Synthesis of Chiral 1,2-Amino Alcohol-Containing Compounds Utilizing Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation of Unprotected α-Ketoamines.

Herein, we disclose a facile synthetic strategy to access an important class of drug molecules that contain chiral 1,2-amino alcohol functionality utilizing highly effective ruthenium-catalyzed asymmetric transfer hydrogenation of unprotected α-ketoamines. Recently, the COVID-19 pandemic has caused a crisis of shortage of many important drugs, especially norepinephrine and epinephrine, for the treatment of anaphylaxis and hypotension because of the increased demand. Unfortunately, the existing technologies are not fulfilling the worldwide requirement due to the existing lengthy synthetic protocols that require additional protection and deprotection steps. We identified a facile synthetic protocol via a highly enantioselective one-step process for epinephrine and a two-step process for norepinephrine starting from unprotected α-ketoamines 1b and 1a, respectively. This newly developed enantioselective ruthenium-catalyzed asymmetric transfer hydrogenation was extended to the synthesis of many 1,2-amino alcohol-containing drug molecules such as phenylephrine, denopamine, norbudrine, and levisoprenaline, with enantioselectivities of >99% ee and high isolated yields.

Design and Discovery of Water-Soluble Benzooxaphosphole-Based Ligands for Hindered Suzuki-Miyaura Coupling Reactions with Low Catalyst Load.

We report a new class of highly effective, benzooxaphosphole-based, water-soluble ligands in the application of Suzuki-Miyaura cross-coupling reactions for sterically hindered substrates in aqueous media. The catalytic activities of the coupling reactions were greatly enhanced by the addition of catalytic amounts of organic phase transfer reagents, such as tetraglyme and tetrabutylammonium bromide. The optimized general protocol can be conducted with a low catalyst load, thereby providing a practical solution for these reactions. The viability of this new Suzuki-Miyaura protocol was demonstrated with various substrates to generate important building blocks, including heterocycles, for the synthesis of biologically active compounds.

Immunogenic potential of DNA vaccine candidate, ZyCoV-D against SARS-CoV-2 in animal models.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), initially originated in China in year 2019 and spread rapidly across the globe within 5 months, causing over 96 million cases of infection and over 2 million deaths. Huge efforts were undertaken to bring the COVID-19 vaccines in clinical development, so that it can be made available at the earliest, if found to be efficacious in the trials. We developed a candidate vaccine ZyCoV-D comprising of a DNA plasmid vector carrying the gene encoding the spike protein (S) of the SARS-CoV-2 virus. The S protein of the virus includes the receptor binding domain (RBD), responsible for binding to the human angiotensin converting enzyme (ACE-2) receptor. The DNA plasmid construct was transformed into E. coli cells for large scale production. The immunogenicity potential of the plasmid DNA has been evaluated in mice, guinea pig, and rabbit models by intradermal route at 25, 100 and 500 µg dose. Based on the animal studies proof-of-concept has been established and preclinical toxicology (PCT) studies were conducted in rat and rabbit model. Preliminary animal study demonstrates that the candidate DNA vaccine induces antibody response including neutralizing antibodies against SARS-CoV-2 and also elicited Th-1 response as evidenced by elevated IFN-γ levels.

Copper-catalyzed asymmetric hydrogenation of 2-substituted ketones via dynamic kinetic resolution.

A new class of tunable heterophosphole dimeric ligands have been designed and synthesized. These ligands have enabled the first examples of Cu-catalyzed hydrogenation of 2-substituted-1-tetralones and related heteroaryl ketones via dynamic kinetic resolution, simultaneously creating two contiguous stereogenic centers with up to >99 : 1 dr and 98 : 2 er. The ligand-Cu complexes were isolated and characterized by single crystal X-ray, and DFT calculations revealed a novel heteroligated dimeric copper hydride transition state.

High-yielding continuous-flow synthesis of antimalarial drug hydroxychloroquine.

