Domoic Acid as a Lead for the Discovery of the First Selective Ligand for Kainate Receptor Subtype 5 (GluK5).

Twenty-one simplified analogues of the natural product domoic acid were designed, synthesized, and then characterized at homomeric kainic acid (KA) receptors (GluK1-3,5). LBG20304 displays a high affinity for homomeric GluK5 receptors (IC50 = 432 nM) with a >40-fold selectivity over homomeric GluK1-3 subtypes and ≫100-fold selectivity over native AMPA and N-methyl d-aspartate receptors. Functional studies of LBG20304 on heteromeric GluK2/5 receptors show no agonist or antagonist functional response at 10 µM, while a concentration of 100 µM at neuronal slices (rat) shows low agonist activity. A molecular dynamics simulation of LBG20304, in a homology model of GluK5, suggests specific interactions with the GluK5 receptor and an occluded ligand binding domain, which is translated to agonist or partial agonist activity. LBG20304 is a new compound for the study of the role and function of the KA receptors with the aim of understanding the involvement of these receptors in health and disease.

The role of phacoemulsification surgery in the incidence rate of rhegmatogenous retinal detachment.

PURPOSE: To investigate changes in the incidence rate of primary rhegmatogenous retinal detachment (RRD) surgery over time and to determine to what extent these changes can be attributed to pseudophakia. METHODS: This nationwide cohort study was based on national patient registries. The study population comprised individuals at risk of RRD aged 40 years and above from 2006 to 2021 in Denmark. The primary outcome was RRD incidence, and the exposure was phacoemulsification surgery. A chart review was conducted to validate and examine the lens status of the outcome. RESULTS: The crude and age-adjusted incidence rate of RRD in the Danish population increased significantly during the study period. The largest increase in RRD was seen in phakic RRD (phRRD) (65%), whereas pseudophakic RRD (pRRD) accounted for 35% of the total increase. A chart review revealed that 17% of phRRDs were misclassified as pseudophakic, resulting in pRRD accounting for a total of 45% of the increase in RRD. The prevalence of pseudophakia in Denmark grew significantly for all age groups and for both sexes (p = 10-6) from 2006 to 2021, but the 1-year incidence of pRRD in the pseudophakic population was constant throughout the entire period. CONCLUSION: The incidence rate of RRD is continuing to increase in Denmark. The increase in phRRD remains undetermined, and while the risk of pRRD seemed to be constant during the study period, 45% of the overall increase in RRD could be attributed to the rise of a growing pseudophakic population.

Surrogacy as fertility treatment in Denmark.

Gestational surrogacy, in which an infertile couple contracts with a woman to carry a foetus that the intended parents will raise, increases worldwide, and offers a route to parenthood for individuals and couples who otherwise have limited options. However, the situation in Denmark at present is that surrogacy with the help of healthcare professionals is illegal, and international adoption is no longer available. This review gives an overview of the legal situation of surrogacy in Denmark, the impact of the legislation, and medical issues to be aware of as healthcare professionals in the future.

New expert advice on cancer in pregnancy.

Cancer in pregnancy is rare, and most physicians lack knowledge in handling pregnant cancer patients. This review summarises the present knowledge on this condition. In the Netherlands, an Advisory Board on Cancer in Pregnancy was established in 2012. The board supports Dutch physicians' decisions in the management of pregnant patients with cancer. In 2021 the International Advisory Board on Cancer in Pregnancy was established, and in continuation, the Danish Advisory Board on Cancer in Pregnancy (DABCIP) has now been founded. DABCIP consists of 22 members from 13 different medical disciplines.

Anaemia in the first trimester and poor physiological plasma expansion during pregnancy negatively impact foetal weight and newborn anthropometrics: An observational cohort study in Tanzania.

