Multigram-scale chemoenzymatic synthesis of diverse aminopolycarboxylic acids as potential metallo-ß-lactamase inhibitors.

Toxin A, a precursor to naturally occurring aspergillomarasmine A, aspergillomarasmine B, lycomarasmine and related aminopolycarboxylic acids, was synthesized as the desired (2S,2'S)-diastereomer on a multigram-scale (>99% conversion, 82% isolated yield, dr > 95 : 5) from commercially available starting materials using the enzyme ethylenediamine-N,N'-disuccinic acid lyase. A single-step protection route of this chiral synthon was developed to aid N-sulfonylation/-alkylation and reductive amination at the terminal primary amine for easy derivatization, followed by global deprotection to give the corresponding toxin A derivatives, including lycomarasmine, in moderate to good yields (23-66%) and with high stereopurity (dr > 95 : 5). Furthermore, a chemoenzymatic route was developed to introduce a click handle on toxin A (yield 72%, dr > 95 : 5) and its cyclized congener for further analogue design. Finally, a chemoenzymatic route towards the synthesis of photocaged aspergillomarasmine B (yield 8%, dr > 95 : 5) was established, prompting further steps into smart prodrug design and precision delivery. These new synthetic methodologies have the prospective of facilitating research into the finding of more selective and potent metallo-ß-lactamase (MBL) inhibitors, which are urgently needed to combat MBL-based infections.

Status of lipid control in Bangladeshi subjects with type 2 diabetes mellitus on lipid-lowering drugs: a multicenter, facility-based, cross-sectional study.

BACKGROUND: Achievement of lipid targets is crucial in patients with type 2 diabetes mellitus (T2DM) to mitigate the risk of cardiovascular diseases (CVD). Data on lipid-control status among patients with T2DM in Bangladesh are scarce. This study was conducted to determine the lipid-control status among patients with T2DM who were on lipid-lowering drugs in the country. METHODS: This cross-sectional study was conducted in the diabetes outpatient departments of several tertiary hospitals in Bangladesh from January 2022 to December 2022. Adults of both sexes diagnosed with T2DM for at least one year and were on the lipid-lowering drug(s) for a minimum of 3 months were included in the study by consecutive sampling. Patients' data were collected by face-to-face interviews, and blood samples were collected for fasting lipid profile. The lipid target was set at < 200 mg/dL for total cholesterol (TC), < 150 mg/dL for triglyceride (TG), < 100 mg/dL for low-density lipoprotein cholesterol (LDL-C), > 40 mg/dL for high-density lipoprotein cholesterol (HDL-C), and < 160 mg/dL for non-HDL cholesterol (non-HDL-C). RESULT: Three thousand sixty patients (age 44.7 ± 13.3 years, female 57%) with T2DM were evaluated. Overall, almost 81% of the study subjects achieved the LDL-C target. Besides, TC, TG, HDL-C, and non-HDL-C targets were achieved by 40.8, 21.6, 66.3, and 44.1% of patients, respectively. However, all the lipid parameters were under control in only 8.8% of patients. Almost 77.6% of the patients with ischemic heart disease, 81.5% of patients with stroke, and 65% of patients with CKD had LDL levels < 70 mg/dL. Only 10.03% achieved the HbA1c target of < 7%. 7.4% of patients achieved both HbA1c < 7% and LDL < 100 mg/dL and 5% achieved both HbA1c < 7% and LDL < 70 mg/dL. Advanced age (aOR 0.97, 95% CI 0.96, 0.98, p < 0.001), longstanding T2DM (aOR 0.53, 95% CI 0.39, 0.72, p < 0.001), and non-statin therapy (aOR 0.25, 95% CI 0.16, 0.37, p < 0.001) were negatively associated with lipid control (LDL < 100 mg/dL) while using oral hypoglycemic drugs or insulin (aOR 2.01, 95% CI 1.45, 2.77, p < 0.001) and having cardiovascular comorbidity (aOR 3.92, 95% CI 3.00, 5.12, p < 0.001) were positively associated with lipid control. CONCLUSION: Though most patients with T2DM achieved their target LDL level, the prevalence of both glycemic and overall lipid control was low in our study despite lipid-lowering therapy.

One-Pot Biocatalytic Synthesis of rac-Syringaresinol from a Lignin-Derived Phenol.

