Sensitive analysis of α-synuclein by nonlinear laser wave mixing coupled with capillary electrophoresis

Multi-photon nonlinear laser wave-mixing spectroscopy is a novel absorption-based technique that offers excellent detection sensitivity for biomedical applications, including early diagnosis and investigation of neurodegenerative diseases. α-Synuclein is linked to Parkinson's disease (PD), and characterization of its oligomers and quantification of the protein may contribute to understanding PD. The laser wave-mixing signal has a quadratic dependence on analyte concentration, and hence the technique is effective in monitoring small changes in concentration within biofluids. A wide variety of labels can be employed for laser wave-mixing detection due to its ability to detect both chromophores and fluorophores. In this investigation, two fluorophores and a chromophore are studied and used as labels for the detection of α-synuclein. Wave-mixing detection limits of PD-related protein conjugated with fluorescein isothiocyanate, QSY 35 acetic acid, succinimidyl ester, and Chromeo P503 were determined to be 1.4 × 10⁻¹³ M, 1.4 × 10⁻¹⁰ M, and 1.9 × 10⁻¹³ M, respectively. Based on the laser probe volume used, the corresponding mass detection limits were determined to be 1.1 × 10⁻²³ mol, 1.1 × 10⁻²⁰ mol, and 1.5 × 10⁻²³ mol. This study also presents molecular-based separation and quantification of α-synuclein by laser wave mixing coupled with capillary electrophoresis.     

Isolation of Festuclavine and Three New Indole Alkaloids,Roquefortine A,B and C from the Cultures of Penicillium roqueforti

The structure and absolute configuration of a metabolite isolated from Aspergillus silvaticus was studied by an X-ray diffraction method. Crystals were orthorhombic, with space group P2₁2₁2₁, and a=9.894 (5), b = 6.803 (4), c=22.519 (6) Å, and Z=4. The structure was solved by a direct method and refined by a block-diagonal least-square method to R=0.07 for 1143 non-zero reflections. The metabolite was identified as naphthalic anhydride obtained from atrovenetin. The absolute configuration determined by the Bijvoet method is consistent with that shown chemically. The molecule has two intramolecular hydrogen bonds.