Ling Liu

China Pharmaceutical University, Nan-ching-hsü, Jiangxi Sheng, China

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Publications (8)27.31 Total impact

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    ABSTRACT: NG, O(2)-(2,4-dinitro-5-{[2-(12-en-28-β-D-galactopyranosyl-oleanolate-3-yl)-oxy-2-oxoethyl] amino} phenyl) 1-(N-hydroxyethylmethylamino) diazen-1-ium-1,2-diolate, was identified in our laboratory as a novel nitric oxide-releasing prodrug with antitumor effects. A previous study showed that NG inhibited cell growth, and induced apoptosis in HepG2 cells. In this study, the inhibitory effects of NG on the viability of MGC803 cells were examined using methylthiazolyl tetrazolium biomide (MTT) assay, neutral red assay and trypan blue exclusion test. The results showed that NG had strong cytotoxicity to induce apoptosis, which was characterized by a significant externalization of phosphatidylserine, nuclear morphological changes and enhanced Bax-to-Bcl-2 ratio. Moreover, the release of cytochrome c (Cyt c) from mitochondria and the activation of caspase-9/3 were also detected, indicating that NG may induce apoptosis through a mitochondrial-mediated pathway. NG induced mitochondrial dysfunction in MGC803 cells by altering membrane potential (△Ψm), the inhibition of complexes I, II and IV consequently decreasing ATP level. Furthermore, the treatment of MGC803 cells with NG caused a marked rise in oxidative stress as characterized by accumulation of reactive oxygen species (ROS), excessive malondialdehyde (MDA) production and a reduction in glutathione hormone (GSH) level and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity. In addition, pretreatment with N-acetylcysteine (NAC), a GSH synthesis precursor, was partially protective against the NG-induced ROS generation and cell apoptosis. In contrast, pretreatment of MGC803 cells with L-buthionine-S, R-sulfoximine (BSO), a GSH synthesis inhibitor, increased the ROS levels, and aggravated cell apoptosis by NG. These results suggest that NG-induced apoptosis in MGC803 cells is mediated, at least in part, by the increase in ROS production, oxidative stress and mitochondrial dysfunction.
    International Immunopharmacology 08/2014; · 2.71 Impact Factor
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    ABSTRACT: A simple, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method was developed for the estimation of 3-pentylbenzo[c]thiophen-1(3H)-one (S5), a potential anti-ischemic stroke agent, in dog plasma. The analytical procedure involves protein precipitation of S5 and nobiletin (internal standard) from dog plasma with acetonitrile. Chromatographic separation was achieved on Sapphire C18 analytical column with methanol–water (80:20, v/v) as mobile phase. The eluate was monitored using a UV detector set at 260 nm. The calibration curves were linear over the range of 0.2–20 µg/mL. Absolute recoveries of S5 were 79.2–86.1% from dog plasma. The intra- and inter-day relative standard deviation precisions were <7 and 5%, respectively. The method was successfully applied to the pharmacokinetic study of S5 in beagle dogs. Copyright © 2014 John Wiley & Sons, Ltd.
    Biomedical Chromatography 04/2014; · 1.95 Impact Factor
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    ABSTRACT: In this study, we describe that a novel synthesized compound, olean-28,13β-olide 2 (OLO-2), exhibits selective cytotoxic activity via inducing apoptosis in human hepatocellular carcinoma (HCC) cell lines but not normal human hepatic cells in vitro. Exposure of human HCC HepG2 cells to OLO-2 results in significant loss of mitochondrial transmembrane potential (ΔΨm), the release of cytochrome c, the recruitment of B-cell lymphoma 2 (Bcl-2) assaciated X protein (Bax) and the downregulation of Bcl-2. The apoptosis induced by OLO-2 is associated with the activation of caspase-3/9 and the nuclear translocation of apoptosis inducing factor (AIF). Moreover, the increase of phosphorylated p38 and c-Jun N-terminal kinase (JNK) is observed. OLO-2-induced the externalization of phosphatidyl-serine (PS) and the loss of ΔΨm are blocked by p38 inhibitor SB203580 or JNK inhibitor SP600125. In addition, OLO-2 provokes the generation of reactive oxygen species (ROS) in HepG2 cells, while the antioxidant N-acetyl cysteine (NAC) almost completely blocks OLO-2-induced apoptosis and the activation of p38 and JNK. Taken together, the present study demonstrates that OLO-2 exhibits its cytotoxic activity through intrinsic apoptosis via ROS generation and the activation of p38 and JNK. Its potential to be a candidate of anti-cancer agent is worth being further investigated.
    Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 11/2013; · 2.99 Impact Factor
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    ABSTRACT: 3-Oxo-29-noroleana-1,9(11),12-trien-2,20-dicarbonitrile (ONTD) is a novel synthetic derivative of glycyrrhetinic acid (GA), which has the ability to inhibit the proliferation of human hepatocellular carcinoma (HCC) cells. However, the mechanisms by which ONTD exerts its inhibitory effects remain elusive. The present study was conducted to investigate the cytotoxicity of ONTD in Bel-7402 cells and its molecular mechanisms. We found that ONTD depleted intracellular GSH, increased the level of ROS, and consequently induced mitochondrial permeability transition (MPT) leading to the release of apoptosis-inducing factor (AIF) and cytochrome c (Cyt c) to the cytosol. Mitochondrial alteration and subsequent apoptotic cell death in ONTD-treated Bel-7402 cells could be blocked by addition of exogenous antioxidants N-acetylcystein (NAC), GSH and the MTP inhibitor cyclosporin A (CsA). In addition, ONTD activated the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPK) but not extracellular signal-regulated protein kinases (ERK 1/2). When the cells were exposed to SP600125 (a JNK inhibitor) and SB203580 (a p38 inhibitor), the deregulation of the expression of apoptotic proteins was attenuated. Furthermore, 40mg/kg ONTD significantly reduced tumor weight (-70.62%, p<0.01) in the H22 tumor-bearing mouse model in vivo. Taken together, these findings provide the first experimental evidence supporting that ONTD could induce apoptosis of Bel-7402 cells via MAPK-mediated mitochondrial pathway and ONTD has the potential to be developed as a therapeutic agent for the treatment of HCC.
    The international journal of biochemistry & cell biology 09/2013; · 4.89 Impact Factor
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    ABSTRACT: A series of hybrids from O(2)-(2,4-dinitrophenyl)diazeniumdiolate and oleanolic acid (OA) were designed, synthesized, and biologically evaluated as novel nitric oxide (NO) releasing prodrugs which could be activated by glutathione S-transferase π (GSTπ) overexpressed in a number of cancer cells. It was discovered that the most active compound 21 released high levels of NO selectively in HCC cells but not in the normal cells, and exhibited potent antiproliferative activity in vitro as well as remarkable tumor-retarding effects in vivo. Compared with the reported GSTπ-activated prodrugs JS-K and PABA/NO, 21 exhibited remarkably improved stability in the absence of GSTπ. Importantly, the decomposition of 21 occurred in the presence of GSTπ, and was much more effective than in GSTα. Additionally, 21 induced HepG2 cells apoptosis by arresting cell cycle at G2/M phase, activating both the mitochondria-mediated pathway and the MAPKs pathway, as well as enhancing the intracellular production of ROS.