OBJECTIVES: Anaemia during pregnancy is a major health challenge affecting pregnancy outcome worldwide. The objectives of this study were to investigate the impact of severe-moderate anaemia in the first trimester, as well as changes in haemoglobin during pregnancy among non-anaemic women, on foetal weight, placental blood flow and newborn anthropometrics. METHODS: In a prospective cohort study, 346 women residing in rural Tanzania were followed throughout pregnancy with serial ultrasound and newborn anthropometrics assessed within 24 h of delivery. Associations between placental blood flow, foetal weight and newborn anthropometrics with either first trimester severe-moderate anaemia (haemoglobin≤9.5 g/dL) or changes in haemoglobin from the first to the third trimester among non-anaemic women, were assessed by mixed model regression and multiple linear regression, adjusting for maternal and foetal co-variables. Foetal weights and birthweight were converted to z-scores using a population based sex-specific weight reference. RESULTS: Severe-moderate anaemia in the first trimester was associated with significantly reduced foetal weight z-scores (adjusted mean difference (aMD) -0.44 (95% CI -0.81, -0.07)) and newborn anthropometric indices (birth weight z-score aMD -0.55 (-0.9, -0.13), abdominal circumference aMD -11 mm (95% CI -20, -3)). There were no association between first trimester severe-moderate anaemia and placental blood flow. Among women who were non-anaemic in the first trimester, women with the least reduction in haemoglobin (Δ ≥ -0.3 g/dL) delivered significantly smaller newborns (birthweight z-score aMD -0.55 (-0.91, -0.20), abdominal circumference aMD -10 mm (95% CI -17, -3), compared to women with the greatest reduction (Δ haemoglobin ≤ -1.4 g/dL)). CONCLUSIONS: Severe-moderate anaemia in early pregnancy was associated with smaller newborn anthropometrics which was reflected in smaller mean foetal weights in the second and third trimester. Furthermore, among women who were non-anaemic in the first trimester, there was an association between smaller newborn anthropometrics and limited haemoglobin decrease during pregnancy, possibly reflecting insufficient plasma expansion.

Cancer in pregnancy - The obstetrical management.

Cancer in pregnancy, defined as a cancer diagnosed during pregnancy, is a rare but severe condition presenting both clinical and ethical challenges. During the last two decades a paradigm shift has occurred towards recommending similar staging and treatment regimens of pregnant and non-pregnant cancer patients. This strategy is a result of an increasing number of reassuring reports on chemotherapy treatment in pregnancy after the first trimester. The management of cancer in pregnancy should be managed in a multidisciplinary team where staging, oncological treatment, social and mental care, timing of delivery, and follow-up of the infant should be planned. Due to the rarity, centralization is recommended to allow experience accumulation. Furthermore, national and international advisory boards are supportive when there is a lack of expertise.

Impact of the war in Ukraine and the COVID-19 pandemic on transnational surrogacy - a qualitative study of Danish infertile couples' experiences of being in 'exile'.

RESEARCH QUESTION: How did Danish permanently infertile couples experience surrogacy when going abroad and what impact did the war in Ukraine and the COVID-19 pandemic have on this? DESIGN: A qualitative study was performed between May and September 2022. The in-depth semi-structured interviews were conducted with 14 permanently infertile couples across Denmark who were in different stages of using surrogacy. The interviews were transcribed and analysed using systematic text condensation. RESULTS: All except one couple went abroad, mainly to Ukraine, to have an enforceable transparent contract, professionals to advise them and the possibility of using the eggs of the intended mother. They did not feel that this was a 'choice' but rather the only option they had to have the longed-for child. According to current Danish legislation, the intended mother could not obtain legal motherhood over the child, not even through stepchild adoption, and this increased the feeling of not being a 'worthy mother'. This study expanded on the term 'reproductive exile' by identifying four different forms of exile: the exiled Danish couple, the gestational carrier in exile, exile at home and, finally, the reproductive body in exile. CONCLUSIONS: Understanding infertile couples' experiences when crossing borders is important for several reasons. It may, among others, assist politicians and authorities in developing a sound Danish legal policy on surrogacy to address the current issues of legal parenthood and avoid missing reproductive opportunities for permanently infertile couples.

Structure-Activity Relationship and Solubility Studies of N1-Substituted Quinoxaline-2,3-diones as Kainate Receptor Antagonists.

