In order to investigate the in vivo dopamine (DA) stimulant properties of selected 3rd generation Spice/K2 cannabinoids, BB-22, 5F-PB-22, 5F-AKB-48 and STS-135, their in vitro affinity and agonist potency at native rat and mice CB1 receptors was studied. The compounds bind with high affinity to CB1 receptors in rat cerebral cortex homogenates and stimulate CB1-induced [(35)S]GTPγS binding with high potency and efficacy. BB-22 and 5F-PB-22 showed the lowest Ki of binding to CB1 receptors (0.11 and 0.13 nM), i.e., 30 and 26 times lower respectively than that of JWH-018 (3.38 nM), and a potency (EC50, 2.9 and 3.7 nM, respectively) and efficacy (Emax, 217% and 203%, respectively) as CB1 agonists higher than JWH-018 (EC50, 20.2 nM; Emax, 163%). 5F-AKB-48 and STS-135 had higher Ki for CB1 binding, higher EC50 and lower Emax as CB1 agonists than BB-22 and 5F-PB-22 but still comparatively more favourable than JWH-018. The agonist properties of all the compounds were abolished or drastically reduced by the CB1 antagonist/inverse agonist AM251 (0.1 μM). No activation of G-protein was observed in CB1-KO mice. BB-22 (0.003-0.01 mg/kg i.v.) increased dialysate DA in the accumbens shell but not in the core or in the medial prefrontal cortex, with a bell shaped dose-response curve and an effect at 0.01 mg/kg and a biphasic time-course. Systemic AM251 (1.0 mg/kg i.p.) completely prevented the stimulant effect of BB-22 on dialysate DA in the NAc shell. All the other compounds increased dialysate DA in the NAc shell at doses consistent with their in vitro affinity for CB1 receptors (5F-PB-22, 0.01 mg/kg; 5F-AKB-48, 0.1 mg/kg; STS-135, 0.15 mg/kg i.v.). 3rd generation cannabinoids can be even more potent and super-high CB1 receptor agonists compared to JWH-018. Future research will try to establish if these properties can explain the high toxicity and lethality associated with these compounds.

Toward Expanded Diversity of Host-Guest Interactions via Synthesis and Characterization of Cyclodextrin Derivatives. ChemRxiv. Preprint.Researchers developing software to predict the binding constants of small molecules for proteins have, in recent years, turned to host-guest systems as simple, computationally tractable model systems to test and improve these computational methods. However, taking full advantage of this strategy requires aqueous host-guest systems that probe a greater diversity of chemical interactions. Here, we advance the development of an experimental platform to generate such systems by building on the cyclodextrin (CD) class of hosts. The secondary face derivative mono-3-carboxypropionamido-β-cyclodextrin (CP-β-CD) was synthesized in a one-pot strategy with 87% yield, and proved to have much greater aqueous solubility than native β-CD. The complexation of anionic CP-β-CD with the cationic drug rimantadine hydrochloride was explored using one and two-dimensional nuclear magnetic resonance (NMR); NOESY analysis showed secondary face binding of the ammonium moiety of the guest, based on cross-correlations between the amic acid functionality and the side-chain of rimantadine. Isothermal titration calorimetry was furthermore used to determine the standard free energy and enthalpy for this binding reaction, and the results were compared with those of rimantadine with native β-CD. File list (2) download file view on ChemRxiv KellettGilson_CD_binding_final.pdf (2.31 MiB) download file view on ChemRxiv KellettGilson_CD_binding_SI.pdf (458.01 KiB) Toward Expanded Diversity of Host-Guest Interactions via Synthesis and Characterization of Cyclodextrin Derivatives

No abstract

An anthracene molecular probe has been synthesised and shown to target mephedrone, a stimulant drug from the cathinone class of new psychoactive substances (NPS). A protocol has been developed to detect mephedrone via the probe using NMR spectroscopy in a simulated street sample containing two of the most common cutting agents, benzocaine and caffeine.

Researchers developing software to predict the binding constants of small molecules for proteins have, in recent years, turned to host-guest systems as simple, computationally tractable model systems to test and improve these computational methods. However, taking full advantage of this strategy requires aqueous host-guest systems that probe a greater diversity of chemical interactions. Here, we advance the development of an experimental platform to generate such systems by building on the cyclodextrin (CD) class of hosts. The secondary face derivative mono-3-carboxypropionamido-β-cyclodextrin (CP-β-CD) was synthesized in a one-pot strategy with 87% yield, and proved to have much greater aqueous solubility than native β-CD. The complexation of anionic CP-β-CD with the cationic drug rimantadine hydrochloride was explored using one and two-dimensional nuclear magnetic resonance (NMR); NOESY analysis showed secondary face binding of the ammonium moiety of the guest, based on cross-correlations between the amic acid functionality and the side-chain of rimantadine. Isothermal titration calorimetry was furthermore used to determine the standard free energy and enthalpy for this binding reaction, and the results were compared with those of rimantadine with native β-CD.

We investigate the binding of native β-cyclodextrin (β-CD) and eight novel β-CD derivatives with two different guest compounds, using isothermal calorimetry (ITC) and 2D NOESY NMR. In all cases, the stoichiometry is 1:1 and binding is exothermic. Overall, modifications at the 3’ position of β-CD, which is at the secondary face, weaken binding by several kJ/mol relative to native β-CD, while modifications at the 6’ position (primary face) maintain or somewhat reduce the binding affinity. The variations in binding enthalpy are larger than the variations in binding free energy, so entropy-enthalpy compensation is observed. Characterization of the bound conformations with NOESY NMR shows that the polar groups of the guests may be situated at either face, depending on the host molecule, and, in some cases, both orientations are populated. The present results were used in the SAMPL7 blinded prediction challenge whose results are detailed in the same special issue of JCAMD.

We have described simple, high-yield, protocols, which require only commonly accessible equipment, to synthesize a wide range of β-CD derivatives mono-substituted at the secondary face. These derivatives may be useful in their own right, and they are also scaffolds for further modification, and examples of the far broader array of derivatives that may be accessed by these procedures.

Using current research and real-life scenarios to motivate students to understand chemistry principles is a key strategy in learning and teaching. An illustration of psychoactive drugs referred to as "legal highs" used in the U.K. and Europe is presented to highlight key chemistry principles and relate the importance of chemistry research in healthcare. Specific topics include stereochemistry, 1 H NMR characterization, organic synthesis, and functional groups, which can be used in chemistry curricula for high school students and also in higher education programs. A contextualized example focused on mephedrone is used during an interpretative spectroscopy exercise in a second-year bioscience program. Student evaluations on the use of this case study approach were very positive. This topic on psychoactive drugs integrates chemistry in social and legal issues relating to patient safety. It highlights public awareness of "legal highs" and the generalized perception that "natural products" are safe and nontoxic.