14-Deoxyandrographolide alleviates ethanol-induced hepatosteatosis through stimulation of AMP-activated protein kinase activity in rats

Abstract

Andrographis paniculata (AP) is a traditional medicinal plant of Ayurveda. It grows widely in Asia and is prescribed in the treatment of liver diseases. Here we have investigated the beneficial role of 14-deoxyandrographolide (14-DAG), a bioactive diterpenoid from AP, against alcoholic steatosis in rats. 14-DAG was extracted from aerial parts (leaves and stems) of AP. Rats were fed with ethanol for 8 weeks. Animals were treated with 14-DAG during the last 4 weeks of ethanol treatment. In vitro studies were undertaken in a human hepatocellular liver carcinoma cell line culture. Hepatosteatosis was assessed from histopathological studies of liver sections. Acetyl-CoA, malonyl-CoA, and triglyceride contents were determined using commercially available kits. Fatty acid synthesis was evaluated from incorporation of 1-(14)C acetate. Regulation of fatty acid oxidation and lipogenesis were monitored with immunoblotting and immunoprecipitation studies. Ethanol exposure led to hepatotoxicity, as evident from the marked enhancement in the levels of AST and ALT. The values decreased almost to control levels in response to 14-DAG treatment. Results showed that ethanol feeding induced deactivation of AMP-activated protein kinase (AMPK) that led to enhanced lipid synthesis and decreased fatty acid oxidation, culminating in hepatic fat accumulation. Treatment with 14-DAG activated AMPK through induction of cyclic AMP-protein kinase A pathway. Activation of AMPK was followed by down-regulation of sterol regulatory element binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase, leading to suppression of lipogenesis. This was associated with up-regulation of sirtuin 1 and depletion of malonyl-CoA, in favor of increased fatty acid oxidation. 14-DAG controlled ethanol-induced hepatosteatosis by interfering with dysregulation of lipid metabolism. In conclusion, our results indicated that 14-DAG was capable of preventing the development of fatty liver through AMPK-mediated regulation of lipid metabolism. This finding supported the hepatoprotective role of 14-DAG, which might serve as a therapeutic option to alleviate hepatosteatosis in chronic alcoholism.

Keywords: 14-Deoxyandrographolide; AMP-activated protein kinase; Ethanol; Hepatosteatosis; Lipid metabolism.