Rat Biological Fluids Research Articles

Detection and characterization of simvastatin and its metabolites in rat tissues and biological fluids using MALDI high resolution mass spectrometry approach

Simvastatin (SV) is a hypolipidemic agent, and it is the 2nd most widely prescribed lipid-lowering drug. Here, the detection and characterization of SV and its metabolites was studied in selected organs/tissues (lung, liver, brain, heart and kidney) and biological samples (blood, urine and feces) of rats. MALDI Orbitrap MS was used as a high-resolution mass analyzer. 2,5-Dihydroxybenzoic acid (DHB) and 1,5-diaminonaphthalene (DAN) were used as matrices. Several sample loading methods onto the MALDI plate were attempted and dried droplet method was found to be superior. Two different cell disruption methods, pulverization and homogenization, were also evaluated for the optimum sensitivity in MALDI. Pulverization allowed the detection of more metabolites in all organs except the liver, where homogenization led to the detection of more metabolites. Altogether, 13 metabolites were detected, and one metabolite tentatively identified as a reduced product is being reported for the first time. SV and its metabolites were distributed to all the tissues studied except the brain. Overall, the results implied that the pulverized samples were more uniform and larger in surface area, resulting in their more efficient and complete extraction during sample preparation. As shown in the present study, MALDI Orbitrap MS is a useful tool to study drug and metabolite detection and characterization.

Identification of absorbed constituents and in vivo metabolites in rats after oral administration of Physalis alkekengi var. franchetii by ultra-high-pressure liquid chromatography quadrupole time-of-flight mass spectrometry.

The calyces of Physalis alkekengi var. franchetii (Chinese Lantern, JDL) are well-known as traditional Chinese medicine owing to its various therapeutic effects. However, the bioactive constituents responsible for the pharmacological effects of JDL and their metabolites in vivo are still unclear to date. In this paper, an ultra-high-pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS/MS) method was established to identify absorbed constituents and in vivo metabolites in rat biological fluids after oral administration of JDL. Based on the proposed strategy, 33 compounds were observed in dosed rat biosamples. Twelve of 33 compounds were indicated as prototype components of JDL, and 21 compounds were predicted to be metabolites of JDL. Finally, the metabolic pathways were proposed, which were glucuronidation, sulfation, methylation and dehydroxylation for flavonoid constituents and sulfonation and hydroxylation for physalin consitituents. This is the first systematic study on the absorbed constituents and metabolic profiling of JDL and will provide a useful template for screening and characterizing the ingredients and metabolites of traditional Chinese medicine.

Analysis of the chemical constituents and rats metabolites after oral administration of Nauclea officinalis by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry.

Nauclea officinalis has long been used in China for the treatment of cold, fever, swelling of throat, pink eyes, and so on; however, the in vivo integrated metabolism of its multiple bioactive components remains unknown. In this paper, an ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) method was established to identify chemical constituents in N. officinalis and metabolites in rat biological fluids after oral administration of N. officinalis. First, 40 chemical constituents in N. officinalis were detected within 19min by UPLC-QTOF/MS. Among them, 18 alkaloids and 7 phenolic acids and iridoids were identified or tentatively characterized. Secondly, 22 metabolites were identified after oral administration of N. officinalis extract, including 3, 9, 6 and 4 metabolites in the plasma, feces, urine and bile samples, respectively. Finally, the metabolic pathway was proposed, which were the hydroxylation, the hydroxylation of deglycosyation product of parent compound, the hydroxylation and dehydrogenation product of parent compound, and acetylation. Among these, hydroxylation was considered as the main metabolic processes. This work suggests that the integrative metabolism approach makes a useful template for drug metabolism research of traditional Chinese medicine (TCM).

