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NeuroEPO plus is a recently developed recombinant human erythropoietin (rhEPO) without erythropoietic activity and shorter plasma half-life due to its low sialic acid content. This novel rhEPO product is under investigation as therapeutic protein in the treatment of neurodegenerative diseases owing to its neuroprotective and neurodegenerative properties. In this study, an in-depth characterization of NeuroEPO plus N-glycans was performed by a glycan isotope [12C6]/[13C6] coded aniline labeling strategy followed by capillary zwitterionic hydrophilic interaction liquid chromatography-mass spectrometry (CapZIC-HILIC-MS). A superior amount of low sialylated glycans and less branched structures were detected in NeuroEPO plus compare to other commercial rhEPOs. At the intact glycoprotein level, NeuroEPO plus glycoforms were separated by capillary zone electrophoresis with ultraviolet detection (CE-UV), optimizing the composition and pH of the separation electrolyte. Moreover, an isoelectric focusing polyacrylamide gel electrophoresis (IEF-PAGE) method was also optimized for the simultaneous analysis of this basic rhEPO and conventional acidic rhEPO products. The proposed glycomic and intact glycoprotein methods provide a robust and reliable analytical platform for NeuroEPO plus characterization and for its future implementation as biopharmaceutical in neurodegenerative diseases.

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RESUMEN

A novel high performance system to control the temperature of the microcartridge in on-line solid phase extraction capillary electrophoresis (SPE-CE) is introduced. The mini-device consists in a thermostatic bath that fits inside of the cassette of any commercial CE instrument, while its temperature is controlled from an external circuit of liquid connecting three different water baths. The circuits are controlled from a switchboard connected to an array of electrovalves that allow to rapidly alternate the water circulation through the mini-thermostatic-bath between temperatures from 5 to 90 °C. The combination of the mini-device and the forced-air thermostatization system of the commercial CE instrument allows to optimize independently the temperature of the sample loading, the clean-up, the analyte elution and the electrophoretic separation steps. The system is used to study the effect of temperature on the C18-SPE-CE analysis of the opioid peptides, Dynorphin A (Dyn A), Endomorphin1 (END) and Met-enkephalin (MET), in both standard solutions and in spiked plasma samples. Extraction recoveries demonstrated to depend, with a non-monotonous trend, on the microcartridge temperature during the sample loading and became maximum at 60 °C. Results prove the potential of temperature control to further enhance sensitivity in SPE-CE when analytes are thermally stable.

RESUMEN

The use of algae as a foodstuff is rapidly expanding worldwide from the East Asian countries, where they are also used for medical care. Harmala alkaloids (HAlk) are a family of bioactive compounds found in the extracts of some plants, including wakame (Undaria pinnatifida), an edible marine invasive algae. HAlks are based on a characteristic ß-carboline structure with at least one amino ionizable group. In this work, we report the successful separation of a mixture of six HAlks (harmine, harmaline, harmol, harmalol, harmane, and norharmane) by capillary electrophoresis ion-trap mass spectrometry (CE-IT-MS) in less than 8 min. Optimum separation in fused-silica capillaries and detection sensitivity in positive-ion mode were achieved using a background electrolyte (BGE) with 25 mmol L(-1) ammonium acetate (pH 7.8) and 10% (v/v) methanol, and a sheath liquid with 60:40 (v/v) isopropanol-water and 0.05% (v/v) formic acid. The separation method was validated in terms of linearity, limits of detection and quantification, repeatability, and reproducibility. Later, a sample pretreatment was carefully optimized to determine HAlks in commercial wakame samples with excellent recovery and repeatability. For the complex wakame extracts, the MS-MS fragmentation patterns of the different HAlks were useful to ensure a reliable identification. The complete procedure was validated using the standard-addition calibration method, determining matrix effects on the studied compounds. Harmalol, harmine, and harmaline were naturally present in the samples and were quantified at very low concentrations, ranging from 7 to 24 µg kg(-1) dry algae.

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