Natural alkaloid harmine promotes degradation of alpha-synuclein via PKA-mediated ubiquitin-proteasome system activation.

BACKGROUND: Parkinson's disease (PD) is an age-dependent progressive movement disorder characterized by a profound and selective loss of nigrostriatal dopaminergic neurons. Accumulation of -synuclein (-syn) positive protein aggregates in the substantia nigra is a pathological hallmark of PD, indicating that protein turnover defect is implicated in PD pathogenesis. PURPOSE: This study aims to identify neuroprotective compounds which can alleviate the accumulation of -syn in neuronal cells and dissect the underlying mechanisms. METHODS: High throughput screening was performed by dot blot assay. The degradation of different forms of -syn by candidate compounds were assessed by western blot. The autophagy lysosome pathway and ubiquitin-proteasome system were examined to dissect the degradation pathway. The UPS activity was assessed by cellular UPS substrates degradation assay and biochemical proteasome activity assay. Q-PCR was performed to test the mRNA level of different proteasome subunits. Furthermore, Neuroprotective effect of candidate compound was tested by LDH assay and PI staining. RESULTS: Through the high throughput screening, harmine was identified as a potent -syn lowering compound. The time-dependent and dose-dependent effects of harmine on the degradation of different forms of -syn were further confirmed. Harmine could dramatically promote the degradation of UPS substrates GFP-CL1, Ub-R-GFP and Ub-G76V-GFP, and activate cellular proteasome activity. Mechanistically, harmine dramatically enhanced PKA phosphorylation to enhance proteasome subunit PSMD1 expression. PKA inhibitor blocked the effects of harmine in activating UPS, up regulating PSMD1 and promoting -syn degradation, indicating that harmine enhances UPS function via PKA activation. Moreover, harmine efficiently rescued cell death induced by over-expression of -syn, via UPS-dependent manner. CONCLUSION: Harmine, as a new proteasome enhancer, may have potential to be developed into therapeutic agent against neurodegenerative diseases associated with UPS dysfunction and aberrant proteins accumulation.

Paeoniflorin Promotes Angiogenesis in A Vascular Insufficiency Model of Zebrafish in vivo and in Human Umbilical Vein Endothelial Cells in vitro.

OBJECTIVE: To investigate the pro-angiogenic effects of paeoniflorin (PF) in a vascular insufficiency model of zebrafish and in human umbilical vein endothelial cells (HUVECs). METHODS: In vivo, the pro-angiogenic effects of PF were tested in a vascular insufficiency model in the Tg(fli-1:EGFP)y1 transgenic zebrafish. The 24 h post fertilization (hpf) embryos were pretreated with vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitor II (VRI) for 3 h to establish the vascular insufficiency model and then post-treated with PF for 24 h. The formation of intersegmental vessels (ISVs) was observed with a fluorescence microscope. The mRNA expression of fms-like tyrosine kinase-1 (flt-1), kinase insert domain receptor (kdr), kinase insert domain receptor like (kdrl) and von Willebrand factor (vWF) were analyzed by real-time polymerase chain reaction (PCR). In vitro, the pro-angiogenic effects of PF were observed in HUVECs in which cell proliferation, migration and tube formation were assessed. RESULTS: PF (6.25-100 µmol/L) could rescue VRI-induced blood vessel loss in zebrafish and PF (25-100 µmol/L), thereby restoring the mRNA expressions of flt-1, kdr, kdrl and vWF, which were down-regulated by VRI treatment. In addition, PF (0.001-0.03 µmol/L) could promote the proliferation of HUVECs while PF stimulated HUVECs migration at 1.0-10 µmol/L and tube formation at 0.3 µmol/L. CONCLUSION: PF could promote angiogenesis in a vascular insufficiency model of zebrafish in vivo and in HUVECs in vitro.

Transcriptome analysis of leaves, roots and flowers of Panax notoginseng identifies genes involved in ginsenoside and alkaloid biosynthesis.

BACKGROUND: Panax notoginseng (Burk.) F.H. Chen is one of the most highly valued medicinal plants in the world. The major bioactive molecules are triterpene saponins, which are also known as ginsenosides. However, its large genome size has hindered the assembly of a draft genome by whole genome sequencing. Hence, genomic and transcriptomic details about P. notoginseng, especially its biosynthetic pathways and gene expression in different parts of the plant, have remained largely unknown until now. RESULTS: In this study, RNA sequencing of three different P. notoginseng tissues was performed using next generation DNA sequencing. After assembling the high quality sequencing reads into 107,340 unigenes, biochemical pathways were predicted and 9,908 unigenes were assigned to 135 KEGG pathways. Among them, 270 unigenes were identified to be involved in triterpene saponin biosynthesis. In addition, 350 and 342 unigenes were predicted to encode cytochrome P450s and glycosyltransferases, respectively, based on the annotation results, some of which encode enzymes responsible for the conversion of the triterpene saponin backbone into different ginsenosides. In particular, one unigene predominantly expressed in the root was annotated as CYP716A53v2, which probably participates in the formation of protopanaxatriol from protopanaxadiol in P. notoginseng. The differential expression of this gene was further confirmed by real-time PCR. CONCLUSIONS: We have established a global transcriptome dataset for P. notoginseng and provided additional genetic information for further genome-wide research and analyses. Candidate genes involved in ginsenoside biosynthesis, including putative cytochrome P450s and glycosyltransferases were obtained. The transcriptomes in different plant tissues also provide invaluable resources for future study of the differences in physiological processes and secondary metabolites in different parts of P. notoginseng.

