Total Synthesis of GE81112A: An Orthoester-Based Approach.

The GE81112 series, consisting of three naturally occurring tetrapeptides and synthetic derivatives, is evaluated as a potential lead structure for the development of a new antibacterial drug. Although the first total synthesis of GE81112A reported by our group provided sufficient amounts of material for an initial in depth biological profiling of the compound, improvements of the routes toward the key building blocks were needed for further upscaling and structure-activity relationship studies. The major challenges identified were poor stereoselectivity in the synthesis of the C-terminal ß-hydroxy histidine intermediate and a concise access to all four isomers of the 3-hydroxy pipecolic acid. Herein, we report a second-generation synthesis of GE81112A, which is also applicable to access further representatives of this series. Based on Lajoie's ortho-ester-protected serine aldehydes as key building blocks, the described route provides both a satisfactory improvement in stereoselectivity of the ß-hydroxy histidine intermediate synthesis and a stereoselective approach toward both orthogonally protected cis and trans-3-hydroxy pipecolic acid.

Long-term effects of preeclampsia on maternal cardiovascular health and postpartum utilization of primary care: an observational claims data study.

PURPOSE: Preeclampsia occurs in up to 15% of pregnancies and constitutes a major risk factor for cardiovascular disease. This observational cohort study aimed to examine the association between preeclamptic pregnancies and cardiovascular outcomes as well as primary and specialized care utilization after delivery. METHODS: Using statutory claims data we identified women with singleton live births between 2010 and 2017. Main outcomes included the occurrence of either hypertension or cardiovascular disease after one or more preeclamptic pregnancies, number of contacts to a general practitioner or cardiologist after delivery and prescribed antihypertensive medication. Data were analyzed using Cox proportional hazard regression models adjusted for maternal age, diabetes, dyslipidemia, and obesity. RESULTS: The study cohort consisted of 181,574 women with 240,698 births. Women who experienced preeclampsia once had an increased risk for cardiovascular (hazard ratio, HR = 1.29) or hypertensive (HR = 4.13) events. In women affected by recurrent preeclampsia, risks were even higher to develop cardiovascular disease (HR = 1.53) or hypertension (HR = 6.01). In the following years after delivery, general practitioners were seen frequently, whereas cardiologists were consulted rarely (0.3 and 2.4%). CONCLUSION: Women affected by preeclampsia experience an increased risk of developing chronic hypertension and cardiovascular disease, especially those with recurrent preeclampsia. Future medical guidelines should take this potential risk into account.

Structure Elucidation, Total Synthesis, Antibacterial In Vivo Efficacy and Biosynthesis Proposal of Myxobacterial Corramycin.

Herein, we describe the myxobacterial natural product Corramycin isolated from Corallococcus coralloides. The linear peptide structure contains an unprecedented (2R,3S)-γ-N-methyl-ß-hydroxy-histidine moiety. Corramycin exhibits anti-Gram-negative activity against Escherichia coli (E. coli) and is taken up via two transporter systems, SbmA and YejABEF. Furthermore, the Corramycin biosynthetic gene cluster (BGC) was identified and a biosynthesis model was proposed involving a 12-modular non-ribosomal peptide synthetase/polyketide synthase. Bioinformatic analysis of the BGC combined with the development of a total synthesis route allowed for the elucidation of the molecule's absolute configuration. Importantly, intravenous administration of 20 mg kg-1 of Corramycin in an E. coli mouse infection model resulted in 100 % survival of animals without toxic side effects. Corramycin is thus a promising starting point to develop a potent antibacterial drug against hospital-acquired infections.

Photoredox-Mediated Hydrogen Isotope Exchange Reactions of Amino-Acids, Peptides, and Peptide-Derived Drugs.