The drive for a circular bioeconomy has resulted in a great demand for renewable, biobased chemicals. We present a one-pot biocatalytic cascade reaction for the production of racemic syringaresinol, a lignan with applications as a nutraceutical and in polymer chemistry. The process consumes dihydrosinapyl alcohol, which can be produced renewably from the lignocellulosic material. To achieve this, a variant of eugenol oxidase was engineered for the oxidation of dihydrosinapyl alcohol into sinapyl alcohol with good conversion and chemoselectivity. The crystal structure of the engineered oxidase revealed the molecular basis of the influence of the mutations on the chemoselectivity of the oxidation of dihydrosinapyl alcohol. By using horseradish peroxidase, the subsequent oxidative dimerization of sinapyl alcohol into syringaresinol was achieved. Conditions for the one-pot, two-enzyme synthesis were optimized, and a high yield of syringaresinol was achieved by cascading the oxidase and peroxidase steps in a stepwise fashion. This study demonstrates the efficient production of syringaresinol from a compound that can be renewed by reductive catalytic fractionation of lignocellulose, providing a biocatalytic route for generating a valuable compound from lignin.

Comparison of fasting and random lipid profiles among subjects with type 2 diabetes mellitus: an outpatient-based cross-sectional study in Bangladesh.

BACKGROUND: Despite the wide acceptability of fasting lipid profiles in practice, emerging evidence suggests that random lipid profiles might be a convenient alternative for lipid measurement. The objective of the present study was to compare the fasting and random lipid profile among subjects with type 2 diabetes mellitus (T2DM). METHODS: The present cross-sectional study included 1543 subjects with T2DM visiting several endocrinology outpatient clinics throughout Bangladesh from January to December 2021. The fasting lipid profile was measured in the morning following 8-10 h of overnight fasting, and the random lipid profile was measured at any time of the day, irrespective of the last meal. The values of fasting and random lipids were compared using the Wilcoxon signed-rank test and Spearman rank correlation coefficients. RESULTS: In this study, a good level of correlation was observed between fasting and random lipid levels [r = 0.793, p < 0.001 for triglyceride (TG); r = 0.873, p < 0.001 for low-density lipoprotein cholesterol (LDL-C); r = 0.609, p < 0.001 for high-density lipoprotein cholesterol (HDL-C); and r = 0.780, p < 0.001 for total cholesterol (TC)]. In addition, TG and TC levels increased by 14% and 0.51%, respectively, in the random state compared to the fasting state (p- <0.05), while LDL-C levels decreased by 0.71% (p-value 0.42). No change was noticed in the HDL-C level. The difference between fasting and random lipid profiles was similar irrespective of patients' age, sex, BMI, glucose-lowering drug(s), and lipid-lowering therapy. CONCLUSIONS: Random lipid profile correlates significantly with fasting lipid profile with little difference. Hence, it might be a reliable alternative for fasting lipid profile in patients with T2DM.

Chemoenzymatic Asymmetric Synthesis of Complex Heterocycles: Dihydrobenzoxazinones and Dihydroquinoxalinones.

Chiral dihydrobenzoxazinones and dihydroquinoxalinones serve as essential building blocks for pharmaceuticals and agrochemicals. Here, we report short chemoenzymatic synthesis routes for the facile preparation of these complex heterocycles in an optically pure form. These synthetic routes involve a highly stereoselective hydroamination step catalyzed by ethylenediamine-N,N'-disuccinic acid lyase (EDDS lyase). This enzyme is capable of catalyzing the asymmetric addition of various substituted 2-aminophenols to fumarate to give a broad range of substituted N-(2-hydroxyphenyl)-l-aspartic acids with excellent enantiomeric excess (ee up to >99%). This biocatalytic hydroamination step was combined with an acid-catalyzed esterification-cyclization sequence to convert the enzymatically generated noncanonical amino acids into the desired dihydrobenzoxazinones in good overall yield (up to 63%) and high optical purity (ee up to >99%). By means of a similar one-pot, two-step chemoenzymatic approach, enantioenriched dihydroquinoxalinones (ee up to >99%) were prepared in good overall yield (up to 78%) using water as solvent for both steps. These chemoenzymatic methodologies offer attractive alternative routes to challenging dihydrobenzoxazinones and dihydroquinoxalinones, starting from simple and commercially available achiral building blocks.

Enantiocomplementary Michael Additions of Acetaldehyde to Aliphatic Nitroalkenes Catalyzed by Proline-Based Carboligases.

The blockbuster drug Pregabalin is widely prescribed for the treatment of painful diabetic neuropathy. Given the continuous epidemic growth of diabetes, the development of sustainable synthesis routes for Pregabalin and structurally related pharmaceutically active γ-aminobutyric acid (GABA) derivatives is of high interest. Enantioenriched γ-nitroaldehydes are versatile synthons for the production of GABA derivatives, which can be prepared through a Michael-type addition of acetaldehyde to α,ß-unsaturated nitroalkenes. Here we report that tailored variants of the promiscuous enzyme 4-oxalocrotonate tautomerase (4-OT) can accept diverse aliphatic α,ß-unsaturated nitroalkenes as substrates for acetaldehyde addition. Highly enantioenriched aliphatic (R)- and (S)-γ-nitroaldehydes were obtained in good yields using two enantiocomplementary 4-OT variants. Our results underscore the synthetic potential of 4-OT for the preparation of structurally diverse synthons for bioactive analogues of Pregabalin.