HPLC–Q-TOF–MS/MS Analysis of the Constituents in the Rat Biological Fluids After Oral Administration of Qing Ru Xiao granules

A high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry method was established to detect as many constituents in rat biological fluids as possible after oral administration of Qing Ru Xiao granules (QRX). An Agilent Poroshell 120 EC-C18 column was adopted to separate the sample constituents, and mass spectra were acquired in positive and negative ion modes. First, the fingerprints of QRX were established, resulting in 28 components being detected within 30 min. Among these compounds, 11 were tentatively identified by comparing the retention times and mass spectral data with those of reference standards and the reference literature; the other 17 components were tentatively assigned solely based on the mass spectrometry data. Furthermore, metabolites in rat plasma and urine after oral administration of QRX were also analyzed. A total of 15 compounds were identified, including 13 prototypes and 2 metabolites through metabolic pathways of oxidation. This is the first systematic study on the metabolic profiling of QRX.

Characterization of chemical constituents and rats metabolites of Shuanghua Baihe tablets by HPLC-Q-TOF-MS/MS.

A high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry method was established to detect as many constituents in rat biological fluids as possible after oral administration of Shuanghua Baihe tablets (SBT). An Agilent Poroshell 120 EC-C18 column was adopted to separate the samples, and mass spectra were acquired in positive and negative modes. First, the fingerprints of SBT were established, resulting in 32 components being detected within 40 min. Among these compounds, 12 were tentatively identified by comparing the retention times and mass spectral data with those of reference standards and the reference literature; the other 20 components were tentatively assigned solely based on the MS data. Furthermore, metabolites in rat plasma and urine after oral administration of SBT were also analyzed. A total of 19 compounds were identified, including 13 prototypes and six metabolites through metabolic pathways of demethylation and glucuronide conjugation. Glucuronidated alkaloids were the main constituents in the plasma, and were then excreted from urine. This is the first systematic study on the metabolic profiling of SBT.

Ultra high performance liquid chromatography method for the determination of pentamidine and analog in rat biological fluids

Pentamidine isethionate (PTMD) is an antiprotozoal agent used in different parasitic diseases as Human African Trypanosomiasis or Pneumocystis pneumonia. Given its side effects, numerous analogs are still under development worldwide. PTMD has been recently described having a potential activity in myotonic dystrophy (type 1). Here we present an UPLC method coupled to fluo or PDA detection for PTMD and one analog determination in rat plasma or urine. The chromatographic separation was achieved on a Acquity UPLC® HSS T3 analytical column using a mobile phase combining formic acid 0.1% (v/v) and acetonitrile (ACN) at a constant flow rate of 0.4mL/min. Preliminary, an innovative μSPE (solid phase extraction) procedure using Oasis® WCX sorbent was processed and gave satisfying and reproducible results in terms of extraction yields.Additionally, the methods were successfully validated using the accuracy profiles approach (β=95% and acceptance limits=15%) over the ranges 2.88–287.52ng/mL and from 143.76ng/mL to 1.72μg/mL in rat plasma and urine for PTMD and for EBAB, from 4.23 to 423.39ng/mL and from 211.69ng/mL to 2.54μg/mL for plasma and urine, respectively.The validated protocols were applied to a pharmacokinetic (PK) study on rats and permitted to point out some relevant PK parameters on PTMD and its studied analog.

Characterization of the Constituents in Rat Biological Fluids After Oral Administration of Longshen Buyi Paste by High-Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry

Characterization of the Constituents in Rat Biological Fluids After Oral Administration of Longshen Buyi Paste by High-Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry

Correlative analysis of metabolite profiling of Danggui Buxue Tang in rat biological fluids by rapid resolution LC–TOF/MS

