Hepatoprotective effects of Artemisia princeps and its active compound eupatilin against oxidative stress

Artemisia princeps is widely used in Korean traditional medicine, especially in moxibustion. Eupatilin (5,7-dihydroxy-3,4,6-trimethoxyflavone) is a major active compound found in A. princeps and known to have many biological activities. However, pharmacological effects of A. princeps and eupatilin against oxidative stress in liver have not been fully understood. In this study, we examined whether A. princeps water extracts (APE) protects hepatocytes against oxidative stress, tried to elucidate active compound in APE, and investigated responsible molecular mechanisms involved. First, co-treatment of arachidonic acid (AA)(10µM) and iron (5µM) decreased cell viability about 25% of control and increased reactive oxygen species (ROS) about 3 fold and mitochondrial dysfunction (about 80% of total cell population) in HepG2 cells. However, APE (10 – 100 µg/ml) and eupatilin (30 – 300µM) significantly protected cells against AA + iron-induced oxidative stress in a concentration-dependent manner, evidenced by increase in cell viability, restoration of mitochondrial membrane permeability and attenuation of ROS and apoptosis. Realtime RT-PCR analysis showed that eupatilin significantly induced the expression of sestrin2 (11.02 fold at 100µM), known as one of antioxidant genes [1]. Eupatilin-mediated sestrin2 induction was also verified by reporter gene and immunoblot assays. In addition, eupatilin increased the numbers of autophagic vacuoles and expression of light chain3-II. Moreover, results from using autophagy inhibitors (3-methyladenine or bafilomycin A1), and transfection of sestrin2 siRNA or adenoviral sestrin2 indicated that sestrin2 was involved in eupatilin-mediated autophagy induction and thereby contributing to cell protection from oxidative stress. Therefore, present results suggest that A. princeps and its active compound eupatilin would be therapeutic candidates for the treatment of oxidative stress-mediated liver injuries.

Acknowledgements: This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (No. 2012 R1A5A2A42671316).

Keywords: Artemisia princeps, eupatilin, sestrin2, autophagy, oxidative stress, liver.

References:

[1] Shin BY, Jin SH, Cho IJ, Ki SH. Nrf2-ARE pathway regulates induction of Sestrin-2 expression. Free Radic Biol Med 2012; 53: 834 – 841