Numerous synthetic methods for the continuous preparation of fine chemicals and active pharmaceutical ingredients (API's) have been reported in recent years resulting in a dramatic improvement in process efficiencies. Herein we report a highly efficient continuous synthesis of the antimalarial drug hydroxychloroquine (HCQ). Key improvements in the new process include the elimination of protecting groups with an overall yield improvement of 52% over the current commercial process. The continuous process employs a combination of packed bed reactors with continuous stirred tank reactors for the direct conversion of the starting materials to the product. This high-yielding, multigram-scale continuous synthesis provides an opportunity to achieve increase global access to hydroxychloroquine for treatment of malaria.

BABIPhos Family of Biaryl Dihydrobenzooxaphosphole Ligands for Asymmetric Hydrogenation.

Novel bidentate phosphine ligands BABIPhos featuring a biaryl bis-dihydrobenzooxaphosphole core are presented. Their synthesis was achieved via Pd-catalyzed reductive homocoupling of dihydrobenzooxaphosphole aryl triflates. An efficient route toward various analogues was also established, giving access to phosphines with different electronic and steric properties. The newly obtained ligands demonstrated high efficiency and selectivity in Rh-catalyzed asymmetric hydrogenation of di- and trisubstituted enamides. This new class of ligands is complementary to previously described bidentate benzooxaphosphole ligands BIBOP.

Enantioselective Synthesis of α-(Hetero)aryl Piperidines through Asymmetric Hydrogenation of Pyridinium Salts and Its Mechanistic Insights.

Enantioselective synthesis of α-aryl and α-heteroaryl piperidines is reported. The key step is an iridium-catalyzed asymmetric hydrogenation of substituted N-benzylpyridinium salts. High levels of enantioselectivity up to 99.3:0.7 er were obtained for a range of α-heteroaryl piperidines. DFT calculations support an outersphere dissociative mechanism for the pyridinium reduction. Notably, initial protonation of the final enamine intermediate determines the stereochemical outcome of the transformation rather than hydride reduction of the resultant iminium intermediate.

Synthesis of Enantioenriched 2-Alkyl Piperidine Derivatives through Asymmetric Reduction of Pyridinium Salts.

An Ir-catalyzed enantioselective hydrogenation of 2-alkyl-pyridines has been developed using ligand MeO-BoQPhos. High levels of enantioselectivities up to 93:7 er were obtained. The resulting enantioenriched piperidines can be readily converted into biologically interesting molecules such as the fused tricyclic structures 5, 6, and 7 in 99:1 er, providing a novel, concise synthetic route to this family of chiral piperidine-containing compounds.

Montelukast for Children with Obstructive Sleep Apnea: Results of a Double-Blind, Randomized, Placebo-Controlled Trial.

RATIONALE: Obstructive sleep apnea (OSA) is highly prevalent in children and is usually treated by adenotonsillectomy. Nonsurgical therapies for OSA consist primarily of antiinflammatory approaches and have gained popularity, but their efficacy remains to be critically examined. OBJECTIVES: To determine the effect of montelukast on pediatric OSA. METHODS: A prospective randomized double-blind controlled trial of polysomnographically diagnosed OSA in children ages 2-10 years who were treated with either oral montelukast (4 or 5 mg daily) or placebo for 16 weeks. Adherence to the medication was ascertained using automated timed pill dispensers along with weekly telephonic reminders. MEASUREMENTS AND MAIN RESULTS: Ninety-two children diagnosed with OSA were approached, and 64 (69.6%) agreed to participate. Of these, 57 (89.0%) completed the 16-week trial, 28 in the montelukast group and 29 in the placebo group. Age, sex, and percentage of obesity were similar in the two groups, as were initial apnea-hypopnea index (AHI) scores. Overall, intention-to-treat analyses revealed that beneficial effects occurred in 20 children receiving montelukast (71.4%), whereas only 2 (6.9%) of the children receiving placebo showed reductions in AHI score (P < 0.001). Indeed, AHI decreased from 9.2 ± 4.1/hour total sleep time (TST) to 4.2 ± 2.8/hour TST (P < 0.0001) in montelukast-treated children, whereas in children receiving placebo, the AHI did not change (from 8.2 ± 5.0/h TST before to 8.7 ± 4.9/h TST at completion of the trial). CONCLUSIONS: When compared with placebo, montelukast for 16 weeks effectively reduced the severity of obstructive sleep apnea in children 2-10 years of age. These results support a therapeutic role for leukotriene modifiers in pediatric OSA provided that long-term trials confirm current findings. Clinical trial registered with www.clinicaltrials.gov (NCT 00599534).

