Pharmacokinetic study of the novel phosphocholine derivative 3-dibutylaminopropylphosphonic acid by LC-MS coupling.

CRP is an important mediator of the inflammatory response. Pro-inflammatory CRP effects are mediated by pCRP* and mCRP, dissociation products of the native pCRP. The concentration of pCRP during inflammation may rise up to concentrations 1000-fold from baseline. By prevention of the conformational change from pCRP to pCRP*, pro-inflammatory immune responses can be inhibited and local tissue damage reduced. 3-(Dibutylamino)propylphosphonic acid (C10m) is a new substance that can suppress ischemic-reperfusion injury by targeting CRP in the complement cascade. It hampers dissociation of pCRP into its monomers, thus preventing exacerbation of tissue inflammation subsequent to reperfusion injury. In this study, the pharmacokinetics and metabolism of the new drug candidate C10m was investigated. A sensitive and selective method for detection of C10m and its metabolites from plasma and urine was developed with LC-MS and LC-MS/MS coupling. The LLOQ is at 0.1 µg mL-1 and recovery at 87.4% ± 2.8%. Accuracy and precision were within 15% coefficient of variation and nominal concentrations, respectively. Concentration time profile after i.v. bolus injection of C10m was analyzed by LC-MS/MS. Bioavailability has shown to be below 30%. Most likely due to the compounds' very polar chemical properties, no phase-I or phase-II metabolism could be observed. Absence of phase-I metabolism was cross-checked by performing microsomal incubations. Our study revealed that C10m is rapidly eliminated via urine excretion and that half-times appear to be increased with coadministration of the target pCRP.

pH detection in biological samples by 1D and 2D 1H-31P NMR.

The chemical shifts of several important endogenous phosphorus compounds under different pH conditions were explored, including adenosine-5'-triphosphate, adenosine-5'-diphosphate, adenosine-5'-monophosphate, phosphorylcholine and phosphorylethanolamine. Their 31P NMR and 1H NMR chemical shifts were all pH-sensitive in the similar pH range. Two dimensional (2D) 1H-31P NMR spectra were found helpful to identify these endogenous phosphorus markers in biological samples from rather complicated NMR spectra. Herein, for the first time, a pH sensor based on 2D 1H-31P NMR was established and applied to biological samples analysis with pH values determined in good agreement with those by potentiometric method. Apart from being simple, green, rapid and less sample-consuming, information concerning both the endogenous phosphorus markers and pH status could be attained in a single NMR run, which demonstrated the great potential of this method in rare sample analysis and even disease diagnosis.

Metabonomic profiling of serum and urine by (1)H NMR-based spectroscopy discriminates patients with chronic obstructive pulmonary disease and healthy individuals.

Chronic obstructive pulmonary disease (COPD) has seriously impacted the health of individuals and populations. In this study, proton nuclear magnetic resonance ((1)H NMR)-based metabonomics combined with multivariate pattern recognition analysis was applied to investigate the metabolic signatures of patients with COPD. Serum and urine samples were collected from COPD patients (n = 32) and healthy controls (n = 21), respectively. Samples were analyzed by high resolution (1)H NMR (600 MHz), and the obtained spectral profiles were then subjected to multivariate data analysis. Consistent metabolic differences have been found in serum as well as in urine samples from COPD patients and healthy controls. Compared to healthy controls, COPD patients displayed decreased lipoprotein and amino acids, including branched-chain amino acids (BCAAs), and increased glycerolphosphocholine in serum. Moreover, metabolic differences in urine were more significant than in serum. Decreased urinary 1-methylnicotinamide, creatinine and lactate have been discovered in COPD patients in comparison with healthy controls. Conversely, acetate, ketone bodies, carnosine, m-hydroxyphenylacetate, phenylacetyglycine, pyruvate and α-ketoglutarate exhibited enhanced expression levels in COPD patients relative to healthy subjects. Our results illustrate the potential application of NMR-based metabonomics in early diagnosis and understanding the mechanisms of COPD.