Kainate receptors are a class of ionotropic glutamate receptors that respond to the excitatory neurotransmitter glutamate in the central nervous system and play an important role in the development of neurodegenerative disorders and the regulation of synaptic function. In the current study, we investigated the structure- activity relationship of the series of quinoxaline-2,3-diones substituted at N1, 6, and 7 positions, as ligands of kainate homomeric receptors GluK1-3 and GluK5. Pharmacological characterization showed that all derivatives obtained exhibited micromolar affinity at GluK3 receptors with Ki values in the range 0.1-4.4 µM range. The antagonistic properties of the selected analogues: N-(7-fluoro-6-iodo-2,3-dioxo-3,4-dihydroquinoxalin-1(2H)-yl)-3-sulfamoylbenzamide, N-(7-(1H-imidazol-1-yl)-6-iodo-2,3-dioxo-3,4-dihydroquinoxalin-1(2H)-yl)-3-sulfamoylbenzamide and N-(7-(1H-imidazol-1-yl)-2,3-dioxo-6-(phenylethynyl)-3,4-dihydroquinoxalin-1(2H)-yl)-3-sulfamoylbenzamide at GluK3 receptors, were confirmed by an intracellular calcium imaging assay. To correlate in vitro affinity data with structural features of the synthesized compounds and to understand the impact of the substituent in N1 position on ability to form additional protein-ligand interactions, molecular modeling and docking studies were carried out. Experimental solubility studies using UV spectroscopy detection have shown that 7-imidazolyl-6-iodo analogues with a sulfamoylbenzamide moiety at the N1 position are the best soluble compounds in the series, with molar solubility in TRISS buffer at pH 9 more than 3-fold higher compared to NBQX, a known AMPA/kainate antagonist.

Discovery of the First Highly Selective Antagonist of the GluK3 Kainate Receptor Subtype.

Kainate receptors belong to the family of glutamate receptors ion channels, which are responsible for the majority of rapid excitatory synaptic transmission in the central nervous system. The therapeutic potential of kainate receptors is still poorly understood, which is also due to the lack of potent and subunit-selective pharmacological tools. In search of selective ligands for the GluK3 kainate receptor subtype, a series of quinoxaline-2,3-dione analogues was synthesized and pharmacologically characterized at selected recombinant ionotropic glutamate receptors. Among them, compound 28 was found to be a competitive GluK3 antagonist with submicromolar affinity and unprecedented high binding selectivity, showing a 400-fold preference for GluK3 over other homomeric receptors GluK1, GluK2, GluK5 and GluA2. Furthermore, in functional assays performed for selected metabotropic glutamate receptor subtypes, 28 did not show agonist or antagonist activity. The molecular determinants underlying the observed affinity profile of 28 were analyzed using molecular docking and molecular dynamics simulations performed for individual GluK1 and GluK3 ligand-binding domains.

(S)-2-Mercaptohistidine: A First Selective Orthosteric GluK3 Antagonist.

The development of tool compounds for the ionotropic glutamate receptors (iGluRs) remains an important research objective, as these are essential for the study and understanding of the roles of these receptors in health and disease. Herein, we report on the pharmacological characterization of (S)-2-hydroxyhistidine (2a) and (S)-2-mercaptohistidine (2b) as mediators of glutamatergic neurotransmission. While 2a displayed negligible binding affinity or activity at all glutamate receptors and transporters investigated, 2b displayed selectivity for homomeric GluK3 with binding affinities in the low micromolar range (Ki = 6.42 ± 0.74 µM). The iGluR subtype selectivity ratio for 2b was calculated at ∼30-fold for GluK1/GluK3, GluA3/GluK3, and GluA4/GluK3 and >100-fold for GluK2/GluK3, GluA1/GluK3, and GluA2/GluK3. Unexpectedly, functional characterization of 2b revealed that the compound is an antagonist (Kb = 7.6 µM) at homomeric GluK3 receptors while exhibiting only weak agonist activity at GluA2 (EC50 = 3.25 ± 0.55 mM). The functional properties of 2b were explored further in electrophysiological recordings of mouse hippocampal neurons.

Falling Insulin Requirement in Pregnant Women With Diabetes Delivering Preterm: Prevalence, Predictors, and Consequences.

CONTEXT: Falling insulin requirements often lead to considerations of whether a pregnancy can continue safely or if delivery is indicated. OBJECTIVE: To evaluate prevalence and predictors of falling insulin requirements in pregnant women with preexisting diabetes delivering preterm and to explore the relationship to fetal asphyxia and neonatal morbidity. METHODS: A prospective cohort study of 101 consecutive singleton pregnant women with preexisting diabetes delivering preterm < 37 weeks (68 type 1 and 33 type 2 diabetes) where the prevalence of falling insulin requirements (≥20%) before delivery was recorded. RESULTS: In total, 27% (27/101) experienced falling insulin requirements of median 30% (interquartile range 24-40) before delivery. In all women with type 1 diabetes, the prevalence was 37% (25/68), whereas it was 43% (24/56) in those with indicated preterm delivery and 6% (2/33) among women with type 2 diabetes. In women with type 1 diabetes and indicated preterm delivery, falling insulin requirements were first identified at 34 + 5 (33 + 6-35 + 4) weeks + days and delivery occurred 3 (1-9) days later. Gestational age at delivery, prevalence of suspected fetal asphyxia, and neonatal morbidity were similar in women with and without falling insulin requirements. Neither glycemic control, nausea, or preeclampsia was associated with falling insulin requirement. CONCLUSION: Falling insulin requirements often preceded preterm delivery in women with type 1 diabetes, foremost when preterm delivery was indicated, but was not related to fetal asphyxia or neonatal morbidity. Whether falling insulin requirements in late pregnancy are a warning sign of placental insufficiency or mainly reflects variations in normal physiology needs further investigation.

