The Intriguing Effects of Substituents in the N-Phenethyl Moiety of Norhydromorphone: A Bifunctional Opioid from a Set of “Tail Wags Dog” Experiments

This work is licensed under a Creative Commons Attribution 4.0 International License.(−)-N-Phenethyl analogs of optically pure N-norhydromorphone were synthesized and pharmacologically evaluated in several in vitro assays (opioid receptor binding, stimulation of [35S]GTPγS binding, forskolin-induced cAMP accumulation assay, and MOR-mediated β-arrestin recruitment assays). “Body” and “tail” interactions with opioid receptors (a subset of Portoghese’s message-address theory) were used for molecular modeling and simulations, where the “address” can be considered the “body” of the hydromorphone molecule and the “message” delivered by the substituent (tail) on the aromatic ring of the N-phenethyl moiety. One compound, N-p-chloro-phenethynorhydromorphone ((7aR,12bS)-3-(4-chlorophenethyl)-9-hydroxy-2,3,4,4a,5,6-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one, 2i), was found to have nanomolar binding affinity at MOR and DOR. It was a potent partial agonist at MOR and a full potent agonist at DOR with a δ/μ potency ratio of 1.2 in the ([35S]GTPγS) assay. Bifunctional opioids that interact with MOR and DOR, the latter as agonists or antagonists, have been reported to have fewer side-effects than MOR agonists. The p-chlorophenethyl compound 2i was evaluated for its effect on respiration in both mice and squirrel monkeys. Compound 2i did not depress respiration (using normal air) in mice or squirrel monkeys. However, under conditions of hypercapnia (using air mixed with 5% CO2), respiration was depressed in squirrel monkeys.NIDA grant P30 DA13429NIDA grant DA039997NIDA grant DA018151NIDA grant DA035857NIDA grant DA047574NIH Intramural Research Programs of the National Institute on Drug AbuseNational Institute of Alcohol Abuse and AlcoholismNIH Intramural Research Programs of the National Institute on Drug AbuseNIH Intramural Research Program through the Center for Information TechnologyNIH Intramural Research Programs of the National Institute on Drug Abus

Synthesis, dopamine and serotonin transporter binding affinities of novel analogues of meperidine

A series of meperidine analogues was synthesized and the binding affinities for the dopamine and serotonin transporters were determined. The substituents on the phenyl ring greatly influenced the potency and selectivity of these compounds for the transporter binding sites. In general, meperidine ( 3) and its analogues were more selective for serotonin transporter binding sites and the esters 9 were more potent than the corresponding nitriles 8. The 3,4-dichloro derivative 9e was the most potent ligand of the series for dopamine transporter binding sites while the 2-naphthyl derivative 9g exhibited the most potent binding affinity and was highly selective for serotonin transporter binding sites. A series of meperidine analogues was synthesized and the binding affinities for the dopamine and serotonin transporters were determined

Structure−Activity Relationships at the Monoamine Transporters and σ Receptors for a Novel Series of 9-[3-(cis-3,5-Dimethyl-1-piperazinyl)-propyl]carbazole (Rimcazole) Analogues

9-[3-(cis-3,5-Dimethyl-1-piperazinyl)propyl]carbazole (rimcazole) has been characterized as a σ receptor antagonist that binds to the dopamine transporter with moderate affinity (K i = 224 nM). Although the binding affinities at the dopamine transporter of rimcazole and cocaine are comparable, rimcazole only depressed locomotor activity in mice and antagonized the stimulant effects produced by cocaine. The neurochemical mechanisms underlying the attenuation of cocaine's effects are not understood, although interaction at a low affinity site/state of the dopamine transporter has been suggested. To explore further this class of compounds, a series of rimcazole analogues was designed and synthesized. Displacement of [3H]WIN 35,428 binding at the dopamine transporter in rat caudate-putamen revealed that aromatic substitutions on rimcazole were not well tolerated, generally, with significant reductions in affinity for the 3,6-dibromo (5; K i = 3890 nM), 1,3,6-tribromo (6; K i = 30300 nM), 3-amino (8; K i = 2400 nM), and 3,6-dinitro (9; K i = 174000 nM) analogues. The N-phenylpropyl group was the only terminal piperazine nitrogen substituent that retained moderate affinity at the dopamine transporter (11; K i = 263 nM). Analogues in which the carbazole ring was replaced with a freely rotating diphenylamine moiety were also prepared. Although the diphenylamino analogue in which the terminal piperazine nitrogen was unsubstituted, as in rimcazole, demonstrated relatively low binding affinity at the dopamine transporter (24; K i = 813 nM), the N-phenylpropyl analogue was found to have the highest affinity for the dopamine transporter within the series (25; K i = 61.0 nM). All of the analogues that had affinity for the dopamine transporter inhibited [3H]dopamine uptake in synaptosomes, and potencies for these two effects showed a positive correlation (r 2 = 0.7731, p = 0.0018). Several of the analogues displaced [3H]paroxetine from serotonin transporters with moderate to high affinity, with the N-phenylpropyl derivative (11) having the highest affinity (K i = 44.5 nM). In contrast, none of the analogues recognized the norepinephrine transporter with an affinity of 6 μM at σ1 sites and 145 to 1990 nM at σ2 sites. The compound with the highest affinity (25) at σ1 sites was also the compound with highest affinity at the dopamine transporter. These novel rimcazole analogues may provide important tools with which to characterize the relationship between the low affinity site or state of the dopamine transporter, σ receptors, and their potential roles in modulating cocaine's psychostimulant actions

