29 research outputs found
Structure analysis and site-directed mutagenesis of defined key residues and motives for pilus-related sortase C1 in group B Streptococcus
No full textIn group B Streptococcus (GBS), 3 structurally distinct types of pili have been discovered as potential virulence factors and vaccine candidates. The pilus-forming proteins are assembled into high-molecular-weight polymers via a transpeptidation mechanism mediated by specific class C sortases. Using a multidisciplinary approach including bioinformatics, structural and biochemical studies, and in vivo mutagenesis, we performed a broad characterization of GBS sortase C1 of pilus island 2a. The high-resolution X-ray structure of the enzyme revealed that the active site, into the β-barrel core of the enzyme, is made of the catalytic triad His157-Cys219-Arg228 and covered by a loop, known as the “lid.” We show that the catalytic triad and the predicted N- and C-terminal transmembrane regions are required for the enzyme activity. Interestingly, by in vivo complementation mutagenesis studies, we found that the deletion of the entire lid loop or mutations in specific lid key residues had no effect on catalytic activity of the enzyme. In addition, kinetic characterizations of recombinant enzymes indicate that the lid mutants can still recognize and cleave the substrate-mimicking peptide at least as well as the wild-type protein.—Cozzi, R., Malito, E., Nuccitelli, A., D’Onofrio, M., Martinelli, M., Ferlenghi, I., Grandi, G., Telford, J. L., Maione, D., Rinaudo, C. D. Structure analysis and site-directed mutagenesis of defined key residues and motives for pilus-related sortase C1 in group B Streptococcus
Psychopharmacological treatment of cognitive deficits in Schizophrenia and mood disorders
No full textObjectives: Cognitive dysfunction is a core feature and a transdiagnostic domain of psychiatric disorders, such as Schizophrenia, Bipolar Disorder and Depression. The study of these disorders may contribute to the development of novel drugs and to the repurposing of existing agents for the treatment of cognitive impairment. This manuscript will review the literature regarding the effects of pharmachological treatment of cognitive deficits in psychiatric disorders. Methods: PubMed was used for the search including the following terms: Schizophrenia, Major Depressive Disorder, Bipolar Disorder, pharmacological treatment, antipsychotics, antidepressants, lithium and anticonvulsant medications. Results: The treatment of Schizophrenia with First Generation Antipsychotics (FGAs) has relatively little influence on cognitive symptoms. It has been indicated that Second Generation Antipsychotics (SGAs) may partially improve cognitive dysfunction, due to their relatively high affinity for serotonin 5HT2A receptors. Dysfunction of γ-aminobutyric acid (GABA) led to the "GABA hypofunction" theory and to the development of novel compounds to treat cognitive deficits. The effects of glutamatergic agents indicated benefits on cognition of a group of amino acids that act as glutamate agonists by binding to the glycine site on NMDA receptors. It was discovered that the administration of muscarinic antagonists potentiated the cognitive impairments, and the α7 nicotinic acetylcholine receptors have been shown to play an important role in cognition with potential therapeutic applications in Schizophrenia. A number of studies regarding drugs targeting neuroinflammation and oxidative stress to improve cognitive deficits emerged. Regarding Major Depressive Disorder (MDD), conventional antidepressants are generally associated with beneficial effects on cognitive impairment in individuals with MDD, which may be mediated at least in part by the improvement obtained in affective symptoms, suggesting a partially indirect effect. Furthermore, it has been hypothesized that vortioxetine may improve the cognitive symptoms of MDD through its effects on serotoninergic receptors which may modulate glutamatergic neurotransmission, exerting its antidepressant and beneficial effect on cognitive function via a distinct mechanism. The literature findings regarding the effects of lithium on cognition in Bipolar Disorder are inconclusive, while anticonvulsant medications, such as valproic acid, lamotrigine and carbamazepine, showed well-established mood stabilizing and cognitive enhancing properties. Conclusions: Cognitive dysfunction in Schizophrenia, Major Depressive Disorder and Bipolar Disorder is a relevant determinant of patient clinical and functional outcomes. Clinical studies evaluated several compounds to estimate their positive impact and their efficacy profiles on cognitive domains
Antidepressant-like effects of pharmacological inhibition of FAAH activity in socially isolated female rats
