Growth hormone (GH)-releasing peptides (GHRPs) and GH secretagogues (GHSs) are listed in the World Anti-Doping Agency (WADA) Prohibited List. In the present study, we developed and validated a method for the simultaneous analysis of seven GHRPs (alexamorelin, GHRP-1, -2, -4, -5, -6, and hexarelin) and three GHSs (anamorelin, ibutamoren, and ipamorelin) in human urine. Method validation was performed at minimum required performance levels specified by WADA technical documents (2 ng/mL) for all substances, and the method was validated with regard to selectivity (no interference), linearity (R2 > 0.9986), matrix effects (50.0%-141.2%), recovery (10.4%-100.8%), and intra- (2.8%-16.5%) and inter-day (7.0%-22.6%) precisions. The limits of detection for screening and confirmation were 0.05-0.5 ng/mL and 0.05-1 ng/mL, respectively.
Scanning electron microscopy combined with thermal ionization mass spectrometry (SEM-TIMS) was used to determine the precise isotope ratios of ultra-trace levels of uranium contained in individual microparticles. An advanced multiple ion counter system consisting of three secondary ion multipliers and two compact discrete dynodes was used for complete simultaneous ion detection. For verification purposes, using TIMS with complete simultaneous measurement, isotopes were analyzed in 5 pg of uranium of a certified reference material. A microprobe in the SEM was used to transfer individual particles from a NUSIMEP-7 sample to TIMS filaments, which were then subjected to SEM-TIMS and complete simultaneous measurement. The excellent agreement in the resulting uranium isotope ratios with the certified NUSIMEP-7 values shows the validity of SEM-TIMS with complete simultaneous measurement for the analysis of uranium isotopes in individual particles. Further experimental study required for investigation of simultaneous measurement using the advanced multiple ion counter system is presented.
High-resolution quadrupole-Orbitrap mass spectrometry (HRMS), with high-resolution (> 10,000 at full-width at half-maximum) and accurate mass (< 5 ppm deviation) capabilities, plays an important role in the structural elucidation of drug metabolites in the pharmaceutical industry. ML106, a derivative of imidazobenzimidazole, decreased melanin content and tyrosinase activity in a dose-dependent manner. Here, we investigated the phase 1 metabolic pathway of ML106 using HRMS in human liver microsomes (HLMs) and recombinant cDNA-expressed cytochrome P450 (CYP). After the incubation of ML106 with pooled HLMs and recombinant cDNA-expressed CYP in the presence of NADPH, five phase 1 metabolites, including three mono-hydroxylated metabolites (M1-3) and two di-hydroxylated metabolites (M4 and M5), were investigated. The metabolite structures were postulated by the elucidation of protonated mass spectra using HRMS. The CYP isoforms related to the hydroxylation of ML106 were studied after incubation with recombinant cDNA-expressed CYP. Here, we identified the phase 1 metabolic pathway of ML106 induced by CYP in HLMs.
Targeted glycoproteomics is an effective way to discover disease-associated glycoproteins in proteomics and serial affinity chromatography (SAC) using lectin and glycan-targeting antibodies shows glycan diversity on the captured glycoproteins. This study suggests a way to determine glycan heterogeneity and structural analysis on the post-translationally modified proteins through serial affinity column set (SACS) using four Lycopersicon esculentum lectin (LEL) columns. The great advantage of this method is that it differentiates between glycoproteins on the basis of their binding affinity. Through this study, some proteins were identified to have glycoforms with different affinity on a single glycoprotein. It will be particularly useful in determining biomarkers in which the disease-specific feature is a unique glycan, or a group of glycans.
We prepared solid dispersion formulations of quercetin to enhance its solubility and dissolution rate. Various quercetinloaded solid dispersion were tested with quercetin, poloxamer 407, and carrier such as hydroxypropyl methyl cellulose (HPMC), polyethylene glycol 8000 (PEG 8000), and polyvinylpyrrolidone K40 (PVP K40) using solvent evaporation and freeze drying methods in terms of both the aqueous solubility and the dissolution rates of quercetin. The solubility of quercetin as its solid dispersion formulations was markedly improved compared with that of quercetin powder. Especially, highest solubility of quercetin was observed when HPMC was used as a carrier. The cumulative dissolution of quercetin within 360 min from solid dispersion composed of quercetin, poloxamer 407, and HPMC was 8.8-fold higher than the dissolution of pure quercetin. The results of powder Xray diffraction (XRD) and scanning electron microscope (SEM) indicated that quercetin transformed from a crystalline to an amorphous form through the solid dispersion formulation process. These results suggest that the solid dispersion formulation of quercetin with poloxamer 407 and HPMC could be a promising option for enhancing the solubility and dissolution rate of quercetin.