Xiaobin Pang

Protection of salvianolic acid A on rat brain from ischemic damage via soluble epoxide hydrolase inhibition

Epoxyeicosatrienoic acids (EETs) and their regulating enzyme soluble epoxide hydrolase (sEH) have been associated with ischemic stroke. Salvianolic acid A (SAA) is proved to display potent cerebroprotection. However, little information is available about the link between them. This study aimed to investigate whether SAA exhibits its protective effects in rats subjected to middle cerebral artery occlusion (MCAO) through sEH and EETs. The results showed that SAA treatment ameliorated neurological deficits and reduced infarct volume. Notably, the beneficial effects of SAA were attenuated by co-administration of (14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE)), a putative selective EETs antagonist. Furthermore, SAA increased the 14,15-EET levels in the blood and brain of sham and MCAO rats. Assay for hydrolase activity showed that 1 and 3 mg/kg of SAA significantly diminished brain sEH activity of MCAO rats. A fluorescent assay in vitro indicated that SAA could inhibit recombinant human sEH activity in a concentration-dependent manner (IC50 = 1.62 μmol/l). Immunohistochemical analysis showed that SAA at the doses of 1 and 3 mg/kg significantly decreased sEH protein expression in hippocampus CA1 region of MCAO rats. In conclusion, cerebral protection of SAA is mediated, at least in part, via inhibiting sEH to increase EETs levels.

Identification of a Small Molecular Insulin Receptor Agonist With Potent Antidiabetes Activity

Insulin replacement therapy is a widely adopted treatment for all patients with type 1 diabetes and some with type 2 diabetes. However, injection of insulin has suffered from problems such as tissue irritation, abscesses, discomfort, and inconvenience. The use of orally bioactive insulin mimetics thus represents an ideal treatment alternative. Here we show that a chaetochromin derivative (4548-G05) acts as a new nonpeptidyl insulin mimetic. 4548-G05 selectively activates an insulin receptor (IR) but not insulin-like growth factor receptor-I or other receptor tyrosine kinases. Through binding to the extracellular domain of the IR, 4548-G05 induces activation of the receptor and initiates the downstream Akt and extracellular signal–related kinase pathways to trigger glucose uptake in C2C12 myotubes. Moreover, it displays a potent blood glucose-lowering effect when administrated orally in normal, type 1 diabetic, and type 2 diabetic mice models. Therefore, 4548-G05 may represent a novel pharmacological agent for antidiabetes drug development.

Effective DNA epitope chimeric vaccines for Alzheimer's disease using a toxin-derived carrier protein as a molecular adjuvant

Active amyloid-beta (Aβ) immunotherapy is under investigation to prevent or treat Alzheimer disease (AD). We describe here the immunological characterization and protective effect of DNA epitope chimeric vaccines using 6 copies of Aβ1-15 fused with PADRE or toxin-derived carriers. These naked 6Aβ15-T-Hc chimeric DNA vaccines were demonstrated to induce robust anti-Aβ antibodies that could recognize Aβ oligomers and inhibit Aβ oligomer-mediated neurotoxicity, result in the reduction of cerebral Aβ load and Aβ oligomers, and improve cognitive function in AD mice, but did not stimulate Aβ-specific T cell responses. Notably, toxin-derived carriers as molecular adjuvants were able to substantially promote immune responses, overcome Aβ-associated hypo-responsiveness, and elicit long-term Aβ-specific antibody response in 6Aβ15-T-Hc-immunized AD mice. These findings suggest that our 6Aβ15-T-Hc DNA chimeric vaccines can be used as a safe and effective strategy for AD immunotherapy, and toxin-derived carrier proteins are effective molecular adjuvants of DNA epitope vaccines for Alzheimers disease.

Strikingly Reduced Amyloid Burden and Improved Behavioral Performance in Alzheimer's Disease Mice Immunized with Recombinant Chimeric Vaccines by Hexavalent Foldable Aβ1-15 Fused to Toxin-Derived Carrier Proteins

Targeting on the amyloid-β (Aβ) is a promising immunotherapeutic strategy for Alzheimers disease (AD). However, Aβ(1-15) sequence alone induces low antibody response and poor protection against AD. We describe here the immunological characterization and protective efficacy of several recombinant chimeric vaccines with hexavalent foldable Aβ(1-15) (6Aβ15) fused to PADRE or toxin-derived carrier proteins. Immunization with these chimeric antigens generated robust Th2 immune responses with high anti-Aβ42 antibody titers in different mice, which recognized neurotoxic Aβ42 oligomers, but did not stimulate Aβ42-specific T cell responses. These 6Aβ15 chimeric vaccines markedly reduced Aβ pathology and prevented development of behavioral deficits in immunized older AD mice. Importantly, toxin-derived carrier proteins as molecular adjuvants of chimeric vaccines could substantially boost immune responses and overcome Aβ- and old age-associated hypo-responsiveness, and elicit long-term Aβ-specific antibody response, which in turn inhibited Aβ-mediated pathology and improved acquisition and retention of spatial memory in immunized AD mice. These data indicate that toxin fragments as molecular adjuvants are promising new tools for the rational design and development of prototype chimeric vaccines for AD and this type of chimeric vaccine design has the added advantage of overcoming hypo-responsiveness in elderly AD patients with pre-existing memory Th cells from tetanus toxin.

