Jingjing Kang

Nanjing Normal University, Nan-ching, Jiangsu Sheng, China

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Publications (3)6.93 Total impact

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    ABSTRACT: l-Theanine is a unique amino acid in green tea. We here evaluated the protective effects of l-theanine on ethanol-induced liver injury in vitro and in vivo. Our results revealed that l-theanine significantly protected hepatocytes against ethanol-induced cell cytotoxicity which displayed by decrease of viability and increase of LDH and AST. Furthermore, the experiments of DAPI staining, pro-caspase3 level and PARP cleavage determination indicated that l-theanine inhibited ethanol-induced L02 cell apoptosis. Mechanically, l-theanine inhibited loss of mitochondrial membrane potential and prevented cytochrome c release from mitochondria in ethanol-treated L02 cells. l-Theanine also prevented ethanol-triggered ROS and MDA generation in L02 cells. l-Theanine restored the antioxidant capability of hepatocytes including GSH content and SOD activity which were reduced by ethanol. In vivo experiments showed that l-theanine significantly inhibited ethanol-stimulated the increase of ALT, AST, TG and MDA in mice. Histopathological examination demonstrated that l-theanine pretreated to mice apparently diminished ethanol-induced fat droplets. In accordance with the in vitro study, l-theanine significantly inhibited ethanol-induced reduction of mouse antioxidant capability which included the activities of SOD, CAT and GR, and level of GSH. These results indicated that l-theanine prevented ethanol-induced liver injury through enhancing hepatocyte antioxidant abilities.
    Full-text · Article · Feb 2012 · Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association
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    ABSTRACT: As a natural alkaloid extracted from Amaryllidaceae, lycorine shows various biological effects on tumor cells. Here we show that lycorine dose-dependently inhibited the LPS-induced up-regulation of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein level in RAW264.7 cells. Besides, it also inhibited NO, PGE(2), TNF-α and IL-6 release from LPS-treated RAW264.7 cells. RT-PCR experiments showed that lycorine suppressed LPS-induced iNOS but not COX-2 gene expression. Moreover, lycorine decreased LPS-induced mortality in mice. Mechanistically, LPS-induced activation of P38 and STATs pathways was suppressed significantly by lycorine. In addition, lycorine did not interfere with the phosphorylation of ERK1/2, JNK1/2 and NF-κB pathways. In conclusion, lycorine inhibits LPS-induced production of pro-inflammatory mediators and increases the survival rate of mice after LPS challenge, suggesting that lycorine could play an anti-inflammatory role in response to LPS.
    No preview · Article · Dec 2011 · International immunopharmacology
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    Guilan Li · Jingjing Kang · Xiangyang Yao · Yinqiang Xin · Qi Wang · Yin Ye · Lan Luo · Zhimin Yin
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    ABSTRACT: L-theanine is a natural amino acid in green tea and it has been well known for its activities of relieving depression and neuroprotection. However, cytoprotective effect and its mechanism of L-theanine on hepatocytes have not been reported. The objective of this work was to investigate the hepatoprotective effect of L-theanine as well as its mechanism by using the human hepatic L02 cells injured by hydrogen peroxide (H2O2). Results showed that L-theanine dose dependently decreased H2O2-induced cell viability loss and lactate dehydrogenase (LDH) release. L-theanine pretreatment improved nuclear morphology of the cells injured by H2O2. By using flow cytometric analysis, we found that L-theanine significantly inhibited H2O2-induced cell apoptosis. Further, L-theanine attenuated H2O2-induced reduction in pro-caspase3 and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP). H2O2-activated p38 mitogen-activated protein kinase (MAPK) was also inhibited by L-theanine. These data suggest that L-theanine could protect L02 cells against H2O2-induced apoptosis via suppression of p38 MAPK. L-theanine might potentially be useful in the prevention and treatment of liver diseases. KeywordsL-theanine–L02 cells–Hydrogen peroxide–Apoptosis
    Full-text · Article · Sep 2011 · European Food Research and Technology