Publications (66) View all
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Article: One-Step Chromatographic Purification of Helicobacter pylori Neutrophil-Activating Protein Expressed in Bacillus subtilis.
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ABSTRACT: Helicobacter pylori neutrophil-activating protein (HP-NAP), a major virulence factor of Helicobacter pylori (H. pylori), is capable of activating human neutrophils to produce reactive oxygen species (ROS) and secrete inammatory mediators. HP-NAP is a vaccine candidate, a possible drug target, and a potential in vitro diagnostic marker for H. pylori infection. HP-NAP has also been shown to be a novel therapeutic agent for the treatment of allergic asthma and bladder cancer. Hence, an efficient way to obtain pure HP-NAP needs to be developed. In this study, one-step anion-exchange chromatography in negative mode was applied to purify the recombinant HP-NAP expressed in Bacillus subtilis (B. subtilis). This purification technique was based on the binding of host cell proteins and/or impurities other than HP-NAP to DEAE Sephadex resins. At pH 8.0, almost no other proteins except HP-NAP passed through the DEAE Sephadex column. More than 60% of the total HP-NAP with purity higher than 91% was recovered in the flow-through fraction from this single-step DEAE Sephadex chromatography. The purified recombinant HP-NAP was further demonstrated to be a multimeric protein with a secondary structure of α-helix and capable of activating human neutrophils to stimulate ROS production. Thus, this one-step negative chromatography using DEAE Sephadex resin can efficiently yield functional HP-NAP from B. subtilis in its native form with high purity. HP-NAP purified by this method could be further utilized for the development of new drugs, vaccines, and diagnostics for H. pylori infection.PLoS ONE 01/2013; 8(4):e60786. · 4.09 Impact Factor -
Article: Neuroprotective effects of carnosic acid on neuronal cells under ischemic and hypoxic stress.
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ABSTRACT: Ischemia/hypoxia induces oxidative stress which is associated with neurodegenerative diseases. The present study investigated protective mechanism of carnosic acid (CA) on ischemia/reperfusion and hypoxia-induced neuronal cell injury. The results showed that CA reduced 52% of the infarct volume from brains under ischemia/reperfusion in vivo and protected the PC12 cells from hypoxic injury in vitro. CA (1.0 µM) enhanced cell viability, prevented lactic dehydrogenase (LDH) release, scavenged reactive oxygen species (ROS), increased superoxide dismutase activity, and attenuated Ca(2+) release, lipid peroxidation, and prostaglandin E(2) production in hypoxic PC12 cells. In addition, CA also reduced nitric oxide (NO) and interleukine (IL)-1 and IL-6 production from activated BV-2 microglia. Furthermore, its effect on hypoxia-induced mitogen-activated protein kinases (MAPKs) signaling pathway and caspase-3 was examined. Extracellular signal-regulated protein kinases, c-jun NH(2)-terminal kinase, and p38 MAPK were activated during hypoxia. CA inhibited MAPKs, caspase-3, and COX-2 activation and correlated well with the diminished LDH release and apoptosis (TUNEL) in PC12 cells under hypoxia. Taken together, CA protected neuronal cells under ischemia/hypoxia through scavenging or reducing of ROS and NO, inhibiting COX-2 and MAPK pathways by anti-inflammatory and anti-oxidative properties.Nutritional Neuroscience 06/2012; · 1.56 Impact Factor -
Article: Synthesis and evaluation of [18F]Fluorobutyl ethacrynic amide: a potential PET tracer for studying glutathione transferase.
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ABSTRACT: [(18)F]Flurobutyl ethacrynic amide ([(18)F]FBuEA) was prepared from the precursor tosylate N-Boc-N-[4-(toluenesulfonyloxy)butyl]ethacrynic amide with a radiochemical yield of 3%, a specific activity of 48 GBq/μmol and radiochemical purity of 98%. Chemical conjugation of [(18)F]FBuEA with glutathione (GSH) via a self-coupling reaction and enzymatic conjugation under catalysis of glutathiontransferase alpha (GST-α) and π provided about 41% yields of radiochemical conjugated product [(18)F]FBuEA-GSH, 85% and 5-16%, respectively. The catalytic selectivity of this tracer toward GST-alpha was addressed. Positron emission tomography (PET) imaging of [(18)F]FBuEA in normal rats showed that a homogeneous pattern of radioactivity was distributed in the liver, suggesting a catalytic role of GST. By contrast, PET images of [(18)F]FBuEA in rats with thioacetamide-induced cholangiocarcinoma displayed a heterogeneous pattern of radioactive accumulation with cold spots in tumor lesions. PET imaging with [(18)F]FBuEA could be used for early diagnosis of hepatic tumor with a low GST activity as well as liver function.Bioorganic & medicinal chemistry letters 04/2012; 22(12):3998-4003. · 2.65 Impact Factor -
Article: Synthesis of amino core compounds of galactosyl phytosyl ceramide analogs for developing iNKT-cell inducers.
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ABSTRACT: 1-Aminophytosphingosine and 6-aminogalactosyl phytosphingosine were prepared in 61% and 40% yield libraries with 44 carboxylic acids showed that a 4-butylbenzoic acid-derived product exe, respectively. Glycosylation using benzoyl-protected lipid resulted in better a-selectivity for ceramide analogs, but the yield was less than that obtained with benzyl moieties. Screening the amide rted less cytotoxicity. These analogs were purified for validation of immunological potencies and the a-GalCer analog but not the sphingosine analog stimulated human iNKT cell population.Molecules 01/2012; 17(3):3058-81. · 2.39 Impact Factor -
Article: Longan seed extract reduces hyperuricemia via modulating urate transporters and suppressing xanthine oxidase activity.
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ABSTRACT: Hyperuricemia causes gouty arthritis, kidney disease, heart disease, and other diseases. Xanthine oxidase (XOD) and urate transporters play important roles in urate homeostasis. Numerous plants have been identified as XOD inhibitors. Longan seeds are known to contain high levels of polyphenols such as corilagin, gallic acid and ellagic acid. We examined the effect of longan seed extract on XOD inhibition and urate transporters GLUT1 and GLUT9 using both in vitro and in vivo assays. The results showed that dried longan seed extract (LSE) and its active components inhibited XOD dose-dependently in vitro. LSE inhibited uric acid production and XOD activity in normal liver cells (clone-9 cells) and was not cytotoxic under the concentration of 200 μg/ml. For the in vivo study, Sprague-Dawley (SD) rats were given intraperitoneally for thirty minutes with or without allopurinol (a XOD inhibitor, 3.5 mg/kg) or LSE (80 mg/kg) and then injected intraperitioneally with 250 mg/kg of oxonic acid and 300 mg/kg of hypoxanthine intragastrically. LSE was able to reduce serum uric acid level and XOD activity in hyperuricemic rats. However, LSE or allopurinol did not inhibit the liver XOD activities. On the other hand, GLUT1 protein was suppressed in kidney and GLUT9 was induced in liver from experimental rats and LSE or allopurinol decreased GLUT9 but increased GLUT1 protein level in the liver and kidney, respectively. These results confirmed the claimed effect of longan seeds on gout and other complications and suggested that its urate reducing effect might be due to modulation of urate transporters and inhibition of circulating xanthine oxidase.The American Journal of Chinese Medicine 01/2012; 40(5):979-91. · 1.98 Impact Factor