Pinocembrin protects rats against cerebral ischemic damage through soluble epoxide hydrolase and epoxyeicosatrienoic acids

AIM To investigate the relationship between cerebroprotection of pinocembrin and epoxyeicosatrienoic acids (EETs) and their regulating enzyme soluble epoxide hydrolase (sEH). METHODS Rats underwent middle cerebral artery occlusion (MCAO) to mimic permanent focal ischemia, and pinocembrin was administrated via tail vein injection at 10 min, 4 h, 8 h and 23 h after MCAO. After 24 MCAO, rats were re-anesthetized, and the blood and brain were harvested and analyzed. RESULTS Pinocembrin displayed significant protective effects on MCAO rats indicated by reduced neurological deficits and infarct volume. Importantly, co-administration of 0.2 mg·kg(-1) 14, 15-EEZE, a putative selective EET antagonist, weakened the beneficial effects of pinocembrin. 14, 15-EET levels in the blood and brain of rats after 24 h MCAO were elevated in the presence of pinocembrin. In an assay for hydrolase activity, pinocembrin significantly lowered brain sEH activity of MCAO rats and inhibited recombinant human sEH activity in a concentration-dependent manner (IC50, 2.58 μmol·L(-1)). In addition, Western blot and immunohistochemistry analysis showed that pinocembrin at doses of 10 mg·kg(-1) and 30 mg·kg(-1) significantly down-regulated sEH protein in rat brain, especially the hippocampus CA1 region of MCAO rats. CONCLUSION Inhibiting sEH and then increasing the potency of EETs may be one of the mechanisms through which pinocembrin provides cerebral protection.

A quinoline-based Cu2 + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2+ ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2+ ion was determined to be 1:1 through fluorescence titration, Jobs plot and ESI-MS. The binding constant (K) of Cu2+ to probe QP was found to be 2.12×104M-1. Further, the Cu2+ ensemble of probe QP was found to respond H2PO4- and HPO42- among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2+ cation and H2PO4- and HPO42- anions in living cells.

Carbon Dots with Red Emission for Sensing of Pt2+, Au3+, and Pd2+ and Their Bioapplications in Vitro and in Vivo

Red emissive carbon dots (CDs) have drawn more and more attention due to their good organ penetration depth and slight biological tissue photodamage. Herein, the fluorescent CDs with red emission were synthesized by the facile one-pot hydrothermal treatment of citric acid and neutral red and they show red fluorescence both in aqueous solution and solid state. The solution of CDs exhibits the quantum yield of 12.1%, good stability against photobleaching, and low cytotoxicity. As-prepared CDs can be used as a fluorescent probe for peculiar detection of Pt2+, Au3+, and Pd2+. Furthermore, the CDs show excellent biocompatibility, which were successfully used as hopeful bioimaging and biosensing of noble metal ions in PC12 cells and zebrafish.

Two type III polyketide synthases from Polygonum cuspidatum: gene structure, evolutionary route and metabolites

In our recent work (Ma et al., in Planta 229(3):457–469, 2009a and 229(4):1077–1086, 2009b), two three-intron type III PKS genes, PcPKS1 and PcPKS2, were isolated from Polygonum cuspidatum Sieb. et Zucc. Phylogenetic and functional analyses revealed PcPKS1 is a three-intron chalcone synthase (CHS) gene, and PcPKS2 is found to be a three-intron benzalacetone synthase (BAS) gene. The regular CHS encoded by a single intron gene have not been isolated and characterized from P. cuspidatum. In this work a further CHS with one intron (PcPKS3) and a stilbene synthase (STS) gene with three-intron (PcPKS5) were isolated and characterized by functional and phylogenetic analyses. In comparison with PcPKS1, a bifunctional enzyme with both CHS and BAS activity, the enzymatic product of recombinant PcPKS3 was naringenin, bis-noryangonin (BNY) and 4-coumaroyltriacetic acid lactone (CTAL) occurred as side products. The PcPKS5 synthesized resveratrol and a trace amount of naringenin from p-coumaroyl-CoA. To our knowledge, PcPKS5 is the first reported three-intron STS gene in flowering plants. In this work, we speculated that this involved a possible evolutionary route of plant-specific type III PKS superfamily in P. cuspidatum.

A novel turn-on fluorescent probe for Al3 + and Fe3 + in aqueous solution and its imaging in living cells

A quinoline-based fluorescence probe has been prepared and characterized. Probe 1 showed a selective sensing ability for Al3+ and Fe3+ ions through fluorescence enhancement response at 515nm when it was excited at 360nm. In the presence of Fe3+ ion, probe 1 exhibited a detection limit of 2.10×10-6M. As for Al3+, its detection limit of 3.58×10-7M was significantly lower than the highest limit of Al3+ in drinking water recommended by the WHO (7.41μM), representing a rare example in reported fluorescent probe for Al3+ ion. The fluorescence microscopy experiments have demonstrated that probe 1 could be used in live cells for the detection of Al3+ and Fe3+ ions.

Acridine-based fluorescence chemosensors for selective sensing of Fe 3+ and Ni 2+ ions

Two novel acridine-based fluorescence chemosensors (L1 and L2) were prepared and their metal ions sensing properties were investigated. L1 (L2) exhibited an excellent selective fluorescence response toward Fe3+ (Ni2+) and the stoichiometry ratio of L1-Fe3+ and L2-Ni2+ were 1:1. The detection limits of L1 and L2 were calculated by the fluorescence titration to be 4.13μM and 1.52μM, respectively, which were below the maximum permissive level of Fe3+ and Ni2+ ions in drinking water set by the EPA. The possible mechanism of the fluorescence detection of Fe3+ and Ni2+ had been proposed according to the analysis of Jobs plot, IR spectra and ESI-MS. The determination of Fe3+ and Ni2+ ions in living cells had been applied successfully.