Hydrogen isotopically labelled compounds are essential diagnostic tools in drug research and development, as they provide vital information about the biological metabolism of drug candidates and their metabolites. Herein we report a photoredox-initiated hydrogen atom transfer (HAT) protocol which efficiently and selectively introduces deuterium or tritium at C(sp3 )-H bonds, utilizing heavy water (D2 O or T2 O) as the hydrogen isotope source, and a guanidine base. This protocol has been successfully applied to the incorporation of deuterium in several amino acids (lysine, glycine and proline) and small peptides. Finally, the method has been applied to tritium, because tritium-labelled peptides are essential for application in biological experiments, such as ligand-binding assays, or absorption, distribution, metabolism, and excretion (ADME) studies.

Total Synthesis and Structure Revision of (-)-Avicennone C.

All four possible stereoisomers of the natural product (-)-avicennone C were synthesized using two different methods for ring closure. The absolute stereochemistry was elucidated unambiguously by comparison of the analytical data with those of the reported natural product and by single X-ray crystal diffraction of synthetic intermediates. The proposed structure needed to be revised with regard to the absolute configuration of the stereogenic center bearing the secondary hydroxyl group. The reported synthesis offers a flexible, selective, and efficient access to all possible stereoisomers and may be of value for the stereoselective synthesis of other epoxyquinone natural products.

Molecular Networking-Guided Discovery and Characterization of Stechlisins, a Group of Cyclic Lipopeptides from a Pseudomonas sp.

Increasingly sensitive analytical instruments and robust downstream data processing tools have revolutionized natural product research over the past decade. A molecular networking-guided survey led to the identification of 33 new cyclic lipopeptides (CLPs) from the culture broth of the proteobacterium Pseudomonas sp. FhG100052. The compound family resembles members of the amphisin group of CLPs that possess a 3-hydroxy fatty acid linked to the N-terminus of an undecapeptide core. Culture optimization led to the isolation and subsequent structure elucidation of one known and five new derivatives by extensive MS/MS and NMR experiments in combination with Marfey's analysis. The data were in agreement with in silico analysis of the corresponding biosynthetic gene cluster. Most strikingly, the length of the incorporated fatty acid defined the growth inhibitory effects against Moraxella catarrhalis FH6810, as observed by MIC values ranging from no inhibition (>128 µg/mL) to 4 µg/mL.

Effects of a Brief Electronic Mindfulness-Based Intervention on Relieving Prenatal Depression and Anxiety in Hospitalized High-Risk Pregnant Women: Exploratory Pilot Study.

BACKGROUND: Peripartum depression and anxiety disorders are highly prevalent and are correlated with adverse maternal and neonatal outcomes. Antenatal care in Germany does not yet include structured screening and effective low-threshold treatment options for women facing peripartum depression and anxiety disorders. Mindfulness-based interventions (MBIs) are increasingly becoming a focus of interest for the management of such patients. Studies have shown a decrease in pregnancy-related stress and anxiety in expectant mothers following mindfulness programs. OBJECTIVE: The aim of this study was to explore the clinical effectiveness of a 1-week electronic course of mindfulness on prenatal depression and anxiety in hospitalized, high-risk pregnant women. We hypothesized that participating in a 1-week electronic MBI (eMBI) could alleviate symptoms of depression and anxiety during the hospital stay. METHODS: A prospective pilot study with an explorative study design was conducted from January to May 2019 in a sample of 68 women hospitalized due to high-risk pregnancies. After enrolling into the study, the participants were given access to an eMBI app on how to deal with stress, anxiety, and symptoms of depression. Psychometric parameters were assessed via electronic questionnaires comprising the Edinburgh Postnatal Depression Scale (EPDS), State-Trait Anxiety Inventory (STAI-S), and abridged version of the Pregnancy-Related Anxiety Questionnaire (PRAQ-R). RESULTS: We observed a high prevalence of peripartum depression and anxiety among hospitalized high-risk pregnant women: 39% (26/67) of the study participants in the first assessment and 41% (16/39) of the participants in the second assessment achieved EPDS scores above the cutoff value for minor/major depression. The number of participants with anxiety levels above the cutoff value (66% [45/68] of the participants in the first assessment and 67% [26/39] of the participants in the second assessment) was significantly more than that of the participants with anxiety levels below the cutoff value, as measured with the STAI-S. After completing the 1-week electronic course on mindfulness, the participants showed a significant reduction in the mean state anxiety levels (P<.03). Regarding pregnancy-related anxiety, participants who completed more than 50% of the 1-week course showed lower scores in PRAQ-R in the second assessment (P<.05). No significant changes in the EPDS scores were found after completing the intervention. CONCLUSIONS: Peripartum anxiety and depression represent a relevant health issue in hospitalized pregnant patients. Short-term eMBIs could have the potential to reduce anxiety levels and pregnancy-related anxiety. However, we observed that compliance to eMBI seems to be related to lower symptoms of pregnancy-related stress among high-risk patients. eMBIs represent accessible mental health resources at reduced costs and can be adapted for hospitalized patients during pregnancy.

