作者: Uprety, Rajendra ; Ko, Mee Jung ; Mores, Kendall L. ; Cassell, Robert J. ; Majumdar, Susruta ; van Rijn, Richard M. ; Robins, Meridith T. ; Pasternak, Gavril W. ; Gutridge, Anna M.

Background and PurposeMitragyna speciosa, more commonly known as kratom, is a plant that contains opioidergic alkaloids but is unregulated in most countries. Kratom is used in the self‐medication of chronic pain and to reduce illicit and prescription opioid dependence. Kratom may be less dangerous than typical opioids because of the stronger preference of kratom alkaloids to induce receptor interaction with G proteins over β‐arrestin proteins. We hypothesized that kratom (alkaloids) can also reduce alcohol intake.Experimental ApproachWe pharmacologically characterized kratom extracts, kratom alkaloids (mitragynine, 7‐hydroxymitragynine, paynantheine, and speciogynine) and synthetic carfentanil‐amide opioids for their ability to interact with G proteins and β‐arrestin at μ, δ, and κ opioid receptors in vitro. We used C57BL/6 mice to assess to which degree these opioids could reduce alcohol intake and whether they had rewarding properties.Key ResultsKratom alkaloids were strongly G protein‐biased at all three opioid receptors and reduced alcohol intake, but kratom and 7‐hydroxymitragynine were rewarding. Several results indicated a key role for δ opioid receptors, including that the synthetic carfentanil‐amide opioid MP102—a G protein‐biased agonist with modest selectivity for δ opioid receptors—reduced alcohol intake, whereas the G protein‐biased μ opioid agonist TRV130 did not.Conclusion and ImplicationsOur results suggest that kratom extracts can decrease alcohol intake but still carry significant risk upon prolonged use. Development of more δ opioid‐selective synthetic opioids may provide a safer option than kratom to treat alcohol use disorder with fewer side effects.

2019-10-01·Talanta

Development of the diffusive gradients in thin films technique (DGT) for platinum (Pt), palladium (Pd), and rhodium (Rh) in natural waters

Article

作者: Van Zutphen, Steve ; Leermakers, Martine ; Abdulbur-Alfakhoury, Ehab

The Diffusive Gradients in Thin Films (DGT) technique was developed for the first time for the platinum group elements (PGEs) platinum (Pt), palladium (Pd), and rhodium (Rh). Different chelating resins, specific designed for the accumulation of PGEs, namely Purolite S914, S920, S985, Italmatch Chemicals IONQUEST^® MPX-317 and MP-102, were compared. The method development involved several different steps: 1) selection of an appropriate diffusive gel, 2) comparison of resins for the PGEs in terms of kinetics of uptake, 3) development of an efficient elution method for the PGEs from the resin gel, 4) Determination of diffusion coefficients for the PGEs in the diffusive gel, 5) Investigation of the influence of pH, ionic strength and dissolved organic matter on the diffusion coefficients and 6) study the selectivity of the tested resins gels in terms of potential interferences on the determination by ICPMS. Pt, Pd and Rh showed a linear accumulation over time for all resins and diffusion coefficients were independent of pH. The diffusion coefficient for Pt increased with increasing ionic strength (>0.5 M NaCl), but not for Pd and Rh. The interference study showed that Sr was the most important interferent for Rh and Pd and must be removed prior to analysis. The resins Purolite S914, Purolite S920, and Italmatch Chemicals IONQUEST^® MPX-317 showed the best performance in terms of detection limits and separation of interferences. Using optimized procedures, the concentrations of Pt, Pd and Rh can be quantified at pg L^-1 levels in natural waters for a 14 day deployment time.

2009-06-16·Biochemistry3区 · 生物学

In Vitro Characterization of a Heterologously Expressed Nonribosomal Peptide Synthetase Involved in Phosphinothricin Tripeptide Biosynthesis

3区 · 生物学

Article

作者: Li, Gongyong ; Kelleher, Neil L. ; Evans, Bradley S. ; van der Donk, Wilfred A. ; Lee, Jin-Hee

The late stages of biosynthesis of phosphinothricin tripeptide (PTT) involve peptide formation and methylation on phosphorus. The exact timing of these transformations is not known. To provide insight into this question, we developed a heterologous expression system for PhsA, one of three NRPS proteins in PTT biosynthesis. The apparent k(cat)/K(m) value for ATP-pyrophosphate exchange activity for d,l-N-acetylphosphinothricin was 3.5 muM(-1) min(-1), whereas the k(cat)/K(m,app) for l-N-acetyldemethylphosphinothricin was 0.5 microM(-1) min(-1), suggesting the former might be the physiological substrate. Each substrate could be loaded onto the phosphopantetheine arm of the thiolation domain as observed by Fourier transform mass spectrometry (FTMS).

100 项与 MP-102 相关的药物交易

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