Liquid chromatography-tandem mass spectrometry bioanalytical method for the determination of kavain in mice plasma: Application to a pharmacokinetic study.

A simple and fast bioanalytical method for the quantification of kavain in mice plasma was developed using liquid chromatography (LC)-tandem mass spectrometry (MS/MS). A full method validation was performed, according to regulatory guidelines, employing isotopically labeled kavain as the internal standard (racemic-kavain-d3). For the quantification, [M+H]+ was formed using an electrospray ionization (ESI) source in the positive ion mode and multiple reaction monitoring (MRM) was employed using a quadrupole-linear ion trap (4000 QTRAP®) instrument. The monitored MRM transitions were 231.0 â†’ 115.1 and 231.0 â†’ 152.8 for kavain; and 234.2 â†’ 199.2 for the internal standard. A linear response was obtained at the concentration range of 10 to 200 ng/mL with intra- and inter-day variations within the acceptable criteria for all quality control samples. After validation, the method was successfully applied for the quantification of kavain in mice plasma after oral administration of the kavain standard and Kava-kava extract. The plasma concentration over time results were applied for a pharmacokinetics study. The obtained pharmacokinetic parameters indicated a considerably higher bioavailability for kavain when Kava-kava extract was administered due to a pharmacokinetic synergism between the analyte and the other compounds present in the extract.

A new tripodal kojic acid derivative for iron sequestration: Synthesis, protonation, complex formation studies with Fe3+, Al3+, Cu2+ and Zn2+, and in vivo bioassays.

This work presents the simple and low cost synthesis of a new tripodal ligand, in which three units of kojic acid are coupled to a tris(2-aminoethyl)amine (tren) backbone molecule. The protonation equilibria, together with the complex formation equilibria of this ligand with Fe3+, Al3+, Cu2+ and Zn2+ ions were studied. The complementary use of potentiometric, spectrophotometric and NMR techniques, and of Density Functional Theory (DFT) calculations, has allowed a thorough characterization of the different species involved in equilibrium. The stability of the formed complexes with Fe3+ and Al3+ are high enough to consider the new ligand for further studies for its clinical applications as a chelating agent. Biodistribution studies were carried out to assess the capacity the ligand for mobilization of gallium in 67Ga-citrate injected mice. These studies demonstrated that this ligand efficiently chelates the radiometal in our animal model, which suggests that it can be a promising candidate as sequestering agent of iron and other hard trivalent metal ions. Furthermore, the good zinc complexation capacity appears as a stimulating result taking into a potential use of this new ligand in analytical chemistry as well as in agricultural and environmental applications.

Bone and Joint Tissue Penetration of the Staphylococcus-Selective Antibiotic Afabicin in Patients Undergoing Elective Hip Replacement Surgery.

Afabicin (formerly Debio 1450, AFN-1720) is a prodrug of afabicin desphosphono (Debio 1452, AFN-1252), a novel antibiotic in development which targets the staphylococcal enoyl-acyl carrier protein reductase (FabI) and exhibits selective potent antibacterial activity against staphylococcal species, including methicillin-resistant Staphylococcus aureus As part of clinical development in bone and joint infections, a distribution study in bone was performed in 17 patients who underwent elective hip replacement surgery. Patients received 3 doses of 240 mg afabicin orally (every 12 h) at various time points before surgery. Afabicin desphosphono concentrations were measured by liquid chromatography-tandem mass spectrometry in plasma, cortical bone, cancellous bone, bone marrow, soft tissue, and synovial fluid collected during surgery at 2, 4, 6, or 12 h after the third afabicin dose. The study showed good penetration of afabicin desphosphono into bone tissues, with mean area under the curve ratios for cortical bone-, cancellous bone-, bone marrow-, soft tissue-, and synovial fluid-to-total plasma concentrations of 0.21, 0.40, 0.32, 0.35, and 0.61, respectively. When accounting for the free fraction in plasma (2%) and synovial fluid (9.4%), the mean ratio was 2.88, which is indicative of excellent penetration and which showed that the afabicin desphosphono concentration was beyond the MIC90 of S. aureus over the complete dosing interval. These findings, along with preclinical efficacy data, clinical efficacy data for skin and soft tissue staphylococcal infection, the availability of both intravenous and oral formulations, and potential advantages over broad-spectrum antibiotics for the treatment of staphylococcal bone or joint infections, support the clinical development of afabicin for bone and joint infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02726438.).