Armeniaspirol Antibiotic Biosynthesis: Chlorination and Oxidative Dechlorination Steps Affording Spiro[4.4]non-8-ene.

Armeniaspirols are potent antibiotics containing an unusual spiro[4.4]non-8-ene moiety. Herein, we describe the cloning and functional analysis of the armeniaspirol biosynthetic gene cluster. Gene-inactivation studies and subsequent isolation of previously unknown biosynthetic intermediates shed light on intriguing biosynthetic details. Remarkably, deletion of ams15, which encodes a protein bearing a flavin-binding domain, led to the accumulation of several non-spiro intermediates with various numbers of chlorine substitutions on the pyrrole moiety. The di- and trichloropyrrole species were converted by Streptomyces albus expressing Ams15 into mono- and dichlorinated spiro derivatives, respectively. In addition, in vitro conversion of these non-spiro intermediates into des-N-methyl spiro intermediates by the cell lysate of the same recombinant strain proved Ams15 to be responsible for spiro formation through oxidative dehalogenation.

Profiling antimicrobial peptides from the medical maggot Lucilia sericata as potential antibiotics for MDR Gram-negative bacteria.

Background: The ability of MDR Gram-negative bacteria to evade even antibiotics of last resort is a severe global challenge. The development pipeline for conventional antibiotics cannot address this issue, but antimicrobial peptides (AMPs) offer an alternative solution. Objectives: Two insect-derived AMPs (LS-sarcotoxin and LS-stomoxyn) were profiled to assess their suitability for systemic application in humans. Methods: The peptides were tested against an extended panel of 114 clinical MDR Gram-negative bacterial isolates followed by time-kill analysis, interaction studies and assays to determine the likelihood of emerging resistance. In further in vitro studies we addressed cytotoxicity, cardiotoxicity and off-target interactions. In addition, an in vivo tolerability and pharmacokinetic study in mice was performed. Results: LS-sarcotoxin and LS-stomoxyn showed potent and selective activity against Gram-negative bacteria and no cross-resistance with carbapenems, fluoroquinolones or aminoglycosides. Peptide concentrations of 4 or 8 mg/L inhibited 90% of the clinical MDR isolates of Escherichia coli, Enterobacter cloacae, Acinetobacter baumannii and Salmonella enterica isolates tested. The 'all-d' homologues of the peptides displayed markedly reduced activity, indicating a chiral target. Pharmacological profiling revealed a good in vitro therapeutic index, no cytotoxicity or cardiotoxicity, an inconspicuous broad-panel off-target profile, and no acute toxicity in mice at 10 mg/kg. In mouse pharmacokinetic experiments LS-sarcotoxin and LS-stomoxyn plasma levels above the lower limit of quantification (1 and 0.25 mg/mL, respectively) were detected after 5 and 15 min, respectively. Conclusions: LS-sarcotoxin and LS-stomoxyn are suitable as lead candidates for the development of novel antibiotics; however, their pharmacokinetic properties need to be improved for systemic administration.

Biological Profiling of Coleoptericins and Coleoptericin-Like Antimicrobial Peptides from the Invasive Harlequin Ladybird Harmonia axyridis.

