Kinetic profile of N,N-dimethyltryptamine and ß-carbolines in saliva and serum after oral administration of ayahuasca in a religious context.

Ayahuasca is a beverage obtained from Banisteriopsis caapi plus Psychotria viridis. B. caapi contains the ß-carbolines harmine, harmaline, and tetrahydroharmine that are monoamine oxidase inhibitors and P. viridis contains N,N-dimethyltryptamine (DMT) that is responsible for the visionary effects of the beverage. Ayahuasca use is becoming a global phenomenon, and the recreational use of DMT and similar alkaloids has also increased in recent years; such uncontrolled use can lead to severe intoxications. In this investigation, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to study the kinetics of alkaloids over a 24 h period in saliva and serum of 14 volunteers who consumed ayahuasca twice a month in a religious context. We compared the area under the curve (AUC), maximum concentration (Cmax ), time to reach Cmax (Tmax ), mean residence time (MRT), and half-life (t1/2 ), as well as the serum/saliva ratios of these parameters. DMT and ß-carboline concentrations (Cmax ) and AUC were higher in saliva than in serum and the MRT was 1.5-3.0 times higher in serum. A generalized estimation equations (GEEs) model suggested that serum concentrations could be predicted by saliva concentrations, despite large individual variability in the saliva and serum alkaloid concentrations. The possibility of using saliva as a biological matrix to detect DMT, ß-carbolines, and their derivatives is very interesting because it allows fast noninvasive sample collection and could be useful for detecting similar alkaloids used recreationally that have considerable potential for intoxication.

ß-Carbolines in Experiments on Laboratory Animals.

Some studies have ascribed a protective effect against neurodegenerative diseases to the ß-carbolines harman (H) and norharman (NH), which occur mostly in coffee and coffee substitutes. We determined the concentrations of ß-carbolines and undesirable compounds (such as acrylamide) in roasted coffee substitute ingredients and found that chicory coffee was optimal. Two in vivo experiments were conducted with seventeen-month-old male Sprague Dawley rats fed a diet with the addition of pure carboline standards in the first stage, and chicory in the second. We observed an increase in the level of H and NH in blood plasma, as well as higher activity of animals in the battery behavioral test, particularly in the second stage. The results of in vitro studies-particularly the level of the expression in brain tissue of genes associated with aging processes and neurodegenerative diseases-clearly show the benefits of a diet rich in ß-carbolines.

An one-pot two-step automated synthesis of [18F]T807 injection, its biodistribution in mice and monkeys, and a preliminary study in humans.

[18F]T807 is a potent tau protein imaging agent. In order to fulfill the demand from preclinical and clinical studies, we developed an automated one-pot two-step synthesis of this potent tau imaging agent and studied its stability, and dosimetry in mice and monkeys. We also conducted a preliminary study of this imaging agent in humans. Using this one-pot two-step method, the radiochemical yield (RCY) of [18F]T807 was 20.5 ± 6.1% (n = 15) at the end of bombardment (EOB) in a synthesis time of 70±5 min. The chemical and radiochemical purities were >90% and the specific activities were 151 ± 52 GBq/µmol. The quality of [18F]T807 synthesized by this method met the U.S. Pharmacopoeia (USP) criteria. The stability test showed that the [18F]T807 injection was stable at room temperature for up to 4 h after the end of synthesis (EOS). The estimated effective dose of the [18F]T807 injection extrapolated from monkeys was 19 µSv/MBq (n = 2), while the estimated effective doses of the [18F]T807 injection extrapolated from fasted and non-fasted mice were 123 ± 27 (n = 3) and 94 ± 19 (n = 4) µSv/MBq, respectively. This one-pot two-step automated method produced the [18F]T807 injection with high reproducibility and high quality. PET imaging and radiation dosimetry evaluation in mice and Formosan rock monkeys suggested that the [18F]T807 injection synthesized by this method is suitable for use in human PET imaging studies. Thus, this method could fulfill the demand for the [18F]T807 injection in both preclinical and clinical studies of tauopathies, especially for nearby study sites without cyclotrons.

