Katsuhiro Yamasaki

DNA repair test of disinfectants by liquid rec-assay

The DNA-damaging capacity and the mutagenicity of 6 disinfectants were studied by liquid rec-assay and Ames test. 5 disinfectants were found to be positive in DNA-damaging capacity while only one of them showed clear mutagenicity in the Ames test. Liquid rec-assay by direct incubation with S9 mix was the most sensitive method and gave the best correlation between the growth ratio (R 50) and the time lag, both of which compared Rec+ and Rec-. Liquid rec-assay may be useful for detecting the DNA-damaging capacity of chemicals with a strong killing effect.

A simple and selective detection method for aristolochic acid in crude drugs using solid-phase extraction

The official Japanese method for analyzing aristolochic acid I (AA-I) in Asiasarum root using conventional high-performance liquid chromatography (HPLC) is described in the Japanese Pharmacopoeia, Sixteenth Edition. Interfering peaks of AA-I sometimes appear after HPLC analysis of crude drugs. A selective analytical method is needed to determine definitively whether AA-I is present in crude drugs. In this study, we developed a selective method that combined solid-phase extraction and liquid chromatography/mass spectrometry (LC/MS) which may be useful for identifying AA-I in crude drugs and for quality control.

Simultaneous analysis of highly polar pharmaceutical adulterants in slimming products by hydrophilic interaction liquid chromatography

ABSTRACT A chromatographic method utilizing hydrophilic interaction liquid chromatography was developed for the estimation of highly polar pharmaceutical adulterants in commercial slimming products. Five adulterants, phenylpropanolamine, salbutamol, phenformin, buformin, and metformin, were successfully separated on an XBridge™ amide column (3.5 µm, 4.6 × 250 mm) using a mobile phase composed of acetonitrile/26.5 mM ammonium formate containing 0.1% formic acid (85:15) flowing at the rate of 0.8 mL/min. Wavelengths for monitoring the elution of these compounds were determined based on the wavelength of their absorption maxima (λmax = 208, 226, and 236 nm). The developed method was validated for specificity, linearity, accuracy, precision, and robustness. Interassay comparison showed that the performance of the hydrophilic interaction liquid chromatography-based method was superior to that of the traditional reversed-phase liquid chromatography-based method. Therefore, the proposed method is useful to analyze highly polar pharmaceutical adulterants in slimming products. GRAPHICAL ABSTRACT