Whole-Grain Oryza sativa L. Flour Extract Exhibits Potent Antioxidant and Anti-Inflammatory Activity in Rats with Experimentally Induced Inflammation.

Whole-grain rice (Oryza sativa L.) is a rich source of polyphenols. The in vivo mechanisms linking its phytochemical profile to antioxidant and anti-inflammatory effects remain incompletely defined. This study investigated the antioxidant and anti-inflammatory activity of a whole-grain rice flour 70% ethanol extract (OSEE) and correlated these effects with its phenolic composition. OSEE showed high total phenolic content 0.121 ± 0.002 mg GAE/g d.w.), a lower total flavonoid content (61.83 ± 4.03 µg QE/g d.w.), and a phenolic profile dominated by phenolic acids (~87%), with ferulic and protocatechuic acids among the most abundant constituents. OSEE displayed significant in vitro antioxidant activity in DPPH, FRAP, hydrogen peroxide, and nitric oxide scavenging assays. In vivo activity was evaluated in male Wistar rats with turpentine oil-induced acute inflammation using both therapeutic (post-induction) and prophylactic (pre-induction) protocols, testing three oral doses of lyophilized extract (1.0, 0.50, and 0.25 g/kg/day). In vivo, OSEE attenuated systemic oxidative stress (TOS, TAC, OSI, AOPP, MDA, NOx, 3-nitrotyrosine, total thiols) and the expression of pro-inflammatory markers (NF-κB p65, IL-1β, IL-18, caspase-1) in a dose-dependent manner with both protocols, with the highest dose producing the most consistent reductions, while the expression level of the anti-inflammatory factor IL-10 remained unchanged. PCA supported a shift in biomarker networks toward a non-inflamed profile. These findings indicate that OSEE exerts coordinated antioxidant and anti-inflammatory effects in vivo that are strongly associated with its phenolic composition.