Biocatalytic Asymmetric Cyclopropanations via Enzyme-Bound Iminium Ion Intermediates.

Cyclopropane rings are an important structural motif frequently found in many natural products and pharmaceuticals. Commonly, biocatalytic methodologies for the asymmetric synthesis of cyclopropanes rely on repurposed or artificial heme enzymes. Here, we engineered an unusual cofactor-independent cyclopropanation enzyme based on a promiscuous tautomerase for the enantioselective synthesis of various cyclopropanes via the nucleophilic addition of diethyl 2-chloromalonate to α,ß-unsaturated aldehydes. The engineered enzyme promotes formation of the two new carbon-carbon bonds with excellent stereocontrol over both stereocenters, affording the desired cyclopropanes with high diastereo- and enantiopurity (d.r. up to 25:1; e.r. up to 99:1). Our results highlight the usefulness of promiscuous enzymes for expanding the biocatalytic repertoire for non-natural reactions.

Management of Malignant Ascites by Indwelling Tunnelled Catheters in Indian Setup: A Case Series.

Malignant Ascites (MA) poses significant symptom burden in patients with peritoneal malignancies at the end of life. Various treatment options are available and Indwelling Tunneled Catheters (ITC) have the advantage of increased patient comfort being soft on abdomen, less painful, easy to tap fluid, and less chances of infection etc. A total of 5 patients underwent insertion of ITC after proper counseling and assessment. Insertion was done in operation theatre under combined ultrasonogram and fluoroscopy guidance. Results: 4 out of 5 patients had favorable outcomes in terms of symptom free days spent at home at end of life. ITC's are a suitable option to manage symptoms in patients with terminal malignant ascites. Careful patient selection and proper education of the caregivers will increase the success rates of procedures.

Discovery, Biocatalytic Exploration and Structural Analysis of a 4-Ethylphenol Oxidase from Gulosibacter chungangensis.

The vanillyl-alcohol oxidase (VAO) family is a rich source of biocatalysts for the oxidative bioconversion of phenolic compounds. Through genome mining and sequence comparisons, we found that several family members lack a generally conserved catalytic aspartate. This finding led us to study a VAO-homolog featuring a glutamate residue in place of the common aspartate. This 4-ethylphenol oxidase from Gulosibacter chungangensis (Gc4EO) shares 42 % sequence identity with VAO from Penicillium simplicissimum, contains the same 8α-N3 -histidyl-bound FAD and uses oxygen as electron acceptor. However, Gc4EO features a distinct substrate scope and product specificity as it is primarily effective in the dehydrogenation of para-substituted phenols with little generation of hydroxylated products. The three-dimensional structure shows that the characteristic glutamate side chain creates a closely packed environment that may limit water accessibility and thereby protect from hydroxylation. With its high thermal stability, well defined structural properties and high expression yields, Gc4EO may become a catalyst of choice for the specific dehydrogenation of phenolic compounds bearing small substituents.

Insulin Injection Practice and Injection Complications - Results from the Bangladesh Insulin Injection Technique Survey.

INTRODUCTION: Diabetes mellitus is highly prevalent in Bangladesh and insulin is often needed for diabetes control. We lack sufficient data on the insulin injection technique and injection-related complications. METHODS: The Bangladesh Insulin Injection Technique Survey (BIITS) was conducted in 2018 in 18 centres throughout Bangladesh, involving 847 patients taking insulin for at least 6 months. All of the study subjects were interviewed using a structured questionnaire focusing on key insulin injection parameters. RESULTS: The mean duration of insulin use by the study subjects was 3.84 (± 4.05) years and the mean daily dose of insulin was 41 (± 25) units. A total of 71.6% participants performed ≤2 injections/day and premixed insulins were the most commonly used insulins. Mean glycated haemoglobin (HbA1c) was 9.5% (± 2%). The proportion of syringe users and pen-device users was 68.1% and 31.9%, respectively. Most of the participants injected in the abdomen and rotated the injection site(s). The majority lifted the skinfold correctly and inserted the needle at a 90-degree angle, but their dwell times after injections were not adequate. A total of 9.2% of the subjects had injection-site lipohypertrophy (LH) and among them, 38.5% injected into the lesion. Patients with LH had higher HbA1c. Higher duration of insulin use (≥5 years), reusing needles more often (>10 times), and injecting at angles other than 90 degrees were independent predictors of LH. The incidences of hypoglycaemia (36.7%) and hyperglycaemia (67.4%) were very high, and subjects with LH had higher chances of both hypoglycaemia and hyperglycaemia. Though most (92.1%) of the patients received education about insulin injection initially, it was not repeated in the recent follow-up and was found to be ineffective. CONCLUSION: A huge gap between the insulin administration guidelines and current practice was observed in this study. Complications of insulin injections were also common. Healthcare providers should pay more attention to insulin education and re-evaluate injection practices from time to time.

