Anethole Dithiolethione Increases Glutathione in Kidney by Inhibiting γ-Glutamyltranspeptidase: Biochemical Interpretation and Pharmacological Consequences.

AIMS: Anethole dithiolethione (ADT) is a marketed drug to treat xerostomia. Its mechanism of action is still unknown, but several preclinical studies indicate that it is able to increase intracellular glutathione (GSH) and protect against oxidative stress. Here, we investigated the molecular mechanisms behind these effects. RESULTS: Oral treatment of rats confirmed the GSH enhancing properties of ADT; among the different organs examined in this study, only the kidney showed a significant GSH increase that was already observed at low-dose treatments. The increase in GSH correlated with a decrease in γ-glutamyltranspeptidase (γ-GT) activity of the different tissues. In vitro and ex vivo experiments with tubular renal cells and isolated perfused rat kidney showed that the cellular uptake of intact GSH was correlated with the extracellular concentrations of GSH. CONCLUSION: s. The prominent in vivopharmacological effect of ADT was a marked increase of GSH concentration in the kidney and a decrease of some systemic and renal biomarkers of oxidative stress. In particular, by inhibition of γ-GT activity, it decreased the production cysteinylglycine, a thiol that has prooxidant effects as the consequence of its autooxidation. The activity of ADT as GSH enhancer in both the circulation and the kidney was long-lasting. All these characteristics make ADT a promising drug to protect the kidney, and in particular proximal tubule cells, from xenobiotic-induced damage.

An HPLC-MS/MS method for the quantitative determination of 4-hydroxy-anethole trithione in human plasma and its application to a pharmacokinetic study.

A selective, rapid and sensitive method for the quantitation of 4-hydroxy-anethole trithione (ATX) in human plasma based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. Paracetamol was used as the internal standard (I.S.). After liquid-liquid extraction of 500 µL plasma with ethyl acetate, ATX and the I.S. were chromatographed on an Inertsil(®) ODS-3 column. The mobile phase was consisted of methanol-water (75:25, v/v) with a flow rate of 0.25 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. The calibration curve was linear over the range of 0.452-603 ng/mL (r(2)≥0.99) with a lower limit of quantitation (LLOQ) of 0.452 ng/mL. The intra- and inter-day precision (relative standard deviation, R.S.D.) values were below 13% and the accuracy (relative error, R.E.) was from -2.7% to -7.5% at three quality control levels. The assay herein described was successfully applied to a pharmacokinetic study of anethole trithione (ATT) tablet in healthy volunteers after oral administration.

Lipid-based formulations to enhance oral bioavailability of the poorly water-soluble drug anethol trithione: effects of lipid composition and formulation.

This study has explored the use of lipid-based formulations to enhance the oral bioavailability of the poorly water-soluble drug anethol trithione (ATT), and compared the performance of different formulations. Two groups of lipid-based formulations, sub-microemulsion (SME) and oil solution, were prepared using short (SCT), medium (MCT) and long (LCT) chain triglycerides respectively; aqueous suspension was used as the reference formulation. In vitro and in vivo studies were conducted to investigate the impact of lipid composition and formulation on drug absorption. In vitro digestion was used to analyze lipid digestion rates and drug distribution/solubilization. After in vitro digestion, the performance rank order for drug solubilization was SCT

HPLC determination of anethole trithione and its application to pharmacokinetics in rabbits.

To evaluate the relative bioavailability of anethole trithione (ATT) from self-microemulsifying drug delivery system (SMEDDS) and tablet, a sensitive, accurate and reliable liquid chromatography method was developed and validated to determine ATT in rabbit plasma. Chromatographic separation was performed on a Diamonsil C18 column by using a mixture of methanol-water (90:10, v/v) delivered at a flow rate of 1.0 ml/min. The wavelength was set at 348 nm and mifepristone was used as the internal standard. A linear relationship for ATT was found in the range of 0.5-32 ng/ml. The mean extraction recoveries of ATT determined over three concentrations were 84.7+/-5.8, 92.3+/-3.4 and 89.9+/-5.1%. After administration of SMEDDS and tablets to rabbits, significant differences were found in main pharmacokinetic parameters of Tmax, Cmax and AUC(0-infinity) between these two formulations, and a 2.5-fold enhancement of relative bioavailability of ATT was observed from the SMEDDS compared with tablets.

Effects of chronic anethole trithione and amitriptyline treatment on rat parotid gland signalling.

The present study examines the mechanism(s) of action of anethole trithione (Sulfarlem S25) compared to the sialogogue pilocarpine. The chronic effects (7 days of treatment) of anethole trithione, pilocarpine and/or amitriptyline on autonomic receptor binding (homogenates) were measured together with parallel tests of stimulation-induced rises in delta [Ca2+]i in collagenase-isolated rat parotid acini. The results revealed that chronic treatment with amitriptyline resulted in significantly increased rises in delta [Ca2+]i after stimulation with 20 microM of carbachol or adrenaline, and a significant increase in muscarinic acetylcholine receptor density. In addition, anethole trithione also increased cholinergic and adrenergic responsiveness. The double treatment of amitriptyline and anethole trithione or amitriptyline and pilocarpine did, however, prevent the rise in delta [Ca2+]i observed under conditions when these drugs were administered alone. Furthermore, anethole trithione, but not pilocarpine, was able to prevent the amitriptyline-induced upregulation in muscarinic acetylcholine receptor density. In conclusion, the experimental data presented in this study are compatible with the hypothesis that anethole trithione might stimulate some post-receptor effect in the coupling to the secretory response. In addition, this study supports the beneficial effects of anethole trithione in treating drug-induced xerostomia.

Synergistic effect of sialagogues in management of xerostomia after radiation therapy.

The combined effects of two sialagogues, with proposed different mechanisms of action, were studied in a phase I/II trial in the management of xerostomia. Improvement in saliva-flow rates and subjective symptoms were seen in the patients.

Chemoprotective effects of two dithiolthiones and of butylhydroxyanisole against carbon tetrachloride and acetaminophen toxicity.

Administration of tert-butyl-4-hydroxyanisole or of two dithiolthiones to female CD-1 mice protected against the acute toxic effects of two hepatotoxic agents, acetaminophen and carbon tetrachloride. Reduced mortality of mice was observed following pretreatment with tert-butyl-4-hydroxyanisole or dithiolthiones. Pretreatment reduced or prevented hepatic glutathione depletion produced by these two hepatotoxic agents. Liver damage, i.e., as determined by serum transaminase and sorbitol dehydrogenase activities, was less after pretreatment with tert-butyl-4-hydroxyanisole or dithiolthiones. Administration of dithiolthiones resulted in increased (from four- to over six-fold) activities of liver glutathione-S-transferases.