Discovery of Carboline Derivatives as Potent Antifungal Agents for the Treatment of Cryptococcal Meningitis.

Clinical treatment of cryptococcal meningitis (CM) remains a significant challenge because of the lack of effective and safe drug therapies. Developing novel CM therapeutic agents with novel chemical scaffolds and new modes of action is of great importance. Herein, new ß-hexahydrocarboline derivatives are shown to possess potent anticryptococcal activities. In particular, compound A4 showed potent in vitro and in vivo anticryptococcal activity with good metabolic stability and blood-brain barrier permeability. Compound A4 was orally active and could significantly reduce brain fungal burdens in a murine model of CM. Moreover, compound A4 could inhibit several virulence factors of Cryptococcus neoformans and might act by a new mode of action. Preliminary mechanistic studies revealed that compound A4 induced DNA double-stranded breaks and cell cycle arrest at the G2 phase by acting on the Cdc25c/CDK1/cyclin B pathway. Taken together, ß-hexahydrocarboline A4 represents a promising lead compound for the development of next-generation CM therapeutic agents.

Pharmacokinetics and tissue distribution of 4,5-dimethoxycanthin-6-one and its major metabolites in rats.

4,5-Dimethoxycanthin-6-one and 5-hydroxy-4-methoxycanthin-6-one are the active ingredients of P. quassiodes. In the present work, a LC-MS/MS method was developed for the determination of 4,5-dimethoxycanthin-6-one and its major metabolites 5-hydroxy-4-methoxycanthin-6-one (M1) and 4-hydroxy-5-methoxycanthin-6-one (M2) in rat plasma and tissues, and applied to study their pharmacokinetics and tissue distribution after intramuscular administration of 4,5-dimethoxycanthin-6-one to rats. By protein precipitation with methanol for plasma samples and liquid-liquid extraction with ethyl acetate for tissue samples, the analytes were separated on an ODS C18 column with a mobile phase consisted of methanol and water (0.1% formic acid), and quantified by a MS detector in positive multiple reaction monitoring (MRM) mode. MS transitions were m/z 281.0→167.1 for 4,5-dimethoxycanthin-6-one, m/z 267.0→168.1 for M1 and M2, m/z 251.0→195.1 for 3-methylcanthin-2,6-dione (IS). The pharmacokinetic results indicate that 4,5-dimethoxycanthin-6-one is absorbed rapidly (Tmax=5.4-6.4min), distributed rapidly and widely in the order of liver>kidney≈lung≈large intestine≈small intestine, and eliminated quickly (t1/2z=64.9-77.7min) following the intramuscular administration. Furthermore, M1 and M2 were detected only in rat plasma and liver at the indicated times after the intramuscular administration.

Effect of Soy Sauce on Serum Uric Acid Levels in Hyperuricemic Rats and Identification of Flazin as a Potent Xanthine Oxidase Inhibitor.

This is the first report on the ability of soy sauce to effectively reduce the serum uric acid levels and xanthine oxidase (XOD) activities of hyperuricemic rats. Soy sauce was partitioned sequentially into ethyl acetate and water fractions. The ethyl acetate fraction with strong XOD inhibition effect was purified further. On the basis of xanthine oxidase inhibitory (XOI) activity-guided purification, nine compounds including 3,4-dihydroxy ethyl cinnamate, diisobutyl terephthalate, harman, daidzein, flazin, catechol, thymine, genistein, and uracil were obtained. It was the first time that 3,4-dihydroxy ethyl cinnamate and diisobutyl terephthalate had been identified from soy sauce. Flazin with hydroxymethyl furan ketone group at C-1 and carboxyl at C-3 exhibited the strongest XOI activity (IC50 = 0.51 ± 0.05 mM). According to fluorescence quenching and molecular docking experiments, flazin could enter into the catalytic center of XOD to interact with Lys1045, Gln1194, and Arg912 mainly by hydrophobic forces and hydrogen bonds. Flazin, catechol, and genistein not only were potent XOD inhibitors but also held certain antioxidant activities. According to ADME (absorption, distribution, metabolism, and excretion) simulation in silico, flazin had good oral bioavailability in vivo.

