Accessing Medium-Sized Rings via Vinyl Carbocation Intermediates.

Medium-sized rings (8-11-membered cycles) are often more challenging to synthesize than smaller rings (5-7-membered cycles) due to ring strain. Herein, we report a catalytic method for forming 8- and 9-membered rings that proceeds via the intramolecular Friedel-Crafts reactions of vinyl carbocation intermediates. These reactive species are generated catalytically through the ionization of vinyl toluenesulfonates by a Lewis acidic lithium cation-weakly coordinating anion salt.

High-Throughput Identification of Crystalline Natural Products from Crude Extracts Enabled by Microarray Technology and microED.

The structural determination of natural products (NPs) can be arduous because of sample heterogeneity. This often demands iterative purification processes and characterization of complex molecules that may be available only in miniscule quantities. Microcrystal electron diffraction (microED) has recently shown promise as a method to solve crystal structures of NPs from nanogram quantities of analyte. However, its implementation in NP discovery remains hampered by sample throughput and purity requirements, akin to traditional NP-discovery workflows. In the methods described herein, we leverage the resolving power of transmission electron microscopy (TEM) and the miniaturization capabilities of deoxyribonucleic acid (DNA) microarray technology to address these challenges through the establishment of an NP screening platform, array electron diffraction (ArrayED). In this workflow, an array of high-performance liquid chromatography (HPLC) fractions taken from crude extracts was deposited onto TEM grids in picoliter-sized droplets. This multiplexing of analytes on TEM grids enables 1200 or more unique samples to be simultaneously inserted into a TEM instrument equipped with an autoloader. Selected area electron diffraction analysis of these microarrayed grids allows for the rapid identification of crystalline metabolites. In this study, ArrayED enabled structural characterization of 14 natural products, including four novel crystal structures and two novel polymorphs, from 20 crude extracts. Moreover, we identify several chemical species that would not be detected by standard mass spectrometry (MS) or ultraviolet-visible (UV/vis) spectroscopy and crystal forms that would not be characterized using traditional methods.

Genome Mining from Agriculturally Relevant Fungi Led to a d-Glucose Esterified Polyketide with a Terpene-like Core Structure.

Comparison of biosynthetic gene clusters (BGCs) found in devastating plant pathogens and biocontrol fungi revealed an uncharacterized and conserved polyketide BGC. Genome mining identified the associated metabolite to be treconorin, which has a terpene-like, trans-fused 5,7-bicyclic core that is proposed to derive from a (4 + 3) cycloaddition. The core is esterified with d-glucose, which derives from the glycosidic cleavage of a trehalose ester precursor. This glycomodification strategy is different from the commonly observed glycosylation of natural products.

Cryptic Chemical Variation in a Marine Red Alga as Revealed by Nontargeted Metabolomics.

Many marine algae occupy habitats that are dark, deep, or encrusted on other organisms and hence are frequently overlooked by natural product chemists. However, exploration of less-studied organisms can lead to new opportunities for drug discovery. Genetic variation at the individual, species, genus, and population levels as well as environmental influences on gene expression enable expansion of the chemical repertoire associated with a taxonomic group, enabling natural product exploration using innovative analytical methods. A nontargeted LC-MS and 1H NMR spectroscopy-based metabolomic study of 32 collections of representatives of the calcareous red algal genus Peyssonnelia from coral reef habitats in Fiji and the Solomon Islands revealed significant correlations between natural products' chemistry, phylogeny, and biomedically relevant biological activity. Hierarchical cluster analysis (HCA) of LC-MS data in conjunction with NMR profiling and MS/MS-based molecular networking revealed the presence of at least four distinct algal chemotypes within the genus Peyssonnelia. Two Fijian collections were prioritized for further analysis, leading to the isolation of three novel sulfated triterpene glycosides with a rearranged isomalabaricane carbon skeleton, guided by the metabolomic data. The discovery of peyssobaricanosides A-C (15-17) from two Fijian Peyssonnelia collections, but not from closely related specimens collected in the Solomon Islands that were otherwise chemically and phylogenetically very similar, alludes to population-level variation in secondary metabolite production. Our study reinforces the significance of exploring unusual ecological niches and showcases marine red algae as a chemically rich treasure trove.

Chemoenzymatic Synthesis of (+)-Xyloketal B.

