1,721,092 research outputs found
Synthesis of a group of novel Xanomeline/77-LH-28-1 hybrid ligands and their FRET investigation at muscarinic acetylcholine receptor subtypes
Full text linkIn connection with our interest in investigating novel rationally designed bitopic (i.e., orthosteric/allosteric) derivatives targeting muscarinic acetylcholine receptor (mAChR) subtypes (1,2,3), in this study we designed and synthesized a new set of ligands that integrate in the same molecular skeleton the pharmacophoric moieties of Xanomeline and of 77-LH-28-1 (1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone). Xanomeline is a well-known M1/M4-preferring orthosteric agonist, which ameliorated cognitive impairments in Alzheimer’s disease patients and showed activity in various models of schizophrenia, thus being potentially beneficial for treatment of positive, negative and cognitive symptoms (4). On the other hand, 77-LH-28-1 was characterized as an M1-selective, positive allosteric modulator, thus representing an interesting pharmacological tool with cognition enhancing properties (5). As illustrated below, we planned the novel bipharmacophoric derivatives as merged structures, with the tetrahydropyridine nucleus of Xanomeline as the central core.
In the last years, different receptor sensors, based on the fluorescence resonance energy transfer (FRET), were generated for various G protein-coupled receptors, and represented a valuable tool to investigate real time receptor activation as well as ligand-receptor interactions. Recently, this analysis was performed also on a set of bitopic ligands designed for a selective interaction with M1 mAChRs (6). Our preliminary results on the group of Xanomeline/77-LH-28-1 hybrid compounds indicate, for the M1 sensor, a reproducible activation response, which depends on the linker length. Conversely, no FRET-related effect could be detected at the M2 sensor. Thus, a critical spacer length of the hybrid compounds induces conformational changes with a degree of selectively for the M1 muscarinic receptor. The synthesis and the results of pharmacological investigation will be presented and discussed.
References: 1. J. Antony, K. Kellershohn, M. Mohr-Andrä, A. Kebig, S. Prilla, M. Muth, E. Heller, T. Disingrini, C. Dallanoce et al., FASEB J 2009, 23, 442-450. 2. A. Bock, B. Chirinda, F. Krebs, R. Messerer, J. Bätz, M. Muth, C. Dallanoce et al., Nat. Chem. Biol. 2014, 10, 18-20. 3. A. Bock, M. Bermudez, F. Krebs, C. Matera, B. Chirinda, D. Sydow, C. Dallanoce et al., J. Biol. Chem. 2016, 291, 16375-16389. 4. S. Barak, I. Weiner, Int. J. Neuropsychoph. 2011, 14, 1233-1246. 5. C. J. Langmead, N. E. Austin, C. L. Branch, J. T. Brown, K. A. Buchanan, C. H. Davies, I. T. Forbes et al., Br. J. Pharmacol. 2008, 154, 1104-1115. 6. R. Messerer, M. Kauk, D. Volpato, M. C. Alonso Canizal, J. Klöckner, U. Zabel, S. Nuber, C. Hoffmann, U. Holzgrabe, ACS Chem. Biol. 2017, 12, 833-843
Nuovi ligandi nicotinici correlati all'Epibatidina e all'Epibossidina: sintesi e valutazione della loro affinità per i recettori nicotinici neuronali alpha4beta2 e alpha7
No full textI recettori nicotinici dell’acetilcolina, appartenenti alla famiglia di canali ionici operati da ligando, sono costituiti da cinque subunità assemblate in modo da consentire la permeazione di cationi quali Na+, K+ e Ca++. I recettori nicotinici neuronali (Rnn) localizzati a livello cerebrale si configurano come bersagli molecolari promettenti per la terapia di malattie del sistema nervoso centrale quali le patologie neurodegenerative, psichiatriche, il dolore, la dipendenza da tabacco, l’epilessia e la sindrome di Tourette.1 In base alle evidenze emerse dagli studi di binding recettoriale, i Rnn sono stati suddivisi in due gruppi: a) i recettori sensibili alla alpha-Bungarotossina (alfa-Bgtx), che sono omomerici, costituiti da cinque subunità alpha(alfa7-alfa9), oppure eteromerici, costituiti da differenti subunità alpha(alfa7 e alfa8 oppure alfa9 e alfa10); b) i recettori non sensibili alla alfa-Bgtx, risultanti da combinazioni di subunità alfa (alfa2-alfa6) e beta (beta2-beta4), per i quali prevale la stechiometria è (alpha)2(beta)3. La differente combinazione di subunità alpha e alpha/beta origina recettori che si diversificano in termini di permeabilità cationica, cinetiche di attivazione e desensibilizzazione, e caratteristiche farmacologiche.
