and σ-tocopherol, and flavonoids, like kaempferol and luteolin, and phenolic acids, including ferulic, vanillic, and 4-hydroxybenzoic acid. In cellular assays, KWB extracts demonstrated the ability to reduce hemolysis in red blood cells to 5-17 % and lowered reactive oxygen species (ROS) generation in human cells to 26-37 %. Furthermore, the optimal Kamut® wheat bran extract (KWBE) exhibited antimalarial activity against Plasmodium falciparum strains, showing greater potency against the chloroquine-resistant W2 strain (IC₅₀ = 21.57 μg/mL), compared to the chloroquine-sensitive 3D7 strain (IC₅₀ = 47.24 μg/mL). During simulated in vitro digestion, KWBE's polyphenols exhibited high bioaccessibility, characterized by increased total phenolic content and antioxidant activity, confirming its stability and enhanced antioxidant potential. Microencapsulation of polyphenols using vibrating nozzle technology exhibited encapsulation efficiencies ranging from 51 % to 57 %. Overall, KWB polyphenols demonstrated strong antioxidant activity, enhanced bioaccessibility after in vitro digestion, and bioactivity against malaria parasites, supporting their potential in food and health applications. However, safety optimization remains necessary.