N‐3,5‐Dinitrobenzoyl‐(R)‐phenylglycinol silylation product was used as a high‐performance liquid chromatography chiral stationary phase (CSP 1) for the resolution of various racemic samples, and some racemic samples were successfully separated. In this study, instead of the commonly used π‐acidic acyl chloride, calix[4]arenes were introduced to prepare two phenylglycinol CSPs (CSP 2, CSP 3). CSP 3 showed similar separation patterns as CSP 1 but different characteristics in specific samples. The newly prepared CSP 3 separated 10 of 13 π‐acidic, π‐basic, and oxazolidinone chiral samples and was especially useful for separating chiral oxazolidinones. In comparison between CSP 2 and CSP 3, CSP 2 separated fewer chiral samples than CSP 3 because of poor cavity and steric interactions. The newly developed C‐methylcalix[4]resorcinarene derived CSP (CSP 3) will be a good model for the development of new stationary phase of this calixarene series.
(R)-N-3,5-dinitrobenzoyl (DNB) leucine derived chiral selector was used as an HPLC chiral stationary phase for the resolution of various racemic amino acids derivatives. In this study, determination of optical purity of an amino acid derivative was performed by chiral high performance liquid chromatography and 1H and 13C NMR spectroscopy by using the DNB leucine derived chiral selector. The accuracy and precision of each optical purity value are calculated and the data are compared to each other.
Tiropramide is an antispasmodic drug that has a chiral center. Resolution of tiropramide enantiomers on various kinds of chiral stationary phases was performed by HPLC. A good resolution on a leucine-derived chiral stationary phase was found. An improved chromatographic condition to resolve racemic tiropramide on the CSP was examined by changing the flow rate, composition, and kind of mobile phases.
Deleterious effects of high dose radiation exposure with high-dose-rate are unarguable, but they are still controversial in low-dose-rate. The regulator of G-protein signaling (RGS) is a negative regulator of G proteincoupled receptor (GPCR) signaling. In addition, it is reported that irradiation stress led to GPCR-mediated mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3-k) signaling. The RGS mRNA expression profiles by whole body radiation with low-dose-rate has not yet been explored. In the present study, we, therefore, examined which RGS was modulated by the whole body radiation with low-dose-rate (3.49 mGy·h -1 ). Among 16 RGS expression tested, RGS6, RGS13 and RGS16 mRNA were down-regulated by low-dose-rate irradiation. This is the first report that whole body radiation with low-dose-rate can modulate the different RGS expression levels. These results are expected to reveal the potential target and/or the biomarker proteins associated with male testis toxicity induced by low-dose-rate irradiation, which might contribute to understanding the mechanism beyond the testis toxicity.
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