A prosecuzione degli studi rivolti allo studio di nuovi agonisti nicotinici selettivi per i sottotipi recettoriali alpha4beta2 oppure alpha7,2,3 verrà illustrato l’approccio sintetico a un gruppo di analoghi strutturali dell’Epibatidina 1 e dell’Epibossidina 2, due agonisti nicotinici di riferimento notevolmente selettivi per il sottotipo recettoriale alpha4beta2. Per la preparazione dei composti progettati, la cui formula generale è rappresentata da A (R=H, CH3), abbiamo fatto ricorso alla reazione palladio-catalizzata di Stille, effettuando il coupling tra un enoltrifato e alcuni stannil derivati recanti opportuni nuclei eterociclici. Tale metodologia consente da un lato di approdare a nuovi analoghi strutturali di 1 e 2 contenenti un vincolo conformazionale aggiuntivo, dall’altro può essere estesa alla sintesi dei singoli isomeri ad elevata purezza enantiomerica. Nel corso della presentazione saranno inoltre discussi i risultati di affinità dei nuovi derivati per i recettori nicotinici alfa4beta2 e alfa7, i due sottotipi più interessanti nell’ottica di un potenziale impiego terapeutico.
(1) M. N. Romanelli et al, ChemMedChem 2007, DOI: 10.1002/cmdc.200600207
(2) C. Dallanoce et al, Eur. J. Org. Chem. 2006, 16, 3746.
(3) C. Dallanoce et al, Domanda di Brevetto Italiano, 2006, # MI2006 A00127
7'-Aminonaphthazarin antibiotic derivatives
No full textThe title compds. I (R = H, OH; R1 = H, (un)substituted C1-4 alkyl), II (Y = C1-5 alkylmercapto, (un)substituted PhS, C1-5 alkylsulfinyl, (un)substituted phenylsulfinyl, etc.), and III (X = Cl, Br), which demonstrate antibiotic activity against gram pos. and neg. microorganisms, fungi, and protozoa, and which are suitable for the treatment of vaginal infections, are prepd. and pharmaceutical formulations contg. them presented. Thus, 7'-(ethylamino)purpuromycin, prepd. in 6 steps from purpuromycin, demonstrated min. inhibitory concn. of 8 μg/mL against Trichomonas vaginalis and 2μg/mL against Gardnerella vaginalus (ATCC 14018)
Sulfonium compounds and methods for making and using the same
No full textDescribed herein are sulfonium compounds that are agonists (e.g., silent or partial) of the mammalian α7 or α9 nicotinic acetylcholine receptors. Further provided are pharmaceutical compositions that allow the administration of the sulfonium compounds to a subject in need of treatment for a pathological condition arising from such as inflammation
Bifunctional dopaminergic/nicotinic agonists: novel pharmacological tools to study the D3R/β2*nAChRs heteromeric complex
No full textBifunctional derivatives have gained a relevant interest in the medicinal chemistry research as potentially innovative therapeutic agents.[1] Indeed, bifunctional drug candidates may concomitantly regulate two biological targets instead of blocking or activating, for example, only one dysfunctional receptor system at a time. As a first contribution in the field, we recently reported the synthesis of new bifunctional derivatives and their affinity/efficacy profiles at D2/non-α7 nAChRs.[2] In this framework, the recent demonstration that D3 dopaminergic and β2-subunit-containing (β2*) nAChRs may assemble in a heteromeric receptor complex [3] has provided the rationale for the investigation of bifunctional compounds targeting such receptor heterodimers. Our study focused on the design and synthesis of novel compounds, which incorporate in a common molecular skeleton two substructures, i.e., the pharmacophoric moiety of the D3 agonist Ropinirole and the fragment of the selective, highly potent α4β2 agonist A-84543 (Figure 1). The synthetic approach and the details of the pharmacological investigation will be illustrated and discussed. Figure 1. Model compounds and target bifunctional derivatives In particular, our findings extend the current understanding of the molecular mechanisms regulating the neuronal plasticity and provide an example of the importance of G protein-coupled receptor and ligand-gated ion channel heteromerization for synaptic efficacy and intrinsic neural properties. Increasing evidence suggests that D2R/D3R agonists may slow the progression of Parkinson’s disease (PD) and that nicotine has neuroprotective effects on dopaminergic neurons. Therefore, the D3/β2*nAChR heteromeric complex may represent a novel therapeutic
target for neuroprotection and, accordingly, bifunctional compounds which activate this complex could provide a new pharmacological approach to the treatment of PD.
References
1. Wang, M.; Wong, A. H.; Liu, F. Interactions between NMDA and dopamine receptors: a potential therapeutic target. Brain Res. 2012, 1476, 154-163.