The pharmacokinetics and bioavailability of three canthinone alkaloids after administration of Kumu injection to rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Kumu injection (KMI) is made from the branches and stems of Picrasma quassiodes (D. Don) Benn. and has been used clinically for the treatment of upper respiratory tract infection, acute tonsillitis, enteritis and bacillary dysentery. 3-methylcanthin-2,6-dione, 5-hydroxy-4-methoxycanthin-6-one, 4,5-dimethoxycanthin-6-one are the active ingredients of KMI because of its therapeutic effects. AIM OF THE STUDY: To develop a LC-MS/MS method for simultaneous determination of three active canthinone alkaloids (4,5-dimethoxycanthin-6-one, 5-hydroxy-4-methoxycanthin-6-one and 3-methylcanthin-2,6-dione) in rat plasma and for the pharmacokinetic study of them after administered of KMI to rats. MATERIALS AND METHODS: Rats were divided into 5 groups (n=5 per group), 3 groups administered intramuscularly with a single dose of KMI at 0.30, 0.45 and 0.90mL/kg respectively, and the other 2 groups administered intragastically or intravenously a single dose of KMI at 0.9mL/kg respectively. The concentrations of 4,5-dimethoxycanthin-6-one, 5-hydroxy-4-methoxycanthin-6-one and 3-methylcanthin-2,6-dione in plasma were determined by the established LC-MS/MS method at different time points and the pharmacokinetic parameters were estimated by non-compartmental analysis. RESULTS: Pharmacokinetic results indicated that all of the alkaloids were absorbed rapidly and 3-methylcanthin-2,6-dione was eliminated fastest in rats. After intramuscular administration of KMI to rats, the absolute bioavailability is excellent, and the pharmacokinetic profiles are characterized by the first order kinetics. CONCLUSION: The established method is suitable for the quantitation of the three alkaloids in rat plasma. And this pharmacokinetic study suggested that intramuscular injection of KMI was suitable in clinical usage.

Evaluation of tadalafil nanosuspensions and their PEG solid dispersion matrices for enhancing its dissolution properties.

The aim of this work was to prepare and evaluate Tadalafil nanosuspensions and their PEG 4000 solid dispersion matrices to enhance its dissolution rate. Nanosuspensions were prepared by precipitation/ultrasonication technique at 5°C where different stabilizers were screened for stabilization. Nanosuspensions were characterized in terms of particle size and charge. Screening process limited suitable stabilizers into structurally related surfactants composed of a mixture of Tween80 and Span80 at 1:1 ratio (in percent, weight/volume) in adjusted alkaline pH (named TDTSp-OH). The surfactant mixture aided the production of nanosuspensions with an average particle size of 193 ± 8 nm and with short-term stability sufficient for further processing. Solid dispersion matrices made of dried Tadalafil nanosuspensions or dried Tadalafil raw powder suspensions and PEG 4000 as a carrier were prepared by direct compression. Drying was performed via dry heat or via freeze dry. Drug release studies showed that, in general, tablet formulations made of freeze-dried product exhibited faster initial release rates than the corresponding tablets made of oven-dried products which could be attributed to possible larger crystal growth and larger crushing strengths of oven-dried formulations. At best, 60% of drug was released from solid dispersion matrices, while more than 90% of drug was released from TDTSp-OH nanosuspension within the first 5 min. In conclusion, Tadalafil nanosuspensions obtained using a mixed surfactant system provided rapid dissolution rates of Tadalafil that can theoretically enhance its bioavailability.

Synthesis, radiolabeling and in vivo evaluation of [11C]RAL-01, a potential phosphodiesterase 5 radioligand.