Esudos radiométricos sobre a oxidação de (1-14C) ácidos graxos por micobactérias sensíveis e resistentes a drogas

Um sistema radiométrico foi utilizado para estudar os padrões de oxidação dos (1-14C) ácidos graxos por microorganismos do gênero Mycobacterium sensíveis e resistentes a drogas. Foram usadas duas cepas do M. tuberculosis sensíveis a todas as drogas, H37Rv e Erdman. As micobactérias resistentes foram M. tuberculosis H37Rv resistente a 5 ug/ml de hidrazida, M. bovis, M. avium, M. intracellulare, M. kansasii e M. chelonei. As micobactérias foram inoculadas em frascos estéreis contendo o meio líquido 7H9 com 10% do complexo albumina-dextrose-catalase e 1,0 uCi de um dos (1-14C) ácidos graxos (butírico, hexanoico, octanoico, decanóico, láurico, mirístico, plamítico, esteárico, olêico, linolêico, linolênico). Os frascos foram incubados a 37°C e o 14C0(2) produzido pelas micobactérias foi medido durante 3 dias, com uma máquina Bactec-R-301. Embora cada micobactéria apresentasse um padrão distinto de oxidação de ácido graxo, estes padrões não foram suficientemente diferentes para identificá-la. Nenhuma combinação de ácidos graxos nem a oxidação preferencial de ácidos graxos de cadeias longas ou curtas foi capaz de separar as micobactérias resistentes das sensíveis. Outras experiências com um maior número de micobactérias sensíveis, incluindo estudo da assimilação de substâncias marcadas, são necessárias para se tentar a diferenciação entre as micobactérias sensíveis e as resistentes a drogas.A radiometric assay system has been used to study oxidation patterns of (1-14C) fatty acids by drug-susceptible and drug-resistant organisms of the genus Mycobacterium. Two strains of M. tuberculosis susceptible to all drugs, H37Rv and Erdman, were used. Drug-resistant organisms included in this investigation were M. tuberculosis H37Rv resistant to 5 ug/ml isoniazid, M. bovis, M. avium, M. intracellular, M. kansasii and M. chelonei. The organisms were inoculated in sterile reaction vials containing liquid 7H9 medium, 10% ADC enrichment and 1.0 uCi of one of the (1-14C) fatty acids (butyric, hexánoic, octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic). Vials were incubated at 37°C and the 14CO2 envolved was measured daily for 3 days with a Bactec R-301 instrument. Although each individual organism displayed a different pattern of fatty oxidation, these patterns were not distinctive enough for identification of the organism. No combination of fatty acids nor preferential oxidation of long chain or of short chain fatty acids were able to separate susceptible from resistant organisms. Further investigation with a larger number of drug susceptible mycobacteria including assimilation studies and oxidation of other substrates may be required to achieve a distinction between drug-susceptible and drug-resistant mycobacteria

Elucidation of Structural Elements for Selectivity across Monoamine Transporters: Novel 2‑[(Diphenylmethyl)sulfinyl]acetamide (Modafinil) Analogues

2-[(Diphenylmethyl)­sulfinyl]­acetamide (modafinil, (±)-<b>1</b>) is a unique dopamine uptake inhibitor that binds the dopamine transporter (DAT) differently than cocaine and may have potential for the treatment of psychostimulant abuse. To further investigate structural requirements for this divergent binding mode, novel thio- and sulfinylacetamide and ethanamine analogues of (±)-<b>1</b> were synthesized wherein (1) the diphenyl rings were substituted with methyl, trifluoromethyl, and halogen substituents and (2) substituents were added to the terminal amide/amine nitrogen. Halogen substitution of the diphenyl rings of (±)-<b>1</b> gave several amide analogues with improved binding affinity for DAT and robust selectivity over the serotonin transporter (SERT), whereas affinity improved at SERT over DAT for the <i>p</i>-halo-substituted amine analogues. Molecular docking studies, using a subset of analogues with DAT and SERT homology models, and functional data obtained with DAT (A480T) and SERT (T497A) mutants defined a role for TM10 in the substrate/inhibitor S1 binding sites of DAT and SERT