A stable isotope dilution tandem mass spectrometry method of major kavalactones and its applications.

Kava is regaining its popularity with detailed characterizations warranted. We developed an ultraperformance liquid chromatography high-resolution tandem mass spectrometry (UPLC-MS/MS) method for major kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin and desmethoxyyangonin) with excellent selectivity and specificity. The method has been validated for different matrices following the Food and Drug Administration guidance of analytical procedures and methods validation. The scope of this method has been demonstrated by quantifying these kavalactones in two kava products, characterizing their tissue distribution and pharmacokinetics in mice, and detecting their presence in human urines and plasmas upon kava intake. As expected, the abundances of these kavalactones differed significantly in kava products. All of them exhibited a large volume of distribution with extensive tissue affinity and adequate mean residence time (MRT) in mice. This method also successfully quantified these kavalactones in human body fluids upon kava consumption at the recommended human dose. This UPLC-MS/MS method therefore can be used to characterize kava products and its pharmacokinetics in animals and in humans.

The Pharmacology, Pharmacokinetics, Efficacy, and Adverse Events Associated With Kava.

Kava is a plant with numerous kavapyrones that can induce pharmacologic effects and drug interactions through the cytochrome P450 and P-glycoprotein systems. Kava is used recreationally and for the treatment of anxiety. Clinical trials verify anxiolytic effects in excess of placebo, but the effects are not seen immediately and the optimal dose and dosing schedule needs to be determined. Clinical trials usually lasting for 4 weeks found generally good tolerability and safety; however, dermatologic, hepatologic, and cognitive adverse effects may occur. Some of these adverse effects are known to occur from the kavapyrones themselves, while others can be caused or exacerbated by use of substandard kava products. There is tremendous variability in the constitution of a kava product based on the parts of the plant that are being extracted and the extraction method. The most commonly studied extract for the treatment of anxiety is the acetone extract.

A systematic review of the protective role of swertiamarin in cardiac and metabolic diseases.

BACKGROUND: Swertiamarin, is a secoiridoid glycoside found in genera of Enicostemma Species (Enicostemma littorale and Enicostemma axillare) belonging to the family of gentianaceae, which has been reported to cure many diseases such as diabetes, hypertension, atherosclerosis, arthritis, malaria and abdominal ulcers. However, to the best of our knowledge, till date systematic studies to understand the molecular basis of cardiac and metabolic disease preventing properties of swertiamarin has not been reported. AIM OF THE REVIEW: The present review aims to compile an up-to-date information on the progress made in the protective role of swertiamarin in cardiac and metabolic diseases with the objective of providing a guide for future research on this bioactive molecule. MATERIALS AND METHODS: Information on the swertiamarin was collected from major scientific databases (Pubmed, Springer, google scholar, and Web of Science) for publication between1974-2016. In this review, the protective role of swertiamarin on cardiac and metabolic diseases was discussed. RESULTS: Swertiamarin reported to exhibit a wide range of biological activities such as anti-atherosclerotic, antidiabetic, anti-inflammatory and antioxidant effects. These activities were mainly due to its effect on various signaling pathways associated with cardiac remodeling events such as inhibition of NF-kB expression, LDL oxidation, apoptosis, inflammatory and lipid peroxidation markers and stimulation of antioxidant enzymes. CONCLUSION: Sweriamarin exhibit a wide range of biological activities. This review presents evidence supporting the point of view that swertiamarin should be considered a potential therapeutic agent against cardiac and metabolic diseases, giving rise to novel applications in their prevention and treatment.

