Gamma-aminobutyric acid amides of nortriptyline and fluoxetine display improved pain suppressing activity

Tertiary Amides as Directing Groups for Enantioselective C-H Amination using Ion-Paired Rhodium Complexes

Enantioselective C-H amination at a benzylic methylene is a vital disconnection towards chiral benzylamines. Here we disclose that butyric and valeric acid-derived tertiary amides can undergo highly enantioselective benzylic amination using an achiral anionic Rh complex that is ion-paired with a Cinchona alkaloid-derived chiral cation. A broad scope of compounds can be aminated encompassing numerous arene substitutions, amides, and two different chain lengths. Excellent tolerance of ortho substituents was observed, which has not been achieved before in asymmetric intermolecular C-H amination with Rh. We speculate that the tertiary amide group of the substrate engages in hydrogen bonding interactions directly with the chiral cation, enabling a high level of organisation at the transition state for C-H amination. This is in contrast with our previous work where a substrate bearing a hydrogen bond donor was required. Control experiments led to the discovery that methyl ethers also function as proficient directing groups under the optimised conditions, potentially also acting as hydrogen bond acceptors. This finding has the promise to dramatically expand the applicability of our ion-paired chiral catalysts.

Synthesis and preliminary biological evaluation of gabactyzine, a benactyzine-GABA mutual prodrug, as an organophosphate antidote

Organophosphates (OPs) are inhibitors of acetylcholinesterase and have deleterious effects on the central nervous system. Clinical manifestations of OP poisoning include convulsions, which represent an underlying toxic neuro-pathological process, leading to permanent neuronal damage. This neurotoxicity is mediated through the cholinergic, GABAergic and glutamatergic (NMDA) systems. Pharmacological interventions in OP poisoning are designed to mitigate these specific neuro-pathological pathways, using anticholinergic drugs and GABAergic agents. Benactyzine is a combined anticholinergic, anti-NMDA compound. Based on previous development of novel GABA derivatives (such as prodrugs based on perphenazine for the treatment of schizophrenia and nortriptyline against neuropathic pain), we describe the synthesis and preliminary testing of a mutual prodrug ester of benactyzine and GABA. It is assumed that once the ester crosses the blood-brain-barrier it will undergo hydrolysis, releasing benactyzine and GABA, which are expected to act synergistically. The combined release of both compounds in the brain offers several advantages over the current OP poisoning treatment protocol: improved efficacy and safety profile (where the inhibitory properties of GABA are expected to counteract the anticholinergic cognitive adverse effects of benactyzine) and enhanced chemical stability compared to benactyzine alone. We present here preliminary results of animal studies, showing promising results with early gabactyzine administration.

Uses of fluoxetine in nociceptive pain management: A literature overview

Fluoxetine is one of the top ten prescribed antidepressants. Other therapeutic applications were approved for fluoxetine including, anxiety disorders, bulimia nervosa, and premature ejaculation. However, the role of fluoxetine in nociceptive pain management is still unclear. In this review, we discuss an overview of five possible roles of fluoxetine in pain management: intrinsic antinociceptive effect, enhancement of acute opioid analgesia, attenuation of tolerance development to opioid analgesia, attenuation of dependence development and abstinence syndrome, and attenuation of opioid induced hyperalgesia. Conflicting data were reported about fluoxetine intrinsic anti-nociceptive effect in preclinical and clinical studies except for inflammatory pain. Similar controversy was described in preclinical and clinical studies which explored the possible enhancement of opioid analgesia by fluoxetine co-administration. However, fluoxetine was found to have a promising effect on opioid tolerance and dependence in animal and human studies. Regarding opioid induced hyperalgesia, no studies examined fluoxetine effects in this regard. Our literature review revealed that, the most likely beneficial use of fluoxetine in nociceptive pain management is for alleviation of inflammatory pain and attenuation of opioid tolerance and dependence. Non-steroidal anti-inflammatory and corticosteroids carry many adverse effects and toxicities. Effective alleviation of opioid tolerance and dependence represents a huge health burden and growing unmet medical need. Moreover, most agents used to attenuate these phenomena are either experimental or poorly tolerable drugs which limit their transitional value. Fluoxetine offers an effective, safe, and tolerable alternative for management of both inflammatory pain and opioid tolerance and dependence presently available to clinicians.

A new multicomponent reaction for direct synthesis of primary γ-nitroamides

The multicomponent synthesis of γ-nitroamides were achieved by the use of ammonium carbonate as reagent and catalyst.

Acylation or phosphorylation of hydroxyurea unexpectedly takes place on N rather than on O, leading to the formation of amides instead of the expected esters

Attempted acylation of the anticancer agent hydroxyurea (HU) with acyl chlorides or anhydrides led to acylation on the NH group rather than on the OH.