Very few tracers are available for imaging studies of second messenger systems. We developed a radiosynthesis for the phosphodiesterase (PDE) 5 inhibitor [(11)C]RAL-01. Whole body distribution studies using positron emission tomography (PET) revealed a time-dependant passage through the liver and accumulation of radioactivity in the bile of the Landrace pig. Displaceable binding was readily discerned in the myocardium, and traces of binding were seen in pulmonary tissue, consistent with the use of this class of drug in the treatment of pulmonary hypertension and heart failure. [(11)C]RAL-01 readily entered the brain and obtained an equilibrium distribution volume of 4-5 ml g(-1). Mean parametric images suggested the presence of a small displaceable binding component, but this binding was not significant in the present group of three pigs. Thus, [(11)C]RAL-01 shows considerable promise for PET studies of biliary elimination and of PDE5 binding in the cardiovascular system. However, analogues of higher affinity may be required for investigations of central nervous system binding sites.

Preclinical assessment of the feasibility of applying controlled release oral drug delivery to a lead series of atypical antipsychotics.

In this paper, we present a preclinical approach for evaluating the feasibility of applying controlled-release (CR) oral drug delivery to increase the duration of exposure and lower the C(max) of compounds in a lead series of short half-life atypical antipsychotics. Three lead compounds in the series had demonstrated potential pharmacological benefits for the treatment of psychosis, in preclinical studies. However, the compounds showed evidence of insufficient half-lives to enable a once-a-day (QD) product using immediate-release (IR) oral delivery. To evaluate and compare the potential for oral CR delivery to extend the duration of action and thereby enable QD administration, the in vitro solubility and permeability, and the duodenal and colonic absorption of three compounds in the series were measured. Based on the results, one candidate was selected for advancement that showed moderate in vitro solubility, but had the highest in vitro permeability and ratio of colonic to duodenal bioavailability (0.9) in the rat. The results from this study provided evidence that a CR drug delivery system could be used to extend the duration of exposure of the compounds in the series and a scientific basis for selecting one of the three compounds as a candidate.

Binding of beta-carbolines at 5-HT(2) serotonin receptors.

A series of ring-substituted (i.e., methoxy and bromo) 3,4-dihydro- and 1,2,3,4-tetrahydro-beta-carbolines was examined at 5-HT(2A) and 5-HT(2C) serotonin receptors. Whereas most of the methoxy-substituted derivatives typically displayed affinities similar to their unsubstituted parents, certain (particularly 8-substituted) bromo derivatives displayed enhanced affinity. A binding profile was obtained for selected beta-carbolines.

Inhibitory effects of tea extracts on the mutagenicity of 1-methyl-1, 2,3,4-tetrahydro-beta-carboline-3-carboxylic acid on treatment with nitrite in the presence of ethanol.

It has been shown that the mutagenicity of 1-methyl-1,2,3, 4-tetrahydro-beta-carboline-3-carboxylic acid (MTCCA), a major mutagen precursor in soy sauce on treatment with nitrite and ethanol, was strongly decreased by the addition of hot water extracts of green, black and oolong teas in the reaction mixture when it was treated with 50mM nitrite at pH3.0, 37 degrees C for 60min in the presence of 7.5% ethanol. The mutagenicity-decreasing activity of the teas was scarcely decreased by washing the teas with chloroform and benzene and was partly decreased by butanol and ethyl acetate. Typical polyphenols such as catechins were shown to have the antimutagenicity dose dependently. The antimutagenicity and the reducing power of tea extracts gave a positive good correlation. The results suggest that the mutagenicity of MTCCA on treatment with nitrite in the presence of ethanol may be decreased by the mixed fractions of lyophilic components such as polyphenols, which have high reducing power such as catechins and the other compounds which have little reducing power including the derivatives of the catechins and so on. Although the antimutagenicity of teas and catechins was also considerably effective when they were added after the nitrosation, that of black tea and some catechins was less effective.