Synthesis and antinociceptive evaluation of bioisosteres and hybrids of naproxen, ibuprofen and paracetamol

Acetaminophen effects upon formalin-evoked flinching, postformalin, and postincisional allodynia and conditioned place preference

Introduction

We explored in mice, the analgesic, tolerance, dependency, and rewarding effects of systemic acetaminophen (APAP).

Methods

Studies employed adult mice (C57Bl6). (1) Intraplantar formalin flinching + post formalin allodynia. Mice were given intraperitoneal APAP in a DMSO (5%)/Tween 80 (5%) or a water-based formulation before formalin flinching on day 1 and tactile thresholds assessed before and after APAP at day 12. (2) Paw incision. At 24 hours and 8 days after hind paw incision in male mice, effects of intraperitoneal APAP on tactile allodynia were assessed. (3) Repeated delivery. Mice received daily (4 days) analgesic doses of APAP or vehicle and tested upon formalin flinching on day 5. (4) Conditioned place preference. For 3 consecutive days, vehicle was given in the morning in either of 2 chambers and in each afternoon, an analgesic dose of morphine or APAP in the other chamber. On days 5 and 10, animals were allowed to select a "preferred" chamber.

Results

Formalin in male mice resulted in biphasic flinching and an enduring postformalin tactile allodynia. Acetaminophen dose dependently decreased phase 2 flinching, and reversed allodynia was observed postflinching. At a comparable APAP dose, female mice showed similarly reduced phase 2 flinching. Incision allodynia was transiently reversed by APAP. Repeated APAP delivery showed no loss of effect after sequential injections or signs of withdrawal. Morphine, but not APAP or vehicle, resulted in robust place preference.

Conclusions

APAP decreased flinching and allodynia observed following formalin and paw incision and an absence of tolerance, dependence, or rewarding properties.

Synthesis, biosimulation and pharmacological evaluation of benzimidazole derivatives with antihypertensive multitarget effect

In this study, we synthesized a series of seven benzimidazole derivatives incorporating the structural acidic framework of angiotensin II (Ang II) type 1 receptor (AT1R) antagonists (ARA-II) employing a three-step reaction sequence. The chemical structures were confirmed by 1H NMR, 13C NMR and mass spectral data. Through biosimulation, compounds 1-7 were identified as computational safe hits, thus, best candidates underwent ex vivo testing against two distinct mechanisms implicated in hypertension: antagonism of the Ang II type 1 receptor and the blockade of calcium channel. Molecular docking studies helped to understand at the molecular level the dual vasorelaxant effects with the recognition sites of the AT1R and the L-type calcium channel. In an in vivo spontaneously hypertensive rat model (SHR), intraperitoneally administration of compound 1 at 20 mg/kg resulted in a 25 % reduction in systolic blood pressure, demonstrating both ex vivo vasorelaxant action and in vivo antihypertensive multitarget efficacy. ©2024 Elsevier.

IBPA a mutual prodrug of ibuprofen and acetaminophen alleviates inflammation, immune dysregulation and fibrosis in preclinical models of systemic sclerosis

Systemic sclerosis (SSc) is a devastating autoimmune illness with a wide range of clinical symptoms, including vascular abnormalities, inflammation, and persistent and progressive fibrosis. The disease's complicated pathophysiology makes it difficult to develop effective therapies, necessitating research into novel therapeutic options. Molecular hybridization is a strategy that can be used to develop new drugs that act on two or multiple targets and represents an interesting option to be explored for the treatment of complex diseases. We aimed to evaluate the effects of a hybrid mutual prodrug of ibuprofen and acetaminophen (IBPA) in peripheral blood mononuclear cells (PBMC) isolated from SSc patients, and in an in vivo model of SSc induced in BALB/c mice by intradermal injections of hypochlorous acid (HOCl) for 6 weeks. The mice were treated at the same time with daily intraperitoneal injections of IBPA (40 mg/kg). Pulmonary and skin fibrosis as well as immune responses were evaluated. IBPA significantly decreased the release of cytokines in PBMC culture supernatants from SSc patients after stimulation with phytohemagglutinin-M (IL-2, IL-4, IL-6, IL-10, IL-13, IL-17A, TNF and IFN-γ).In HOCl-induced SSc, IBPA treatment prevented dermal and pulmonary fibrosis, in addition to reducing CD4 + T and B cells activation and reversing the M2 polarization of macrophages in spleen cells, and inhibiting IFN-γ secretion in splenocyte cultures. These results show the anti-inflammatory and antifibrotic effects of IBPA in SSc and highlight the therapeutic potential of this mutual prodrug, providing support for future studies.