No full textPharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid N-arachidonoylethanolamine (or anandamide, AEA), exerts favourable effects in rodent models of stress-related depression. Yet although depression seems to be more common among women than men and in spite of some evidence of sex differences in treatment efficacy, preclinical development of FAAH inhibitors for the pharmacotherapy of stress-related depression has been predominantly conducted in male animals. Here, adult female rats were exposed to six weeks of social isolation and, starting from the second week, treated with the FAAH inhibitor URB694 (0.3 mg/kg/day, i.p.) or vehicle. Compared to pair-housed females, socially isolated female rats treated with vehicle developed behavioral (mild anhedonia, passive stress coping) and physiological (reduced body weight gain, elevated plasma corticosterone levels) alterations. Moreover, prolonged social isolation provoked a reduction in brain-derived neurotrophic factor (BDNF) and AEA levels within the hippocampus. Together, these changes are indicative of an increased risk of developing a depressive-like state. Conversely, pharmacological inhibition of FAAH activity with URB694 restored both AEA and BDNF levels within the hippocampus of socially isolated rats and prevented the development of behavioral and physiological alterations. These results suggest a potential interplay between AEA-mediated signaling and hippocampal BDNF in the pathogenesis of depression-relevant behaviors and physiological alterations and antidepressant action of FAAH inhibition in socially isolated female rats
N-(Anilinoethyl)amide Melatonergic Ligands with Improved Water Solubility and Metabolic Stability
No full textThe MT2-selective melatonin receptor ligand UCM765 (N-(2-((3-methoxyphenyl)(phenyl)amino)ethyl)acetamide), showed interesting sleep inducing, analgesic and anxiolytic properties in rodents, but suffers from low water solubility and modest metabolic stability. To overcome these limitations, different strategies were investigated, including modification of metabolically liable sites, introduction of hydrophilic substituents and design of more basic derivatives. Thermodynamic solubility, microsomal stability and lipophilicity of new compounds were experimentally evaluated, together with their MT1 and MT2 binding affinities. Introduction of a m-hydroxymethyl substituent on the phenyl ring of UCM765 and replacement of the replacement of the N,N-diphenyl-amino scaffold with a N-methyl-N-phenyl-amino one led to highly soluble compounds with good microsomal stability and receptor binding affinity. Docking studies into the receptor crystal structure provided a rationale for their binding affinity. Pharmacokinetic characterization in rats highlighted higher plasma concentrations for the N-methyl-N-phenyl-amino derivative, consistent with its improved microsomal stability and makes this compound worthy of consideration for further pharmacological investigation
Palladium Catalyst Recycling for Heck-Cassar-Sonogashira Cross-Coupling Reactions in Green Solvent/Base Blend
No full textThe identification of a green, versatile, user-friendly, and efficient methodology is necessary to facilitate the use of Heck-Cassar-Sonogashira (HCS) cross-coupling reaction in drug discovery and industrial production in the pharmaceutical segment. The Heck-Cassar and Sonogashira protocols, using N-hydroxyethylpyrrolidone (HEP)/water/N,N,N′,N′-tetramethyl guanidine (TMG) as green solvent/base mixture and sulfonated phosphine ligands, allowed to recycle the catalyst, always guaranteeing high yields and fast conversion under mild conditions, with aryl iodides, bromides, and triflates. No catalyst leakage or metal contamination of the final product were observed during the HCS recycling. To our knowledge, a turnover number (TON) up to 2375, a turnover frequency (TOF) of 158 h−1, and a process mass intensity (PMI) around 7 that decreased around 3 after solvent, base, and palladium recovery, represent one of the best results to date using a sustainable protocol. The Heck-Cassar protocol using sSPhos was successfully applied to the telescoped synthesis of Erlotinib (TON: 1380; TOF: 46 h−1)
Steps towards sustainable solid phase peptide synthesis: use and recovery ofN-octyl pyrrolidone
No full textThe investigation of new green biogenic pyrrolidinones as alternative solvents toN,N-dimethylformamide (DMF) for solid phase peptide synthesis (SPPS) led to the identification ofN-octyl pyrrolidone (NOP) as the best candidate. NOP showed good performances in terms of swelling, coupling efficiency and low isomerization generating peptides with very high purity. A mixture of NOP with 20% dimethyl carbonate (DMC) allowed a decrease in solvent viscosity, making the mixture suitable for the automated solid-phase protocol. Aib-enkephalin and linear octreotide were successfully used to test the methodologies. It is worth noting that NOP, DMC and the piperidine used in the deprotection step could be easily recovered by direct distillation from the process waste mixture. The process mass intensity (PMI), being reduced by 63-66%, achieved an outstanding value representing a clear step forward in achieving green SPPS
