Recent progress in non-opioid analgesic peptides.

Pain is a prevalent complex medical problem, characterized by physically debilitating and mentally destabilizing conditions. Current pain therapeutics mainly include non-steroidal anti-inflammatory drugs and narcotics (opioids), but they exhibit limitations in efficacy, unwanted side effects and the problem of drug abuse. To overcome these issues, the discovery of different molecular players within pain pathways could lead to new opportunities for therapeutic intervention. Among other strategies, peptides could be powerful pharmaceutical agents for effective opioid-free medications for pain treatment. This review is a compendium of representative non-opioid analgesic peptides acting directly or indirectly at different ion channels and receptors distributed in nociceptive pathways. They include peptides targeting Ca2+, Na+ and K+ voltage-gated ion channels, the neuronal nicotinic receptors (nAChR), transient receptor potential channels (TRP), and different non-opioid G-protein coupled receptors (GPCRs), like the calcitonin gen-related peptide (CGRP), cannabinoid, bradykinin and neurotensin receptors, among others. Peptides engineered from protein-protein interactions among pain-related receptors and regulatory proteins also led to new therapeutic approaches for pain management. Following some successful examples, already in the clinics or under clinical trials, the improved understanding of pain mechanisms, and the advances in peptide permeation and/or delivery, could afford new analgesic peptides in the near future.

Frecuencia y factores asociados a la histerectomía obstétrica en un hospital de segundo nivel en México / Frequency and factors associated with obstetric hysterectomy in a second level hospital in México

INTRODUCCION La histerectomía obstétrica es procedimiento de urgencia para resolver una situación grave, su incidencia es de 5 a 15 por cada 1000 eventos obstétricos OBJETIVO GENERAL Determinar la frecuencia y factores asociados a la histerectomía obstétrica en un hospital de segundo nivel en México. METODOLOGIA Estudio descriptivo, transversal y retrospectivo en el periodo de Enero de 2014 a Diciembre del 2016, se incluyeron todos los casos de histerectomía posterior a un evento obstétrico, se estudiaron: edad, paridad, vía de interrupción del embarazo, antecedente de cesárea previa, indicaciones y complicaciones de la histerectomía, ingreso al servicio de terapia intensiva y mortalidad, el análisis se realizó con estadística descriptiva. RESULTADOS Durante el periodo de estudio, se atendieron 37 308 eventos obstétricos, efectuándose histerectomía obstétrica a 153 pacientes que representan el 0.57%, es decir, una HO por cada 243 embarazos. La edad promedio de quienes se les efectuó la histerectomía fue de 34 años de edad, siendo más frecuente en el grupo de mayores de 35 años, que habían tenido dos o tres embarazos previos. El antecedente de cesárea previa fue del 69.2%. La vía de interrupción del embarazo actual fue de cesárea en el 72.1%. La principal indicación fue la atonía uterina en 51 casos (33.3%). La complicación más frecuente fue la anemia aguda en el 83%. Hubo 1 muerte materna (0.6%). CONCLUSIONES La Histerectomía obstétrica es una cirugía de urgencia, por lo que se deben de identificar durante el control prenatal los factores asociados a las principales indicaciones de esta complicación.

INTRODUCTION Obstetric Hysterectomy (OH) is an emergency procedure to solve a life threatening condition, and its incidence is 5 to 15 per 1000 obstetric events. GENERAL OBJETIVE To determine the frequency and factors related with obstetric hysterectomy at a secondary hospital in Mexico. METHODOLOGY Descriptive, cross-sectional and retrospective study from January 2014 to December 2016 including all hysterectomy cases due to an obstetric event. Factors such as Age, number of deliveries, abortions, and previous cesarean sections, admission to the Intensive care unit, surgical indications, complications and mortality because of hysterectomy were analyzed thru descriptive statistics. RESULTS 37 308 obstetric events were registered and 153 were treated with Obstetric Hysterectomy representing 0.57% of the total, meaning one OH per every 243 pregnancies. The average age of those who had a hysterectomy was 28.5 years, and the procedure had its peak at the group of age older than 35 years who had had two or more pregnancies. The history of previous cesarean section was 39.2%. In 72.1% the pregnancy was terminated with a cesarean section. The main indication for hysterectomy was Uterine Atony in 33.3% (51 cases). The most frequent complication was acute anemia in 83%. There was a maternal death (0.6%). CONCLUSIONS Obstetric Hysterectomy is an emergency surgery, there are related factors that must be identified during the prenatal control to avoid this complication.

