Amino Acid Derivatives Research Articles

Electrochemical Synthesis of Unnatural Amino Acids via Anodic Decarboxylation of N-Acetylamino Malonic Acid Derivatives.

Broad application of α,α-disubstituted cyclic amino acid derivatives in medicinal chemistry urges for analogue design with improved pharmacokinetic properties. Herein, we disclose an electrochemical approach toward unnatural THF- and THP-containing amino acid derivatives that relies on anodic decarboxylation-intramolecular etherification of inexpensive and readily available N-acetylamino malonic acid monoesters under Hofer-Moest reaction conditions. The decarboxylative cyclization proceeds under constant current conditions in an undivided cell in an aqueous medium without any added base. A successful bioisosteric replacement of the 1-aminocyclohexane-1-carboxylic acid subunit by the THP-containing amino acid scaffold in cathepsin K inhibitor balicatib helped to reduce lipophilicity while retaining low nanomolar enzyme inhibitory potency and comparable microsomal stability.

Kokumi-Enhancing Mechanism of N-l-lactoyl-l-Met Elucidated by Sensory Experiments and Molecular Simulations.

Recent research indicates that N-lactoyl amino acid derivatives have the potential as kokumi substances, with their kokumi profile closely linked to that of amino acids. This study aimed to explore the unexplored effects resulting from the introduction of lactate groups into l-Methional (l-Met), a prevalent flavor compound found in foods, such as tomatoes, known for its ability to activate the monosodium glutamate response. N-l-Lac-l-Met was enzymatically synthesized using food grade, and its taste profile and underlying mechanisms were investigated. The structure of N-l-Lac-l-Met was determined by high-performance liquid chromatography (HPLC)-mass spectrometry (MS)/MS. Sensory evaluation revealed the presence of astringency, kokumi, and bitterness of N-l-Lac-l-Met. In a stimulated broth, N-l-Lac-l-Met exhibited enhanced umami and kokumi taste perception compared to l-Met while demonstrating good stability within pH 5 to 9. A molecular simulation and quantum mechanics analysis indicated that the formation of an amide bond played a crucial role in the kokumi-enhancing effect of N-l-Lac-l-Met, specifically by increasing its affinity with umami receptors T1R1-T1R3 and a kokumi receptor CaSR. These findings established the relationship between amide bond formation and the kokumi-enhancing effect of N-l-Lac-l-Met, presenting its potential application as the kokumi substance in the food industry.

Synthesis of Charge-Compensated nido-Carboranyl Derivatives of Sulfur-Containing Amino Acids and Biotin.

A new group of charge-compensated nido-carboranyl derivatives of sulfur-containing amino acids and biotin has been synthesized in which the boron atom in position 9 or 10 of carborane is attached to a positively charged sulfur atom. The possibilities of obtaining symmetrical B(10)-substituted and asymmetric B(9)-substituted nido-carboranes were studied. Using the example of (S)-methionine and D-biotin derivatives, water-soluble S-substituted charge-compensated nido-carboranes with free functional groups were prepared. The results obtained open up prospects for the development of potential boron delivery agents for BNCT as well as new bioactive compounds containing a negatively charged nido-carboranyl fragment bearing a positive charge on the sulfur atom associated with the boron cluster.

Taurine accelerates the synthesis of ceramides and hyaluronic acid in cultured epidermis and dermal fibroblasts.

Taurine is a sulfur-containing amino acid derivative that can be found in the majority of mammalian tissues. Taurine is also present in the skin and is involved in maintaining skin homeostasis by exerting osmoregulatory and antioxidant effects. Previous studies have indicated that taurine treatment is effective against age-, ultraviolet- or detergent-induced skin dysfunction. To determine the mechanism responsible for the beneficial actions of taurine in the skin, the present study aimed to evaluate the effects of taurine on epidermal components (ceramides and filaggrin) and on the dermal extracellular matrix, in three-dimensionally (3D) cultured epidermis and dermal fibroblasts, respectively. These cells were cultured in the presence of 3-50 mM taurine, and cells or culture medium were collected for analysis. The effects of taurine on transepidermal water loss (TEWL) in the skin and the expression of inflammatory cytokines, including IL-1α, IL-1β and IL-1 receptor antagonist, were investigated in acetone-treated 3D-cultured epidermis using a Tewameter and reverse transcription-quantitative PCR (RT-qPCR), respectively. The mRNA expression levels of MMP-1 and hyaluronic acid (HA) production were measured in skin dermal fibroblasts using RT-qPCR and ELISA, respectively. Taurine was found to suppress acetone-induced elevation in TEWL in 3D-cultured epidermis. Taurine also stimulated the mRNA expression of ceramide synthase 4 and filaggrin, a major structural protein in the stratum corneum, in 3D-cultured epidermis. In skin dermal fibroblasts, taurine inhibited the IL-1α-stimulated mRNA and protein expression of MMP-1. In addition, taurine treatment increased HA synthase-2 mRNA expression and in turn HA production. Results from the present study suggest that the protective effect of taurine on the skin is associated with the enhancement of epidermal barrier component expression and modulation of dermal extracellular matrix metabolism.