The GABAB receptor positive allosteric modulator COR659: In vitro metabolism, in vivo pharmacokinetics in rats, synthesis and pharmacological characterization of metabolically protected derivatives
No full textWe report an in vitro phase I metabolism study on COR659 (1), a 2-acylaminothiophene derivative able to suppress alcohol and chocolate self-administration in rats, likely via positive allosteric modulation of the GABAB receptor and antagonism/inverse agonism at the cannabinoid CB1 receptor. Given the identification of the methyl ester group at C-3 of the thiophene ring as a metabolic soft spot, we also report the chemical optimization project aimed to balance metabolic stability with in vitro and in vivo potency on a set of 3-substituted COR659 analogues. High performance liquid chromatography coupled to tandem and high resolution mass spectrometry was employed for the characterization of in vitro metabolism and in vivo pharmacokinetics of COR659 in rats. In vitro [35S]GTPγS binding assays on stimulated GABAB and CB1 receptors, in combination with alcohol and chocolate self-administration experiments in rats, were employed to assess the pharmacological profile of this novel set of analogues, using COR659 as reference compound. Eight metabolites of COR659 were discovered in liver microsomal incubates; two of them (M1, M2) were identified by comparison with synthetic reference standards. M2, oxidation product of methyl group at C-5 of the thiophene ring, was a major metabolite in vitro, but showed a low systemic exposure in vivo. M1, cleavage product of the methyl ester group at C-3, revealed in vitro an unusual mechanism of metabolism by a NADPH-dependent route and, in vivo, it maintained high and persistent levels in plasma, which could represent a potential pharmacokinetic and toxicological issue. In the novel set of COR659 analogues, those bearing branched alkyl substituents on the ester group, showed an improved in vitro metabolic stability (2–4), had an in vitro GABAB PAM (2–4) and/or CB1 partial agonist/antagonist profile (2–3) and maintained the ability to reduce alcohol (2–4) and/or chocolate (4) self-administration in rats. Both PK and PD data ruled out any involvement of metabolite M1 in the in vivo potency of COR659 and 4. The present results, therefore, highlight the importance to design and synthesize novel compounds endowed with the dual activity profile and devoid of metabolic liabilities
Design, Synthesis, and Physicochemical and Pharmacological Profiling of 7-Hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamide Derivatives with Antiosteoarthritic Activity in Vivo
No full textThe hallmark of joint diseases, such as osteoarthritis (OA), is pain, originating from both inflammatory and neuropathic components, and compounds able to modulate the signal transduction pathways of the cannabinoid type-2 receptor (CB2R) can represent a helpful option in the treatment of OA. In this perspective, a set of 18 cannabinoid type-2 receptor (CB2R) ligands was developed based on an unprecedented structure. With the aim of improving the physicochemical properties of previously reported 4-hydroxy-2-quinolone-3-carboxamides, a structural optimization program led to the discovery of isosteric 7-hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamide derivatives. These new compounds are endowed with high affinity for the CB2R and moderate to good selectivity over the cannabinoid type-1 receptor (CB1R), associated with good physicochemical characteristics. As to the functional activity at the CB2R, compounds able to act either as agonists or as inverse agonists/antagonists were discovered. Among them, compound 51 emerged as a potent CB2R agonist able to reduce pain in rats carrying OA induced by injection of monoiodoacetic acid (MIA)
Chemical modification of NSC12 leads to a specific FGF-trap with antitumor activity in multiple myeloma
No full textInhibition of FGF/FGFR signaling is a promising strategy for the treatment of malignances dependent from FGF stimulation, including multiple myeloma (MM). The steroidal derivative NSC12 (compound 1) is a pan-FGF trap endowed with antitumor activity in vivo. Chemical modifications of compound 1 were explored to investigate structure-activity relationships, focusing on the role of the bis(trifluoromethyl)1,3-propanediol chain, the stereochemistry at C20 and functionalization of C3 position. Our studies unveiled compound 25b, the pregnane 3-keto 20R derivative of compound 1 as an effective agent, blocking the proliferation of MM cells in vitro by inhibiting FGF-dependent receptor activation and slowing MM growth in vivo. Importantly, the absence of the hydroxyl group at C3 prevents binding to estrogen receptors, which might concur to the antitumor activity observed for compound 1, leading to a specific FGF/FGFR system inhibitor, and further supporting the role of FGFR in anticancer therapy in MM