Synthesis, high-throughput screening and pharmacological characterization of ß-lactam derivatives as TRPM8 antagonists.

The mammalian transient receptor potential melastatin channel 8 (TRPM8), highly expressed in trigeminal and dorsal root ganglia, mediates the cooling sensation and plays an important role in the cold hypersensitivity characteristic of some types of neuropathic pain, as well as in cancer. Consequently, the identification of selective and potent ligands for TRPM8 is of great interest. Here, a series of compounds, having a ß-lactam central scaffold, were prepared to explore the pharmacophore requirements for TRPM8 modulation. Structure-activity studies indicate that the minimal requirements for potent ß-lactam-based TRPM8 blockers are hydrophobic groups (benzyl preferentially or t Bu) on R1, R2, R3 and R5 and a short N-alkyl chain (≤3 carbons). The best compounds in the focused library (41 and 45) showed IC50 values of 46 nM and 83 nM, respectively, in electrophysiology assays. These compounds selectively blocked all modalities of TRPM8 activation, i.e. menthol, voltage, and temperature. Molecular modelling studies using a homology model of TRPM8 identified two putative binding sites, involving networks of hydrophobic interactions, and suggesting a negative allosteric modulation through the stabilization of the closed state. Thus, these ß-lactams provide a novel pharmacophore scaffold to evolve TRPM8 allosteric modulators to treat TRPM8 channel dysfunction.

Transient Receptor Potential Melastatin 8 Channel (TRPM8) Modulation: Cool Entryway for Treating Pain and Cancer.

TRPM8 ion channels, the primary cold sensors in humans, are activated by innocuous cooling (<28 °C) and cooling compounds (menthol, icilin) and are implicated in sensing unpleasant cold stimuli as well as in mammalian thermoregulation. Overexpression of these thermoregulators in prostate cancer and in other life-threatening tumors, along with their contribution to an increasing number of pathological conditions, opens a plethora of medicinal chemistry opportunities to develop receptor modulators. This Perspective seeks to describe current known modulators for this ion channel because both agonists and antagonists may be useful for the treatment of most TRPM8-mediated pathologies. We primarily focus on SAR data for the different families of compounds and the pharmacological properties of the most promising ligands. Furthermore, we also address the knowledge about the channel structure, although still in its infancy, and the role of the TRPM8 protein signalplex to channel function and dysfunction. We finally outline the potential future prospects of the challenging TRPM8 drug discovery field.

De novo designed library of linear helical peptides: an exploratory tool in the discovery of protein-protein interaction modulators.

Protein-protein interactions (PPIs) have emerged as important targets for pharmaceutical intervention because of their essential role in numerous physiological and pathological processes, but screening efforts using small-molecules have led to very low hit rates. Linear peptides could represent a quick and effective approach to discover initial PPI hits, particularly if they have inherent ability to adopt specific peptide secondary structures. Here, we address this hypothesis through a linear helical peptide library, composed of four sublibraries, which was designed by theoretical predictions of helicity (Agadir software). The 13-mer peptides of this collection fixes either a combination of three aromatic or two aromatic and one aliphatic residues on one face of the helix (Ac-SSEEX(5)ARNX(9)AAX(12)N-NH2), since these are structural features quite common at PPIs interfaces. The 81 designed peptides were conveniently synthesized by parallel solid-phase methodologies, and the tendency of some representative library components to adopt the intended secondary structure was corroborated through CD and NMR experiments. As proof of concept in the search for PPI modulators, the usefulness of this library was verified on the widely studied p53-MDM2 interaction and on the communication between VEGF and its receptor Flt-1, two PPIs for which a hydrophobic α-helix is essential for the interaction. We have demonstrated here that, in both cases, selected peptides from the library, containing the right hydrophobic sequence of the hot-spot in one of the protein partners, are able to interact with the complementary protein. Moreover, we have discover some new, quite potent inhibitors of the VEGF-Flt-1 interaction, just by replacing one of the aromatic residues of the initial F(5)Y(9)Y(12) peptide by W, in agreement with previous results on related antiangiogenic peptides. Finally, the HTS evaluation of the full collection on thermoTRPs has led to a few antagonists of TRPV1 and TRPA1 channels, which open new avenues on the way to innovative modulators of these channels.