Xyloketal B is a pentacyclic fungal marine natural product that has shown potential for the treatment of diseases such as Alzheimer's disease and atherosclerosis. Herein, we describe the first asymmetric synthesis of this natural product, which relies on a chemoenzymatic strategy. This approach leverages a biocatalytic benzylic hydroxylation to access to an ortho-quinone methide intermediate which is captured in a [4 + 2] cycloaddition to stereoselectively yield a key cyclic ketal intermediate enroute to (+)-xyloketal B. The relative configuration of this intermediate was rapidly confirmed as the desired stereoisomer using MicroED. To complete the synthesis, a second ortho-quinone methide was accessed through a reductive approach, ultimately leading to the stereoselective synthesis of (+)-xyloketal B.

Medically tailored meals for food insecurity and type 2 diabetes: Protocol for the Food as Medicine for Diabetes (FAME-D) trial.

BACKGROUND: Food insecurity is associated with worse glycemic management for individuals with type 2 diabetes mellitus (T2DM), but whether medically tailored meals (MTM), a food insecurity intervention, can improve glycemic management is unclear. OBJECTIVE: To describe the protocol for a trial assessing whether an MTM plus lifestyle intervention improves hemoglobin A1c (HbA1c) and participant-reported outcomes, relative to a food subsidy (money that can be spent on foods participants choose), for adults with both T2DM and food insecurity. METHODS: The Food as Medicine for Diabetes (FAME-D) randomized clinical trial (goal n = 200) is a pragmatic trial with an active comparator. Participants, who will have T2DM and report food insecurity, will be randomly assigned to a 6-month MTM plus telephone-delivered lifestyle change intervention, or a 6-month food subsidy ($40/month). The primary outcome is HbA1c at 6 months. Secondary outcomes include HbA1c at 12 months to assess whether the intervention effect (if any) is sustained, along with weight, food insecurity, diabetes distress, and health-related quality of life. Qualitative analyses of semi-structured interviews will help understand why, how, and under what circumstances the intervention achieved its observed results. CONCLUSION: Results from FAME-D will help inform clinical management of food insecurity when it co-occurs with T2DM. Further, results may be useful as healthcare payors are considering coverage for MTM interventions. CLINICALTRIALS: gov: NCT04828785.

Identification of Uric Acid Gluconucleoside-Ascaroside Conjugates in Caenorhabditis elegans by Combining Synthesis and MicroED.

Few nucleoside-derived natural products have been identified from animals, despite the ubiquity of nucleosides in living organisms. Here, we use a combination of synthesis and the emerging electron microscopy technique microcrystal electron diffraction to determine the structures of several N3-(ß-glucopyranosyl)uric acid derivatives in Caenorhabditis elegans. These noncanonical gluconucleosides further integrate an ascaroside moiety, for which we present a shortened synthetic route. The production of a phosphorylated gluconucleoside is influenced by evolutionarily conserved insulin signaling.

Mechanistic insights into the potassium tert-butoxide-mediated synthesis of N-heterobiaryls.

We report herein that symmetrical and non-symmetrical N-heterobiaryls are produced by a potassium tert-butoxide-mediated dimerization of heterocyclic N-oxides. The reaction is scalable and transition metal-free, and can be carried out under thermal and microwave conditions. Preliminary mechanistic studies point to the involvement of radical anionic intermediates arising from the N-oxide substrates and potassium tert-butoxide.

Additive- and Metal-Free, Predictably 1,2- and 1,3-Regioselective, Photoinduced Dual C-H/C-X Borylation of Haloarenes.

We report herein a simple, additive- and metal-free, photoinduced, dual C-H/C-X borylation of chloro-, bromo-, and iodoarenes. The reaction produces 1,2- and 1,3-diborylarenes on gram scales under batch and continuous flow conditions. The regioselectivity of the dual C-H/C-X borylation is determined by the solvent and the substituents in the parent haloarenes.

Characterization of novel perylene diimides containing aromatic amino acid side chains.

Perylene diimide derivatives have attracted initial interest as industrial dyes. Recently, much attention has been focused on their strong π-π stacks resulting from the large PDI aromatic core. These PDI stacks have distinct optical properties, and provide informative models that could mimic light-harvesting systems and initial charge transfer typical of photosynthetic systems. The absorption property of PDI derivatives may be tuned from visible to near-infrared region by peripheral substitution. We have studied a new class of PDI derivatives with aryl substituents derived from the side chains of aromatic aminoacids (Tyrosine, Tryptophan and Phenylalanine). We have investigated their absorption and the fluorescence properties in a set of organic solvents and established their different tendencies to aggregate in solution despite their solubility. Most aggregation appears to be unordered. One PDI analogue (the one formed from Tyr) in Methanol, however, appears to form J-type aggregates. Based on our results the compounds appear to be promising for future investigations regarding the interaction of these dyes with biomolecules.