In this work, the metabolite profiles of Danggui Buxue Tang (DBT) in rat bile and plasma were qualitatively described, and the possible metabolic pathways of DBT were subsequently proposed. Emphasis was put on correlative analysis of metabolite profiling in different biological fluids. After oral administration of DBT, bile and plasma samples were collected and pretreated by solid phase extraction. Rapid resolution liquid chromatography coupled to time-of-flight mass spectrometry (RRLC–TOFMS) was used for characterization of DBT-related compounds (parent compounds and metabolites) in biological matrices. A total of 142 metabolites were detected and tentatively identified from the drug-containing bile and plasma samples. Metabolite profiling shows that rat bile contained relatively more glutathione-derived conjugates, more saponins compounds and more diverse forms of metabolites than urine. The metabolite profile in plasma revealed that glucuronide conjugates of isoflavonoids, dimmers, acetylcysteine conjugates and parent form of phthalides, as well as saponin aglycones were the major circulating forms of DBT. Collectively, the metabolite profile analysis of DBT in different biological matrices provided a comprehensive understanding of the in vivo metabolic fates of constituents in DBT.

Characterization of the constituents in rat biological fluids after oral administration of Fufang Danshen tablets by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry

An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry method was established to detect as many constituents in rat biological fluids as possible after oral administration of Fufang Danshen tablets (FDTs). A C18 column (1.8 μm particle size) was adopted to separate the samples, and mass spectra were acquired in both negative and positive modes. First, the fingerprints of FDTs were established, resulting in 43 components being detected within 25 min. Among these compounds, 37 were tentatively identified by comparing the retention times and mass spectral data with those of reference standards and the reference literature; the other 6 components were tentatively assigned solely based on the MS data. In vivo, 14 components and 8 metabolites of FDT were observed in plasma, and 12 components of FDT were detected in urine. Tanshinaldehyde, danshexinkun B, a glycine conjugate of danshensu and a methylated conjugate of danshexinkun B were newly detected in rat biological fluids. This study developed a high-speed and sensitive method that was successfully utilized for screening the active ingredients of a Chinese medical formula and provided helpful chemical information for further pharmacology and active mechanism research on Chinese medicine.

Kinetics of metabolism and degradation of mometasone furoate in rat biological fluids and tissues.

Mometasone furoate (MF) is a potent glucocorticoid developed for the treatment of glucocorticoid-responsive inflammatory disorders. The in-vitro and ex-vivo kinetics of the degradation and metabolism of MF were studied in selected biological fluids of rat and subcellular fractions of different rat tissues. In-vitro, MF was found to degrade slowly into four products in serum and urine, and metabolized rapidly and extensively in rat liver, minimally in extrahepatic tissues, including intestine, stomach, lung and kidney. Further investigation found that the microsomal fraction was the major intracellular site of MF 6 beta-hydroxylation in rat liver. Using chemical inhibitors, CYP3A was found to be the major enzyme involved in the in-vitro MF 6 beta-hydroxylation in rat liver microsomes. Enzyme kinetic studies in rat liver microsomes showed that the overall metabolic process of MF followed biphasic Michaelis-Menten kinetics, while 6 beta-hydroxylation obeyed monophasic Michaelis-Menten kinetics. The kinetic parameters derived from the kinetic models along with the enzyme inhibition studies suggest that MF is mainly metabolized via 6 beta-hydroxylation mediated by CYP3A primarily, and also biotransformed via other pathway(s) catalysed by other enzymes in rat liver in-vitro.

Analysis of aplidine (dehydrodidemnin B), a new marine-derived depsipeptide, in rat biological fluids by liquid chromatography–tandem mass spectrometry

Aplidine (dehydrodidemnin B) is a new marine-derived depsipeptide with a powerful cytotoxic activity, which is under early clinical investigation in Europe and in the US. In order to investigate the pharmacokinetic properties of this novel drug, an HPLC–tandem mass spectrometry method was developed for the determination of aplidine in biological samples. Didemnin B, a hydroxy analogue, was used as internal standard. After protein precipitation with acetonitrile and extraction with chloroform, aplidine was chromatographed with a RP octadecylsilica column using a water–acetonitrile linear gradient in the presence of formic acid at the flow-rate of 500 μl/min. The method was linear over a 5–100 ng/ml range (LOD=0.5 ng/ml) in plasma and over a 1.25–125 ng/ml range (LOD=0.2 ng/ml) in urine with precision and accuracy below 14.0%. The intra- and inter-day precision and accuracy were below 12.5%. The extraction procedure recoveries for aplidine and didemnin B were 69% and 68%, respectively in plasma and 91% and 87%, respectively in urine. Differences in linearity, LOQ, LOD and recoveries between plasma and urine samples seem to be matrix-dependent. The applicability of the method was tested by measuring aplidine in rat plasma and urine after intravenous treatment.