2. Matera, C.; Pucci, L.; Fiorentini, C.; Fucile, S.; Missale, C.; Grazioso, G.; Clementi, F.; Zoli, M.; De Amici, M.; Gotti, C.; Dallanoce, C. Bifunctional compounds
targeting both D2 and non-α7 nACh receptors: design, synthesis and pharmacological characterization. Eur. J. Med. Chem. 2015, in press.
3. Missale, C. et al., manuscript in preparation
Design, synthesis and pharmacological properties of alkylbisammonio bitopic ligands of muscarinic acetylcholine receptors
No full textOver the past two decades, novel opportunities for drug discovery have risen from a greater understanding of the complexity of GPCR signaling. A striking example of this is the appreciation that GPCRs possess functional allosteric binding sites.[1] The five muscarinic acetylcholine receptor (mAChR) subtypes bind their physiological transmitter in the highly conserved orthosteric site within the transmembrane domain of the receptors. Orthosteric muscarinic agonists have negligible binding selectivity and poor signaling specificity. A less conserved allosteric site has been also characterized at the extracellular entrance of the binding pocket of mAChRs. Our interest in the research field on mAChR ligands has been recently extended to the study of derivatives designed to simultaneously interact with the orthosteric and the allosteric site (bitopic ligands) of these receptors, thus exploiting the complementary characteristics of the two different binding sites by a single ligand molecule.[2,3] This approach is a variation of the more traditional bivalent ligand concept and shares some of the same challenges, including the choice and role of the linker between the two pharmacophores and the validation of mechanism of action.[4] The most interesting bitopic compounds which emerged from our investigation (represented by the general molecular skeleton A in Figure 1) are alkylbisammonio derivatives incorporating a) iperoxo, an oxotremorine-related unselective muscarinic superagonist, b) a polymethylene spacer chain, and c) a heteroaromatic fragment targeting the allosteric site.
The synthetic approach of target compounds and the most relevant results of their pharmacological investigation will be presented. In particular, the analgesic effects observed for a group of the compounds under study will be illustrated in detail.
References
1. Wang, L.; Martin, B.; Brenneman, R.; Luttrell, L. M.; Maudsley, S. Allosteric Modulators of G Protein-Coupled Receptors: Future Therapeutics for Complex Physiological Disorders. J. Pharmacol. Exp. Ther. 2009, 331, 340-348
2. Antony, J.; Kellershohn, K.; Disingrini, T.; Dallanoce, C.; Tränkle, C.; Christopoulos, A.; Barocelli, E.; De Amici, M.; Holzgrabe, U.; Mohr, K. et al. Dualsteric GPCR targeting: a novel route to binding and signaling pathway selectivity. FASEB J. 2009, 23, 442-450
3. Bock, A.; Merten, N.; Schrage, R.; Dallanoce, C.; Matera, C.; Hoffmann, C.; De Amici, M.; Holzgrabe, U.; Kostenis, E.; Mohr, K. et al. The allosteric vestibule of a seven transmembrane helical receptor controls G-protein coupling. Nat. Commun. 2012, 3, 1044
4. Valant, C.; Lane, J. R.; Sexton, P. M.; Christopoulos, A. The Best of Both Worlds? Bitopic Orthosteric/Allosteric Ligands of G Protein-Coupled Receptors. Annu. Rev. Pharmacol. Toxicol. 2012, 52, 153-17
FREE-SOLUTION CAPILLARY ELECTROPHORETIC RESOLUTION OF CHIRAL AMINO-ACIDS VIA DERIVATIZATION WITH HOMOCHIRAL ISOTHIOCYANATES .1.
No full textWithin the framework of a more general study aimed at the enantiomeric
resolution of non-UV-absorbing chiral amino acids via derivatization
with chiral isothiocyanates, we have examined the applicability of two
such derivatizing agents, (S)-1-(1-naphthyl)ethyl isothiocyanate (SNEIT)
and (S)-1-phenylethyl isothiocyanate (SAMBI), to the resolution of the
enantiomers of alanine, phenylalanine, and valine in free-solution
capillary electrophoresis (FSCE). Isothiocyanates have distinct
advantages as chiral derivatizing agents in enantiospecific
chromatographic analysis, and the two reagents were readily synthesized
from commercially available reagents. SNEIT, previously not fully
described in the literature, was characterized by rigorous
physicochemical and spectroscopic means. The two diastereoisomeric
thiourea derivatives of each amino acid were separated by FSCE.