Pre- and perinatal characteristics and breast milk immune markers.

BACKGROUND: Maternal allergy and gestational exposures can alter the concentration of type-1/type-2/T-regulatory markers in breast milk. We tested whether maternal risk factors are related to breast milk immune markers. METHODS: Expecting mothers were enrolled in 2008-2010 in South Carolina in prenatal clinics and classes. Interferon (IFN)-γ-induced protein 10 (CXCL10), CCL11, interleukin (IL)-1ß, IL-4, IL-5, IL-6, CXCL8, IL-10, IL-12(p70), IL-13, transforming growth factor (TGF)-ß1, and immunoglobulin (Ig)A in 115 whey samples were measured by immunoassays. Maternal asthma, eczema, rhinitis, smoking, urogenital infections during gestation, pet exposure, education, race/ethnicity, age, body mass, and the child's birth date and sex were ascertained. The effects of these risk factors on immune markers were estimated using general linear models. RESULTS: Maternal asthma was linked to higher levels of IL-5, rhinitis to lower levels of IL-5 and INF-γ, and eczema to lower levels of IL-6. Gestational smoking was related to increased concentrations of CXCL8 and IL-6. African-American mothers had markedly higher levels of IL-6, IFN-γ, and CXCL8. Urogenital infections, maternal age, body mass, child's sex, and season of birth contributed to the variation. CONCLUSION: The impact of maternal allergies on immune markers in breast milk was small compared with that of maternal nondisease characteristics.

Safety, efficacy, and dosing requirements of bivalirudin in patients with heparin-induced thrombocytopenia.

STUDY OBJECTIVE: To evaluate the safety, efficacy, and dosing requirements of bivalirudin in patients with heparin-induced thrombocytopenia (HIT). DESIGN: Retrospective cohort study. SETTING: University-affiliated hospital. PATIENTS: Thirty-seven adults with a diagnosis or history of HIT who were treated with bivalirudin between January 1, 2004, and March 31, 2007. MEASUREMENTS AND MAIN RESULTS: Patients had a mean +/- SD age of 50 +/- 16 years and weighed 80 +/- 20 kg; 62% were male, 73% were Caucasian, and 95% were treated in the intensive care unit. Patients were divided into three renal function groups for assessment of bivalirudin dosing requirements: creatinine clearance (Cl(cr)) greater than 60 ml/minute (12 patients, group 1); Cl(cr) 30-60 ml/minute (11 patients, group 2); and Cl(cr) lower than 30 ml/minute or receiving continuous renal replacement therapy ([RRT] 14 patients, group 3). Except for renal function, baseline demographic characteristics were similar among groups. A total of 19 (51%) of the 37 patients achieved goal activated partial thromboplastin time (aPTT) with initial mean +/- SD bivalirudin doses of 0.14 +/- 0.04 (median 0.15), 0.1 +/- 0.07 (median 0.08), and 0.05 +/- 0.05 (median 0.05) mg/kg/hour in groups 1, 2, and 3, respectively. Doses remained similar over the study period and were 0.13 +/- 0.04 (median 0.15), 0.1 +/- 0.06 (median 0.1), and 0.04 +/- 0.02 (median 0.03) mg/kg/hour for groups 1, 2, and 3, respectively. The mean +/- SD aPTT value after achieving goal range was 64 +/- 9 seconds (all patients). Bivalirudin dosing requirements correlated with Cl(cr) (r(2) = 0.37, p<0.0001). Therapy duration was a mean +/- SD of 11 +/- 13 days (median 7 days). Systemic thrombosis and bleeding while receiving bivalirudin were also evaluated. Thrombosis occurred in one patient; clinically significant bleeding occurred in two patients. CONCLUSION: Bivalirudin dosing requirements correlated with renal function; therefore, dosage reduction is required in patients with moderate or severe renal dysfunction. Starting bivalirudin at 0.15 mg/kg/hour in patients with Cl(cr) greater than 60 ml/minute, 0.08-0.1 mg/kg/hour in patients with Cl(cr) 30-60 ml/minute, and 0.03-0.05 mg/kg/hour in patients with Cl(cr) below 30 ml/minute or receiving continuous RRT is effective at achieving goal aPTT values in most patients.