Ahn Chang-Bum, Je Jae-Young, Kim Young-Sang, Park Sun-Joo, Kim Boo Il
Division of Food and Nutrition, Chonnam National University, Gwangju, 61186, Republic of Korea.
Department of Marine-Bio Convergence Science, Pukyong National University, Busan, 48547, Republic of Korea.
Mol Cell Biochem. 2017 Jan;424(1-2):79-86. doi: 10.1007/s11010-016-2845-4. Epub 2016 Oct 15.
Chemical modification of chitosan is a promising method for the improvement of biological activity. In this study, chitosan-caffeic acid (CCA) was prepared and its in vitro hepatoprotective ability against hydrogen peroxide-induced hepatic damage in liver cells was evaluated. Treatment with CCA (50-400 µg/mL) did not show cytotoxicity and also significantly (p < 0.05) recovered cell viability against 650 µM hydrogen peroxide-induced hepatotoxicity. CCA treatment attenuated reactive oxygen species generation and lipid peroxidation in addition to increasing cellular glutathione level in cultured hepatocytes. To validate the underlying mechanism, antioxidant and phase II detoxifying enzyme expressions, which are mediated by NF-E2-related factor 2 (Nrf2) activation, were analyzed and CCA treatment was found to increase the expression of superoxide dismutase-1 (SOD-1), glutathione reductase (GR), heme oxygenase-1 (HO-1), and NAD(P)H:quinine oxidoreductase 1 (NQO1). CCA treatment resulted in increased Nrf2 nuclear translocation. The phosphorylation of extracellular regulated kinase (ERK), c-Jun NH-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) by CCA treatment contributed to Nrf2 activation. Pharmacological blockade of ERK, JNK, and p38 MAPK revealed that SP600125 (JNK inhibitor) and PD98059 (ERK inhibitor) treatment reduced Nrf2 translocation into the nucleus while SB203580 (p38 inhibitor) exhibited weak inhibition. Collectively, CCA protects liver cells against hydrogen peroxide-induced injury and this ability is attributed to the induction of antioxidants and phase II detoxifying enzymes that are mediated by Nrf2 translocation via JNK/ERK signaling.
壳聚糖的化学修饰是一种改善生物活性的有前景的方法。在本研究中，制备了壳聚糖 - 咖啡酸（CCA），并评估了其对过氧化氢诱导的肝细胞肝损伤的体外肝保护能力。用CCA（50 - 400μg/mL）处理未显示出细胞毒性，并且还显著（p < 0.05）恢复了针对650μM过氧化氢诱导的肝毒性的细胞活力。CCA处理除了增加培养的肝细胞中的细胞内谷胱甘肽水平外，还减弱了活性氧的产生和脂质过氧化。为了验证潜在机制，分析了由NF - E2相关因子2（Nrf2）激活介导的抗氧化剂和II期解毒酶的表达，发现CCA处理可增加超氧化物歧化酶 - 1（SOD - 1）、谷胱甘肽还原酶（GR）、血红素加氧酶 - 1（HO - 1）和NAD(P)H：醌氧化还原酶1（NQO1）的表达。CCA处理导致Nrf2核转位增加。CCA处理对细胞外调节激酶（ERK）、c - Jun氨基末端激酶（JNK）和p38丝裂原活化蛋白激酶（MAPK）的磷酸化有助于Nrf2激活。对ERK、JNK和p38 MAPK的药理学阻断表明，SP600125（JNK抑制剂）和PD98059（ERK抑制剂）处理减少了Nrf2向细胞核的转位，而SB203580（p38抑制剂）表现出较弱的抑制作用。总体而言，CCA保护肝细胞免受过氧化氢诱导的损伤，并且这种能力归因于通过JNK/ERK信号传导介导的Nrf2转位诱导的抗氧化剂和II期解毒酶。