[Preparation and characterization of upconversion phosphor based on AlF3-YbF3 : Er3+].

In the present paper, AlF3-YbF3 : Er3+ was prepared by high temperature solid phase reaction, and the concentration effect of Er3+ on luminous intensity of phosphors was studied. The crystal structures of the phosphors were characterized by means of X-ray diffraction (XRD), and the upconversion luminescence properties of phosphor were studied by fluorescence emission spectra. Upon 980 nm excitation, when the Er3+ concentration was fixed to be 0.7 mol%, the maximum red emission intensities can be obtained in the sample. Furthermore, the research results showed that the fitted slope for red transition emission was 2.24, indicating that red emission is due to a two-photon excitation process.

[Investigation of synthesis and luminescent properties of the Sr2CeO4: Dy3+].

In the present article, Sr2CeO4:Dy3+ was synthesized with N,N-methylene bisacrylamide (MBAA) as the net agent. The structure, morphology and luminescent properties were also characterized. It is indicated that Sr2CeO4:Dy3+ was single-phased without other phase existing and also had good dispersion The UV-visible absorption spectra suggested that the absorption bands were almost at 480 nm. The excitation spectrum for 270 nm emission has several excitation bands; The emission spectrum of Sr2 CeO4:Dy3+ shows two broad bands at 292 and 338 nm under the 370 nm excitation. The effects of Dy3+ doping concentration on the emission spectrum intensity of Sr2 CeO4:Dy3+ were also studied, the results showed that the ratio of yellow emission to blue emission increases with increasing the D/3+ doping concentration, but with increasing the Dy3+ doping concentration, the emission intensity firstly increased, then decreased, and the maximal emission intensity was at 0.4 mol% Dy3+ concentration.

[Synthesis and luminescence properties of europium (III) complexes].

Three types of europium complexes were synthesized by introducing benzoylacetone as the first ligand and 1, 10-phenanthroline, triphenylphosphine oxide, 2,2'-bipyridyl as the second ligand, respectively. The properties of above materials were characterized by infrared absorption spectra, UV-Vis absorption spectra and fluorescence spectra. Then, it was discussed that the different second ligands of europium complexes can affect their luminescence properties, and their intramolecular energy transfer models had been set up. The results indicated that ligands and complexes have a strong absorption of UV light and the three types of europium complexes exhibit characteristic luminescence of europium ion when excited by UV light. In addition, it is suggested that the fluorescence yield of europium complexes mostly depend on both the energy difference between the second ligand and the Eu3+ ion and the energy difference between the second ligand and the first ligand.

[Spectral analysis and band gap of RbVO3].

In the present paper, RbVO3 was prepared by wet chemistry synthesis from hybrid precursor. The structure of RbVO3 was characterized by X-ray diffraction (XRD) pattern and FTIR spectra. Photoluminescent (PL) properties were investigated by UV-Vis absorption spectrum and PL spectrum. In addition, the band gap of RbVO3 was calculated by using the CASTEP code with density-functional theory (DFT) method. The results indicated that RbVO3 could emit intense green-white fluorescence with peak wavelength at 525 nm and the color coordinates was (0.318 0, 0.430 9) under UV excitation at 357 nm. It was demonstrated that the theoretical result of band gap, which is 2.67 eV, agreed well with the experiment.

[A novel yellow organic light-emitting device].

The fabrication of a novel organic yellow-light-emitting device using Rhodamine B as dopant with double quantum-well (DQW) structure was introduced in the present article. The structure and thickness of this device is ITO/CuPc (6 nm) /NPB (20 nm) /Alq3 (3 nm)/Alq3 : Rhodamine B (3 nm) /Alq3 (3 nm) /Al q3 : Rhodamine B(3 nm) /Alq3 (30 nm) /Liq (5 nm)/Al (30 nm). With the detailed investigation of electroluminescence of the novel organic yellow-light-emitting device, the authors found that the doping concentration of Rhodamine B (RhB) had a very big influence on luminance and efficiency of the organic yellow-light-emitting device. When doping concentration of Rhodamine B (RhB) was 1.5 wt%, the organic yellow-light-emitting device was obtained with the maximum current efficiency of 1.526 cd x A(-1) and the maximum luminance of 1 309 cd x m(-2). It can be seen from the EL spectra of the devices that there existed energy transferring from Alq3 to RhB in the organic light-emitting layers. When the doping concentration of RhB increased, lambda(max) of EL spectra redshifted obviously. The phenomenon was attributed to the Stokes effect of quantum wells and self-polarization of RhB dye molecules.

[Luminescence properties of white LED blue light conversion materials].