Determination and pharmacokinetic study of gentiopicroside, geniposide, baicalin, and swertiamarin in Chinese herbal formulae after oral administration in rats by LC-MS/MS.

A sensitive and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of gentiopicroside, geniposide, baicalin, and swertiamarin in rat plasma. To avoid the stress caused by restraint or anesthesia, a freely moving rat model was used to investigate the pharmacokinetics of herbal medicine after the administration of a traditional Chinese herbal prescription of Long-Dan-Xie-Gan-Tang (10 g/kg, p.o.). Analytes were separated by a C18 column with a gradient system of methanol-water containing 1 mM ammonium acetate with 0.1% formic acid. The linear ranges were 10-500 ng/mL for gentiopicroside, geniposide, and baicalin, and 5-250 ng/mL for swertiamarin in biological samples. The intra- and inter-day precision (relative standard deviation) ranged from 0.9% to 11.4% and 0.3% to 14.4%, respectively. The accuracy (relative error) was from -6.3% to 10.1% at all quality control levels. The analytical system provided adequate matrix effect and recovery with good precision and accuracy. The pharmacokinetic data demonstrated that the area under concentration-time curve (AUC) values of gentiopicroside, geniposide, baicalin, and swertiamarin were 1417 ± 83.8, 302 ± 25.8, 753 ± 86.2, and 2.5 ± 0.1 min µg/mL. The pharmacokinetic profiles provide constructive information for the dosage regimen of herbal medicine and also contribute to elucidate the absorption mechanism in herbal applications and pharmacological experiments.

A rapid and sensitive UFLC-MS/MS method for the simultaneous determination of gentiopicroside and swertiamarin in rat plasma and its application in pharmacokinetics.

OBJECTIVES: Radix Gentianae is a traditional Chinese medicine derived from medicinal plants of the family Gentianaceae. Its pharmacological effects have been primarily attributed to the presence of a number of secoiridoid glycosides, in particular gentiopicroside and swertiamarin. In this study, a rapid and sensitive method based on ultrafast liquid chromatography-tandem mass spectrometry has been developed for the simultaneous determination of gentiopicroside and swertiamarin in rat plasma using paeoniflorin as internal standard (IS). METHODS: After liquid-liquid extraction with ethyl acetate-isopropanol (95 : 5, v/v), separation was achieved on a Shim-pack XR-ODS C18 column (75 mm × 3.0 mm, 2.2 µm) with a mobile phase consisting of methanol : 0.1% formic acid (30 : 70, v/v) at a flow rate of 0.4 ml/min. Detection on an API 3200 QTRAP mass spectrometer equipped with an electrospray ionization source operated in the negative ionization mode was performed by multiple reaction monitoring of the precursor-to-product ion transitions of gentiopicroside, swertiamarin and IS at m/z 401.0 → 179.0, 419.0 → 179.1 and 525.1 → 121.0 respectively. The calibration curves were linear over the concentration range of 20-10 000 and 2-1000 ng/ml for gentiopicroside and swertiamarin with corresponding lower limits of quantification of 20 and 2 ng/ml. The limits of detection were 4 and 0.5 ng/ml for gentiopicroside and swertiamarin, respectively. The intraday and interday precisions were below 11.9% for gentiopicroside and below 9.5% for swertiamarin in terms of relative standard deviation, and the accuracy was within ±8.3% for gentiopicroside and within ±10.2% for swertiamarin in terms of relative error. Extraction recovery, matrix effect and stability were satisfactory in rat plasma. The method was fully validated and applied to a pharmacokinetic study involving oral administration of a Radix Gentianae extract to groups of male and female rats. KEY FINDINGS: Results showed that in female rats, both compounds were absorbed to a greater extent and eliminated more slowly than in male rats, although the rate of absorption was similar in the two groups. CONCLUSIONS: There were remarkable differences in pharmacokinetic properties of gentiopicroside and swertiamarin between male and female rats. The results will provide helpful information for the development of suitable dosage forms and clinical references on rational administration.

Comparative pharmacokinetics of swertiamarin in rats after oral administration of swertiamarin alone, Qing Ye Dan tablets and co-administration of swertiamarin and oleanolic acid.