Preparation and self-assembly study of amphiphilic and bispolar diacetylene-containing glycolipids.

Diacetylene-containing glycolipids are a unique class of compounds that are able to self-assemble and form ordered supramolecular structures. Polymerizable diacetylene glycolipids that can function as low molecular weight gelators are particularly interesting molecules which can lead to stimuli-responsive smart materials. To discover efficient organogelators with built-in functionality that may be useful in sensing local environmental changes, we have synthesized a series of novel diacetylene-containing amide and urea derivatives using D-glucosamine as the starting material. Both amphiphilic and dipolar glycolipids were synthesized, and these compounds are effective gelators for several organic solvents and aqueous solutions. The resulting gels can be cross-linked under 6 W UV light to produce blue or purple polydiacetylene gels. The cross-linked gels obtained from urea derivatives are generally dark blue and exhibit blue to red color transitions upon heating. Compared to the urea derivatives, the analogous diacetylene amides produced blue to deep purple polymerized gels, depending on the structures of the gelators. The morphologies of the gels were characterized by optical microscopy and scanning electron microscopy. Typically, self-assembled fibrous networks were observed. The synthesis and characterization of these polymerizable gelators and their UV-vis absorption upon polymerization are reported.

Nitric oxide production by monocytes in children with OSA and endothelial dysfunction.

OSA (obstructive sleep apnoea) is associated with a higher risk for alterations in post-occlusive hyperaemia, an eNOS (endothelial NO synthase)-dependent endothelial response. However, since not all children manifest endothelial dysfunction, we hypothesized that differences in circulating monocyte subsets and NO production may underlie the vascular phenotype in paediatric OSA. Matched pre-pubertal children with OSA with abnormal endothelial function (OSAab) and with normal endothelial function (OSAn), and controls (CO) were recruited. Peripheral blood mononuclear cells were subtyped into CD14+ and CD16+ cells, and NO production was assessed using flow cytometry. Endothelial dysfunction was defined as Tmax (time to reach maximal reperfusion)>45 s by laser Doppler flowmetry. A total of 11 OSAab, 12 OSAn and 12 CO-matched children completed the study. The OSAab group had increased CD16+ and decreased CD14+ cell numbers. They also had increased CX3CR1 (CX3C chemokine receptor 1) expression in CD16+ monocytes (P<0.01). Furthermore, monocytes from the OSAab group exhibited overall reduced NO production (787±71 compared with 1226±229 and 1089±116 median fluorescence intensity in the OSAn group and CO children respectively; P<0.01). Significant bivariate associations emerged between NO production, monocyte subsets, CX3CR1 in CD16+ monocytes, the CD14+/CD16+ ratio and Tmax. Thus OSA in children is associated with increased numbers of pro-inflammatory monocytes and reduced NO production in circulating monocytes that are closely associated with endothelial function.

Overnight polysomnography versus respiratory polygraphy in the diagnosis of pediatric obstructive sleep apnea.

