The marine environment is a rich source of metabolites with potential therapeutic properties and applications for humans. Here we describe the first isolation, solid-phase total synthesis, and full structural assignment of a new class of cyclodepsipeptides from the Madagascan sponge Ecionemia acervus that shows in vitro cytotoxic activities at submicromolar concentrations. Seven structures belonging to a new family of compounds, given the general name stellatolides, were characterized. The sequence and stereochemistry of all the amino acids in these molecules were established by a combination of spectroscopic analysis, chemical degradation, and derivatization studies. Furthermore, the complete structure of stellatolide A was confirmed by an efficient solid-phase method for the first total synthesis and the full structural assignment of this molecule, including the asymmetric synthesis of the unique β-hydroxy acid moiety (Z)-3-hydroxy-6,8-dimethylnon-4-enoic acid.
We report the synthesis of new compounds 4− 35 based on structural modifications of different moieties of previously described lead UCM-2550. The new nonpiperazine derivatives, representing second-generation agonists, were assessed for binding affinity, selectivity, and functional activity at the 5-HT 1A receptor (5-HT 1A R). Computational β 2 -based homology models of the ligand−receptor complexes were used to explain the observed structure−affinity relationships. Selected candidates were also evaluated for their potential in vitro and in vivo neuroprotective properties. Interestingly, compound 26 (2-{6-[(3,4-dihydro-2H-chromen-2-ylmethyl)amino]hexyl}tetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione) has been characterized as a high-affinity and potent 5-HT 1A R agonist (K i = 5.9 nM, EC 50 = 21.8 nM) and exhibits neuroprotective effect in neurotoxicity assays in primary cell cultures from rat hippocampus and in the MCAO model of focal cerebral ischemia in rats.
We report the synthesis of new compounds 4-35 based on two different openings (A and B) of the chromane ring present in the previously identified 5-HT1A receptor (5-HT1AR) ligand 3. The synthesized compounds were assessed for binding affinity, selectivity, and functional activity at the 5-HT1AR. Selected candidates resulting from B opening were also evaluated for their potential antinociceptive effect in vivo and pharmacokinetic properties in vitro. Analogue 19 [2-(4-{[2-(2-ethoxyphenoxy)ethyl]amino}butyl)tetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione] has been characterized as a high-affinity and potent 5-HT1AR agonist (Ki = 2.3 nM; EC50 = 19 nM). Pharmacokinetic studies indicated that compound 19 displays a good metabolic stability in human liver microsomes (t1/2 ∼ 3 h and CLint = 3.5 mL/min/kg, at 5 μM), and a low level of protein binding (25%, at 5 μM). Interestingly, 19 (3 mg/kg, ip, and 30 mg/kg, po) caused significant attenuation of formalin-induced behavior in early and late phases of the mouse intradermal formalin test of pain, and this in vivo effect was reversed by the selective 5-HT1AR antagonist WAY-100635. Thus, the new 5-HT1AR agonist identified in this work, 19, exhibits oral analgesic activity, and the results herein represent a step toward identifying new therapeutics for the control of pain.
Ligands. -Members of the title series, in particular (IIIb), show high affinity for both serotonin receptors and an excellent selectivity profile with respect to α1-adrenergic and dopamine D2 receptors. -(LOPEZ-RODRIGUEZ*, M. L.; BENHAMU, B.; MORCILLO, M. J.; TEJADA, I.; AVILA, D.; MARCO, I.; SCHIAPPARELLI, L.; FRECHILLA, D.; DEL RIO, J.; Bioorg. Med. Chem. Lett. 13
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