ETHNOPHARMACOLOGICAL RELEVANCE: Qing Ye Dan is a well-known herbal drug that is widely used to treat viral hepatitis in the Yi and Hani minority regions in the Yunnan province of China. MATERIALS AND METHODS: An LC-MS/MS method was developed to determine the levels of swertiamarin in rat plasma. Swertiamarin and naringin (internal standard, IS) were extracted from rat plasma using solid-phase extraction (SPE) to purify the samples. The pharmacokinetics of the following different administration methods of swertiamarin in rats were studied: oral administration of swertiamarin alone, a Qing Ye Dan tablet (QYDT) and co-administration of swertiamarin and oleanolic acid, with each method delivering approximately 20mg/kg of swertiamarin. Non-compartmental pharmacokinetic profiles were constructed by using the software DAS (version 2.1.1), and the pharmacokinetic parameters were compared using an unpaired Student's t-test. RESULTS: The results showed that the pharmacokinetic parameters Cmax, AUC0-∞, Vz/F and CLz/F were significantly different (P<0.05) among the three types of swertiamarin administration. CONCLUSIONS: The data indicate that oleanolic acid and the other ingredients present in QYDT could affect the pharmacokinetic behaviour of swertiamarin in rats.

[Quickly investigating the absorption ingredients of Gentianae Radix et Rhizoma by SEMAC].

OBJECTIVE: To establish a method for quickly investigating the absorption ingredients which could be used as the index of quality control of Gentianae Radix et Rhizoma. METHOD: The absorption ingredients of Gentianae Radix et Rhizoma were investigated by using the model of in vitro everted intestinal sac (VEIS). The intestinal sac liquors of jejunum and ileum were collected at 6 intervals (15, 30, 45, 60, 90, 120 min) and gentiopicroside, loganin acid, swertiamarin and sweroside were detected by HPLC as the representative marker. The accumulative absorption quantity of gentiopicroside, loganin acid, swertiamarin and sweroside were calculated, respectively. RESULT: Six components could be detected in intestinal sac. In different concentrations of Gentianae Radix et Rhizoma, gentiopicroside and swertiamarin in various intestinal sections were the linear absorption (R2 > 0.9), conformed to zero order absorption rate. In jejunum the constant of absorption rate (Ka) of gentiopicroside and swertiamarin increased with the raised dosage of Gentianae Radix et Rhizoma (P < 0.05), which indicated a passive absorption manner, and the value of Ka of high and middle dosage of those in ileum were higher than that of low dosage, and the difference of Ka between high and middle dosage were not significant, which indicated a positive absorption manner. The Ka of high and middle dosage of sweroside in ileum and jejunum were higher than that of low dosage (P < 0.05), and the difference of Ka between high and middle dosage were not significant, which indicated a positive absorption manner. The Ka of loganin acid in jejunum and ileum increased along with the raised dosage of Gentianae Radix et Rhizoma (P < 0.05), which indicated a passive absorption manner. CONCLUSION: SEMAC could be used as a tool to investigate the absorption ingredients of Gentianae Radix et Rhizoma. Drug in intestine sac was selective, and the absorption part of intestine was also different.

[Study of the process of diffusion of gentin tablets through the artificial lipid barrier].

Currently during medical treatment of the patients suffering with gastrointestinal system diseases, particular attention is being devoted to the medical remedies of plant origin, which allow its protracted use during these diseases without expressed negative influence on important functions and structures of organism. Study of the dependence of the diffusion rate of active substances presented here as a multi-component plant origin dosage form, from the dissolution profile of solid dosage form in gastrointestinal tract, is an actual biopharmaceutical problem, which gives an information about the completeness of release of the active substances from the dosage form and its bioavailability. Gentin tablets developed at the department of pharmaceutical technology of Tbilisi State Medical University, presents the phytopreparation recommended for the prevention and treatment of the diseases of gastro-intestinal system. In-vitro study of the diffusion kinetics of active compounds from gentin tablets were performed using membrane model "SARTORIUS" Sm 16750 (FRG), which allows study of the diffusion rate of medical substances in the conditions closely imitating gastro-intestinal tract. Obtained experimental data showed that gamma-pyronic compounds are better absorbed in intestines than in stomach, as the value of diffusion rate constant k(d) in intestinal juice (pH=6,8) is 9, 17 x 10(-3) cm/min, while k(d) in gastric juice (pH=1,2) is 1, 63 x 10(-3) cm/min, thus the diffusion process is much more intensive in intestinal media with pH=6,8.

