A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry method to determine plasma biotin in hemodialysis patients.
A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 μm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 μL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd.
Plasma Levels of Biotin Metabolites Are Elevated in Hemodialysis Patients with Cramps.
Patients with renal failure undergoing hemodialysis (HD) are susceptible to muscle cramps during and after HD. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied by severe pain. Through HD, water-soluble vitamins are drawn out with water. Since biotin, a water-soluble vitamin, plays an essential role as one of the coenzymes in producing energy, we have hypothesized that deficiency of biotin may be responsible for HD-associated cramps. We previously reported that biotin administration ameliorated the muscle cramps, despite the elevated plasma biotin levels before HD and biotin administration, as judged by an enzyme-linked immunosorbent assay (ELISA). However, the ELISA measures not only biotin but also total avidin-binding substances (TABS) including biotin metabolites. In the present study, we determined biotin in HD patients as well as healthy controls, using a newly developed method with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The plasma samples were collected from 28 HD patients (16 patients with cramps and 12 patients without cramps) before HD and biotin administration and from 11 controls. The results showed that the accumulation of biotin and TABS in plasma of HD patients compared to controls. Importantly, the levels of biotin metabolites, i.e. TABS subtracted by biotin, increased significantly in patients with cramps over those without cramps. Moreover, the levels of biotin metabolites were significantly higher in patients with a poor response to administered biotin, compared to those with a good response. We propose that accumulated biotin metabolites impair biotin's functions as a coenzyme.
One-pot synthesis of annulated pyrido[2,3-d:6,5-d]dipyrimidine derivatives using nitrogen based DBU catalyst in aqueous ethanol medium
Abstract We have reported DBU as an efficient organocatalyst for one-pot three-component synthesis of annulated pyrido[2,3- d :6,5- d ]dipyrimidine derivatives using aromatic aldehyde, thio-barbituric acid and 6-amino-uracil in aqueous ethanol under reflux. The attractive advantages of this process are mild reaction conditions, environment friendly procedure, short reaction times, easy isolation of products, and excellent yields (72–89%).