    Journal of Medicinal Chemistry 04/2013; · 5.48 Impact Factor
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    ABSTRACT: Neuroinflammatory responses caused by amyloid β(Aβ) play an important role in the pathogenesis of Alzheimer's disease (AD). Aβ is known to be directly responsible for the activation of glial cells and induction of apoptosis. Akebia Saponin D (ASD) is extracted from a traditional herbal medicine Dipsacus asper Wall, which has been shown to protect against ibotenic acid-induced cognitive deficits and cell death in rats. In this study, we investigated the in vivo protective effect of ASD on learning and memory impairment induced by bilateral intracerebroventricular injections of Aβ1-42 using Morris water and Y-maze task. Furthermore, the anti-inflammatory activity and neuroprotective effect of ASD was examined with methods of histochemistry and biochemistry. These data showed that oral gavage with ASD at doses of 30, 90 and 270mg/kg for 4 weeks exerted an improved effect on cognitive impairment. Subsequently, the ASD inhibited the activation of glial cells and the expression of tumor necrosis factor (TNF)-α, interleukin-1 beta (IL-1β) and cyclooxygenase-2 (COX-2) in rat brain. Moreover, ASD afforded beneficial actions on inhibitions of Akt and IκB kinase (IKK) phosphorylations, as well as nuclear factor κB (NF-κB) activation induced by Aβ1-42. These results suggest that ASD may be a potential agent for suppressing both Alzheimer's disease-related neuroinflammation and memory system dysfunction.
    Behavioural brain research 08/2012; 235(2):200-9. · 3.22 Impact Factor
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    ABSTRACT: O(2)-(2,4-dinitro-5-{[2-(12-en-28-β-D- galactopyranosyl-oleanolate-3-yl) -oxy-2-oxoethyl]amino}phenyl)1-(N-hydroxyethylmethylamino)diazen-1-ium-1,2- diolate (NG), a novel PABA/NO-based derivative of oleanolic acid (OA), has been found to show potent antitumor activity both in vivo and in vitro. In the present study, NG could significantly reduce tumor volume and weight in the H22 solid tumor mouse model. Meanwhile, NG showed selective effects on the HepG2 cells including NO generation, cytotoxic effect and apoptosis, which were prevented by hemoglobin (NO scavenger). Moreover, NG-induced apoptosis of HepG2 cells was characteristic of intracellular reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential (Δψm) and enhanced Bax-to-Bcl-2 ratio. The release of apoptotic inducing factor (AIF) and cytochrome c (Cyt c) from mitochondria and the activation of caspase-3, 9 were also detected, indicating that NG may induce apoptosis through a mitochondrial-mediated pathway. Simultaneously, NG treatment could lead to the activation of the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK but not ERK1/2. Treatment with SP600125 (an inhibitor of JNK) and SB203580 (an inhibitor of p38) prior to NG was found to reverse NG-induced apoptosis. Moreover, it was found that antioxidant N-acetylcysteine (NAC) blocked the induction of apoptosis and partly reversed the activation of JNK and p38, up-regulation of Bax, down-regulation of Bcl-2 and the activation of caspase-3 in NG-treated cells. Taking together, these findings suggest that NO can be released from NG, which induces apoptosis through a ROS/MAPK-mediated mitochondrial pathway.
    European journal of pharmacology 07/2012; 691(1-3):61-8. · 2.59 Impact Factor
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    ABSTRACT: A series of O(2)-glycosylated diazeniumdiolate-based derivatives of oleanolic acid (4-19) were synthesized and their anti-human hepatocellular carcinoma (HCC) activities were evaluated. Compound 6 selectively inhibited HCC, but not non-tumor liver cell proliferation. This inhibition was attributed to high levels of nitric oxide (NO) released in HCC cells. Importantly, 6 exhibited low acute toxicity (LD(50) = 173.3 mg kg(-1)) and potent inhibition of HCC tumor growth in mice (3 mg kg(-1) iv). Furthermore, 6 induced HCC cell apoptosis, which was accompanied by lower mitochondrial membrane potentials and Bcl2 expression, but with higher cytochrome C release, Bax, caspase 3 and 9 expression activities in HCC cells. Collectively, 6 may be a promising candidate drug for the intervention of HCC.
    Organic & Biomolecular Chemistry 04/2012; 10(19):3882-91. · 3.49 Impact Factor