Quantification of Clara cell protein in rat and mouse biological fluids using a sensitive immunoassay

Clara cell protein is a 16-17 kDa protein (CC16) secreted by Clara cells in the bronchiolar lining fluid of the lung. In order to investigate the potential of this protein as a pulmonary marker in animals, CC16 was isolated from rat bronchoalveolar lavage fluid (BALF) and a sensitive latex immunoassay applicable to both rat and mouse CC16 was developed. The pattern of CC16 concentrations in rat biological fluids determined by the immunoassay was consistent with the hypothesis of a passive diffusion of the protein across the bronchoalveolar/blood barriers showing a difference of more than 5,000 fold between the concentration in the epithelial lining fluid (mean, 140 mg x L(-1)) and that in serum (20 microg x L(-1)) or urine (3 microg x L(-1)). In BALF, the CC16 concentration averaged 5,500 microg x L(-1) and was of the same magnitude as that determined on lung and trachea homogenates. CC16 was also detectable in amniotic fluid with a mean value of 800 microg x L(-1) before delivery. Damage of Clara cells produced by methylcyclopentadienyl manganese tricarbonyl resulted in a significant decrease of CC16 in BALF but did not affect the serum levels of the protein. The nephrotoxicant sodium chromate by contrast had no influence on the CC16 content of BALF but markedly increased CC16 levels in both serum and urine as a result of impaired glomerular filtration and tubular reabsorption, respectively. In conclusion, mouse or rat Clara cell protein of 16-17 kDa can easily be quantified, not only in bronchoalveolar lavage fluid, but also in extrapulmonary fluids such as serum or urine. Thus, in rodents, Clara cell protein of 16-17 kDa follows the same metabolic pathway as in humans, diffusing from the respiratory tract into serum where it is eliminated by the kidneys. This serum Clara cell protein of 16-17 kDa may be useful as a peripheral marker of events taking place in the respiratory tract.

High-performance liquid chromatographic determination of quinine in rat biological fluids

A high-performance liquid chromatographic (HPLC) method with ultraviolet detection for the determination of quinine in rat biological fluids is described. Due to its selectivity and sensitivity, the proposed method can be used in the case of such rat biological fluids as cerebrospinal fluid (CSF) and perilymph for which the accessible volumes are limited to 100 μl and 10 μl, respectively. Consequently, the assay method has been applied to the measurements of quinine concentration in rat plasma, CSF and perilymph samples.

In-vitro evaluation of biphenylyl acetic acid-beta-cyclodextrin conjugates as colon-targeting prodrugs: drug release behaviour in rat biological media.

Biphenylyl acetic acid was selectively conjugated to one of the primary hydroxyl groups of beta-cyclodextrin through an ester- or amide-linkage, and the physicochemical properties (aqueous solubility and hydrolysis) were investigated. Aqueous solubility of the conjugates was lower than those of either drug or parent beta-cyclodextrin. The amide conjugate was stable in aqueous solution and in rat biological fluids and gastrointestinal contents. The ester conjugate was hydrolysed to beta-cyclodextrin and biphenylyl acetic acid at moderate rates resulting in a V-shaped rate-pH profile in aqueous solution. The ester conjugate released the drug preferentially when incubated with the contents of caecum or colon, whereas no appreciable drug release was observed on incubation with contents of stomach or intestine, nor on incubation with intestinal or liver homogenates, nor on incubation with rat blood. The present results suggest that the ester-type drug conjugate of beta-cyclodextrin may serve as a colon-targeting prodrug.