Effect of different stress conditions on the formation of amino acid derivatives by Brewer’s and Baker’s yeast during fermentation

The effects of environmental stresses on the formation of amino acid derivatives by Saccharomyces cerevisiae NCYC 88 and Saccharomyces cerevisiae NCYC 79 were investigated. Fermentation was performed in model systems under different temperature, pH, alcohol, phenolic, and osmotic stress conditions, as well as in beer and dough. According to stress response molecules, yeasts were more affected by osmotic, temperature, and alcohol stresses. Both yeast strains increased the formation of kynurenic acid, tryptophan ethyl ester, tryptophol, and gamma-aminobutyric acid under osmotic stress conditions in model systems. Indole-3-acetic acid was found to be higher in the ferulic acid stress dough (262 µg/kg dry weight, d.w.) compared to the control dough (132 µg/kg d.w.) at the end of the fermentation. The results may enable the development of new strategies for designing novel foods with a desired composition of bioactive amino acid derivatives.

Hot-air full drying driven metabolome changes in white tea (Camellia sinensis L.)

ABSTRACT White tea (Camillia sinensis L.) is the least processed tea, and due to simpler processing steps involved, its flavor and nutritive compound composition is least disturbed. However, only a limited number of research has explored the key metabolomic changes during white tea processing (especially drying). The freshly harvested leaves of C. sinensis var. Tieguanyin were initially withered at room temperature for 72 h, and first-dried on fire at 70°C for 3 h. Then, they were spread at room temperature for 7 days and fully dried at 80°C for 4 h, followed by cooled at room temperature. The metabolome of the tea leaves before (CK) and after full drying (RO) were compared using UPLC-MS/MS. The LC-MS/MS analysis identified 1,253 compounds belonging to 11 classes. The highest number of accumulated compounds belonged to flavonoids, phenolic acids, and lipids. Of the 57 differentially accumulated metabolites (DAMs), 49 were up-accumulated in RO. These were classified as amino acids derivatives, lipids, organic acids, vitamins, alkaloids, nucleotides and derivatives, flavonoids, tannins, terpenoids, lignans and coumarins. We found that several health beneficial compounds showed up-accumulation in RO compared to CK. We concluded that Hot-air full drying alters white team metabolome composition.

Fluoroalkylation of Activated Allylic Acetates through Radical-Radical Coupling: Organophotoredox/DABCO Catalytic System.

A novel organophotoredox/DABCO catalytic system for the fluoroalkylation of activated allylic acetates via radical-radical coupling is described. The method offers mild reaction conditions, high selectivity, and broad substrate compatibility and enabled diverse bioactive molecules, FDA-approved drugs, and amino acid derivatives to be incorporated into transformation. This study expands the synthetic toolbox for the construction of fluorine-containing molecules.

Serum Amino Acid Profiling in Children with Autistic Spectrum Disorder: Insights from a Single-Center Study in Southern Romania.

The objective of this study was to analyze the serum amino acid profile in children diagnosed with autistic spectrum disorder (ASD) in southern Romania. The analysis aimed to provide insights into the underlying metabolic dysregulations associated with ASD. ASD is a neurodevelopmental disorder characterized by impaired social interaction, communication deficits, and restricted repetitive behaviors. Although the exact cause of ASD is largely unknown, recent evidence suggests that abnormalities in amino acid metabolism may contribute to its pathogenesis. Therefore, studying the amino acid profile in children with ASD could offer valuable information for understanding the metabolic disturbances associated with this complex disorder. This single-center study examined serum samples from children diagnosed with ASD, utilizing advanced analytical techniques to quantify the levels of different amino acids, amino acid derivatives, and amino acid-like substances. The results showed a lower level of taurine and a higher level of asparagine and leucine in the ASD group versus the control group. In the ASD group, we observed significant differences in tryptophan and alpha-aminobutyric acid levels based on age, with higher tryptophan levels in children older than 7 years when compared to children younger than 7 years; however, no significant correlations were found with the ASD group older than 7 years old. Additionally, younger children with ASD exhibited higher levels of alpha-aminobutyric acid than older children with ASD. The findings from this study contribute to the growing body of knowledge on the metabolic aspects of ASD, highlighting potential biomarkers and therapeutic targets for improving the management and treatment of ASD in children.