The spread of antibiotic-resistant human pathogens and the declining number of novel antibiotics in the development pipeline is a global challenge that has fueled the demand for alternative options. The search for novel drug candidates has expanded to include not only antibiotics but also adjuvants capable of restoring antibiotic susceptibility in multidrug-resistant (MDR) pathogens. Insect-derived antimicrobial peptides (AMPs) can potentially fulfil both of these functions. We tested two coleoptericins and one coleoptericin-like peptides from the invasive harlequin ladybird Harmonia axyridis against a panel of human pathogens. The AMPs displayed little or no activity when tested alone but were active even against clinical MDR isolates of the Gram-negative ESKAPE strains when tested in combination with polymyxin derivatives, such as the reserve antibiotic colistin, at levels below the minimal inhibitory concentration. Assuming intracellular targets of the AMPs, our data indicate that colistin potentiates the activity of the AMPs. All three AMPs achieved good in vitro therapeutic indices and high intrahepatic stability but low plasma stability, suggesting they could be developed as adjuvants for topical delivery or administration by inhalation for anti-infective therapy to reduce the necessary dose of colistin (and thus its side effects) or to prevent development of colistin resistance in MDR pathogens.

Total Synthesis and Structural Revision of the Antibiotic Tetrapeptide GE81112A.

The total synthesis of the naturally occurring antibiotic GE81112A, a densely functionalized tetrapeptide, is reported. Comparison of spectral data with those of the natural product and the lack of biological activity of the synthesized compound led us to revise the published configuration of the 3-hydroxypipecolic acid moiety. This hypothesis was fully validated by the synthesis of the corresponding epimer.

Conformational Analysis of an Antibacterial Cyclodepsipeptide Active against Mycobacterium tuberculosis by a Combined ROE and RDC Analysis.

Griselimycin (GM) and methylgriselimycin (MGM), naturally produced by microorganisms of the genus Streptomyces, are cyclic depsipeptides composed of ten amino acids. They exhibit antibacterial activity against Mycobacterium species by inhibiting the sliding clamp of prokaryotic DNA polymerase III and are therefore considered as potential anti-tuberculosis drugs. The difference between the peptides is the presence of l-(R)-4-methyl-proline in MGM instead of l-proline in GM at position 8 of the amino acid sequence. Methylation increases both metabolic stability and activity of MGM compared to GM. To get deeper insight into the structure-activity relationship, the solution structure of the cyclic part of MGM was determined using rotating-frame nuclear Overhauser effect (ROE) distance restraints and residual dipolar couplings (RDC). The structure of MGM in solution is compared to the structure of GM in a co-crystal with DNA polymerase III subunit beta. As a result, a highly defined structural model of MGM is obtained, which shows related characteristics to the bound GM.

Svetamycins A-G, Unusual Piperazic Acid-Containing Peptides from Streptomyces sp.

Seven new halogenated peptides termed svetamycins A-G (1-7) have been isolated from laboratory cultures of a Streptomyces sp. Svetamycins A-D, F, and G are cyclic depsipeptides, whereas svetamycin E is a linear analogue of svetamycin C. Their structures were determined using extensive spectroscopic analysis, and their stereochemical configuration was established by a combination of NMR data, quantum mechanical calculations, and chemical derivatizations. Svetamycins are characterized by the presence of a hydroxyl acetic acid and five amino acids including a rare 4,5-dihydroxy-2,3,4,5-tetrahydropyridazine-3-carboxylic acid, a γ-halogenated piperazic acid, and a novel δ-methylated piperazic acid in svetamycins B-C, E, and G. Moreover, isotope-labeled substrate feeding experiments demonstrated ornithine as the precursor of piperazic acid and that methylation at the δ position of the piperazyl scaffold is S-adenosyl-l-methionine (SAM)-dependent. Svetamycin G, the most potent antimicrobial of this suite of compounds, inhibited the growth of Mycobacterium smegmatis with an MIC80 value of 2 µg/mL.