Identification and characterization of kava-derived compounds mediating TNF-alpha suppression.

There is a substantial unmet need for new classes of drugs that block TNF-alpha-mediated inflammation, and particularly for small molecule agents that can be taken orally. We have screened a library of natural products against an assay measuring TNF-alpha secretion in lipopolysaccharide-stimulated THP-1 cells, seeking compounds capable of interfering with the TNF-alpha-inducing transcription factor lipopolysaccharide-induced TNF-alpha factor. Among the active compounds were several produced by the kava plant (Piper mysticum), extracts of which have previously been linked to a range of therapeutic effects. When tested in vivo, a representative of these compounds, kavain, was found to render mice immune to lethal doses of lipopolysaccharide. Kavain displays promising pharmaceutical properties, including good solubility and high cell permeability, but pharmacokinetic experiments in mice showed relatively rapid clearance. A small set of kavain analogs was synthesized, resulting in compounds of similar or greater potency in vitro compared with kavain. Interestingly, a ring-opened analog of kavain inhibited TNF-alpha secretion in the cell-based assay and suppressed lipopolysaccharide-induced TNF-alpha factor expression in the same cells, whereas the other compounds inhibited TNF-alpha secretion without affecting lipopolysaccharide-induced TNF-alpha factor levels, indicating a potential divergence in mechanism of action.

Pharmacovirological impact of an integrase inhibitor on human immunodeficiency virus type 1 cDNA species in vivo.

Clinical trials of the first approved integrase inhibitor (INI), raltegravir, have demonstrated a drop in the human immunodeficiency virus type 1 (HIV-1) RNA loads of infected patients that was unexpectedly more rapid than that with a potent reverse transcriptase inhibitor, and apparently dose independent. These clinical outcomes are not understood. In tissue culture, although their inhibition of integration is well documented, the effects of INIs on levels of unintegrated HIV-1 cDNAs have been variable. Furthermore, there has been no report to date on an INI's effect on these episomal species in vivo. Here, we show that prophylactic treatment of transgenic rats with the strand transfer INI GSK501015 reduced levels of viral integrants in the spleen by up to 99.7%. Episomal two-long-terminal-repeat (LTR) circles accumulated up to sevenfold in this secondary lymphoid organ, and this inversely correlated with the impact on the proviral burden. Contrasting raltegravir's dose-ranging study with HIV patients, titration of GSK501015 in HIV-infected animals demonstrated dependence of the INI's antiviral effect on its serum concentration. Furthermore, the in vivo 50% effective concentration calculated from these data best matched GSK501015's in vitro potency when serum protein binding was accounted for. Collectively, this study demonstrates a titratable, antipodal impact of an INI on integrated and episomal HIV-1 cDNAs in vivo. Based on these findings and known biological characteristics of viral episomes, we discuss how integrase inhibition may result in additional indirect antiviral effects that contribute to more rapid HIV-1 decay in HIV/AIDS patients.

Simultaneous estimation of mangiferin and four secoiridoid glycosides in rat plasma using liquid chromatography tandem mass spectrometry and its application to pharmacokinetic study of herbal preparation.