Adverse bioenergetic effects of N-acyl amino acids in human adipocytes overshadow beneficial mitochondrial uncoupling

ObjectiveEnhancing energy turnover via uncoupled mitochondrial respiration in adipose tissue has great potential to improve human obesity and other metabolic complications. However, the amount of human brown adipose tissue and its uncoupling protein 1 (UCP1) is low in obese patients. Recently, a class of endogenous molecules, N-acyl amino acids (NAAs), was identified as mitochondrial uncouplers in murine adipocytes, presumably acting via the adenine nucleotide translocator (ANT). Given the translational potential, we investigated the bioenergetic effects of NAAs in human adipocytes, characterizing beneficial and adverse effects, dose ranges, amino acid derivatives and underlying mechanisms. MethodNAAs with neutral (phenylalanine, leucine, isoleucine) and polar (lysine) residues were synthetized and assessed in intact and permeabilized human adipocytes using plate-based respirometry. The Seahorse technology was applied to measure bioenergetic parameters, dose-dependency, interference with UCP1 and adenine nucleotide translocase (ANT) activity, as well as differences to the established chemical uncouplers niclosamide ethanolamine (NEN) and 2,4-dinitrophenol (DNP). ResultNAAs with neutral amino acid residues potently induce uncoupled respiration in human adipocytes in a dose-dependent manner, even in the presence of the UCP1-inhibitor guanosine diphosphate (GDP) and the ANT-inhibitor carboxyatractylate (CAT). However, neutral NAAs significantly reduce maximal oxidation rates, mitochondrial ATP-production, coupling efficiency and reduce adipocyte viability at concentrations above 25 μM. The in vitro therapeutic index (using induced proton leak and viability as determinants) of NAAs is lower than that of NEN and DNP. ConclusionNAAs are potent mitochondrial uncouplers in human adipocytes, independent of UCP1 and ANT. However, previously unnoticed adverse effects harm adipocyte functionality, reduce the therapeutic index of NAAs in vitro and therefore question their suitability as anti-obesity agents without further chemical modifications.

C<sub>60</sub> Fullerene Amino Acid Derivatives: Synthesis and Biomedical Applications

Water-soluble forms of fullerene C60 possess unique physicochemical and biological properties, making them promising candidates for the development of various drugs in the fields of medicine and veterinary science. Of particular interest are studies on the synthesis and characterization of C60 fullerene derivatives with biogenic additives such as amino acids and peptides. This review focuses on different approaches to the synthesis of amino acid derivatives of fullerene C60 and their promising biomedical applications.

Quality Control in Targeted GC-MS for Amino Acid-OMICS.

Gas chromatography-mass spectrometry (GC-MS) is suitable for the analysis of non-polar analytes. Free amino acids (AA) are polar, zwitterionic, non-volatile and thermally labile analytes. Chemical derivatization of AA is indispensable for their measurement by GC-MS. Specific conversion of AA to their unlabeled methyl esters (d0Me) using 2 M HCl in methanol (CH3OH) is a suitable derivatization procedure (60 min, 80 °C). Performance of this reaction in 2 M HCl in tetradeutero-methanol (CD3OD) generates deuterated methyl esters (d3Me) of AA, which can be used as internal standards in GC-MS. d0Me-AA and d3Me-AA require subsequent conversion to their pentafluoropropionyl (PFP) derivatives for GC-MS analysis using pentafluoropropionic anhydride (PFPA) in ethyl acetate (30 min, 65 °C). d0Me-AA-PFP and d3Me-AA-PFP derivatives of AA are readily extractable into water-immiscible, GC-compatible organic solvents such as toluene. d0Me-AA-PFP and d3Me-AA-PFP derivatives are stable in toluene extracts for several weeks, thus enabling high throughput quantitative measurement of biological AA by GC-MS using in situ prepared d3Me-AA as internal standards in OMICS format. Here, we describe the development of a novel OMICS-compatible QC system and demonstrate its utility for the quality control of quantitative analysis of 21 free AA and metabolites in human plasma samples by GC-MS as Me-PFP derivatives. The QC system involves cross-standardization of the concentrations of the AA in their aqueous solutions at four concentration levels and a quantitative control of AA at the same four concentration levels in pooled human plasma samples. The retention time (tR)-based isotope effects (IE) and the difference (δ(H/D) of the retention times of the d0Me-AA-PFP derivatives (tR(H)) and the d3Me-AA-PFP derivatives (tR(D)) were determined in study human plasma samples of a nutritional study (n = 353) and in co-processed QC human plasma samples (n = 64). In total, more than 400 plasma samples were measured in eight runs in seven working days performed by a single person. The proposed QC system provides information about the quantitative performance of the GC-MS analysis of AA in human plasma. IE, δ(H/D) and a massive drop of the peak area values of the d3Me-AA-PFP derivatives may be suitable as additional parameters of qualitative analysis in targeted GC-MS amino acid-OMICS.