Identification and optimization of a new series of anti-tubercular quinazolinones.

A high throughput phenotypic screening against Mycobacterium smegmatis led us to the discovery of a new class of bacteriostatic, highly hydrophobic antitubercular quinazolinones that potently inhibited the in vitro growth of either extracellular or intramacrophagic M. tuberculosis (Mtb), via modulation of an unidentified but yet novel target. Optimization of the initial hit compound culminated in the identification of potent but poorly soluble Mtb growth inhibitors, three of which were progressed to in vivo efficacy studies. Despite nanomolar in vitro potency and attractive PK properties, none of these compounds was convincingly potent in our in vivo mouse tuberculosis models. This lack of efficacy may be linked to the poor drug-likeness of the test molecules and/or to the properties of the target.

Biosynthetic Studies of Telomycin Reveal New Lipopeptides with Enhanced Activity.

Telomycin (TEM) is a cyclic depsipeptide antibiotic active against Gram-positive bacteria. In this study, five new natural telomycin analogues produced by Streptomyces canus ATCC 12646 were identified. To understand the biosynthetic machinery of telomycin and to generate more analogues by pathway engineering, the TEM biosynthesis gene cluster has been characterized from S. canus ATCC 12646: it spans approximately 80.5 kb and consists of 34 genes encoding fatty acid ligase, nonribosomal peptide synthetases (NRPSs), regulators, transporters, and tailoring enzymes. The gene cluster was heterologously expressed in Streptomyces albus J1074 setting the stage for convenient biosynthetic engineering, mutasynthesis, and production optimization. Moreover, in-frame deletions of one hydroxylase and two P450 monooxygenase genes resulted in the production of novel telomycin derivatives, revealing these genes to be responsible for the specific modification by hydroxylation of three amino acids found in the TEM backbone. Surprisingly, natural lipopeptide telomycin precursors were identified when characterizing an unusual precursor deacylation mechanism during telomycin maturation. By in vivo gene inactivation and in vitro biochemical characterization of the recombinant enzyme Tem25, the maturation process was shown to involve the cleavage of previously unknown telomycin precursor-lipopeptides, to yield 6-methylheptanoic acid and telomycins. These lipopeptides were isolated from an inactivation mutant of tem25 encoding a (de)acylase, structurally elucidated, and then shown to be deacylated by recombinant Tem25. The TEM precursor and several semisynthetic lipopeptide TEM derivatives showed rapid bactericidal killing and were active against several multidrug-resistant (MDR) Gram-positive pathogens, opening the path to future chemical optimization of telomycin for pharmaceutical application.

Nanomolar inhibitors of Mycobacterium tuberculosis glutamine synthetase 1: synthesis, biological evaluation and X-ray crystallographic studies.

A series of imidazo[1,2-a]indeno[1,2-e]pyrazin-4-ones that potently inhibit M. tuberculosis glutamine synthetase (GlnA1) has been identified by high throughput screening. Exploration of this series was performed owing to a short chemistry program. Despite possibly nanomolar inhibitions, none of these compounds was active on whole cell Mtb, suggesting that GlnA1 may not be a suitable target to find new anti-tubercular drugs.

Discovery, Structure Elucidation, and Biological Characterization of Nannocystin†A, a Macrocyclic Myxobacterial Metabolite with Potent Antiproliferative Properties.

Microbial natural products are a rich source of bioactive molecules to serve as drug leads and/or biological tools. We investigated a little-explored myxobacterial genus, Nannocystis sp., and discovered a novel 21-membered macrocyclic scaffold that is composed of a tripeptide and a polyketide part with an epoxyamide moiety. The relative and absolute configurations of the nine stereocenters was determined by NMR spectroscopy, molecular dynamics calculations, chemical degradation, and X-ray crystallography. The compound, named nannocystin A (1), was found to inhibit cell proliferation at low nanomolar concentrations through the early induction of apoptosis. The mode of action of 1 could not be matched to that of standard drugs by transcriptional profiling and biochemical experiments. An initial investigation of the structure-activity relationship based on seven analogues demonstrated the importance of the epoxide moiety for high activity.

