Low-Dose, Long-Term Callistemon citrinus and Its Main Compounds Alter Hepatic Fatty Acid Profiles and Protect Liver Histology in Rats Fed a High-Fat–Sucrose Diet

Diets high in fat and refined carbohydrates reliably mimic key features of metabolic dysfunction-associated fatty liver disease (MAFLD), including hepatic lipid accumulation, oxidative stress, and ongoing liver injury. This study evaluated the long-term, low-dose administration of Callistemon citrinus ethanolic leaf extract and its primary bioactive compounds: d-limonene, ellagic acid, gallic acid, and p-coumaric acid to prevent lipotoxicity in rats fed a high-fat–sucrose diet (HFSD). Sixty male Wistar rats were randomly divided into 10 groups: normal control group, an untreated HFSD group, and eight HFSD groups treated for 23 weeks with metformin, C. citrinus extract, the individual bioactive compounds, or a mixture of these compounds. We assessed body and organ weights, liver macroscopic features, serum markers of liver injury, oxidative stress biomarkers, histopathological changes, and hepatic fatty acid profiles. HFSD feeding induced significant body weight gain, hepatomegaly, severe tissue damage, elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), glucose and triglycerides, alongside heightened hepatic oxidative stress, and altered saturated fatty acid profiles. Conversely, treatment with metformin and the natural compounds attenuated HFSD-induced liver injury to varying degrees. Improvements in histopathological severity and serum liver enzymes correlated with decreased oxidative stress biomarkers. Notably, ellagic acid, gallic acid, d-limonene, and the bioactive mixture, significantly improved hepatic fatty acid profiles, whereas p-coumaric acid exhibited more modest effects. These results demonstrate that long-term administration of low-dose treatment can successfully improve all evaluated metabolic, biochemical, and histological parameter, suggesting that modulating oxidative stress and liver lipid composition is strongly linked to the mitigation of liver injury in this experimental MAFLD model.