Integrated Metabolome and Transcriptome Analyses Reveal Amino Acid Biosynthesis Mechanisms during the Physiological Maturity of Grains in Yunnan Hulled Wheat (Triticum aestivum ssp. yunnanense King).

Yunnan hulled wheat (YHW) possesses excellent nutritional characteristics; however, the precise amino acid (AA) composition, contents, and molecular mechanisms underlying AA biosynthesis in YHW grains remain unclear. In this study, we aimed to perform metabolomic and transcriptomic profiling to identify the composition and genetic factors regulating AA biosynthesis during the physiological maturation of grains of two YHW genotypes, Yunmai and Dikemail, with high and low grain protein contents, respectively. A total of 40 and 14 differentially accumulated amino acids (AAs) or AA derivatives were identified between the waxy grain (WG) and mature grain (MG) phenological stages of Yunmai and Dikemail, respectively. The AA composition differed between WG and MG, and the abundance of AAs-especially that of essential AAs-was significantly higher in WG than in MG (only 38.74-58.26% of WG). Transcriptome analysis revealed differential regulation of structural genes associated with the relatively higher accumulation of AAs in WG. Weighted gene co-expression network analysis and correlation analyses of WG and MG indicated differences in the expression of clusters of genes encoding both upstream elements of AA biosynthesis and enzymes that are directly involved in AA synthesis. The expression of these genes directly impacted the synthesis of various AAs. Together, these results contribute to our understanding of the mechanism of AA biosynthesis during the different developmental stages of grains and provide a foundation for further research to improve the nutritional value of wheat products.

Sustainable valorization approaches on crustacean wastes for the extraction of chitin, bioactive compounds and their applications - A review

The unscientific disposal of the most abundant crustacean wastes, especially those derived from marine sources, affects both the economy and the environment. Strategic waste collection and management is the need of the hour. Sustainable valorization approaches have played a crucial role in solving those issues as well as generating wealth from waste. The shellfishery wastes are rich in valuable bioactive compounds such as chitin, chitosan, minerals, carotenoids, lipids, and other amino acid derivatives. These value-added components possessed pleiotropic applications in different sectors viz., food, nutraceutical, cosmeceutical, agro-industrial, healthcare, and pharmaceutical sectors. The manuscript covers the recent status, scope of shellfishery management, and different bioactive compounds obtained from crustacean wastes. In addition, both sustainable and conventional routes of valorization approaches were discussed with their merits and demerits along with their combinations. The utilization of nano and microtechnology was also included in the discussion, as they have become prominent research areas in recent years. More importantly, the future perspectives of crustacean waste management and other potential valorization approaches that can be implemented on a large scale.

Visible‐Light‐Driven Three‐Component Reaction of Unactivated Alkenes Enables Access to Monofluoro γ‐Amino Acids

AbstractA strategy for the synthesis of diverse protected α‐monofluoro‐γ‐amino acid derivatives has been developed. This reaction assembles a simple enamide, quinoxalin‐2(1H)‐one, and diethyl 2‐bromo‐2‐fluoromalonate through a three‐component reaction driven by visible light. The advantages of this protocol include the simplicity of its operation, mild conditions, high functional group tolerance, and applicability to a wide variety of substrates. The synthesis of this fluorine‐containing amino acid derivative has significant value for potential applications in medicinal chemistry and chemical biology.

