Casuarine Stereoisomers from Achiral Substrates: Chemoenzymatic Synthesis and Inhibitory Properties

A straightforward chemoenzymatic synthesis of four uncovered casuarine stereoisomers is described. The strategy consists of l-fuculose-1-phosphate aldolase F131A-variant-catalyzed aldol addition of dihydroxyacetone phosphate to aldehyde derivatives of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) and its enantiomer (LAB) and subsequent one-pot catalytic deprotection–reductive amination. DAB and LAB were obtained from dihydroxyacetone and aminoethanol using d-fructose-6-phosphate aldolase and l-rhamnulose-1-phosphate aldolase catalysts, respectively. The new <i>ent</i>-3-<i>epi</i>-casuarine is a strong inhibitor of α-d-glucosidase from rice and of rat intestinal sucrase

Aldolase-Catalyzed Synthesis of Conformationally Constrained Iminocyclitols: Preparation of Polyhydroxylated Benzopyrrolizidines and Cyclohexapyrrolizidines

A straightforward chemo-enzymatic synthesis of new polyhydroxylated benzo­pyrrolizidines and cyclo­hexa­pyrrolizidines is developed. The two-step strategy consists of l-fuculose-1-phosphate aldolase variant F131A-catalyzed aldol addition of dihydroxy­acetone phosphate to <i>rac</i>-<i>N</i>-benzyl­oxycarbonyl­indoline-2-carb­aldehyde as well as (2<i>S</i>*,3a<i>S</i>*,7a<i>S</i>*)- and (2<i>S</i>*,3a<i>R</i>*,7a<i>R</i>*)-<i>N</i>-benzyl­oxycarbonyl­octa­hydro­indole-2-carb­aldehydes and a subsequent one-step catalytic deprotection–reductive amination

Combining Aldolases and Transaminases for the Synthesis of 2‑Amino-4-hydroxybutanoic Acid

Amino acids are of paramount importance as chiral building blocks of life, for drug development in modern medicinal chemistry, and for the manufacture of industrial products. In this work, the stereoselective synthesis of (<i>S</i>)- and (<i>R</i>)-2-amino-4-hydroxybutanoic acid was accomplished using a <i>systems biocatalysis</i> approach comprising a biocatalytic one-pot cyclic cascade by coupling of an aldol reaction with an ensuing stereoselective transamination. A class II pyruvate aldolase from E. coli, expressed as a soluble fusion protein, in tandem with either an <i>S</i>- or <i>R</i>-selective, pyridoxal phosphate dependent transaminase was used as a catalyst to realize the conversion, with formaldehyde and alanine being the sole starting materials. Interestingly, the class II pyruvate aldolase was found to tolerate formaldehyde concentrations of up to 1.4 M. The cascade system was found to reach product concentrations for (<i>S</i>)- or (<i>R</i>)-2-amino-4-hydroxybutanoic acid of at least 0.4 M, rendering yields between 86% and >95%, respectively, productivities of >80 g L^–1 d^–1, and <i>ee</i> values of >99%

Unsaturated Fatty Alcohol Derivatives of Olive Oil Phenolic Compounds with Potential Low-Density Lipoprotein (LDL) Antioxidant and Antiobesity Properties

A new route for the synthesis of fatty alcohol derivatives of hydroxytyrosol and other olive oil phenolic compounds was developed to allow the preparation of unsaturated derivatives. The biological activity of synthesized compounds was evaluated. Most of the compounds presented a significant antioxidant activity on low-density lipoprotein (LDL) particles. The activity of the tested products was significantly influenced by the number and position of unsaturations as well as modifications on the polar head of the synthesized compounds. Some of them presented modulation of food intake in rats and, due to their molecular similarity with CB₁ endogenous ligands, the endocannabinoid system and PPAR-α were also evaluated as potential targets. The pharmacodynamics could not be totally explained by CB₁ and PPAR-α receptor interactions because only two of the four compounds with biological activity showed a CB₁ activity and all of them presented low PPAR-α affinity, not justifying its whole in vivo activity. The hydroxytyrosol linoleylether (<b>7</b>) increased LDL resistance to oxidation with a capacity similar to that of hydroxytyrosol and was the most active in vivo compound with a hypophagic effect comparable to that of oleoylethanolamine. We consider that this compound could be a good lead compound for future drug development in obesity treatments

Untargeted Metabolomics in Doping Control: Detection of New Markers of Testosterone Misuse by Ultrahigh Performance Liquid Chromatography Coupled to High-Resolution Mass Spectrometry

The use of untargeted metabolomics for the discovery of markers is a promising and virtually unexplored tool in the doping control field. Hybrid quadrupole time-of-flight (QTOF) and hybrid quadrupole Orbitrap (Q Exactive) mass spectrometers, coupled to ultrahigh pressure liquid chromatography, are excellent tools for this purpose. In the present work, QTOF and Q Exactive have been used to look for markers for testosterone cypionate misuse by means of untargeted metabolomics. Two different groups of urine samples were analyzed, collected before and after the intramuscular administration of testosterone cypionate. In order to avoid analyte losses in the sample treatment, samples were just 2-fold diluted with water and directly injected into the chromatographic system. Samples were analyzed in both positive and negative ionization modes. Data from both systems were treated under untargeted metabolomic strategies using XCMS application and multivariate analysis. Results from the two mass spectrometers differed in the number of detected features, but both led to the same potential marker for the particular testosterone ester misuse. The in-depth study of the MS and MS/MS behavior of this marker allowed for the establishment of 1-cyclopentenoylglycine as a feasible structure. The putative structure was confirmed by comparison with synthesized material. This potential marker seems to come from the metabolism of the cypionic acid release after hydrolysis of the administered ester. Its suitability for doping control has been evaluated