A simple lysosome-targeted fluorescent probe based on flavonoid for detection of cysteine in living cells.

Cysteine (Cys) is one of the most important biothiols that plays a crucial role in many physiological and pathological processes, and therefore it is of great importance to detect and analyze Cys in subcellular environments, such as in lysosomes. However, only a few fluorescent probes were reported to be capable of detecting Cys in lysosomes selectively. In this wok, we designed and developed a simple, accessible flavone-based fluorescent probe LFA for detecting Cys in lysosomes. Morpholine was employed as the targeting unit for lysosome, and acrylate group was chosen as the Cys-response unit. The probe was easily prepared by a two-step procedure and displayed large Stokes shift, high sensitivity, turn-on response toward Cys over homocysteine (Hcy), glutathione (GSH), and other amino acids. With low cytotoxicity and good cell permeability, the probe could be successfully applied for fluorescence imaging of Cys in living cells. Furthermore, colocalization experiment revealed that lysosomal-targetable ability of LFA was significant. These results indicated that such simple fluorescent probe could provide a promising tool for detection of lysosomal Cys in living biological systems.

UPLC-QTOF-MS Based Comparison of Rotundic Acid Metabolic Profiles in Normal and NAFLD Rats.

Rotundic acid, the principal bioactive constituent of the herbal remedy "Jiubiying", has been considered as a candidate compound for treating non-alcoholic fatty liver disease (NAFLD). However, the in vivo and in vitro metabolism of rotundic acid has remained unclear. With the aim of elucidating its metabolic profile, a reliable approach that used ultra-high performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was applied for screening and identifying rotundic acid in vivo (plasma, feces, urine, and liver tissue of normal and NAFLD model rats) and in vitro (rat liver microsomes) metabolites. Herein, 26 metabolites of rotundic acid were identified, including 22 metabolites in normal rats, 20 metabolites in NAFLD model rats, and eight metabolites in rat liver microsomes. Among them, 17 metabolites were identified for the first time. These data illustrate that the pathological status of NAFLD affects the metabolism of rotundic acid. Furthermore, the major pathways of metabolism included phase Ⅰ (demethylation, desaturation, etc.) and phase Ⅱ (sulfation and glucuronidation) reactions, as well as a combined multiple-step metabolism. This work provides important information on the metabolism of rotundic acid and lays the foundation for its future clinical application.

Pharmacokinetic and metabolic studies of Vortioxetine in rats using ultra high performance liquid chromatography with tandem mass spectrometry.

Vortioxetine is a multimodal antidepressant that has been recently utilized globally. Vortioxetine hemi-hydrochloride is a novel salt that was previously reported in our research. However, the pharmacokinetics of this salt and the metabolites of Vortioxetine in vivo remain unknown. In this study, the pharmacokinetics of the Vortioxetine hemi-hydrochloride salt is explored in rats through a newly developed ultra-performance liquid chromatography with tandem mass spectrometry method. In addition, ultra-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry was used to identify the metabolites of Vortioxetine in vivo. The results demonstrate that after a single, 3 mg/kg oral dose, the maximum concentration for the Vortioxetine hemi-hydrochloride salt is 14.63 ± 4.00 ng/mL, and is attained in 1.00∼4.00 h. The area under the plasma concentration-time curve from time 0 to 24 h is 67.30 ± 23.78 ng·h·mL-1 . Additionally, 29 metabolites were identified after the oral administration of 10 mg/kg, including 17 metabolites in the plasma, nine in the urine, and 12 in the feces. Eleven metabolites were novel. The major metabolic pathways include methylation, hydroxylation, oxidation, and glucuronidation. In conclusion, this study provides insight for further development of the Vortioxetine hemi-hydrochloride salt.

Ultrasensitive colorimetric immunoassay for hCG detection based on dual catalysis of Au@Pt core-shell nanoparticle functionalized by horseradish peroxidase.

In this paper, an ultrasensitive colorimetric biosensor for human chorionic gonadotrophin (hCG) detection was designed from bottom-up method based on the dual catalysis of the horseradish peroxidase (HRP) and Au@Pt nanoparticles (NPs) relative to H2O2-TEM system. HRP and monoclonal mouse anti-hCG antibody (ß-submit, mAb1) were co-immobilized onto the Au@Pt NP surface to improve catalytic efficiency and specificity, which formed a dual functionalized Au@Pt-HRP probe with the mean size of 42.8nm (D50). The colorimetric immunoassay was developed for the hCG detection, and the Au@Pt-HRP probe featured a higher sensitivity in the concentration range of 0.4-12.8IUL-1 with a low limit of detection (LOD) of 0.1IUL-1 compared with the LODs of 0.8IUL-1 for BA-ELISA and of 2.0IUL-1 for Au@Pt, which indicated that the Au@Pt-HRP probe possessed higher catalytic efficiency with 2.8-fold increase over Au@Pt and 33.8-fold increase over HRP. Also, the Au@Pt-HRP probe exhibited good precision and reproducibility, high specificity and acceptable accuracy with CV being less than 15%. The dual functionalized Au@Pt-HRP probe as a type of signal amplified method was firstly applied in the colorimetric immunoassay for the hCG detection.

Synthesis and bioevaluation of 1-phenyl-pyrazole-4-carboxylic acid derivatives as potent xanthine oxidoreductase inhibitors.

A diverse library of 1-phenyl-pyrazole-4-carboxylic acid derivatives were synthesized and evaluated for their inhibitory potency against xanthine oxidoreductase (XOR) in vitro and vivo, and the structure-activity relationship (SAR) analyses were also presented. Approximately half of the target compounds exhibited the inhibitory potency for XOR at the nanomolar level. Compounds 16c, 16d, and 16f emerged as the most potent xanthine oxidoreductase inhibitors with IC50 values of 5.7, 5.7 and 4.2 nM, respectively, in comparison to febuxostat (IC50 of 5.4 nM). Steady-state kinetics measurements indicated that 16c is a mixed-type inhibitor. A computer molecular docking study of 16c bound to XOR was performed to gain an insight into its bind mode and SAR for the series. A potassium oxonate-hypoxanthine-induced hyperuricemia model in mice was chosen to further confirm the hypouricemic effects of 16c and 16f, and the results demonstrated that 16c exhibits similar hypouricemic potency to febuxostat.