Various betaines (amino acid derivatives possessing a quaternary ammonium group) are present in various foods and have significant roles in health maintenance and enhancement for humans. Although rice bran (RB) fermented with Aspergillus oryzae (A. oryzae) is expected to be a foodstuff rich in the bioactive betaines, its betaine contents have not been elucidated. To address this concern, a hydrophilic interaction liquid chromatography (HILIC)/electrospray ionization-tandem mass spectrometry method was developed and validated for the determination of the five bioactive betaines, i.e., γ-butyrobetaine, L-carnitine, L-stachydrine, L-ergothioneine and L-hercynine, in the A. oryzae-fermented RB products. These betaines were satisfactorily retained and separated on an InertSustain Amide column with an acetonitrile-rich mobile phase. A solvent extraction-based pretreatment, HILIC separation and internal standard calibrations provided the precise (relative standard deviations: ≤ 5.6 %) and accurate (analytical recovery rates: 97.1–100.6 %) measured values. No significant matrix effect was observed. By using this method, we demonstrated that the A. oryzae-fermentation significantly increased the contents of all five betaines in the RB. The A. oryzae-fermented RB products had compatible or greater betaine contents compared to the plant-based foods that have been reported to be rich in betaines.

I This study employs ethylene glycol (EG) as a solvent for dissolving 2,4-dinitrophenylhydrazine (DNPH) in the collection and derivatization of gaseous formaldehyde using a miniaturized liquid absorption cartridge comprising a polypropylene cartridge and a functional polytetrafluoroethylene (PTFE) membrane, which permits the passage of gas and blocks the flow of liquid. DNPH dissolved in 400 μL EG was used as the absorption solvent in the cartridge. The gas sample was collected at 50 mL/min through the PTFE membrane, and the analyte formaldehyde was derivatized and collected in the solvent. After air collection, the absorption solution was heated at 80 °C for 5 min to enhance the derivatization reaction. Thereafter, the absorption solvent was injected into a high-performance liquid chromatography system for the determination of formaldehyde. EG has a considerably higher viscosity than acetonitrile, which enables a high flow rate during sample gas collection. Additionally, the loss of absorption solvent during sample collection and heating due to solvent evaporation is prevented. The limit of detection of the proposed method is 2.5 ng/L, and the relative standard deviation of the peak area for the standard formaldehyde gas sample (10 ng/L) is less than 7 %.

Denopamine (DP, R(-)-1-(p-hydroxyphenyl)-2-((3,4-dimethoxyphenethyl)amino)ethanol), which has been developed as a single enantiomer from its pharmacological aspect, is a clinically useful cardiotonic drug. From our previous photostability and chiral stability studies of DP, chiral inversion of DP was observed in aqueous solutions of DP drug substances and suspensions of DP tablets under the heat stress conditions dependent on the heating temperature and the storage period. In this paper, chiral inversion mechanism of DP was investigated employing phenylephrine hydrochloride (HCl) (R (-)-form) and ephedrine HCl (1R, 2S (-)-form) as samples for comparison. These drugs have the same phenylethylamine structure and the relationship between asymmetric C-atom and N-atom is similar. As a result, phenylephrine HCl and ephedrine HCl were found to be stable for heat stress. No chiral inversion was observed in both drugs. The difference between DP and phenylephrine HCl is the bond position of the hydroxy group in the phenyl group, and the difference between DP and ephedrine HCl is the existence of the hydroxy group in the phenyl group. From this study, an important step for the chiral inversion of DP was speculated as the formation of the stable benzyl cation in DP due to its hydroxy group at para-position of the phenyl group.