Further evidence for 2-alkyl-2-carboxyazetidines as gamma-turn inducers.

Reverse turns, a common motif in proteins and peptides, have attracted attention due to their relevance in a wide variety of biological processes. In an attempt to artificially imitate and stabilize these turns in short peptides, we have developed versatile synthetic methodologies for the preparation of 2-alkyl-2-carboxyazetidines and incorporated them into the i + 1 position of model tetrapeptides, where they have shown a tendency to induce gamma-turns. However, to ascertain the general utility of these restricted amino acids as gamma-type reverse turn inducers, it was then required to study the conformational preferences when located at other positions. To this end, model tetrapeptides R-CO-Ala-Xaa-NHMe, containing differently substituted azetidine moieties (Xaa = Aze, 2-MeAze, 2-BnAze) at the i + 2 position, were synthesized and subjected to a thorough conformational analysis. The theoretical and experimental results obtained, including the X-ray diffraction structure of a dipeptide derivative containing this skeleton, provide evidence that the 2-alkyl-2-carboxyazetidine scaffold is able to efficiently induce gamma-turns when incorporated into these short peptides, irrespective of their localization in the peptide chain.

Disulfide bonds versus TrpTrp pairs in irregular beta-hairpins: NMR structure of vammin loop 3-derived peptides as a case study.

Structural studies on model peptides have led to a good understanding of the rules behind the formation and stability of regular beta-hairpins. To test their applicability to the successful design of irregular beta-hairpins with long loops and/or beta-bulges at the strands, we mimicked loop 3 of vammin, a 4:6 beta-hairpin with a non-Gly beta-bulge. The most stabilising cross-strand pairs, disulfide bonds or/and TrpTrp pairs, were incorporated at non-hydrogen-bonded sites in peptides spanning the 69-80 region of vammin. According to NMR data, these modified peptides adopt beta-hairpin conformations as intended by design. The Trp-containing peptides reproduce even the unusual positive phi angle for the Gln residue, with the indole rings in the preferred edge-to-face orientation. For the first time the beta-hairpin-stabilising capacities of a disulfide bond and a TrpTrp pair are compared in the same model system. We found that the contribution to stability of the noncovalent indole-indole interaction is larger than that of the covalent disulfide bond, and that their combination gives rise to an even more stable beta-hairpin.

Synthesis and biological properties of beta-turned Abeta(31-35) constrained analogues.

A series of constrained pentapeptide analogues of the fragment Abeta(31-35) has been prepared using solid phase synthesis protocols. The results of conformational studies and surface plasmon resonance (SPR) experiments seem to indicate that the affinity of these constrained analogues for immobilized Abeta(25-35) peptide could be related to their ability to adopt a Leu34N-Ile31O beta-turn-like folded conformation.

Azetidine-derived amino acids versus proline derivatives. alternative trends in reverse turn induction.

The influence of 2-alkyl-2-carboxyazetidines (Aze) on the 3D structure of model tetrapeptides R2CO-2-R1Aze-l-Ala-NHMe has been analyzed by molecular modeling, 1H NMR, and FT-IR studies. The conformational constraints introduced by the four-membered ring resulted in an effective way to stabilize gamma-turn-like conformations in these short peptides. The conformational preferences of these Aze-containing peptides have been compared to those of the corresponding peptide analogues containing Pro or alpha-MePro in the place of 2-alkyl-Aze residue. In the model studied, both Pro and Aze derivatives are able to induce reverse turns, but the nature of the turn is different as a function of the ring size. While the five-membered ring of Pro tends to induce beta-turns, as previously suggested by different authors, the four-membered ring of Aze residues forces the peptide to preferentially adopt gamma-turn conformations. In both cases, the presence of an alkyl group at the alpha-position of Pro or the azetidine-2-carboxylate ring enhances significantly the turn-inducing ability. These results might open the opportunity of using 2-alkyl-Aze residues as versatile tools in defining the role of gamma-turn structures within the bioactive conformation of selected peptides, and represent an alternative to Pro derivatives as turn inducers.

Exceptional stereoselectivity in the synthesis of 1,3,4-trisubstituted 4-carboxy beta-lactam derivatives from amino acids.

