5-Fluorouracil (5-FU) is a widely used chemotherapeutic agent, but its hepatotoxic potential poses clinical challenges, as it induces oxidative stress, inflammation, and apoptosis in liver tissue. Butein, a natural chalcone flavonoid that possesses varied biological activity, such as anticancer, anti-inflammatory, and antiplatelet effects. This study aimed to evaluate the possible protective effects of Butein against 5-FU-induced hepatotoxicity in rats. Male albino rats were divided into 4 Groups (of 7 animals each): control, 5-FU, and two Butein-pretreated Groups (50 and 100 mg/kg/day, orally for 14 days) each before a single intraperitoneal dose of 150 mg/kg 5-FU, which was injected on day 14. Serum liver enzymes (ALT and AST), cytokines (IL-6, IL-10, and NF-κB), oxidative stress markers (MDA and GSH), TNF-α gene expression, and protein levels of caspase-3 and NRF2 were evaluated. Histological assessments were also conducted. 5-FU significantly elevated serum ALT and AST levels, increased NF-κB, IL-6, MDA, and TNF-α expression, and decreased IL-10, GSH, and NRF2 levels (p < 0.05). Histological changes included sinusoidal dilation, congestion, and hepatocyte degeneration. Pre-treatment with Butein markedly attenuated these alterations, where both doses of Butein significantly reduced transaminases, pro-inflammatory cytokines, and oxidative stress markers while enhancing antioxidant defenses and anti-inflammatory IL-10 levels. Notably, the high dose of Butein restored NRF2 expression and reduced caspase-3 protein levels more effectively than the lower dose. Histologically, the high dose of Butein preserved normal hepatic architecture with minimal pathological changes. In conclusoin, Butein offers dose-dependent hepatoprotection against 5-FU-induced liver injury through the attenuation of oxidative stress, suppression of pro-inflammatory and apoptotic markers, and upregulation of antioxidant defenses; moreover, the histopathological evaluation further supported the biochemical and molecular findings, particularly at the 100 mg/kg/day, which preserved normal hepatic architecture and minimized cellular damage; and, thus support the prophylactic potentialof Butein in managing chemotherapeutic liver toxicity.