Synthesis and biological evaluation of a novel sigma-1 receptor antagonist based on 3,4-dihydro-2(1H)-quinolinone scaffold as a potential analgesic

The synthesis and sigma-1 receptor (σ1R) antagonist activity of a new series of 3,4-dihydro-2(1H)-quinolinone derivatives are reported. The new compounds were evaluated in vitro in sigma-1 and sigma-2 receptor-binding assays in guinea pig brain membranes. The structure-activity relationship led us to the promising derivative 7-(3-(piperidin-1-yl)propoxy)-1-(4-fluorobenzyl)-3,4-dihydro-2(1H)-quinolinone (35). The compounds with highest affinity and greatest selectivity were further profiled, and compound 35 had a high binding constant for sigma-1 receptor (Kiσ1 = 1.22 nM) and high sigma-1/2 selectivity (1066-fold). Thus, compound 35, which proved to be an antagonist of sigma-1 receptor, emerged as the most interesting candidate. In addition, compound 35 exerted dose-dependent anti-nociceptive effects in the formalin test. These characteristics suggested that the potent and selective compound 35 could be a potent candidate for pain treatment.

Monoaminergic Antidepressants in the Relief of Pain: Potential Therapeutic Utility of Triple Reuptake Inhibitors (TRIs)

Over 75% of depressed patients suffer from painful symptoms predicting a greater severity and a less favorable outcome of depression. Imaging, anatomical and functional studies have demonstrated the existence of common brain structures, neuronal pathways and neurotransmitters in depression and pain. In particular, the ascending serotonergic and noradrenergic pathways originating from the raphe nuclei and the locus coeruleus; respectively, send projections to the limbic system. Such pathways control many of the psychological functions that are disturbed in depression and in the perception of pain. On the other hand, the descending pathways, from monoaminergic nuclei to the spinal cord, are specifically implicated in the inhibition of nociception providing rationale for the use of serotonin (5-HT) and/or norepinephrine (NE) reuptake inhibitors (SSRIs, NRIs, SNRIs), in the relief of pain. Compelling evidence suggests that dopamine (DA) is also involved in the pathophysiology and treatment of depression. Indeed, recent insights have demonstrated a central role for DA in analgesia through an action at both the spinal and suprasinal levels including brain regions such as the periaqueductal grey (PAG), the thalamus, the basal ganglia and the limbic system. In this context, dopaminergic antidepressants (i.e., containing dopaminergic activity), such as bupropion, nomifensine and more recently triple reuptake inhibitors (TRIs), might represent new promising therapeutic tools in the treatment of painful symptoms with depression. Nevertheless, whether the addition of the dopaminergic component produces more robust effects than single- or dual-acting agents, has yet to be demonstrated. This article reviews the main pathways regulating pain transmission in relation with the monoaminergic systems. It then focuses on the current knowledge regarding the in vivo pharmacological properties and mechanism of action of monoaminergic antidepressants including SSRIs, NRIs, SNRIs and TRIs. Finally, a synthesis of the preclinical studies supporting the efficacy of these antidepressants in analgesia is also addressed in order to highlight the relative contribution of 5-HT, NE and DA to nociception.

The histone deacetylase inhibitor butyroyloxymethyl diethylphosphate (AN-7) protects normal cells against toxicity of anticancer agents while augmenting their anticancer activity

The histone deacetylase inhibitor (HDACI) butyroyloxymethyl diethylphosphate (AN-7) has been shown to synergize doxorubicin (Dox) anticancer activity while attenuating its cardiotoxicity. In this study we further explored the selectivity of AN-7's action in several cancer and normal cells treated with anticancer agents. The cells studied were murine mammary 4T1, human breast T47D and glioblastoma U251 cancer cell lines, neonatal rat cardiomyocytes, cardiofibroblasts and astrocytes, and immortalized cardiomyocyte H9C2 cells. Cell death, ROS production and changes in protein expression were measured and in vivo effects were evaluated in Balb-c mice. AN-7 synergized Dox and anti-HER2 cytotoxicity against mammary carcinoma cells with combination indices of 0.74 and 0.79, respectively, while it protected cardiomyocytes against their toxicity. Additionally AN-7 protected astrocytes from Dox-cytoxicity. Cell-type specific changes in the expression of proteins controlling survival, angiogenesis and inflammation by AN-7 or AN-7+Dox were observed. In mice, the protective effect of AN-7 against Dox cardiotoxicity was associated with a reduction in inflammatory factors. In summary, AN-7 augmented the anticancer activity of Dox and anti-HER2 and attenuated their toxicity against normal cells. AN-7 modulation of c-Myc, thrombospondin-1, lo-FGF-2 and other proteins were cell type specific. The effects of AN-7, Dox and their combination were preserved in vivo indicating the potential benefit of combining AN-7 and Dox for clinical use.

Selected Gamma Aminobutyric Acid (GABA) Esters may Provide Analgesia for Some Central Pain Conditions

Central pain is an enigmatic, intractable condition, related to destruction of thalamic areas, resulting in likely loss of inhibitory synaptic transmission mediated by GABA. It is proposed that treatment of central pain, a localized process, may be treated by GABA supplementation, like Parkinson’s disease and depression. At physiologic pH, GABA exists as a zwitterion that is poorly permeable to the blood brain barrier (BBB). Because the pH of the cerebral spinal fluid (CSF) is acidic relative to the plasma, ion trapping may allow a GABA ester prodrug to accumulate and be hydrolyzed within the CSF. Previous investigations with ester local anesthetics may be applicable to some GABA esters since they are weak bases, hydrolyzed by esterases and cross the BBB. Potential non-toxic GABA esters are discussed. Many GABA esters were investigated in the 1980s and it is hoped that this paper may spark renewed interest in their development.