The Effects of a Mindfulness Program on Mental Health in Students at an Undergraduate Program for Teacher Education: A Randomized Controlled Trial in Real-Life.

Background: In this study, we aimed to investigate the effects of a mindfulness program including Mindfulness-Based Stress Reduction (MBSR) on the mental health of student teachers when offered at their educational institution in a real-life context. Methods: A parallel randomized controlled trial (RCT) was conducted among self-selected student teachers at a Danish undergraduate program for teacher education in the autumns of 2019 and 2020. Participation was not recommended in case of (1) clinical depression or a diagnosis of psychosis or schizophrenia, (2) abuse of alcohol, drugs, and/or medicine. Randomization was performed by a Statistician who was blinded to the identity of the students. Data was collected using self-reported questionnaires. The primary outcome was a change in perceived stress 3 months from baseline. Secondary outcome measures were symptoms of anxiety and depression, well-being, resilience, mindfulness, and thoughts and feelings during rest. The effects were analyzed according to the intention-to-treat principle using mixed-effect linear regression models. Mediating effects of mindfulness skills on the mental health outcomes were explored using structural equation modeling. Results: The study group included 67 student teachers with 34 allocated to the intervention group (median age: 25 years; women: n = 24, 71%); and 33 students (median age: 25 years; women: n = 25, 76%) allocated to a waiting list control group. At baseline, mean Perceived Stress Scale (PSS) scores were 18.88 (SD: 5.75) in the intervention group and 17.91 (SD: 6.36) in the waiting list control group. A total of 56 students completed the questionnaire at a 3-month follow-up (28 in both the intervention- and the control group). Statistically significant effects of the intervention were found on perceived stress, symptoms of anxiety and depression, well-being, and on three of seven resting-state dimensions. No effects were found on resilience or mindfulness. Statistically significant mediated effects via resting-state dimensions were found. Conclusion The findings suggested that offering a mindfulness program at an undergraduate program for teacher education could significantly improve the mental health among self-selected students within 3 months. Results of mediation analysis supported the hypothesis that some of the effects might be explained by reduced distracting thoughts. Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT04558099].

Structure-Activity Studies of 3,9-Diazaspiro[5.5]undecane-Based γ-Aminobutyric Acid Type A Receptor Antagonists with Immunomodulatory Effect.

The 3,9-diazaspiro[5.5]undecane-based compounds 2027 and 018 have previously been reported to be potent competitive γ-aminobutyric acid type A receptor (GABAAR) antagonists showing low cellular membrane permeability. Given the emerging peripheral application of GABAAR ligands, we hypothesize 2027 analogs as promising lead structures for peripheral GABAAR inhibition. We herein report a study on the structural determinants of 2027 in order to suggest a potential binding mode as a basis for rational design. The study identified the importance of the spirocyclic benzamide, compensating for the conventional acidic moiety, for GABAAR ligands. The structurally simplified m-methylphenyl analog 1e displayed binding affinity in the high-nanomolar range (Ki = 180 nM) and was superior to 2027 and 018 regarding selectivity for the extrasynaptic α4ßδ subtype versus the α1- and α2- containing subtypes. Importantly, 1e was shown to efficiently rescue inhibition of T cell proliferation, providing a platform to explore the immunomodulatory potential for this class of compounds.

Potentially modifiable risk factors of preterm delivery in women with type 1 and type 2 diabetes.

