14beta-Arylpropiolylamino-17-cyclopropylmethyl-7,8-dihydronormorphinones and related opioids. Further examples of pseudoirreversible mu opioid receptor antagonists.
ABSTRACT: 14beta-4'-Chlorocinnamoylaminodihydronormorphinone (2a), and analogues, are selective pseudoirreversible antagonists of the mu opioid receptor (MOR). The preparation of analogues with ethynic bonds, replacing the ethenic bond of 2a, is described. The new ligands, in mouse antinociceptive assays, had pseudoirreversible MOR antagonist activity, which, in the case of 8b was of longer duration than that of 2a. The related codeinone (9b) had only antagonist activity in vivo, in contrast to 2a's codeinone equivalent 3a, which had potent antinociceptive activity.
Project description:We have previously shown that cinnamoyl derivatives of 14?-amino-17-cyclopropylmethyl-7,8-dihydronormorphinone and 7?-aminomethyl-6,14-endoethanonororipavine have pronounced pseudoirreversible ? opioid receptor (MOR) antagonism. The present communication describes the synthesis and evaluation of fumaroylamino analogues of these cinnamoylamino derivatives together with some related fumaroyl derivatives. The predominant activity of the new ligands was MOR antagonism. The fumaroylamino analogues (2a, 5a) of the pseudoirreversible antagonist cinnamoylamino morphinones and oripavines (2b, 5b) were themselves irreversible antagonists in vivo. However the fumaroylamino derivatives had significantly higher MOR efficacy than the cinnamoylamino derivatives in mouse antinociceptive tests. Comparison of 2a and 5a with the prototypic fumaroylamino opioid ?-FNA (1a) shows that they have similar MOR irreversible antagonist actions but differ in the nature of their opioid receptor agonist effects; 2a is a predominant MOR agonist and 5a shows no opioid receptor selectivity, whereas the agonist effect of ?-FNA is clearly ? opioid receptor (KOR) mediated.
Project description:14-O-Cinnamoyl esters of naltrexone (6) were synthesized and evaluated in isolated tissue assays in vitro and in vivo in mouse antinociceptive assays. Their predominant opioid receptor activity was mu receptor (MOR) antagonism, but the unsubstituted cinnamoyl derivative (6a) had partial MOR agonist activity in vitro and in vivo. When compared to the equivalent 14-cinnamoylaminomorphinones (5), the cinnamoyloxy morphinones (6) as MOR antagonists had a shorter duration of action and were less effective as pseudoirreversible antagonists. The antinociceptive activity of the cinnamoyloxycodeinones (7) was not significantly greater than that of the morphinones (6), but they exhibited no evidence of any pseudoirreversible MOR antagonism. In both respects, these profiles differed from those of the equivalent 14-cinnamoylaminocodeinones (4).
Project description:An alanine scan was performed on the novel ??opioid receptor (KOR) peptide ligand CJ-15,208 to determine which residues contribute to the potent in?vivo agonist activity observed for the parent peptide. These cyclic tetrapeptides were synthesized by a combination of solid-phase peptide synthesis of the linear precursors, followed by cyclization in solution. Like the parent peptide, each of the analogues exhibited agonist activity and KOR antagonist activity in an antinociceptive assay in?vivo. Unlike the parent peptide, the agonist activity of the potent analogues was mediated predominantly, if not exclusively, by ??opioid receptors (MOR). Thus analogues 2 and 4, in which one of the phenylalanine residues was replaced by alanine, exhibited both potent MOR agonist activity and KOR antagonist activity in?vivo. These peptides represent novel lead compounds for the development of peptide-based opioid analgesics.
Project description:We previously reported a small series of mixed-efficacy ? opioid receptor (MOR) agonist/? opioid receptor (DOR) antagonist peptidomimetics featuring a tetrahydroquinoline scaffold and showed the promise of this series as effective analgesics after intraperitoneal administration in mice. We report here an expanded structure-activity relationship study of the pendant region of these compounds and focus in particular on the incorporation of heteroatoms into this side chain. These analogues provide new insight into the binding requirements for this scaffold at MOR, DOR, and the ? opioid receptor (KOR), and several of them (10j, 10k, 10m, and 10n) significantly improve upon the overall MOR agonist/DOR antagonist profile of our previous compounds. In vivo data for 10j, 10k, 10m, and 10n are also reported and show the antinociceptive potency and duration of action of compounds 10j and 10m to be comparable to those of morphine.
Project description:A series of 17-cyclopropylmethyl-3,14?-dihydroxy-4,5?-epoxy-6?-(isoquinoline-3'-carboxamido)morphinan (NAQ) analogues were synthesized and pharmacologically characterized to study their structure-activity relationship at the mu opioid receptor (MOR). The competition binding assay showed two-atom spacer and aromatic side chain were optimal for MOR selectivity. Meanwhile, substitutions at the 1'- and/or 4'-position of the isoquinoline ring retained or improved MOR selectivity over the kappa opioid receptor while still possessing above 20-fold MOR selectivity over the delta opioid receptor. In contrast, substitutions at the 6'- and/or 7'-position of the isoquinoline ring reduced MOR selectivity as well as MOR efficacy. Among this series of ligands, compound 11 acted as an antagonist when challenged with morphine in warm-water tail immersion assay and produced less significant withdrawal symptoms compared to naltrexone in morphine-pelleted mice. Compound 11 also antagonized the intracellular Ca(2+) increase induced by DAMGO. Molecular dynamics simulation studies of 11 in three opioid receptors indicated orientation of the 6'-nitro group varied significantly in the different 'address' domains of the receptors and played a crucial role in the observed binding affinities and selectivity. Collectively, the current findings provide valuable insights for future development of NAQ-based MOR selective ligands.