Extracts from Swertia chirata (family Gentianaceae) have antidiabetics and antioxidant activity, largely attributed to the flavonoids and secoiridoids, which are a major class of functional components in methanolic extracts from aerial part of plants. In order to facilitate analysis of systemic exposure to S. chirata derived products in animals, we developed a liquid chromatography tandem mass spectrometry (LC-MS/MS) based method that is capable of routinely monitoring plasma levels of flavonoids and secoiridoids. An LC-MS/MS-based method has been developed for the simultaneous estimation of two bioactive markers, mangiferin and amarogentin along with three other components, amaroswerin, sweroside and swertiamarin in rat plasma. All the analytes including the internal standard (kutkoside) were chromatographed on RP-18 column (250 mm x 4 mm i.d., 5 microm.) coupled with guard column using acetonitrile: 0.5 mM ammonium acetate buffer, pH approximately 3.0 as mobile phase at a flow rate of 1 ml/min in gradient mode. The final flow to source was splitted in 1:1 ratio. The detection of the analytes was performed on API 4000 LC-MS/MS system in the multiple reaction-monitoring (MRM) mode. The quantitation for analytes other than the pure markers was based on relative concentration. The method was validated in terms of establishing linearity, specificity, sensitivity, recovery, accuracy and precision (Intra- and Inter-day), freeze-thaw stability, peltier stability, dry residue stability and long-term stability. The recoveries from spiked control samples were >90% for all analytes and internal standard except mangiferin where recovery was >60%. Intra- and inter-day accuracy and precision of the validated method were within the acceptable limits of <15% at low and <10% at other concentrations. The quantitation method was successfully applied to generate pharmacokinetic (PK) profile of markers as well as to detect other components in plasma after intravenous dose administration of herbal preparation in male Sprague-Dawley (SD) rats.

Permeability studies of Kavalactones using a Caco-2 cell monolayer model.

OBJECTIVE: To examine the bioavailability of kavalactones in vitro and the possible differences in their bioavailability because of variations in either chemical structure or the method of extraction used. RESEARCH DESIGN AND METHODS: Caco-2 cell monolayers were used to determine the potential bioavailability of kavalactones. Kavalactones were added to the apical layer and basolateral samples were taken over 150 min to examine the concentration diffusing across the cell monolayer. Kavalactone concentrations in these samples were determined by high pressure liquid chromatography. RESULTS: Kavalactones were found to be potentially bioavailable as they all readily crossed the Caco-2 monolayers with apparent permeabilities (P(app)) increasing from 42 x 10(-6) cm/s and most exhibiting more than 70% crossing within 90 min. Not all differences in their bioavailability can be related to kavalactone structural differences as it appears that bioavailability may also be affected by co-extracted compounds. For example, the P(app) for kawain from ethanol extracts was higher than the values obtained for the same compound from water extracts or for the kavalactone alone. CONCLUSIONS: While the extraction method used (ethanol or water) influences the total (but not the relative) concentrations of kavalactones, it does not markedly affect their bioavailability. Hence, any differences between an ethanolic or an aqueous extract in terms of the propensity of kava to cause liver damage is not because of differing kavalactone bioavailabilities.

Pharmacokinetics and disposition of the kavalactone kawain: interaction with kava extract and kavalactones in vivo and in vitro.

Reported adverse drug interactions with the popular herb kava have spurred investigation of the mechanisms by which kava could mediate these effects. In vivo and in vitro experiments were conducted to examine the effects of kava extract and individual kavalactones on cytochrome P450 (P450) and P-glycoprotein activity. The oral pharmacokinetics of the kavalactone, kawain (100 mg/kg), were determined in rats with and without coadministration of kava extract (256 mg/kg) to study the effect of the extract on drug disposition. Kawain was well absorbed, with >90% of the dose eliminated within 72 h, chiefly in urine. Compared with kawain alone, coadministration with kava extract caused a tripling of kawain AUC(0-8 h) and a doubling of C(max). However, a 7-day pretreatment with kava extract (256 mg /kg/day) had no effect on the pharmacokinetics of kawain administered on day 8. The 7-day pretreatment with kava extract only modestly induced hepatic P450 activities. The human hepatic microsomal P450s most strongly inhibited by kava extract (CYP2C9, CYP2C19, CYP2D6, CYP3A4) were inhibited to the same degree by a "composite" kava formulation composed of the six major kavalactones contained in the extract. K(i) values for the inhibition of CYP2C9 and CYP2C19 activities by methysticin, dihydromethysticin, and desmethoxyyangonin ranged from 5 to 10 microM. Kava extract and kavalactones (< or =9 microM) modestly stimulated P-glycoprotein ATPase activities. Taken together, the data indicate that kava can cause adverse drug reactions via inhibition of drug metabolism.

