Recent Chemical and Pharmacological Developments on 14-Oxygenated-N-methylmorphinan-6-ones

Discovery of novel tris-1,2,3-triazole-based hybrids as VEGFR2 inhibitors with potent anti-proliferative and cytotoxicity through apoptosis induction

The discovery of novel anti-cancer drugs motivated us to synthesize a new series of triple 1,2,3-triazole-based arm scaffolds featuring distinct un functionalized alkyl and/or aryl side chains with possible anti-cancer action using the click chemistry approach under both conventional and green microwave irradiation (MWI) methods. The Cu(I) catalyzed cycloaddition reaction of targeted tris-alkyne with un functionalized aliphatic and aromatic azides has been adopted as an efficient approach for synthesizing the desired click adducts. Microwave irradiation improved the synthetic processes, resulting in higher yields and faster reaction times. Spectroscopic techniques (FT-IR, 1H, 13C NMR andCHN analysis) were used for the elucidation of the resulting click structures. The newly synthesized tris-1,2,3-triazoles exhibited promising cytotoxicity, particularly compounds 26 and 28, with IC50 values of 22.18 µM and 20.3 µM against A549 and CaCo-2 cells, respectively. While they had IC50 values of 23.06 µM and 21.91 µM against T-47D and CaCo-2 cells, respectively. Both compounds exhibited promising anti-proliferative activity through the wound healing assay. Additionally, both compounds induced total apoptotic cell death by 68.3 % and 58.5 %, respectively, compared to untreated cells (7.7 %). Furthermore, they induced necrotic cell death by 1.4 % and 10.5 %, respectively, compared to 0.1 % in the untreated cells. For the molecular target, compounds 26 and 28 exhibited potent VEGFR2 inhibition with IC50 values of 35.5 nM and 27.8 nM, respectively, and this was highlighted through the molecular docking findings. Tris-1,2,3-triazoles (26 and 28) exhibited promising cytotoxicity and anti-proliferative against T-47D breast cancer cells through apoptosis and VEGFR2 inhibition using both enzyme kit and western blotting protein expression assays. Molecular docking study highlighted the binding affinity of tested compounds towards the VEGFR2 protein. Accordingly, tris-1,2,3-triazoles (26 and 28) can be further developed as more potent anti-cancer agents.

In Vitro and In Vivo Pharmacological Profiles of LENART01, a Dermorphin-Ranatensin Hybrid Peptide

Diverse chemical and pharmacological strategies are currently being explored to minimize the unwanted side effects of currently used opioid analgesics while achieving effective pain relief. The use of multitarget ligands with activity at more than one receptor represents a promising therapeutic approach. We recently reported a bifunctional peptide-based hybrid LENART01 combining dermorphin and ranatensin pharmacophores, which displays activity to the mu-opioid receptor (MOR) and dopamine D2 receptor (D2R) in rat brains and spinal cords. In this study, we investigated the in vitro binding and functional activities to the human MOR and the in vivo pharmacology of LENART01 in mice after subcutaneous administration. In vitro binding assays showed LENART01 to bind and be selective to the human MOR over the other opioid receptor subtypes and delta, kappa and nociceptin receptors. In the [35S]GTPγS binding assay, LENART01 acted as a potent and full agonist to the human MOR. In mice, LENART01 produced dose-dependent antinociceptive effects in formalin-induced inflammatory pain, with increased potency than morphine. Antinociceptive effects were reversed by naloxone, indicating MOR activation in vivo. Behavioral studies also demonstrated LENART01's properties to induce less adverse effects without locomotor dysfunction and withdrawal syndrome compared to conventional opioid analgesics, such as morphine. LENART01 is the first peptide-based MOR-D2R ligand known to date and the first dual MOR-dopamine D2R ligand for which in vivo pharmacology is reported with antinociceptive efficacy and reduced opioid-related side effects. Our current findings may pave the way to new pain therapeutics with limited side effects in acute and chronic use.

