The diagnosis of bacterial infections at deep body sites benefits from noninvasive imaging of molecular probes that can be traced by positron emission tomography (PET). We specifically labeled bacteria by targeting their iron transport system with artificial siderophores. The cyclen-based probes contain different binding sites for iron and the PET nuclide gallium-68.A panel of 11 siderophores with different iron coordination numbers and geometries was synthesized in up to eight steps, and candidates with the best siderophore potential were selected by a growth recovery assay. The probes [ 68 Ga]7 and [ 68 Ga]15 were found to be suited for PET imaging based on their radiochemical yield, radiochemical purity, and complex stability in vitro and in vivo. Both showed significant uptake in mice infected with E.coli and were able to discern infection from LPS-triggered, sterile-inflammation. The study qualifies cyclen-based artificial siderophores as readily accessible scaffolds for the in vivo imaging of bacteria. 7 and 8 from cyclen: (i) bromoacetyl bromide, K2CO3,

The cannabinoid receptor subtype 2 (CB 2 R) is rapidly upregulated in neuroinflammatory processes and respective agonists have a high potential to combat several central nervous system disorders related to neuroinflammation and neurodegeneration. As a new strategy for ligand design, dualsteric binding is applied by chemically combining a positive allosteric modulator with an orthosteric ligand. The resulting two sets of potential dualsteric (or bitopic) ligands with different chain lengths of two to five methylene groups are evaluated in [ 3 H]CP55940 binding studies to determine receptor affinity at CB 1 R and CB 2 R. Calcium mobilization, receptor endocytosis and BRET assays determine their efficacy and identify compounds of set B to act as agonists with efficacy higher than the reference compound in G protein mediated calcium signaling. Pharmacological evaluation and docking studies support the dualsteric nature of binding of the herein presented compounds.

Activation of the human cannabinoid receptor type 1 (hCB 1 R) with high spatiotemporal control is useful to study processes involved in different pathologies related to nociception, metabolic alterations, and neurological disorders. To synthesize new agonist ligands for hCB 1 R, we have designed different classes of photoswitchable molecules based on an indole core. The modifications made to the central core have allowed us to understand the molecular characteristics necessary to design an agonist with optimal pharmacological properties. Compound 27a shows high affinity for CB 1 R (K i (cis-form) = 0.18 μM), with a marked difference in affinity with respect to its inactive "trans-off" form (CB 1 R K i trans/cis ratio = 5.4). The novel compounds were evaluated by radioligand binding studies, receptor internalization, sensor receptor activation (GRABeCB2.0), Western blots for analysis of ERK1/2 activation, NanoBiT βarr2 recruitment, and calcium mobilization assays, respectively. The data show that the novel agonist 27a is a candidate for studying the optical modulation of cannabinoid receptors (CBRs), serving as a new molecular tool for investigating the involvement of hCB 1 R in disorders associated with the endocannabinoid system.

We present the synthesis and characterization of merged human butyrylcholinesterase (hBChE) inhibitor/cannabinoid receptor 2 (hCB2R) ligands for the treatment of neurodegeneration. In total, 15 benzimidazole carbamates were synthesized and tested for their inhibition of human cholinesterases, also with regard to their pseudoirreversible binding mode and affinity toward both cannabinoid receptors in radioligand binding studies. After evaluation in a calcium mobilization assay as well as a β-arrestin 2 (βarr2) recruitment assay, two compounds with balanced activities on both targets were tested for their immunomodulatory effect on microglia activation and regarding their pharmacokinetic properties and blood–brain barrier penetration. Compound 15d, containing a dimethyl carbamate motif, was further evaluated in vivo, showing prevention of Aβ25–35-induced learning impairments in a pharmacological mouse model of Alzheimer’s disease for both short- and long-term memory responses. Additional combination studies proved a synergic effect of BChE inhibition and CB2R activation in vivo.

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