On-line preconcentration of fluorescein derivatives of essential amino acids using sweeping in a nonionic micellar system

A rapid and effective method of nonionic micellar electrokinetic chromatography with laser-induced fluorescence detection and sweeping as an online preconcentration method was developed for the simultaneous determination of free essential amino acids in supplement formulations. The analytes were derivatized using fluorescein isothiocyanate isomer I dissolved in dimethyl sulfoxide. Optimal separation conditions were achieved using an uncoated fused silica capillary (40.0 cm effective length, 50.2 cm total length, 50 µm internal diameter), 20 mM Na2B4O7, (pH 9.3), 50 mM Brij-35, and 15% (v v-1) methanol as running buffer. Complete separation of all analytes was achieved within 15 min. The optimized method exhibited good linearity (r2 > 0.997), acceptable precision (1.3 – 12.4%), and accuracy (88 – 112%) in concentration range 20 – 1000 ng mL−1. The limit of detection was 6 ng mL−1. The method successfully determined the quantity of free essential amino acids in a dietary supplement containing spirulina.

Homochiral Metallacycle Used as a Stationary Phase for Capillary Gas Chromatographic Separation of Chiral and Achiral Compounds.

Metallacycles are a novel class of supramolecular materials with circular structures, internal cavities, and abundant host-guest chemical properties that have exhibited good application prospects in many fields. However, to the best of our knowledge, no research on the use of metallacycles as stationary phases for gas chromatographic (GC) separations has been published yet. In this work, we report for the first time the use of a homochiral metallacycle, [ZnCl2L]2, as a stationary phase for GC separations. [ZnCl2L]2 was synthesized by reaction of (S)-(1-isonicotinoylpyrrolidin-2-yl)methyl-isonicotinate (L) with ZnCl2 via coordination-driven self-assembly. The [ZnCl2L]2-coated column displayed an excellent separation performance not only of organic isomers but also of racemic compounds. Sixteen racemates (including alcohols, esters, amino acid derivatives, ethers, organic acids, and epoxides) and 21 isomeric compounds (including positional, structural, and cis/trans-isomers) were well separated on the [ZnCl2L]2-coated column. Impressively, some racemates were resolved with high resolution values (Rs), including 1,2-butanediol diacetate (Rs = 25.86), ethyl 3-hydroxybutyrate (Rs = 20.97), 1,3-butanediol diacetate (Rs = 18.09), and threonine derivative (Rs = 18.61). Compared with the commercial β-DEX 120 column for separation of the tested racemates, the [ZnCl2L]2-coated column exhibited good enantioseparation complementarity, enabling separation of some racemates that could not be separated, or were not well resolved, by the β-DEX 120 column. In addition, many organic mixtures, such as n-alkanes, alkylbenzenes, n-alcohols, and a Grob test mixture, were also well separated on the [ZnCl2L]2-coated column. The column also has good reproducibility and thermal stability on separation. This work not only reveals the great potential of metallacycles for GC separations but also opens up a new application of metallacycles in separation science.

Hand Grip Strength: A Tool of Nutritional Assessment in Prevalent Hemodialysis Patients

Abstract Background Malnutrition is a common problem in patients with end stage renal disease (ESRD) undergoing hemodialysis that is associated with increased morbidity and mortality. There are several clinical, nutritional, and biochemical parameters that may be indicative of PEW in patients using hemodialysis (HD). Handgrip strength is a simple, quick, non-invasive, inexpensive, rapid, and objective procedure. In addition, it has other advantages as a diagnostic/screening tool for nutritional assessment. However, HGS relies on the motivation of the subjects, and therefore it is imperative that researchers and clinicians are sufficiently trained in HGS assessment. L-Carnitine supplementation, levocarnitine is an amino acid derivative which is an essential cofactor of fatty acid metabolism, may improve several situations. Aim of the Work The aim of our study, a longitudinal observational study, is to assess HGS as an independent tool for assessment of the nutritional status in hemodialysis patients. This study can also show the significance of the commitment to high protein diet (1.2-1.4 g/ kg/ d) and receiving L-carnitine (10-20 mg/kg intravenously after each dialysis session) and its effect on the handgrip strength and other studied nutritional tools. Patients and Methods In our study, a longitudinal observational study, study duration was 3 months after washout period; our population is all End Stage Renal Disease patients in Kasr AlAiny Hemodialysis Unit, Cairo University. The unit provides hemodialysis and medical service for 104 patients from whom 50 were excluded and 54 patients were enrolled. Results the study showed comparison between both studied groups regarding the studied laboratory parameters and different nutrition assessment tools showed no statistically significant differences. The study showed Comparison between the effect of high protein diet and L Carnitine (pre and post) in patients of group B on the studied nutritional tools and laboratory parameters. Again HGS was the only tool that showed statistical significance. %BF(body fat) assessed by anthropometry was negativelycorrelated with HGS. Also they found lower HGSvalues in patients on HD with higher estimates of abdominal fatdeposition. Thus, it seems that low muscle mass can occurdespite fat accumulation, and one possible explication for thiswould be the proinflammatory phenotype presented by individualswith abdominal fat deposition. This confirms that subjects can have normal or higher BMI and have a depletionprocess, thus increasing the need for screening proceduresrelated to functional status. Conclusion In this study, we concluded that HGS was the only significant (p value: <.001), while all other nutrition assessment tools didn’t show any significant difference.The correlation between nPCR and HGS was statistically significant (p value:.001, r:.616). L-carnitine supplementation has no role over commitment to high protein diet only regarding improving the nutritional status and hemoglobin level in hemodialysis patients.