Design and structural validation of peptide-drug conjugate ligands of the kappa-opioid receptor

Despite the increasing number of GPCR structures and recent advances in peptide design, the development of efficient technologies allowing rational design of high-affinity peptide ligands for single GPCRs remains an unmet challenge. Here, we develop a computational approach for designing conjugates of lariat-shaped macrocyclized peptides and a small molecule opioid ligand. We demonstrate its feasibility by discovering chemical scaffolds for the kappa-opioid receptor (KOR) with desired pharmacological activities. The designed De Novo Cyclic Peptide (DNCP)-β-naloxamine (NalA) exhibit in vitro potent mixed KOR agonism/mu-opioid receptor (MOR) antagonism, nanomolar binding affinity, selectivity, and efficacy bias at KOR. Proof-of-concept in vivo efficacy studies demonstrate that DNCP-β-NalA(1) induces a potent KOR-mediated antinociception in male mice. The high-resolution cryo-EM structure (2.6 Å) of the DNCP-β-NalA-KOR-Gi1 complex and molecular dynamics simulations are harnessed to validate the computational design model. This reveals a network of residues in ECL2/3 and TM6/7 controlling the intrinsic efficacy of KOR. In general, our computational de novo platform overcomes extensive lead optimization encountered in ultra-large library docking and virtual small molecule screening campaigns and offers innovation for GPCR ligand discovery. This may drive the development of next-generation therapeutics for medical applications such as pain conditions.

Peripheralization Strategies Applied to Morphinans and Implications for Improved Treatment of Pain

Opioids are considered the most effective analgesics for the treatment of moderate to severe acute and chronic pain. However, the inadequate benefit/risk ratio of currently available opioids, together with the current 'opioid crisis', warrant consideration on new opioid analgesic discovery strategies. Targeting peripheral opioid receptors as effective means of treating pain and avoiding the centrally mediated side effects represents a research area of substantial and continuous attention. Among clinically used analgesics, opioids from the class of morphinans (i.e., morphine and structurally related analogues) are of utmost clinical importance as analgesic drugs activating the mu-opioid receptor. In this review, we focus on peripheralization strategies applied to N-methylmorphinans to limit their ability to cross the blood-brain barrier, thus minimizing central exposure and the associated undesired side effects. Chemical modifications to the morphinan scaffold to increase hydrophilicity of known and new opioids, and nanocarrier-based approaches to selectively deliver opioids, such as morphine, to the peripheral tissue are discussed. The preclinical and clinical research activities have allowed for the characterization of a variety of compounds that show low central nervous system penetration, and therefore an improved side effect profile, yet maintaining the desired opioid-related antinociceptive activity. Such peripheral opioid analgesics may represent alternatives to presently available drugs for an efficient and safer pain therapy.

Bifunctional Peptidomimetic G Protein-Biased Mu-Opioid Receptor Agonist and Neuropeptide FF Receptor Antagonist KGFF09 Shows Efficacy in Visceral Pain without Rewarding Effects after Subcutaneous Administration in Mice

There is still an unmet clinical need to develop new pharmaceuticals for effective and safe pain management. Current pharmacotherapy offers unsatisfactory solutions due to serious side effects related to the chronic use of opioid drugs. Prescription opioids produce analgesia through activation of the mu-opioid receptor (MOR) and are major contributors to the current opioid crisis. Multifunctional ligands possessing activity at more than one receptor represent a prominent therapeutic approach for the treatment of pain with fewer adverse effects. We recently reported on the design of a bifunctional MOR agonist/neuropeptide FF receptor (NPFFR) antagonist peptididomimetic, KGFF09 (H-Dmt-DArg-Aba-βAla-Bpa-Phe-NH2), and its antinociceptive effects after subcutaneous (s.c.) administration in acute and persistent pain in mice with reduced propensity for unwanted side effects. In this study, we further investigated the antinociceptive properties of KGFF09 in a mouse model of visceral pain after s.c. administration and the potential for opioid-related liabilities of rewarding and sedation/locomotor dysfunction following chronic treatment. KGFF09 produced a significant dose-dependent inhibition of the writhing behavior in the acetic acid-induced writhing assay with increased potency when compared to morphine. We also demonstrated the absence of harmful effects caused by typical MOR agonists, i.e., rewarding effects (conditioned-place preference test) and sedation/locomotor impairment (open-field test), at a dose shown to be highly effective in inhibiting pain behavior. Consequently, KGFF09 displayed a favorable benefit/side effect ratio regarding these opioid-related side effects compared to conventional opioid analgesics, such as morphine, underlining the development of dual MOR agonists/NPFFR antagonists as improved treatments for various pain conditions.