Heptakis-2,3,6-tri-O-methyl-beta-cyclodextrin was effective in assuring
the solubility of the derivatives in the working buffer and was more
efficient than beta-cyclodextrin in both dissolving the thioureas and
improving the electrophoretic resolution. Enantiomeric pairs migrated in
the order L before D. Under the conditions used SAMBI-derivatized amino
acids had longer elution times than the corresponding SNEIT derivatives.
The diastereomeric derivatives of valine and of phenylalanine had larger
separation factors alpha than the corresponding SAMBI derivatives, while
the derivatives of alanine had nearly identical alpha values with the
two derivatizing agents. The two reagents may be advantageous in the
enantiospecific analysis of amino acids, and it appears that further
exploration of these and other similar reagents is warranted
Orthosteric and allosteric ligands selectively acting at cholinergic receptor subtypes
No full textThe presentation will focus on the results recently achieved by our research group in the design, synthesis and pharmacological evaluation of selective ligands which target cholinergic receptor subtypes, belonging to both the nicotinic (nAChR) and the muscarinic (mAChR) acetylcholine receptor families. A set of spirocyclic derivatives will be illustrated, in which the simultaneous presence of the quinuclidinyl and Delta2-isoxazolinyl moieties, coupled with suitable stereoelectronic features of the substituent at position 3 of the spirocyclic ring, engendered a selective agonist profile at the homomeric neuronal alpha7 nAChRs [1]. The most promising compound in the series has been further investigated in preclinical studies and in in vivo models of CNS disorders and neuropathic pain. A group of novel hybrid peptides structurally related to natural alpha-conotoxins MII and PIA will be also presented, which behave as competitive antagonists able to discriminate alpha6beta2* and alpha3beta2* nAChR subtypes [2]. The five mAChR subtypes bind their physiological transmitter in the highly conserved orthosteric site within the transmembrane domains of the receptors. Orthosteric muscarinic agonists have negligible binding selectivity and poor signaling specificity. A less conserved allosteric site has been also characterized at the extracellular entrance of the binding pocket of mAChRs. To gain subtypeselective M2 receptor activation, we designed a group of putative bitopic compounds, i. e. hybrid derivatives fusing highly potent, unselective oxotremorinelike orthosteric activators with M2-selective bis(ammonio)alkane-type allosteric fragments. The new ligands interacted simultaneously with both recognition areas of the receptor protein, thus allowing the exploitation of favorable features of the orthosteric and the allosteric site by a single ligand molecule. The orthosteric interaction provided high affinity binding and activation of M2 mAChRs. The allosteric interaction yielded receptor subtype-selectivity and, in addition, could modulate efficacy and activate pathway-specific intracellular signaling [3]. [1] C.Dallanoce, P.Magrone, C.Matera, F.Frigerio, G.Grazioso, M.De Amici, S.Fucile, V.Piccari, K.Frydenvang, L.Pucci, C.Gotti, F.Clementi, C.De Micheli, ChemMedChem, 6, 2011, 889-903. [2] M.De Amici, G.Grazioso, C.Dallanoce, C.De Micheli et al., submitted. [3] K.Mohr, C.Tränkle, E.Kostenis, E.Barocelli, M.De Amici, U.Holzgrabe, Br.J.Pharmacol., 159, 2010, 997-1008
Transdermal delivery of morphine derivatives : a qualitative structure/in vitro permeability relationship
No full textPurpose
The in vitro permeability of six different morphine derivatives (morphine, codeine, hydromorphone, hydrocodone, oxymorphone, oxycodone) through human epidermis was studied to elucidate the influence of three different substituents, namely the methoxy (CH3O), carbonyl (CO) and hydroxyl (OH) groups in position 3, 6 and 14, respectively.
Methods
The in vitro permeation studies were performed using the Franz diffusion cells and aqueous saturated solutions. At the end of experiment (i.e. 24h), the maximum flux (J) and the permeation coefficient [pKp=-log(J/S), where S is the drug solubility at saturation] were calculated and statistical analysis of possible structure-permeability relationship was performed. Results
The substituents of each tested compound and the related pKp values are listed in Table 1. The pKp values of hydromorphone and hydrocodone were not statistically different from morphine and codeine ones indicating that the 6-CO group did not influence the permeation through human epidermis. Conversely, the 3-CH3O group lead to a significant increase of the permeation coefficient (<pKp). Indeed, the pKp values of codeine derivatives (3-CH3O)
were at least 25% lower than morphine derivative ones (p<0.01). Furthermore, 14-OH had a synergic effect with 3-CH3O on pKp: the pKp of oxycodone (3-CH3O, 14-OH) was 40% lower than one of oxymorphone (14-OH).
Conclusion
The permeation of tested morphine derivatives through human epidermis appears influenced by the polarity distribution in the molecular structure
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