BACKGROUND: Substantial discrepancies exist in the type of sleep studies performed to diagnose pediatric obstructive sleep apnea (OSA) in different countries. Respiratory polygraphic (RP) recordings are primarily performed in sleep laboratories in Europe, whereas polysomnography (PSG) constitutes the majority in the US and Australia. Home RP show consistent apnea-hypopnea index (AHI) underscoring, primarily because the total recording time is used as the denominator when calculating the AHI compared to total sleep time (TST). However, laboratory-based RP are less likely affected, since the presence of sleep technicians and video monitoring may enable more accurate TST estimates. We therefore examined differences in AHI in PSG and in-lab RP, and whether RP-based AHI may impact clinical decision making. METHODS: Of all the children assessed for possible OSA who underwent PSG evaluation, 100 were identified and divided into 4 groups: (A) those with AHI < 1/h TST (n = 20), (B) 1 ≤ AHI < 5/h TST (n = 40), (C) 5 ≤ AHI < 10/h TST (n = 20), and (D) AHI ≥ 10/h TST (n = 20). Electroencephalography, electrooculography, and electromyography channels were deleted from the original unscored recordings to transform them into RP, and then rescored in random sequence. AHI-RP were compared to AHI-PSG, and therapeutic decisions based on AHI-RP and AHI-PSG were formulated and analyzed using clinical details derived from the patient's clinic letter. RESULTS: Bland Altman analysis showed that in lab RP underestimated the AHI despite more accurate estimates of TST. This underestimation was due to missed hypopneas causing arousals without desaturation. Basing the therapeutic management decision on RP instead of PSG results changed the clinical management in 23% of all patients. The clinical management for patients in groups A and D was unaffected. However, 27.5% of patients in group B would have been given no treatment, as they would be diagnosed as having no OSA (AHI < 1/h TST) when they should have received a trial of anti-inflammatory therapy or been referred for ear, nose, and throat (ENT) review. Sixty percent of patients in group C would have received either a trial of medical treatment to treat mild OSA or no treatment, instead of referral to ENT services or commencement of continuous positive airway pressure. CONCLUSION: Apnea-hypopnea index (AHI) is underestimated in respiratory polygraphy (RP), and the disparity in AHI-RP and AHI-polysomnography can significantly affect clinical management decisions, particularly in children with mild and moderate obstructive sleep apnea (1 < AHI < 10/h total sleep time).

Antiinflammatory therapy outcomes for mild OSA in children.

BACKGROUND: OSA is highly prevalent in children and usually initially treated by adenotonsillectomy. Nonsurgical alternatives for mild OSA primarily consisting of antiinflammatory approaches have emerged, but their efficacy has not been extensively assessed. METHODS: A retrospective review of clinically and polysomnographically diagnosed patients with OSA treated between 2007 and 2012 was performed to identify otherwise healthy children ages 2 to 14 years who fulfilled the criteria for mild OSA and who were treated with a combination of intranasal corticosteroid and oral montelukast (OM) for 12 weeks (ICS + OM). A subset of children continued OM treatment for 6 to 12 months. RESULTS: A total of 3,071 children were diagnosed with OSA, of whom 836 fulfilled mild OSA criteria and 752 received ICS + OM. Overall, beneficial effects occurred in > 80% of the children, with nonadherence being documented in 61 children and adenotonsillectomy being ultimately performed in 12.3%. Follow-up polysomnography in a subset of 445 patients showed normalization of sleep findings in 62%, while 17.1% showed either no improvement or worsening of their OSA. Among the latter, older children (aged > 7 years; OR, 2.3; 95% CI, 1.43-4.13; P < .001) and obese children (BMI z-score > 1.65; OR: 6.3; 95% CI, 4.23-11.18; P < .000001) were significantly more likely to be nonresponders. CONCLUSIONS: A combination of ICS + OM as initial treatment of mild OSA appears to provide an effective alternative to adenotonsillectomy, particularly in younger and nonobese children. These results support implementation of multicenter randomized trials to more definitively establish the role of ICS + OM treatment in pediatric OSA.

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators.

Small molecular gelators are a class of compounds with potential applications for soft biomaterials. Low molecular weight hydrogelators are especially useful for exploring biomedical applications. Previously, we found that 4,6-O-benzylidene acetal protected D-glucose and D-glucosamine are well-suited as building blocks for the construction of low molecular weight gelators. To better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually enhanced the gelation tendency for many derivatives. The introduction of the additional methoxy group on the phenyl ring led to low molecular weight gelators with a higher pH responsiveness. The resulting gels were stable at neutral pH values but degraded in an acidic environment. The release profiles of naproxen from the pH responsive gels were also analyzed under acidic and neutral conditions. Our findings are useful for the design of novel triggered release self-assembling systems and can provide an insight into the influence of the the structure on gelation.