[reaction: see text] The base-promoted cyclization of optically pure N-(p-methoxybenzyl)-N-(2-chloro)propionyl amino acid derivatives resulted in a diastereo- and enantioselective approach to valuable 1,3,4,4-tetrasubstituted beta-lactams. The stereochemical outcome of the reaction is exclusively governed by the configuration of the N-(2-chloro)propionyl moiety.

Incidencia y factores relacionados con el síndrome climatérico en una población de mujeres mexicanas / Incidence and factor related to climacteric syndrome in a population of Mexican women

Objetivo: Determinar las características del entorno familiar y actitud frente a la menopausia y su influencia en el síndrome climatérico. Métodos: Estudio comparativo en mujeres con menopausia que acudieron como acompañantes a las Unidades de Medicina Familiar de Querétaro, México. De Julio 2004 a Febrero 2005. Se formaron dos grupos: sin y con sintomatología del climaterio, los resultados fueron analizados con t de student, Chi cuadrado y Odds Ratio con un valor alfa de 0,05. Resultados: De 140 mujeres entrevistadas, 94 (67 por ciento) refirieron algún síntoma relacionado con el climaterio. Los factores que se asociaron al climaterio con una diferencia estadísticamente significativa (p<0,05) fueron: pareja disfuncional (OR: 4,69), baja autoestima (OR: 4,52), actitud negativa frente al climaterio (OR: 3,4), antecedentes del uso de anticonceptivos orales (OR: 2,69) y familia disfuncional (OR: 2,48). La residencia, escolaridad, ocupación, paridad, tener pareja sexual actual, índice de masa corporal, ejercicio, tabaquismo, alcoholismo, tipología familiar, cohesión familiar, no presentaron asociación significativa. Los síntomas más frecuentes fueron: fatiga (69 por ciento), bochornos (67 por ciento), piel seca (47 por ciento), cefalea (46 por ciento), irritabilidad (43 por ciento), insomnio (39 por ciento), ansiedad (39 por ciento), disminución de la libido (36 por ciento), depresión (34 por ciento), pérdida de la concentración y/o memoria (30 por ciento), artralgias (29 por ciento), resequedad vaginal (24 por ciento). Conclusiones: El entorno familiar, conyugal y una predisposición negativa ante la menopausia favorecen la presentación de síntomas climatéricos, por lo que es importante un manejo integral e interdisciplinario para el manejo del climaterio.

Objective: To determine the characteristics of the family environment and the attitude to menopause and its influence on the climateric syndrome. Methods: It was a comparative study on menopausal women who were attended to the Family Medicine Units in Querétaro, México, from July 2004 to February 2005. Two groups were formed: one with and one without climateric symptoms. The results were analyzed with Chi Square and Odds Ratio with an alpha value 0.05. Results: Of 140 women interview, 94 (67 percent) mentioned some climateric-related symptom. The factors associated with climateric with a significant statistical difference (p< 0.05) were: dysfunctional couple (OR: 4.69), low self-esteem (OR: 4.52), negative attitude to climateric (OR: 3.4), history of oral contraceptive use (OR: 2.69), dysfunctional family (OR: 2.48). Residence, education, occupation, history of childbirth, being in an active sexual relationship, body mass, exercise, nicotine addiction, alcoholism, family typology and family cohesion had no significant association. The most common symptoms were fatigue (69 percent), hot rashes (67 percent), dry skin (47 percent), headache (46 percent), irritability (43 percent), insomnia (39 percent), anxiety (39 percent), reduction in libido (36 percent), depression (34 percent), loss of concentration and/or memory (30 percent), arthralgia (29 percent), vaginal dryness (24 percent). Conclusions: The family and conjugal environment and a negative predisposition to menopause are more likely to cause climateric symptoms, for which reason an integral and interdisciplinary handling of the climateric period is very important.

Old molecules for new receptors: Trp(Nps) dipeptide derivatives as vanilloid TRPV1 channel blockers.

