LC–MS/MS quantitative analysis of phylloquinone, menaquinone-4 and menaquinone-7 in the human serum of a healthy population

Abstract

A novel application of the liquid chromatography method combined with the triple quadrupole tandem mass spectrometry method was developed for the quantification of vitamin K1 and two forms of vitamin K2 (menaquinone-4, menaquinone-7) in human serum. Total chromatography time for each run was 9 min. Time required for the sample pretreatment procedures was approximately 4 h. The coefficients of variation (CVs) of intra-assay were 10.4%, 3.2 % and 2.3% for vitamin K1 in three levels of quality control samples; were 14.3%, 3.2% and 6.7% for menaquinone-4; and were 11.1%, 6.0% and 7.0% for menaquinone-7. The inter-assay CVs were 12.8%, 11.3% and 7.4% for vitamin K1; were 15.2%, 9.2% and 8.7% for menaquinone-4; and were 13.2%,11.1% and 7.2% for menaquinone-7. No interference was found between K1, menaquinone-4 and menaquinone-7, nor any deuterated internal standards. This method was then used to determine reference values for Caucasian populations of central European origin. Samples were measured from 191 healthy volunteers (51.2 ± 16.2 years (mean ± SD)) and the values concerning K1 were 0.044–1.357 ng/mL for women and 0.030–1.214 ng/mL for men. The values for menaquinone-4 and menaquinone-7 did not exhibit any differences between women and men, and were 0.050–1.598 and 0.074–0.759 ng/mL, respectively.

The Reductive Activity of Human Liver Microsomes for Vitamin K Epoxides

“…2, Table 1). Although about 90% of human VK intake is VK1 [16], the blood concentrations of VK1 and MK4 are similar (0.044-1.357 and 0.074-0.759 ng/mL for VK1 and MK4, respectively) [25], and most of the VK in organs such as the brain, pancreas, and liver are also MK4 [26]. Those data also support our results.…”

Vitamin K2 Needs an RDI Separate from Vitamin K1

“…The variety of methods for detecting vitamin K and its analogs has been recently described in detail by others [ 33 ]. Recently, a combination of liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS) was reported to be able to quantify VK1 and VK2 isoforms MK-4 and MK-7 from human serum in different populations [ 34 , 35 , 36 , 37 ]. Whether this is the beginning of the establishment of a gold standard remains an open question, and further efforts are being made to include VK2 in the KEQAS with pilot studies on MK-4 and MK-7 ongoing ( ).…”

Inhibition of the futalosine pathway for menaquinone biosynthesis suppresses Chlamydia trachomatis infection

“…Chlamydial and uninfected HeLa cell samples were first subjected to hexanes extractions to isolate isoprenoid quinones [28]. Because bacterial menaquinones have polyisoprenyl side chains of varying lengths [34], we employed an LC‐MS/MS precursor ion scan for the 2‐methyl‐1,4‐naphthoquinone product ion (m/z 187.0) [35]. Analysis of both extraction samples identified MK‐7 exclusively in the chlamydial extract as the [M + H] + and [M+NH 4 ] + ions (observed [M + H] + = 649.4, calculated [M + H] + = 649.5; observed [M+NH 4 ] + = 666.3, calculated [M+NH 4 ] + = 666.5) (Figure 2).…”