Simultaneous determination of homocysteine and asymmetric dimethylarginine in human urine by liquid chromatography-tandem mass spectrometry.

Increased circulating concentrations of homocysteine (HCY) and asymmetric dimethylarginine (ADMA) are associated with vascular disease and vascular risk factors. HCY has been shown to inhibit the activity of endothelial dimethylaminohydrolase (DDAH), causing the accumulation of ADMA and the inhibition of nitric oxide synthesis. The concentrations of HCY and ADMA in biological fluids are used in the clinical diagnosis of cardiovascular diseases and this necessitates the development of a rapid and sensitive method for simultaneous determination of HCY and ADMA. A rapid, simple and sensitive method for simultaneous determination of HCY and ADMA by liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with electro spray ionization (ESI) in human urine was reported here. The methodology designed here was used to estimate these molecules in urine samples collected from patients reported to Cardiology Department of our hospital. Chromatographic separation was performed on Atlantis HILIC silica (100mm×2.1mm, 5µm, Waters). Positive multiple reactions monitoring (MRM) mode was chosen for quantification of each analyte and cystamine dihydrochloride (CYA) was used as the internal standard (IS) for the assay. The intra-assay precision and accuracy were in the range of 2.4-4.8 and -1.8% to 3.1%, respectively. The inter-assay precision and accuracy were in the range of 3.0-4.2% and -1.2% to 3.2%, respectively. The recoveries were between 94.9% and 101.4%. Our approach is simple, rapid and could be extended to routine urine assay.

T regulatory lymphocytes and endothelial function in pediatric obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is a low-grade inflammatory disease affecting the cardiovascular and metabolic systems. Increasing OSA severity reduces T-regulatory lymphocytes (Tregs) in OSA children. Since Tregs modulate endothelial activation, and attenuate insulin resistance, we hypothesized that Tregs are associated with endothelial and metabolic dysfunction in pediatric OSA. METHODS: 50 consecutively recruited children (ages 4.8-12 years) underwent overnight polysomnography and fasting homeostatic model (HOMA) of insulin resistance was assessed. Percentage of Tregs using flow cytometry, and endothelial function, expressed as the time to peak occlusive hyperemia (Tmax), were examined. In a subgroup of children (n = 21), in vitro Treg suppression tests were performed. RESULTS: Circulating Tregs were not significantly associated with either BMI z score or HOMA. However, a significant inverse correlation between percentage of Tregs and Tmax emerged (p<0.0001, r = -0.56). A significant negative correlation between Tregs suppression and the sleep pressure score (SPS), a surrogate measure of sleep fragmentation emerged (p = 0.02, r = -0.51) emerged, but was not present with AHI. CONCLUSIONS: Endothelial function, but not insulin resistance, in OSA children is strongly associated with circulating Tregs and their suppressive function, and appears to correlate with sleep fragmentation. Thus, alterations in T cell lymphocytes may contribute to cardiovascular morbidity in pediatric OSA.

Circulating adropin concentrations in pediatric obstructive sleep apnea: potential relevance to endothelial function.