Identification of higenamine and its metabolites in rat by gas chromatography/mass spectrometry

(±)-Higenamine is known as a cardiotonic principle of aconite root (root ofAconitum spp., Ranunculaceae). A simple and sensitive detection method for higenamine was developed by using gas chromatography-mass spectrometry (GC/MS). The recovery of higenamine after extraction and concentration with XAD-2 resin column was around 95% from rat biological fluids such as bile, plasma and urine. The limits of detection of higenamine in these biological fluids were approximately 0.1 ng/ml each. It has well been suggested that tetrahydroisoquinolines possessing catechol moiety such as higenamine should be subjected to the catechol-O-methyl transferase (COMT) activityin vivo. We detected two major peaks of presumed metabolites of higenamine in the total ion chromatogram obtained from the rat urine sample after the oral administration of (±)-higenamine. The scan mass spectrum of one of the metabolites coincided with those obtained from coclaurine (C6-O-methyl higenamine) and those of the other metabolite are suggestive of isococlaurine (C7-O-methyl higenamine).

Development and validation of a highperformance liquid chromatographic method for the determination of benzophenone‐3 in rats

A precise, accurate, selective and sensitive liquid chromatographic method for the determination of benzophenone-3 in rat biological fluids and different tissues has been developed. The minimum detection limit for benzophenone-3 was 2.0 ng ml-1 and the retention time was 6.01 min. Standard curves for benzophenone-3 were linear in a wide range of concentrations in methanol and different body fluids, ranging from 6.25 ng ml-1 to 100 micrograms ml-1. To detect benzophenone-3 in rat whole blood after oral administration, HCl hydrolysis was required. Benzophenone-3 was found to produce a peak blood concentration 1 h after administration. Free benzophenone-3 in urine represented a very small percentage during the first 12 h after administration, while a higher concentration of the glucuronide conjugate was detected in the same time period.

Sensitive and rapid colorimetric immunoenzymometric assay of ferritin in biological samples

We describe a rapid and sensitive enzyme-linked immunosorbent assay (ELISA) for quantifying ferritin in human and rat biological fluids. We used chlorophenol red beta-D-galactopyranoside as the colorimetric substrate of beta-galactosidase (EC 3.2.1.23), which is coupled to specific antibodies to either human or rat liver ferritin. The assay is sensitive (detection limit for human assay = 0.58 micrograms/L and for rat assay = 0.37 micrograms/L), accurate (average recovery for human assay = 93% and for rat assay = 92%), and precise (total CVs for human assay = 2.3-12.2% and for rat assay = 5.6-11.3%). The results correlated well with those of an established immunoradiometric technique (r = 0.99691). This assay has a prolonged shelf-life, is inexpensive, and utilizes a stable colorimetric substrate that requires relatively short incubation.

A sensitive enzyme immunoassay system of rat epidermal growth factor in biological fluids and tissue extracts.

Rat epidermal growth factor was purified from rat submandibular glands to obtain specific antiserum for the establishment of an immunoassay system. Purified rat epidermal growth factor showed a single peak on reverse phase HPLC and a single band on sodium dodecyl sulphate polyacrylamide gel electrophoresis at mol wt 5100 in the presence of 2-mercaptoethanol and at mol wt 41,000 in the absence of 2-mercaptoethanol. Antibody against rat epidermal growth factor showed cross-reactivities with mouse and human epidermal growth factors on soft agar-double immunodiffusion test. The established sandwich enzyme immunoassay for rat epidermal growth factor had a high sensitivity (500 fg/tube), which made it possible to measure minute amounts of endogenous rat epidermal growth factor without pretreatment. Physiological concentrations of rat epidermal growth factor in rat biological fluids and tissues were determined. Species differences in physiological distributions of epidermal growth factor are discussed.