Using rare earth oxides as raw materials, yttrium aluminum garnets activated by cerium and gadolinium ions were prepared by high energy ball milling and solid-state reaction at 1300 degrees C. The crystal structures of the products were studied by XRD, and the luminescence characteristics of Ce ion and the influence of Gd ion were studied by emission and excitation spectra. The results indicated that the products were yttrium aluminum garnet crystals of cubic system, and they were excited by blue light chips effectively. The emission peak of phosphors could change among 530-560 nm by adjusting the mole density of doping ions. The red shift of emission spectra could be interpreted with the configuration coordination figure. White LEDs were fabricated by phosphor conversion. When electric current is 20 mA, and the working voltage is 3.5 V, the white light LED chromaticity coordinates are x=0.310 and y=0.323, the lumen efficiency is 26.131 m x W(-1), the color rendering index is 81.8, and the color temperature is 6605 K.

[Spectroscopic properties of salicylaldehyde anil zinc and its thin film].

A new light emitting material, salicylaldehyde anil zinc (SAZ), was synthesized. It can form high quality nano-scale amorphous thin films on clean glass substrates by vacuum evaporation. Its structure, crystallization, thermal stability, and optical property were investigated by IR spectra, DTA-TG analysis, XRD spectra, UV-Vis spectra, and fluorescence spectra. Its energy band structure was confirmed by cyclic voltammogram and optical absorption band edge. Results show that the SAZ film is a thermally stable material, and can emit intense green fluorescence with a peak wavelength at 508 nm and a full width at half-maximum of 90.2 nm under UV irradiation. Its HOMO energy level is about -5.659 eV, LUMO energy level is about -3.054 eV, optical gap band is about 2.604 eV. The fluorescence decay of stored films under ambient atmosphere is more rapid than that of 8-hydroxyquinoline aluminum films. However, the fluorescence decay of the films under UV irradiation is slower than that of 8-hydroxyquinoline aluminum films.

[Spectral analysis and photoluminescence properties of 1,5-naphthalene diamine derivative].

In the present paper, 1,5-bis[N-(1-naphthyl)-N-phenyl] naphthalene diamine (NPN) with high purity was synthesized by liquid-phase Ullmann reaction, and high quality film of NPN was formed on cleaned glass substrates by vacuum evaporation. Photoluminescence properties were studied by solvent effects on UV-Vis absorption spectra and fluorescence spectra. In addition the structure of energy band of NPN was studied by cyclic voltammetry, UV-Vis absorption spectra, and fluorescence spectra. The results indicate that the fluorescence emitting is attributed to the charge transfer transition from nitrogen to aromatic ring. The molecules of NPN in its film form "J-aggregate". The HOMO energy and optical gap of NPN are -5.74 and 2.79 eV respectively. NPN film could emit intense blue fluorescence with a peak wavelength at 448.6 nm and a bandwidth of 72.6 nm under UV-Vis excitation at 365 nm.

[Preparation and spectral analysis of a new type of blue light-emitting material delta-Alq3].

In the present article, delta-Alq3, a new type of blue light-emitting material, was synthesized and investigated by IR spectra, XRD spectra, UV-Vis absorption spectra, photoluminescence (PL) spectra, and electroluminescence (EL) spectra. The relationship between molecular spatial structure and spectral characteristics was studied by the spectral analysis of delta-Alq3 and alpha-Alq3. Results show that a new phase of Alq3 (delta-Alq3) can be obtained by vacuum heating alpha-Alq3, and the molecular spatial structure of alpha-Alq3 changes during the vacuum heating. The molecular spatial structure of delta-Alq3 lacks symmetry compared to alpha-Alq3. This transformation can reduce the electron cloud density on phenoxide of Alq3 and weaken the intermolecular conjugated interaction between adjacent Alq3 molecules. Hence, the pi--pi* electron transition absorption peak of delta-Alq3 shifts toward short wavelength in UV-Vis absorption spectra, and the maximum emission peak of delta-Alq3 (lamda max = 480 nm) blue-shifts by 35 nm compared with that of alpha-Alq3 (lamda max = 515 nm) in PL spectra. The maximum emission peaks of delta-Alq3 and alpha-Alq3 are all at 520 nm in EL spectra.

[Preparation and characterization of 2(8-hydroxyquinoline)-2( phenol) zirconium thin film].

In this paper, the new emitting material zirconium complex with 8-hydroxyquinoline and phenol (Zr(OPh)2 q2), which can form high quality nano-scale amorphous thin films at glass substrates cleaned by vacuum evaporation, was synthesized. Its crystallization, thermal stability, the structure of energy band and PL mechanism were investigated respectively by FTIR spectra, DTA-TG analysis, SEM, XRD spectra, UV-Vis absorption spectra and fluorescence spectra. Results show that the Zr(OPh)2 q2 is a thermally stable material, whose melting point is 381.2 degrees C, decomposition temperature is 467.1 degrees C, whose film can emits intense yellow-green fluorescence with peak wavelength at 525 nm and a full width at half-maximum of 107.6 nm under UV excitation (390 nm), powder has intense yellow fluorescence, therefore it may be a excellent electroluminescent material.