AIMS/HYPOTHESIS: We aimed to identify potentially modifiable risk factors and causes for preterm delivery in women with type 1 or type 2 (pre-existing) diabetes. METHODS: A secondary analysis of a prospective cohort study of 203 women with pre-existing diabetes (117 type 1 and 86 type 2 diabetes) was performed. Consecutive singleton pregnancies were included at the first antenatal visit between September 2015 and February 2018. RESULTS: In total, 27% (n = 55) of the 203 women delivered preterm at median 36 + 0 weeks. When stratified by diabetes type, 33% of women with type 1 diabetes delivered preterm compared with 20% in women with type 2 diabetes (p = 0.04). Women delivering preterm were characterised by a higher prevalence of pre-existing kidney involvement (microalbuminuria or diabetic nephropathy) (16% vs 3%, p = 0.002), preeclampsia (26% vs 5%, p < 0.001), higher positive ultrasound estimated fetal weight deviation at 27 gestational weeks (2.7% vs -1.6% from the mean, p = 0.008), higher gestational weight gain (399 g/week vs 329 g/week, p = 0.01) and similar HbA1c levels in early pregnancy (51 mmol/mol [6.8%] vs 49 [6.6%], p = 0.22) when compared with women delivering at term. Independent risk factors for preterm delivery were pre-existing kidney involvement (OR 12.71 [95% CI 3.0, 53.79]), higher gestational weight gain (per 100 g/week, OR 1.25 [1.02, 1.54]), higher positive ultrasound estimated fetal weight deviation at 27 gestational weeks (% from the mean, OR 1.07 [1.03, 1.12]) and preeclampsia (OR 7.04 [2.34, 21.19]). Two-thirds of preterm deliveries were indicated and one-third were spontaneous. Several contributing factors to indicated preterm delivery were often present in each woman. The main indications were suspected fetal asphyxia (45%), hypertensive disorders (34%), fetal overgrowth (13%) and maternal indications (8%). Suspected fetal asphyxia mainly included falling insulin requirement and abnormal fetal haemodynamics. CONCLUSIONS/INTERPRETATIONS: Presence of preeclampsia, higher positive ultrasound estimated fetal weight deviation at 27 gestational weeks and higher gestational weight gain were independent potentially modifiable risk factors for preterm delivery in this cohort of women with pre-existing diabetes. Indicated preterm delivery was common with suspected fetal asphyxia or preeclampsia as the most prevalent causes. Prospective studies evaluating whether modifying these predictors will reduce the prevalence of preterm delivery are warranted.

Maternal health and pregnancy outcome in diagnosed and undiagnosed Marfan syndrome: A registry-based study.

In Marfan syndrome (MFS), pregnancy is considered as high risk due to the deficiency of fibrillin in the connective tissue and increased risk of aortic dissection. The objective was to demonstrate the consequences on maternal health, in women with diagnosed and undiagnosed MFS at the time of pregnancy and childbirth. By using national health care registries, we identified all pregnancy related outcomes, from women with MFS (n = 183) and an age-matched background population (n = 18,300). We found 91 pregnancies during follow-up. Significantly fewer women with MFS gave birth, compared to the background population. No women with known MFS had a pregnancy related aortic dissection but complications related to the cervix were increased (HR:19.8 [95% CI:2.2-177.5]). Fifty women with MFS were undiagnosed at the time of their first pregnancy and/or childbirth. Among these, there were more birth canal related complications HR:27.2 (95% CI: 2.3-315.0), preeclampsia (HR:2.25 [95% CI: 1.11-4.60]), fetal deaths (HR:12.3 [95% CI: 1.51-99.8]), and all delivery-related dissections came from this subgroup. In conclusion, undiagnosed women with MFS experienced more pregnancy and childbirth related complications including fetal death, birth canal issues, preeclampsia, and aortic disease, which emphasizes the need for an early MFS diagnosis and special care during pregnancy and childbirth.

Cerebral Microdialysis in Aneurismal Subarachnoid Hemorrhage Patient Reveals a Detrimental Shift in Brain Energy Metabolism, Despite Normal Perfusion Pressure.

The present case study concerns a patient admitted to our neuro-intensive care unit with a severe aneurismal subarachnoid hemorrhage rebleeding. The patient was equipped with multimodal neuromonitoring, including cerebral microdialysis. During the neuro-intensive care unit, there was a gradual decrease in cerebral perfusion pressure, which was within normally accepted levels, correlated to a detrimental shift in cerebral metabolism, from mitochondrial dysfunction to an ischemic pattern. Subsequently, the clinical and paraclinical status of the patient worsened. The present case highlights how the dynamic assessment of cerebral metabolic patterns and the concept of mitochondrial dysfunction can be relevant in the day-to-day clinical setting, to evaluate and optimize basic, well-known physiological parameters, such as cerebral perfusion pressure.

High Prevalence of Gestational Diabetes Mellitus in Rural Tanzania-Diagnosis Mainly Based on Fasting Blood Glucose from Oral Glucose Tolerance Test.