Influence of chelation and oxidation state on vanadium bioavailability, and their effects on tissue concentrations of zinc, copper, and iron.

Today, vanadium compounds are frequently included in nutritional supplements and are also being developed for therapeutic use in diabetes mellitus. Previously, tissue uptake of vanadium from bis(maltolato)oxovanadium(IV) (BMOV) was shown to be increased compared to its uptake from vanadyl sulfate (VS). Our primary objective was to test the hypothesis that complexation increases vanadium uptake and that this effect is independent of oxidation state. A secondary objective was to compare the effects of vanadium complexation and oxidation state on tissue iron, copper, and zinc. Wistar rats were fed either ammonium metavanadate (AMV), VS, or BMOV (1.2 mM each in the drinking water). Tissue uptake of V following 12 wk of BMOV or AMV was higher than that from VS (p < 0.05). BMOV led to decreased tissue Zn and increased bone Fe content. The same three compounds were compared in a cellular model of absorption (Caco-2 cells). Vanadium uptake from VS was higher than that from BMOV or AMV at 10 min, but from BMOV (250 microM only, 60 min), uptake was far greater than from AMV or VS. These results show that neither complexation nor oxidation state alone are adequate predictors of relative absorption, tissue accumulation, or trace element interactions.

Pharmacokinetic study of allixin, a phytoalexin produced by garlic.

The pharmacokinetic behavior of allixin (3-hydroxy-5-methoxy-6-methyl-2-penthyl-4H-pyran-4-one) was investigated in an experimental animal, mice. Allixin was administered using an inclusion compound because the solubility of allixin in aqueous solution is very low. The allixin content in serum and in the organs of administered animals was analyzed by liquid chromatography (LC)-MS. Most of the administered allixin disappeared within 2 h, and the bioavailability of allixin was estimated to be 31% by obtained area under the blood concentration-time curve (AUC). The metabolites of allixin were studied using the metabolic enzyme fraction of liver and liver homogenate. Several new peaks corresponding to allixin metabolites were observed in the HPLC chromatoprofile. The chemical structure of the metabolites was investigated using LC-MS and NMR. Three of them were identified as allixin metabolites having a hydroxylated pentyl group.

4-Hydroxy-5,6-dihydropyrones as inhibitors of HIV protease: the effect of heterocyclic substituents at C-6 on antiviral potency and pharmacokinetic parameters.

Due largely to the emergence of multi-drug-resistant HIV strains, the development of new HIV protease inhibitors remains a high priority for the pharmaceutical industry. Toward this end, we previously identified a 4-hydroxy-5,6-dihydropyrone lead compound (CI-1029, 1) which possesses excellent activity against the protease enzyme, good antiviral efficacy in cellular assays, and promising bioavailability in several animal species. The search for a suitable back-up candidate centered on the replacement of the aniline moiety at C-6 with an appropriately substituted heterocyle. In general, this series of heterocyclic inhibitors displayed good activity (in both enzymatic and cellular tests) and low cellular toxicity; furthermore, several analogues exhibited improved pharmacokinetic parameters in animal models. The compound with the best combination of high potency, low toxicity, and favorable bioavailabilty was (S)-3-(2-tert-butyl-4-hydroxymethyl-5-methyl-phenylsulfanyl)-4-hydroxy-6-isopropyl-6-(2-thiophen-3-yl-ethyl)-5,6-dihydro-pyran-2-one (13-(S)). This thiophene derivative also exhibited excellent antiviral efficacy against mutant HIV protease and resistant HIV strains. For these reasons, compound 13-(S) was chosen for further preclinical evaluation.