Enantioselective Aldol Addition of Acetaldehyde to Aromatic Aldehydes Catalyzed by Proline-Based Carboligases.

Aromatic ß-hydroxyaldehydes, 1,3-diols, and α,ß-unsaturated aldehydes are valuable precursors to biologically active natural products and drug molecules. Herein we report the biocatalytic aldol condensation of acetaldehyde with various aromatic aldehydes to give a number of aromatic α,ß-unsaturated aldehydes using a previously engineered variant of 4-oxalocrotonate tautomerase [4-OT(M45T/F50A)] as carboligase. Moreover, an efficient one-pot two-step chemoenzymatic route toward chiral aromatic 1,3-diols has been developed. This one-pot chemoenzymatic strategy successfully combined a highly enantioselective aldol addition step catalyzed by a proline-based carboligase [4-OT(M45T/F50A) or TAUT015] with a chemical reduction step to convert enzymatically prepared aromatic ß-hydroxyaldehydes into the corresponding 1,3-diols with high optical purity (e.r. up to >99:1) and in good isolated yield (51-92%). These developed (chemo)enzymatic methodologies offer alternative synthetic choices to prepare a variety of important drug precursors.

Selective Colorimetric "Turn-On" Probe for Efficient Engineering of Iminium Biocatalysis.

The efficient engineering of iminium biocatalysis has drawn considerable attention, with many applications in pharmaceutical synthesis. Here, we report a tailor-made iminium-activated colorimetric "turn-on" probe, specifically designed as a prescreening tool to facilitate engineering of iminium biocatalysis. Upon complexation of the probe with the catalytic Pro-1 residue of the model enzyme 4-oxalocrotonate tautomerase (4-OT), a brightly colored merocyanine-dye-type structure is formed. 4-OT mutants that formed this brightly colored species upon incubation with the probe proved to have a substantial activity for the iminium-based Michael-type addition of nitromethane to cinnamaldehyde, whereas mutants that showed no staining by the probe exhibited no or very low-level "Michaelase" activity. This system was exploited in a solid-phase prescreening assay termed as activated iminium colony staining (AICS) to enrich libraries for active mutants. AICS prescreening reduced the screening effort up to 20-fold. After two rounds of directed evolution, two artificial Michaelases were identified with up to 39-fold improvement in the activity for the addition of nitromethane to cinnamaldehyde, yielding the target γ-nitroaldehyde product with excellent isolated yield (up to 95%) and enantiopurity (up to >99% ee). The colorimetric activation of the turn-on probe could be extended to the class I aldolase 2-deoxy-d-ribose 5-phosphate aldolase, implicating a broader application of AICS in engineering iminium biocatalysis.

Biocatalytic Asymmetric Michael Additions of Nitromethane to α,ß-Unsaturated Aldehydes via Enzyme-bound Iminium Ion Intermediates.

The enzyme 4-oxalocrotonate tautomerase (4-OT) exploits an N-terminal proline as main catalytic residue to facilitate several promiscuous C-C bond-forming reactions via enzyme-bound enamine intermediates. Here we show that the active site of this enzyme can give rise to further synthetically useful catalytic promiscuity. Specifically, the F50A mutant of 4-OT was found to efficiently promote asymmetric Michael additions of nitromethane to various α,ß-unsaturated aldehydes to give γ-nitroaldehydes, important precursors to biologically active γ-aminobutyric acids. High conversions, high enantiocontrol, and good isolated product yields were achieved. The reactions likely proceed via iminium ion intermediates formed between the catalytic Pro-1 residue and the α,ß-unsaturated aldehydes. In addition, a cascade of three 4-OT(F50A)-catalyzed reactions followed by an enzymatic oxidation step enables assembly of γ-nitrocarboxylic acids from three simple building blocks in one pot. Our results bridge organo- and biocatalysis, and they emphasize the potential of enzyme promiscuity for the preparation of important chiral synthons.