The transient receptor potential vanilloid member 1 (TRPV1), an integrator of multiple pain-producing stimuli, is regarded nowadays as an important biological target for the discovery of novel analgesics. Here, we describe the first experimental evidence for the behavior of an old family of analgesic dipeptides, namely Xaa-Trp(Nps) and Trp(Nps)-Xaa (Xaa=Lys, Arg) derivatives, as potent TRPV1 channel blockers. We also report the synthesis and biological investigation of a series of new conformationally restricted Trp(Nps)-dipeptide derivatives with improved TRPV1/NMDA selectivity. Compound 15 b, which incorporates an N-terminal 2S-azetidine-derived Arg residue, was the most selective compound in this series. Collectively, a new family of TRPV1 channel blockers emerged from our results, although further modifications are required to fine-tune the potency/selectivity/toxicity balance.

The neuroprotective activity of GPE tripeptide analogues does not correlate with glutamate receptor binding affinity.

The influence of several modifications on the GPE tripeptide structure upon the binding to GluRs and on their neuroprotective effects has been studied. The results indicated that the prevention of neuronal death showed by GPE and some analogues is not directly related to their affinity at glutamate receptors.

New Gly-Pro-Glu (GPE) analogues: expedite solid-phase synthesis and biological activity.

A suitable solid-phase approach, based on Fmoc/(t)Bu methodology and on the use of 2-chlorotrityl resin, allowed a rapid and efficient preparation of new GPE analogues. Most of the synthesized tripeptides displayed glutamate receptor binding affinity comparable to that of GPE, but only a few derivatives showed significant neuroprotective activity.

From 1-acyl-beta-lactam human cytomegalovirus protease inhibitors to 1-benzyloxycarbonylazetidines with improved antiviral activity. A straightforward approach to convert covalent to noncovalent inhibitors.

Starting from the structure of known beta-lactam covalent human cytomegalovirus (HCMV) protease inhibitors and from the knowledge of the residues implicated in the active site of this enzyme, we designed a series of phenylalanine-derived 2-azetidinones bearing a 4-carboxylate moiety that could be apt for additional interactions with the guanidine group of the Arg165/Arg166 residues of the viral protease. Some compounds within this series showed anti-HCMV activity at 10-50 muM, but rather high toxicity. The presence of aromatic 1-acyl groups and a certain hydrophobic character in the region of the 4-carboxylate were stringent requirements for anti-HCMV activity. To go a step ahead into the search for effective HCMV medicines, we then envisaged a series of noncovalent inhibitors by simple deletion of the carbonyl group in the beta-lactam derivatives to provide the corresponding azetidines. This led to low micromolar inhibitors of HCMV replication, with 17 and 27 being particularly promising lead compounds for further investigation, although their toxicity still needs to be lowered.

9-cis-retinoic acid analogues with bulky hydrophobic rings: new RXR-selective agonists.

Stille cross-coupling of aryltriflates 10 and dienylstannane 11, oxidation and Horner-Wadsworth-Emmons reaction afforded stereoselectively retinoates 15. Saponification provided the carboxylic acids 8a and 8b, retinoids that incorporate a bulky hydrophobic ring while preserving the 9-cis-geometry of the parent system. In contrast to the pan-RAR/RXR agonistic profile of the lower homologue of 8a, compound 7 (LG100567), retinoids 8 showed selective binding and transactivation of RXR, devoid of significant RAR activation. In PLB985 leukemia cells that require RXR agonists for differentiation compounds 8 induced maturation in the presence of the RAR-selective pan-agonist TTNPB; this effect was blocked by an RXR-selective antagonist.

Synthesis and anti-HCMV activity of 1-acyl-beta-lactams and 1-acylazetidines derived from phenylalanine.

Different Phe-derived 1-acyl-beta-lactams, analogous to a series of 2-azetidinones acting as HCMV serine protease inhibitors, were synthesized. Some of these compounds were modest inhibitors of the HCMV replication. Interestingly, removal of the carbonyl group of the beta-lactam ring, most likely acting as the serine trap, resulted in an azetidine derivative with anti-HCMV activity comparable to that of the reference compound ganciclovir.

Synthesis and characterization of a new RXR agonist based on the 6-tert-butyl-1,1-dimethylindanyl structure.

A new ligand for RXR is described, which is based on a 6-tert-butyl-1,1-dimethylindanyl skeleton as bioisostere of the hydrophobic retinoid region. The Stille cross-coupling reaction allowed the attachment of the polyene side chain to the indanyl ring. Docking studies were carried out to explain the RXR binding profile of this analogue.