1. Academic Validation
  2. 4,5-di-O-caffeoylquinic acid methyl ester isolated from Lonicera japonica Thunb. targets the Keap1/Nrf2 pathway to attenuate H2O2-induced liver oxidative damage in HepG2 cells

4,5-di-O-caffeoylquinic acid methyl ester isolated from Lonicera japonica Thunb. targets the Keap1/Nrf2 pathway to attenuate H2O2-induced liver oxidative damage in HepG2 cells

  • Phytomedicine. 2020 Apr 23;70:153219. doi: 10.1016/j.phymed.2020.153219.
Lingyun Xiao 1 Shu Liang 2 Lanlan Ge 1 Haoqiang Wan 3 Weigang Wu 2 Jia Fei 4 Shipin Wu 2 Boping Zhou 5 Xiaobin Zeng 6
Affiliations

Affiliations

  • 1 Centre Lab of Longhua Branch and Department of Infectious Disease, 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China; Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou 510632, Guangdong Province, China.
  • 2 Centre Lab of Longhua Branch and Department of Infectious Disease, 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China.
  • 3 Centre Lab of Longhua Branch and Department of Infectious Disease, 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China; Department of Pathology (Longhua Branch), 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China.
  • 4 Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou 510632, Guangdong Province, China.
  • 5 Centre Lab of Longhua Branch and Department of Infectious Disease, 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China. Electronic address: zhou.boping@szhospital.com.
  • 6 Centre Lab of Longhua Branch and Department of Infectious Disease, 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China; Department of Pathology (Longhua Branch), 2nd Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen 518020, Guangdong Province, China; Guangdong Provincial Key Laboratory of Regional Immunity and Diseases, Medicine School of Shenzhen University, Shenzhen 518037, Guangdong Province, China. Electronic address: zeng.xiaobin@szhospital.com.
Abstract

Background: 4,5-di-O-caffeoylquinic acid methyl ester (4,5-CQME) is a caffeoylquinic acid (CQA) isolated from Lonicera japonica Thunb., a traditional Chinese medicine. To date, the biological activity of 4,5-CQME has not been fully investigated.

Purpose: The aim of the current study was to explore the anti-oxidative activity and the underlying mechanism of 4,5-CQME.

Methods: MTT assay was used to evaluate the cytoprotective effect of 4,5-CQME. DCFH-DA was used as a fluorescence probe to detect intracellular ROS. The mitochondrial membrane potential was detected using the fluorescent probe JC-1. MDA and GSH levels were measured using MDA and GSH commercial kits, respectively. Apoptosis assay was performed using the Annexin V-FITC/PI method. The functional mechanism of 4,5-CQME was investigated by analyzing relative signaling pathways through immunofluorescent staining, quantitative PCR and western blot analysis.

Results: HepG2 cells were incubated with different concentrations of 4,5-CQME for 12 h before exposure to 500 μM H2O2 for 3 h. 4,5-CQME attenuated H2O2-induced oxidative damage and had a higher cytoprotective effect than 3-caffeoylquinic acid, 3-caffeoylquinic acid methyl ester, or 4,5-di-O-caffeoylquinic acid. 4,5-CQME also reduced ROS and MDA levels and rescued GSH depletion. Western blots demonstrated that 4,5-CQME decreased Bax/Bcl-2 and Bak levels. A mechanistic study confirmed that 4,5-CQME significantly suppressed H2O2-induced MAPKs phosphorylation but had little effect on MAPKs phosphorylation under normal conditions. By contrast, 4,5-CQME induced Akt phosphorylation in the presence or absence of H2O2. 4,5-CQME also regulated the Keap1/Nrf2 signaling pathway and enhanced both the mRNA and protein expressions of HO-1 and NQO1. The anti-oxidative effect of 4,5-CQME was greatly abolished by co-incubation with the Nrf2 inhibitor ML385 or PI3K Inhibitor wortmannin.

Conclusions: Taken together, these results showed that 4,5-CQME offered significant protection against H2O2-induced oxidative stress, and its effect was in part due to the modulation of the Keap1/Nrf2 pathway.

Keywords

4,5-di-O-caffeoylquinic acid methyl ester; Keap1/Nrf2; Liver disease; Oxidative stress.

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