Efficacy of bilateral greater occipital nerve block in postdural puncture headache: a narrative review.

The Epidural blood patch is considered the gold standard for managing postdural puncture headache when supportive measures fail. However, it is a procedure which can lead to another inadvertent dural puncture. Other potential adverse events that could occur during a blood patch are meningitis, neurological deficits, and unconsciousness. The bilateral greater occipital nerve block has been used for treating chronic headaches in patients with PDPH with a single injection. This minimally invasive, simple procedure can be considered for patients early, along with other supportive treatment, and an epidural blood patch can be avoided.

Rapid chemoenzymatic route to glutamate transporter inhibitor l-TFB-TBOA and related amino acids.

The complex amino acid (l-threo)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (l-TFB-TBOA) and its derivatives are privileged compounds for studying the roles of excitatory amino acid transporters (EAATs) in regulation of glutamatergic neurotransmission, animal behavior, and in the pathogenesis of neurological diseases. The wide-spread use of l-TFB-TBOA stems from its high potency of EAAT inhibition and the lack of off-target binding to glutamate receptors. However, one of the main challenges in the evaluation of l-TFB-TBOA and its derivatives is the laborious synthesis of these compounds in stereoisomerically pure form. Here, we report an efficient and step-economic chemoenzymatic route that gives access to enantio- and diastereopure l-TFB-TBOA and its derivatives at multigram scale.

Ischemic Strokes: Observations from a Hospital Based Stroke Registry in Bangladesh.

Background. Stroke is an important morbidity for low and middle income countries like Bangladesh. We established the first stroke registry in Bangladesh. Methods. Data was collected from stroke patients who were admitted in Department of Neurology of BIRDEM with first ever stroke, aged between 30 and 90 years. Patients with intracerebral hemorrhage, subarachnoid and subdural hemorrhage, and posttrauma features were excluded. Results. Data was gathered from 679 stroke patients. Mean age was 60.6 years. Almost 68% of patients were male. Small vessel strokes were the most common accounting for 45.4% of all the patients followed by large vessel getting affected in 32.5% of the cases. Only 16 (2.4%) died during treatment, and 436 (64.2%) patients had their mRS score of 3 to 5. Age greater than 70 years was associated with poor outcome on discharge [OR 1.79 (95% CI: 1.05 to 3.06)] adjusting for gender, duration of hospital stay, HDL, and pneumonia. Age, mRS, systolic blood pressure, urinary tract infection, pneumonia, and stroke severity explained the Barthel score. Conclusion. Mortality was low but most of patient had moderate to severe disability at discharge. Age, mRS, systolic blood pressure, urinary tract infection, pneumonia, and stroke severity influenced the Barthel score.

A diversity-oriented approach to indolocarbazoles via Fischer indolization and olefin metathesis: total synthesis of tjipanazole D and I.

New synthetic strategies to indolocarbazoles have been reported via two-fold Fischer indolization under green conditions using l-(+)-tartaric acid and N,N-dimethyl urea. Starting with cyclohexanone, a bench-top starting material, this methodology has been extended to the total synthesis of natural products such as tjipanazoles D and I as well as the core structure of asteropusazole and racemosin B. Here, atom economical reactions like ring-closing metathesis, enyne-metathesis, and the Diels-Alder reaction have been used as key steps. Diverse strategies demonstrated here are useful in medicinal chemistry and materials science to design a library of decorated indoles.

Spiro annulation of cage polycycles via Grignard reaction and ring-closing metathesis as key steps.

A simple synthetic strategy to C 2-symmetric bis-spiro-pyrano cage compound 7 involving ring-closing metathesis is reported. The hexacyclic dione 10 was prepared from simple and readily available starting materials such as 1,4-naphthoquinone and cyclopentadiene. The synthesis of an unprecedented octacyclic cage compound through intramolecular Diels-Alder (DA) reaction as a key step is described. The structures of three new cage compounds 7, 12 and 18 were confirmed by single crystal X-ray diffraction studies.

Gold-catalyzed sequential alkyne activation: one-pot synthesis of NH-carbazoles via cascade hydroarylation of alkyne/6-endo-dig carbocyclization reactions.

A simple and efficient one-pot protocol for the synthesis of NH-carbazoles has been described. The strategy comprises a one-pot reaction involving the treatment of 2-alkynyl indoles with arylacetylenes in the presence of an Au-Ag combination catalyst. The salient feature of the strategy involves sequential activation of terminal and internal alkynes leading to the cascade hydroarylation of terminal alkynes and 6-endo-dig carbocyclization reactions. The generality of the method has been demonstrated by using a series of 2-alkynyl indoles and arylacetylenes.