Industrial natural product chemistry for drug discovery and development.

Covering: up to March 2013. In addition to their prominent role in basic biological and chemical research, natural products are a rich source of commercial products for the pharmaceutical and other industries. Industrial natural product chemistry is of fundamental importance for successful product development, as the vast majority (ca. 80%) of commercial drugs derived from natural products require synthetic efforts, either to enable economical access to bulk material, and/or to optimize drug properties through structural modifications. This review aims to illustrate issues on the pathway from lead to product, and how they have been successfully addressed by modern natural product chemistry. It is focused on natural products of current relevance that are, or are intended to be, used as pharmaceuticals.

Implementation and Evaluation of a Breast Cancer Disease Model Using Real-World Claims Data in Germany from 2010 to 2020.

Breast cancer is the leading cause of cancer-related mortality among women in Germany and worldwide. This retrospective claims data analysis utilizing data from AOK Baden-Wuerttemberg, a major statutory German health insurance provider, aimed to construct and assess a real-world data breast cancer disease model. The study included 27,869 female breast cancer patients and 55,738 age-matched controls, analyzing data from 2010 to 2020. Three distinct breast cancer stages were analyzed: Stage A (early breast cancer without lymph node involvement), Stage B (early breast cancer with lymph node involvement), and Stage C (primary distant metastatic breast cancer). Tumor subtypes were estimated based on the prescription of antihormonal or HER2-targeted therapy. The study established that 77.9% of patients had HR+ breast cancer and 9.8% HER2+; HR+/HER2- was the most common subtype (70.9%). Overall survival (OS) analysis demonstrated significantly lower survival rates for stages B and C than for controls, with 5-year OS rates ranging from 79.3% for stage B to 35.4% for stage C. OS rates were further stratified by tumor subtype and stage, revealing varying prognoses. Distant recurrence-free survival (DRFS) analysis showed higher recurrence rates in stage B than in stage A, with HR-/HER2- displaying the worst DRFS. This study, the first to model breast cancer subtypes, stages, and outcomes using German claims data, provides valuable insights into real-world breast cancer epidemiology and demonstrates that this breast cancer disease model has the potential to be representative of treatment outcomes.

App-based assessment of patient-reported outcomes in the Molecular Tumor Board in the Center for Personalized Medicine-(TRACE).

Background: Biomarker-based therapies are increasingly used in cancer patients outside clinical trials. Systematic assessment of patient-reported outcomes (PRO) is warranted to take patients' perspectives during biomarker-based therapies into consideration. We assessed the feasibility of an electronic PRO assessment via a smartphone application. Methods: An interdisciplinary expert panel developed a smartphone application based on symptom burden and health-related quality of life (HRQoL) metrics reported in a retrospective analysis of 292 neuro-oncological patients. The app included validated assessments of health-related quality of life (HRQoL), the burden of symptoms, and psychological stress. Feasibility and usability were tested in a pilot study. Semi-structured interviews with patients and health care professionals (HCP) were conducted, transcribed, and analyzed according to Mayring´s qualitative content analysis. Furthermore, we assessed compliance and descriptive data of ePROs. Results: A total of 14 patients have been enrolled, (9 female, 5 male). A total of 4 HCPs, 9 patients, and 1 caregiver were interviewed regarding usability/feasibility. The main advantages were the possibility to complete questionnaires at home and comfortable implementation in daily life. Compliance was high, for example, 82% of the weekly distributed NCCN distress thermometer questionnaires were answered on time, however, with interindividual variability. We observed a median distress score of 5 (range 0-10, 197 results, n = 12, weekly assessed) and a median Global health score of 58.3 according to the EORTC QLQ-C30 instrument (range 16.7-100, 77 results, n = 12, monthly assessed). Conclusions: This pilot study proved the feasibility and acceptance of the app. We will therefore expand its application during biomarker-guided therapies to enable systematic PRO assessments.