Project description:The 14-aminodihydromorphinone and codeinone series of opioid ligands have produced a number of ligands of substantial interest. To investigate the importance of the 14-substituent, a series of analogues in which the side chain length is varied and the amide and alkene functions are reduced have been prepared. Binding affinity, particularly at the mu-opioid receptor (MOR), was largely determined by the aromatic group of the side chain. In the [35S]GTPgammaS functional assay, the ligands having a three-carbon side chain were more potent antagonists than their longer chain counterparts, while shorter, two-carbon chain analogues were of higher MOR efficacy, an effect that was confirmed in vivo. Wash-resistant binding was observed within this series and appeared to be unrelated to side-chain length.
Project description:Peripheral selective ? opioid receptor (MOR) antagonists could alleviate the symptoms of opioid-induced constipation (OIC) without compromising the analgesic effect of opioids. However, a variety of adverse effects were associated with them, partially due to their relatively low MOR selectivity. NAP, a 6?-N-4'-pyridyl substituted naltrexamine derivative, was identified previously as a potent and highly selective MOR antagonist mainly acting within the peripheral nervous system. The noticeable diarrhea associated with it prompted the design and synthesis of its analogues in order to study its structure-activity relationship. Among them, compound 8 showed improved pharmacological profiles compared to the original lead, acting mainly at peripheral while increasing the intestinal motility in morphine-pelleted mice (ED(50) = 0.03 mg/kg). The slight decrease of the ED(50) compared to the original lead was well compensated by the unobserved adverse effect. Hence, this compound seems to be a more promising lead to develop novel therapeutic agents toward OIC.
Project description:OBJECTIVE(S):Nowadays, COX - 2 inhibitors such as valdecoxib are removed from the market because of their cardiovascular toxicity and their potential to increase the risk of strokes. In response to this, medicinal chemists have attempted to synthesize new classes of COX-2 Inhibitors. MATERIALS AND METHODS:In this study, three novel analogues of thiazolidin-4-ones derivatives 2a-c were synthesized. The ability of these compounds to inhibit ovine COX-1 and COX-2 (0.2- 0.8 µM) was determined using a colorimetric method. The cytotoxic effect of the synthesized compounds (25-100 M) was also investigated by measuring their cytotoxicity against Caco-2 and MCF-7 cell lines using MTT assay. Cell apoptosis was determined by ?ow cytometry. Writhing test (7.5-75 mg/kg) was used to examine the antinociceptive effects in mice. The effect of the analogues against acute inflammation (7.5-75 mg/kg) was also studied using xylene-induced ear edema test in mice. RESULTS:The synthesized compounds showed a weak capacity to inhibit the proliferation of Caco-2 and MCF-7 cell lines. The COX-2 inhibition potency and selectivity index for test compounds 2a-b were as follows; celecoxib > 2b > 2a. On the other hand, all three analogues exhibited strong antinociceptive activity against acetic acid-induced writhing. The anti-inflammatory and antinociceptive effects of the analogues were markedly more than positive control, celecoxib. CONCLUSION:This study demonstrates that the antinociceptive and anti-inflammatory activity profiles exhibited by the novel synthesized compounds are independent from their COX-2 inhibitory potencies. The found antinociceptive and anti-inflammatory effects can be caused by interaction with other target; independent from COX-2. Accordingly, the compounds 2a-c could serve as lead compounds to develop novel anti-inflammation and antinociceptive drugs.
Project description:Short-acting ?-opioid receptor (MOR) agonists have long been used for the treatment of severe, breakthrough pain. However, selective MOR agonists including fentanyl and morphine derivatives are limited clinically due to high risks of dependence, tolerance, and respiratory depression. We recently reported the development of a long-acting, bifunctional MOR agonist/?-opioid receptor (DOR) antagonist analgesic devoid of tolerance or dependence in mice (AAH8, henceforth referred to as 2B). To address the need for short-acting treatments for breakthrough pain, we present a series of novel, short-acting, high-potency MOR agonist/DOR antagonist ligands with antinociceptive activity in vivo. In this study, we utilized a two-dimensional structure-activity relationship matrix to identify pharmacological trends attributable to combinations of two key pharmacophore elements within the chemotype. This work enhances our ability to modulate efficacy at MOR and DOR, accessing a variety of bifunctional profiles while maintaining high affinity and potency at both receptors.
Project description:Based on the structure of the superpotent 5-HT(2A) agonist 2-(4-bromo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine, which consists of a ring-substituted phenethylamine skeleton modified with an N-benzyl group, we designed and synthesized a small library of constrained analogues to identify the optimal arrangement of the pharmacophoric elements of the ligand. Structures consisted of diversely substituted tetrahydroisoquinolines, piperidines, and one benzazepine. Based on the structure of (S,S)-9b, which showed the highest affinity of the series, we propose an optimal binding conformation. (S,S)-9b also displayed 124-fold selectivity for the 5-HT(2A) over the 5-HT(2C) receptor, making it the most selective 5-HT(2A) receptor agonist ligand currently known.