Nonalcoholic fatty liver disease (NAFLD) is a type of chronic liver disease widely spread around the globe. In fact, it is the most common liver disease nowadays surpassing viral hepatitis [1,2]. The prevalence of NAFLD is estimated in 25 to 30% of the population and is a potential risk of progression to cirrhosis and hepatocellular carcinoma (HCC) becoming a frequent cause of liver transplantation [1]. Associated with obesity and diabetes prevalence, the rapid increase in NAFLD epidemiology is reflected in a growing burden of end-stage liver diseases [3]. NAFLD is a multi-factorial disease linked to a complexity of metabolic changes. Comprising a broad spectrum of alterations, NAFLD ranges from simple steatosis to steatohepatitis (NASH), progressing to liver fibrosis which can reach a cirrhotic state and end in HCC development [4].

The pathogenic mechanisms are still not entirely understood and different hypotheses have been postulated in the literature. Hepatic steatosis is the onset of the pathophysiology and the main hallmark of the disease [5]. The increment of circulating free fatty acid from diet or adipose tissue lipolysis combined with hepatic fatty acid synthesis through de novo lipogenesis promotes lipid accumulation in lipid droplets (i.e. steatosis). Glucose and fructose, dietary sugar, are the substrates for de novo lipogenesis, especially fructose since its uptake by hepatocytes is non-dependent on insulin levels [6,7].

Steatosis creates an environment for the progression to NASH. Lipid-mediated overload can lead to several pathogenic processes, such as insulin resistance, lipotoxicity, apoptosis, ferroptosis, macrophage recruitment, pro-inflammatory cytokine release, reduction of antioxidant defense, and increase in reactive oxygen species (ROS) [5]. These events can activate hepatic stellate cells (HSCs), responsible for fibrinogenesis and liver stiffness. Moreover, the maintenance of hepatic damage is closely linked to oxidative stress induced by mitochondrial production or lipotoxicity [4,8].

Treatment of fibrosis is difficult to achieve [9]. Hereby, the search for effective alternatives to treat or prevent hepatic lipid accumulation is crucial. Treatment and preventive strategies for chronic liver diseases are extensively explored [10]. The current alternative is lifestyle changes improving eating habits and practicing physical activity [11]. Thus, using natural compounds has become an attractive approach to avoid NAFLD and its progression (e.g. liver fibrosis) [11].

Gamma-oryzanol (Orz) is a natural compound structurally composed of multiple molecular species being a mixture of ferulic acid esters and phytosterols [12]. Present in brown rice, Orz is primarily found in rice subproducts such as rice bran and rice bran oil, the richest source of the compound. Interesting Orz protective effects have been reported and investigations in different pathologies were conducted, mainly in metabolic diseases and related disorders [13]. Orz presents activity in lowering plasma triglycerides and cholesterol levels, antioxidant, anti-inflammatory, and induction of transcriptional factors, such as nuclear factor erythroid 2-related factor 2 (NRF2) and peroxisome proliferator-activated receptors (PPARs) [13], [14], [15]. However, the role of Orz preventive effect on the hepatic proteome has not been described. Therefore, this study aimed to investigate the preventive effect of Orz on the hepatic proteome in a diet-induced NAFLD model.