Pathological Bergmann glia alterations and disrupted calcium dynamics in ataxic Canavan disease mice.

Canavan disease (CD) is a recessively inherited pediatric leukodystrophy resulting from inactivating mutations to the oligodendroglial enzyme aspartoacylase (ASPA). ASPA is responsible for hydrolyzing the amino acid derivative N-acetyl-L-aspartate (NAA), and without it, brain NAA concentrations increase by 50% or more. Infants and children with CD present with progressive cognitive and motor delays, cytotoxic edema, astroglial vacuolation, and prominent spongiform brain degeneration. ASPA-deficient CD mice (Aspanur7/nur7 ) present similarly with elevated NAA, widespread astroglial dysfunction, ataxia, and Purkinje cell (PC) dendritic atrophy. Bergmann glia (BG), radial astrocytes essential for cerebellar development, are intimately intertwined with PCs, where they regulate synapse stability, functionality, and plasticity. BG damage is common to many neurodegenerative conditions and frequently associated with PC dysfunction and ataxia. Here, we report that, in CD mice, BG exhibit significant morphological alterations, decreased structural associations with PCs, loss of synaptic support proteins, and altered calcium dynamics. We also find that BG dysfunction predates cerebellar vacuolation and PC damage in CD mice. Previously, we developed an antisense oligonucleotide (ASO) therapy targeting Nat8l (N-acetyltransferase-8-like, "Nat8l ASO") that inhibits the production of NAA and reverses ataxia and PC atrophy in CD mice. Here, we show that Nat8l ASO administration in adult CD mice also leads to BG repair. Furthermore, blocking astroglial uptake of NAA is neuroprotective in astroglia-neuron cocultures exposed to elevated NAA. Our findings suggest that restoration of BG structural and functional integrity could be a mechanism for PC regeneration and improved motor function.

Preparative Biocatalytic Synthesis of α-Ketomethylselenobutyrate-A Putative Agent for Cancer Therapy.

Biomedical studies of the role of organic selenium compounds indicate that the amino acid derivative of L-selenomethionine, α-ketomethylselenobutyrate (KMSB), can be considered a potential anticancer therapeutic agent. It was noted that, in addition to a direct effect on redox signaling molecules, α-ketoacid metabolites of organoselenium compounds are able to change the status of histone acetylation and suppress the activity of histone deacetylases in cancer cells. However, the wide use of KMSB in biomedical research is hindered not only by its commercial unavailability, but also by the fact that there is no detailed information in the literature on possible methods for the synthesis of this compound. This paper describes in detail the procedure for obtaining a high-purity KMSB preparation (purity ≥ 99.3%) with a yield of the target product of more than 67%. L-amino acid oxidase obtained from C. adamanteus was used as a catalyst for the conversion of L-selenomethionine to KMSB. If necessary, this method can be used as a basis both for scaling up the synthesis of KMSB and for developing cost-effective biocatalytic technologies for obtaining other highly purified drugs.

Sugar-Assisted Kinetic Resolutions in Metal/Chiral Amine Co-Catalyzed α-Allylations and [4+2] Cycloadditions: Highly Enantioselective Synthesis of Sugar and Chromane Derivatives.

Functionalized triose-, furanose and chromane-derivatives were synthesized by the titled reactions. The sugar-assisted kinetic resolution/C-C bond-forming cascade processes generate a functionalized sugar derivative with a quaternary stereocenter in a highly enantioselective fashion (up to >99 % ee) by using a simple combination of metal and chiral amine co-catalysts. Notably, the interplay between the chiral sugar substrate and the chiral amino acid derivative allowed for the construction of a functionalized sugar product with high enantioselectivity (up to 99 %) also when using a combination of racemic amine catalyst (0 % ee) and metal catalyst.