Gestational diabetes mellitus (GDM) is associated with poor pregnancy outcomes and increased long-term risk of metabolic diseases for both mother and child. In Tanzania, GDM prevalence increased from 0% in 1991 to 19.5% in 2016. Anaemia has been proposed to precipitate the pathogenesis of GDM. We aimed to examine the prevalence of GDM in a rural area of Tanzania with a high prevalence of anaemia and to examine a potential association between haemoglobin concentration and blood glucose during pregnancy. The participants were included in a population-based preconception, pregnancy and birth cohort study. In total, 538 women were followed during pregnancy and scheduled for an oral glucose tolerance test (OGTT) at week 32-34 of gestation. Gestational diabetes mellitus was diagnosed according to the WHO 2013 guidelines. Out of 392 women screened, 39% (95% CI: 34.2-44.1) had GDM, the majority of whom (94.1%) were diagnosed based solely on the fasting blood sample from the OGTT. No associations were observed between haemoglobin or ferritin and glucose measurements during pregnancy. A very high prevalence of GDM was found in rural Tanzania. In view of the laborious, costly and inconvenient OGTT, alternative methods such as fasting blood glucose should be considered when screening for GDM in low- and middle-income countries.

The incidence of rhegmatogenous retinal detachment is increasing.

PURPOSE: To study the development over time of the age- and sex-standardized incidence of rhegmatogenous retinal detachment (RRD) in Denmark. METHODS: Registry study, based on the Danish National Patient Registry data. End-point: Individuals undergoing the first surgery for RRD. RESULTS: During 2000-2016 we identified 11 769 individuals with a primary RRD surgery in either eye. The age- and sex-standardized incidence rate of RRD increased by more than 50% during the study period. We found a significant increase in this incidence rate for both men and women older than 50 years, and in men, but not in women, younger than 50 years (p < 0.001). However, the increase of primary RRD surgery during the study period was most pronounced in men aged 50 years or older, where the rate of increase was 1.7 ± 0.1 cases per 100 000 person-years per year (p < 10-11 ). CONCLUSION: The incidence of RRD is increasing, and this increase is primarily driven by men aged 50 years or older.

A Diversity Oriented Synthesis Approach to New 2,3-trans-Substituted l-Proline Analogs as Potential Ligands for the Ionotropic Glutamate Receptors.

Discovery of chemical tools for the ionotropic glutamate receptors continues to be a challenging task. Herein we report a diversity-oriented approach to new 2,3-trans-l-proline analogs whereby we study how the spatial orientation of the distal carboxylate group influences the binding affinity and receptor class and subtype selectivity. In total, 10 new analogs were synthesized and 14 stereoisomers characterized in binding assays at native rat ionotropic glutamate receptors, and at cloned human homomeric kainic acid (KA) receptor subtypes GluK1-3. The study identified isoxazole analogs 3d,e, which displayed selectivity in binding at native N-methyl-d-aspartate (NMDA) receptors over native α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and KA receptors, in the high nanomolar to low micromolar range. Furthermore, analogs 3i-A/B showed a preference in binding affinity for GluK3 over GluK1,2. Finally, analog 3j displayed high nanomolar affinity for native NMDA receptors as well as for homomeric GluK3 receptors.

Stereoselective Synthesis of New (2S,3R)-3-Carboxyphenyl)pyrrolidine-2-carboxylic Acid Analogues Utilizing a C(sp3)-H Activation Strategy and Structure-Activity Relationship Studies at the Ionotropic Glutamate Receptors.

Competitive antagonists for ionotropic glutamate receptors (iGluRs) are highly valuable tool compounds for studying health and disease states in the central nervous system. However, only few subtype selective tool compounds are available and the discovery of antagonists with novel iGluR subtype selectivity profiles remains a profound challenge. In this paper, we report an elaborate structure-activity relationship (SAR) study of the parental scaffold 2,3-trans-3-carboxy-3-phenyl-proline by the synthesis of 40 new analogues. Three synthetic strategies were employed with two new strategies of which one being a highly efficient and fully enantioselective strategy based on C(sp3)-H activation methodology. The SAR study led to the conclusion that selectivity for the NMDA receptors was a general trend when adding substituents in the 5'-position. Selective NMDA receptor antagonists were obtained with high potency (IC50 values as low as 200 nM) and 3-34-fold preference for GluN1/GluN2A over GluN1/GluN2B-D NMDA receptors.