NiII-containing l-glutamic acid cross-linked chitosan anchored on Fe3O4/f-MWCNT: a sustainable catalyst for the green reduction and one-pot two-step reductive Schotten-Baumann-type acetylation of nitroarenes

In this research, new and eye-catching catalytic applications of the nickelII (NiII) nanoparticles (NPs)-containing l-glutamic acid cross-linked chitosan anchored on magnetic carboxylic acid-functionalized multi-walled carbon nanotube (Fe3O4/f-MWCNT-CS-Glu/NiII) system, which was characterized by Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), SEM-based energy-dispersive X-ray (EDX) and elemental mapping, inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and vibrating sample magnetometry (VSM), have been introduced for the environmentally benign and efficient reduction and one-pot two-step reductive Schotten-Baumann-type acetylation of nitroarenes in water at 60 °C under an air atmosphere. It is worth noting that the NiII-containing hybrid nanocatalyst, in the mentioned organic reactions, showed short reaction times, high yields of the desired products, acceptable turnover numbers (TONs) and turnover frequencies (TOFs), and also satisfactory magnetic recycling and reusability performance even after ten times of reuse. As another significant point, all the titled organic transformations have been carried out in water as an entirely favorable and green solvent for chemical reactions.

Exploring acetaminophen prodrugs and hybrids: a review

This critical review highlights the advances in developing new molecules for treating pain syndrome, an important issue for human health. Acetaminophen (APAP, known as paracetamol) and nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used in clinical practice despite their adverse effects. Research is being conducted to develop innovative drugs with improved pharmaceutical properties to mitigate these effects. A more practical way to achieve that is to study well-known and time-tested drugs in their molecular combinations. Accordingly, the present work explores APAP and their combined chemical entities, i.e., prodrugs (soft drugs), codrugs (mutual prodrugs), and hybrids. Due to their molecular structure, APAP prodrugs or codrugs could be considered merged or conjugated hybrids; all these names are very fluid terms. This article proposed a structural classification of these entities to better analyze their advances. So, the following: carrier-linked O-modified APAP, -linked N-modified APAP derivatives (prodrugs), and direct- and spacer-N,O-linked APAP hybrids (codrugs) are the central parts of this review and are examined, especially ester and amide NSAID-APAP molecules. The C-linked APAP and nitric oxide (NO)-releasing APAP hybrids were also briefly discussed. Prime examples of APAP-based drugs such as propacetamol, benorylate, acetaminosalol, nitroparacetamol, and agent JNJ-10450232 weave well into this classification. The proposed classification is the first and original, giving a better understanding of the SAR studies for new pain relievers research and the design development for the analgesic APAP-(or NSAID)-based compounds.

Isobolographic analysis of antinociceptive effect of ketorolac, indomethacin, and paracetamol after simultaneous peripheral local and systemic administration

This study was designed to characterize the type of interaction (subadditive, additive, or synergistic) after simultaneous administration by two different routes (intraperitoneal plus peripheral local) of the same nonsteroidal anti-inflammatory drugs (NSAID) ketorolac and indomethacin or paracetamol. The antinociceptive effects of locally or intraperitoneally delivery of NSAIDs or paracetamol, and the simultaneous administration by the two routes at fixed-dose ratio combination were evaluated using the formalin test. Pain-related behavior was quantified as the number of flinches of the injected paw. Isobolographic analysis was used to characterize the interaction between the two routes. ED30 values were estimated for individual drugs, and isobolograms were constructed. Ketorolac, indomethacin, or paracetamol and fixed-dose ratio combinations produced a dose-dependent antinociceptive effect in the second but not in the first phase of the formalin test. The analysis of interaction type after simultaneous administration by the two routes the same NSAID or paracetamol (on basis of their ED30), revealed that the simultaneous administration of ketorolac or paracetamol was additive and for indomethacin was synergistic. Since the mechanisms underlying the additive effect of ketorolac or paracetamol and the synergistic effect of indomethacin were not explored; it is possible that the peripheral and central mechanism is occurring at several anatomical sites. The significance of these findings for theory and pain pharmacotherapy practice indicates that the combination of one analgesic drug given simultaneously by two different administration routes could be an additive or it could lead to a synergistic interaction.

Systematic Review of Systemic and Neuraxial Effects of Acetaminophen in Preclinical Models of Nociceptive Processing

Acetaminophen (APAP) in humans has robust effects with a high therapeutic index in altering postoperative and inflammatory pain states in clinical and experimental pain paradigms with no known abuse potential. This review considers the literature reflecting the preclinical actions of acetaminophen in a variety of pain models. Significant observations arising from this review are as follows: 1) acetaminophen has little effect upon acute nociceptive thresholds; 2) acetaminophen robustly reduces facilitated states as generated by mechanical and thermal hyperalgesic end points in mouse and rat models of carrageenan and complete Freund’s adjuvant evoked inflammation; 3) an antihyperalgesic effect is observed in models of facilitated processing with minimal inflammation (eg, phase II intraplantar formalin); and 4) potent anti-hyperpathic effects on the thermal hyperalgesia, mechanical and cold allodynia, allodynic thresholds in rat and mouse models of polyneuropathy and mononeuropathies and bone cancer pain. These results reflect a surprisingly robust drug effect upon a variety of facilitated states that clearly translate into a wide range of efficacy in preclinical models and to important end points in human therapy. The specific systems upon which acetaminophen may act based on targeted delivery suggest both a spinal and a supraspinal action. Review of current targets for this molecule excludes a role of cyclooxygenase inhibitor but includes effects that may be mediated through metabolites acting on the TRPV1 channel, or by effect upon cannabinoid and serotonin signaling. These findings suggest that the mode of action of acetaminophen, a drug with a long therapeutic history of utilization, has surprisingly robust effects on a variety of pain states in clinical patients and in preclinical models with a good therapeutic index, but in spite of its extensive use, its mechanisms of action are yet poorly understood.

