Cytochrome P450 2E1 (CYP2E1) is a key target protein in the development of alcoholic and nonalcoholic fatty liver disease (FLD). The pathophysiological correlate is the massive production of reactive oxygen species. The role of CYP2E1 in the development of hepatocellular carcinoma (HCC), the final complication of FLD, remains controversial. Specifically, CYP2E1 has not yet been defined as a molecular target for HCC therapy. In addition, a CYP2E1-specific drug has not been developed. We have already shown that our newly developed CYP2E1 inhibitor 12-imidazolyl-1-dodecanol (I-ol) was therapeutically effective against alcoholic and nonalcoholic steatohepatitis. In this study, we investigated the effect of I-ol on HCC tumorigenesis and whether I-ol could serve as a possible treatment option for terminal-stage FLD. I-ol exerted a very highly significant antitumour effect against hepatocellular HepG2 cells. Cell viability was reduced in a dose-dependent manner, with only the highest doses causing a cytotoxic effect associated with caspase 3/7 activation. Comparable results were obtained for the model colorectal adenocarcinoma cell line, DLD-1, whose tumorigenesis is also associated with CYP2E1. Transcriptome analyses showed a clear effect of I-ol on apoptosis and cell-cycle regulation, with the increased expression of p27Kip1 being particularly noticeable. These observations were confirmed at the protein level for HepG2 and DLD-1 cells grafted on a chorioallantoic membrane. Cell-cycle analysis showed a complete loss of proliferating cells with a simultaneous increase in S-phase arrest beginning at a threshold dose of 30 μM. I-ol also reduced xenograft tumour growth in nude mice. This antitumour effect was not associated with tumour cachexia. I-ol was not toxic to healthy tissues or organs. This study demonstrates for the first time the therapeutic effect of the specific CYP2E1 inhibitor I-ol on the tumorigenesis of HCC. Our findings imply that I-ol can potentially be applied therapeutically on patients at the final stage of FLD.

Cytochrome P450 2E1 (CYP2E1)‐associated reactive oxygen species production plays an important role in the development and progression of inflammatory liver diseases such as alcoholic steatohepatitis. We developed two new inhibitors for this isoenzyme, namely 12‐imidazolyl‐1‐dodecanol (I‐ol) and 1‐imidazolyldodecane (I‐an), and aimed to test their effects on non‐alcoholic steatohepatitis (NASH). The fat‐rich and CYP2E1 inducing Lieber‐DeCarli diet was administered over 16 weeks of the experimental period to induce the disease in a rat model, and the experimental substances were administered simultaneously over the last four weeks. The high‐fat diet (HFD) pathologically altered the balance of reactive oxygen species and raised the activities of the liver enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP) and γ‐glutamyl‐transferase (γ‐GT); lowered the level of adiponectine and raised the one of tumor necrosis factor (TNF)‐α; increased the hepatic triglyceride and phospholipid content and diminished the serum HDL cholesterol concentration. Together with the histological findings, we concluded that the diet led to the development of NASH. I‐ol and, to a lesser extent, I‐an shifted the pathological values toward the normal range, despite the continued administration of the noxious agent (HFD). The hepatoprotective drug ursodeoxycholic acid (UDCA), which is used off‐label in clinical practice, showed a lower effectiveness overall. I‐ol, in particular, showed extremely good tolerability during the acute toxicity study in rats. Therefore, cytochrome P450 2E1 may be considered a suitable drug target, with I‐ol and I‐an being promising drug candidates for the treatment of NASH.

Background and aims Alcoholic steatohepatitis (ASH)—the inflammation of fatty liver—is caused by chronic alcohol consumption and represents one of the leading chronic liver diseases in Western Countries. ASH can lead to organ dysfunction or progress to hepatocellular carcinoma (HCC). Long-term alcohol abstinence reduces this probability and is the prerequisite for liver transplantation—the only effective therapy option at present. Elevated enzymatic activity of cytochrome P450 2E1 (CYP2E1) is known to be critically responsible for the development of ASH due to excessively high levels of reactive oxygen species (ROS) during metabolization of ethanol. Up to now, no rational drug discovery process was successfully initiated to target CYP2E1 for the treatment of ASH. Methods In this study, we applied a rational drug design concept to develop drug candidates (NCE) including preclinical studies. Results A new class of drug candidates was generated successfully. Two of the most promising small compounds named 12-Imidazolyl-1-dodecanol (abbr.: I-ol) and 1-Imidazolyldodecane (abbr.: I-an) were selected at the end of this process of drug discovery and developability. These new ω-imidazolyl-alkyl derivatives act as strong chimeric CYP2E1 inhibitors at a nanomolar range. They restore redox balance, reduce inflammation process as well as the fat content in the liver and rescue the physiological liver architecture of rats consuming continuously a high amount of alcohol. Conclusions Due to its oral application and therapeutic superiority over an off-label use of the hepatoprotector ursodeoxycholic acid (UDCA), this new class of inhibitors marks the first rational, pharmaceutical concept in long-term treatment of ASH.

Cytochrome P450 2E1 (CYP2E1) and its production of ROS play an essential role in the development and progression of inflammatory liver diseases such as alcoholic steatohepatitis. For this isoenzyme we have developed two new inhibitors - 12-imidazolyl-1-dodecanol (I-ol) and 1-imidazolyldodecane (I-an) - and wanted to test their effect on the related disease of non-alcoholic steatohepatitis (NASH). The fat-rich Lieber-DeCarli diet, which was administered over the entire experimental period of 16 weeks, was used for disease induction in the rat model, while the experimental substances were administered in parallel over the last four weeks. This high-calorie diet pathologically altered the ROS balance, the amount of adipocytokines, TNF-α and lipids as well as the activities of liver enzymes. Together with the histological examinations, the conclusion could be drawn that the diet led to the formation of NASH. I-ol and to a lesser extent I-an were able to shift the pathological values towards the normal range - despite continued administration of the noxious agent. I-ol, in particular, showed an extremely good tolerability in the acute toxicity study in rats. Thus, CYP2E1 appears to be a suitable drug target as well as I-ol and I-an promising drug candidates for the treatment of NASH.