OBJECTIVE: To test the hypothesis that concentrations of adropin, a recently discovered peptide that displays important metabolic and cardiovascular functions, are lower in obstructive sleep apnea (OSA), especially when associated with endothelial dysfunction. STUDY DESIGN: Age-, sex-, and ethnicity-matched children (mean age, 7.2 ± 1.4 years) were included into 1 of 3 groups based on the presence of OSA in an overnight sleep study, and on the time to postocclusive maximal reperfusion (Tmax >45 seconds) with a modified hyperemic test. Plasma adropin concentrations were assayed using a commercial enzyme-linked immunosorbent assay kit. RESULTS: Among controls, the mean morning adropin concentration was 7.4 ng/mL (95% CI, 5.2-16.3 ng/mL). Children with OSA and abnormal endothelial function (EF) (OSA(+)/EF(+) group) had significantly lower adropin concentrations (2.7 ± 1.1 ng/mL; n = 35) compared with matched controls (7.6 ± 1.4 ng/mL; n = 35; P < .001) and children with OSA and normal EF (OSA(+)/EF(-) group; 5.8 ± 1.5 ng/mL; n = 47; P < .001). A plasma adropin concentration <4.2 ng/mL reliably predicted EF status, but individual adropin concentrations were not significantly correlated with age, body mass index z-score, obstructive apnea-hypopnea index, or nadir oxygen saturation. Mean adropin concentration measured after adenotonsillectomy in a subset of children with OSA (n = 22) showed an increase in the OSA(+)/EF(+) group (from 2.5 ± 1.4 to 6.4 ± 1.9 ng/mL; n = 14; P < .01), but essentially no change in the OSA(+)EF(-) group (from 5.7 ± 1.3 to 6.4 ± 1.1 ng/mL; n = 8; P > .05). CONCLUSION: Plasma adropin concentrations are reduced in pediatric OSA when endothelial dysfunction is present, and return to within normal values after adenotonsillectomy. Assessment of circulating adropin concentrations may provide a reliable indicator of vascular injury in the context of OSA in children.

Alterations in circulating T-cell lymphocyte populations in children with obstructive sleep apnea.

STUDY OBJECTIVES: Changes in lymphocyte phenotype and functionality have been described in adult patients with obstructive sleep apnea (OSA). We hypothesized that OSA is associated with T lymphocyte alterations in children, particularly in T regulatory lymphocytes (T regs), and aimed to characterize circulating T lymphocyte subsets in children with OSA. DESIGN: Cross-sectional. SETTING: Kosair Children's Hospital (Louisville, KY, USA) and Comer Children's Hospital (Chicago, IL, USA). PARTICIPANTS: Consecutively recruited children being evaluated for habitual snoring. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Overnight polysomnography (PSG) was performed and a fasting blood sample was obtained from the patients. Flow cytometry was performed on peripheral blood mononuclear cells stained for CD3, CD4, CD8, CD25, FOXP3, interleukin-4 (IL-4), interferon-γ (IFN-γ), and IL-17. Patients were divided into three groups based on their PSG: controls (apnea-hypopnea indices [AHI] < 1/h total sleep time [TST]), mild OSA (1 ≤ AHI < 5/hTST), moderate-severe OSA (AHI ≥ 5/h TST). The percentage of CD4+ and T reg lymphocytes differed across groups. Children with moderate-severe OSA had significantly reduced T reg than control children (median [interquartile range] 4.8 [3.8-5.7% CD4+] versus 7.8 [7.0-9.2% CD4+]; P < 0.001). There were also significant differences in the percentage of T helper 1 (Th1) lymphocytes and in Th1:Th2 ratios between groups. Children with moderate-severe OSA had increased Th1 cells (P = 0.001) and Th1:Th2 ratios (P = 0.0026) compared with children with mild OSA and control children. Associations between AHI and T reg (P = 0.0003; r = -0.46), CD4+ lymphocytes (P = 0.0047; r = -0.37), and Th1:Th2 ratios (P = 0.0009; r = 0.43) emerged. In addition, the percentage of T reg was inversely correlated with Th1:Th2 ratios (P = 0.029; r = -0.29). CONCLUSIONS: Pediatric OSA is associated with reduced T reg population and altered Th1:Th2 balance toward Th1 predominance, suggesting a shift to a proinflammatory state. The changes in lymphocytic phenotypes associated with OSA may contribute to the variance in systemic inflammation and downstream morbidities associated with this condition.

Synthesis of peptoid based small molecular gelators by a multiple component reaction.

We report the synthesis and self-assembling properties of a new class of tripeptoids synthesized by a one-pot Ugi reaction from simple starting materials. Among the focused library of tripeptoids synthesized, several efficient low molecular weight gelators were obtained for aqueous DMSO and ethanol mixtures.