Design, Synthesis, In Silico and In Vitro Studies for New Nitric Oxide-Releasing Indomethacin Derivatives with 1,3,4-oxadiazole-2-thiol Scaffold

Starting from indomethacin (IND), one of the most prescribed non-steroidal anti-inflammatory drugs (NSAIDs), new nitric oxide-releasing indomethacin derivatives with 1,3,4-oxadiazole-2-thiol scaffold (NO-IND-OXDs, 8a-p) have been developed as a safer and more efficient multitarget therapeutic strategy. The successful synthesis of designed compounds (intermediaries and finals) was proved by complete spectroscopic analyses. In order to study the in silico interaction of NO-IND-OXDs with cyclooxygenase isoenzymes, a molecular docking study, using AutoDock 4.2.6 software, was performed. Moreover, their biological characterization, based on in vitro assays, in terms of thermal denaturation of serum proteins, antioxidant effects and the NO releasing capacity, was also performed. Based on docking results, 8k, 8l and 8m proved to be the best interaction for the COX-2 (cyclooxygense-2) target site, with an improved docking score compared with celecoxib. Referring to the thermal denaturation of serum proteins and antioxidant effects, all the tested compounds were more active than IND and aspirin, used as references. In addition, the compounds 8c, 8h, 8i, 8m, 8n and 8o showed increased capacity to release NO, which means they are safer in terms of gastrointestinal side effects.

Molecular Docking and Dynamics Simulation of Protein β-Tubulin and Antifungal Cyclic Lipopeptides

To elucidate interactions between the antifungal cyclic lipopeptides iturin A, fengycin, and surfactin produced by Bacillus bacteria and the microtubular protein β-tubulin in plant pathogenic fungi (Fusarium oxysporum, Colletrotrichum gloeosporioides, Alternaria alternata, and Fusarium solani) in molecular docking and molecular dynamics simulations, we retrieved the structure of tubulin co-crystallized with taxol from the Protein Data Bank (PDB) (ID: 1JFF) and the structure of the cyclic lipopeptides from PubChem (Compound CID: 102287549, 100977820, 10129764). Similarity and homology analyses of the retrieved β-tubulin structure with those of the fungi showed that the conserved domains shared 84% similarity, and the root mean square deviation (RMSD) was less than 2 Å. In the molecular docking studies, within the binding pocket, residues Pro274, Thr276, and Glu27 of β-tubulin were responsible for the interaction with the cyclic lipopeptides. In the molecular dynamics analysis, two groups of ligands were formed based on the number of poses analyzed with respect to the RMSD. Group 1 was made up of 10, 100, and 500 poses with distances 0.080 to 0.092 nm and RMSDs of 0.10 to 0.15 nm. For group 2, consisting of 1000 poses, the initial and final distance was 0.1 nm and the RMSDs were in the range of 0.10 to 0.30 nm. These results suggest that iturin A and fengycin bind with higher affinity than surfactin to β-tubulin. These two lipopeptides may be used as lead compounds to develop new antifungal agents or employed directly as biorational products to control plant pathogenic fungi.

Synthesis of new ent-labdane diterpene derivatives from andrographolide and evaluation of their anti-inflammatory activities

Two series of andrographolide derivatives with nitrogen-containing heterocycles, phenols and aromatic acids as bioisostere moiety of lactone ring were synthesized. 8 from 18 tested compounds showed stronger inhibitory effect on LPS-induced NO production in RAW264.7 macrophage than hydrocortisone. Among them, compound 8m exhibited the most potent inhibition with IC₅₀ of 3.38 ± 1.03 μM. The structure-activity relationships (SARs) suggested that the replacement of lactone ring with small-molecule phenols could improve the anti-inflammatory efficacy. Furthermore, compound 8m significantly reduced the levels of pro-inflammatory cytokine IL-1β and IL-6 with no influence on cell survival, decreased the expression of iNOS and COX-2, and down-regulated the level and phosphorylation of IκBα, as well as the expression of NF-κB. Also it blocked the nuclear translocation of NF-κB in LPS-induced macrophage. Therefore, the anti-inflammation mechanism of compound 8m was related to the inhibition of COX-2, iNOS and NF-κB signal pathway.