Urea Decomposition Mechanism by Dinuclear Nickel Complexes.

Urease is an enzyme containing a dinuclear nickel active center responsible for the hydrolysis of urea into carbon dioxide and ammonia. Interestingly, inorganic models of urease are unable to mimic its mechanism despite their similarities to the enzyme active site. The reason behind the discrepancy in urea decomposition mechanisms between inorganic models and urease is still unknown.

Ultrasound-mediated radical cascade reactions: Fast synthesis of functionalized indolines from 2-(((N-aryl)amino)methyl)acrylates.

Novel functionalized indolines were synthesized from 2-(((N-aryl)amino)methyl)acrylates and formamides under ultrasonic irradiation for the first time. Aiming to develop a straightforward and easy-to-implement methodology for the synthesis of indolines, an instrumentation setup was designed, including ultrasound (US) equipment (Ultrasonic Horn; tip diameter of 12.7 mm, 20 kHz, maximum power of 400 W), an open reaction flask, and an inexpensive and green catalyst (1 mol%; FeSO·7HO; CAS: 7782-63-0) without the need for anhydrous conditions.

Cascade Reactions Assisted by Microwave Irradiation: Ultrafast Construction of 2-Quinolinone-Fused γ-Lactones from -(-Ethynylaryl)acrylamides and Formamide.

An ultrafast (10 s) methodology to construct novel highly functionalized 2-quinolinones from -(o-ethynylaryl)acrylamides (1,7-enynes) is described for the first time. Microwave irradiation enabled the ultrafast synthesis of 2-quinolinone-fused γ-lactones from Fenton's reagents in formamide. After six key consecutive reactions, including a diastereoselective step, 2-quinolinone-fused γ-lactones were obtained in good overall yield (up to 46%; 10 s).

Flow Biocatalysis: A Challenging Alternative for the Synthesis of APIs and Natural Compounds.

Biocatalysts represent an efficient, highly selective and greener alternative to metal catalysts in both industry and academia. In the last two decades, the interest in biocatalytic transformations has increased due to an urgent need for more sustainable industrial processes that comply with the principles of green chemistry. Thanks to the recent advances in biotechnologies, protein engineering and the Nobel prize awarded concept of direct enzymatic evolution, the synthetic enzymatic toolbox has expanded significantly.

An efficient approach for the synthesis of new (±)-coixspirolactams.

Coixspirolactams, spiro[oxindole-γ-lactones], are found in adlay seeds and exhibit anticancer activity. A novel synthetic methodology was developed to enable an easy access to (±)-coixspirolactam A and a large number of new coixspirolactams in excellent overall yields. The exquisite exploitation of formamide reactivity was essential for the construction of oxindole and lactone scaffolds.

Magnetic bio-nanocomposite catalysts of CoFeO/hydroxyapatite-lipase for enantioselective synthesis provide a framework for enzyme recovery and reuse.

Enzymatic catalysis is a sustainable alternative for cost-prohibitive catalysts based on noble metals and rare earths. Enzymes can catalyze selective reactions under mild conditions. Enzyme recovery after a reaction for its reuse is still a challenge for industrial application.

Green synthesis of Au decorated CoFeO nanoparticles for catalytic reduction of 4-nitrophenol and dimethylphenylsilane oxidation.

Gold nanoparticles (Au NPs) have been widely employed in catalysis. Here, we report on the synthesis and catalytic evaluation of a hybrid material composed of Au NPs deposited at the surface of magnetic cobalt ferrite (CoFeO). Our reported approach enabled the synthesis of well-defined Au/CoFeO NPs.

Enzymatic reactions involving the heteroatoms from organic substrates.

Several enzymatic reactions of heteroatom-containing compounds have been explored as unnatural substrates. Considerable advances related to the search for efficient enzymatic systems able to support a broader substrate scope with high catalytic performance are described in the literature. These reports include mainly native and mutated enzymes and whole cells biocatalysis.

One pot biocatalytic synthesis of a biodegradable electroactive macromonomer based on 3,4-ethylenedioxytiophene and poly(l-lactic acid).

A novel electroactive macromonomer based on poly(l-lactic acid) (PLLA) with (3,4-ethylenedioxythiophene) (EDOT) functional end groups, was prepared by a traditional approach of organometallic polymerization with stannous octanoate [Sn(oct)] and enzymatic polymerization using immobilized Candida antarctica Lipase B (CAL-B) and Amano lipase Pseudomonas cepacia(PS-IM), as catalysts. In the synthetic strategy, (2,3-dihydrothieno[3,4-b] dioxin-2-yl)methanol (EDOT-OH) was used to initiate the ring opening polymerization of lactide to yield PLLA with EDOT end group. All macromonomers (EDOT-PLLA) were characterized by H and C RMN, MALDI-TOF, GPC and EDX.

Draft Whole-Genome Sequence of Psychrotrophic sp. Strain 7749, Isolated from Antarctic Marine Sediments with Applications in Enantioselective Alcohol Oxidation.

Here, we report the 4.12-Mb draft genome sequence of sp. strain 7749, isolated from marine sediment samples of the Antarctic Peninsula, using enriched medium with ()-1-(4-phenyl)-ethanol as a carbon source.

Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles.

The conversion of carbon dioxide into important industrial feedstock is a subject of growing interest in modern society. A possible way to achieve this goal is by carrying out the CO2/methanol cascade reaction, allowing the recycle of CO2 using either chemical catalysts or enzymes. Efficient and selective reactions can be performed by enzymes; however, due to their low stability, immobilization protocols are required to improve their performance.

Iron-Catalyzed Synthesis of Oxindoles: Application to the Preparation of Pyrroloindolines.

A novel and highly efficient synthetic approach to pyrroloindolines has been developed. The process is based on tandem radical addition/cyclization with inexpensive iron catalyst. This method tolerates a wide range of N-methyl-N-arylacrylamides as well carbamoyl radicals, providing access to a variety of functionalized 3,3-disubstituted oxindoles, key intermediates for many bioactive pyrroloindolines such as (±)-esermethole, (±)-deoxyeseroline, and (±)-physovenol methyl ether.

Plasmonic Nanorattles as Next-Generation Catalysts for Surface Plasmon Resonance-Mediated Oxidations Promoted by Activated Oxygen.

Nanorattles, comprised of a nanosphere inside a nanoshell, were employed as the next generation of plasmonic catalysts for oxidations promoted by activated O2 . After investigating how the presence of a nanosphere inside a nanoshell affected the electric-field enhancements in the nanorattle relative to a nanoshell and a nanosphere, the SPR-mediated oxidation of p-aminothiophenol (PATP) functionalized at their surface was investigated to benchmark how these different electric-field intensities affected the performances of Au@AgAu nanorattles, AgAu nanoshells and Au nanoparticles having similar sizes. The high performance of the nanorattles enabled the visible-light driven synthesis of azobenzene from aniline under ambient conditions.

Association of Yeast Alcohol Dehydrogenase with Superparamagnetic Nanoparticles: Improving the Enzyme Stability and Performance.

Alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae was covalently attached, via glutaraldehyde, to magnetite nanoparticles (MagNP) previously coated with aminopropyltriethoxysilane (MagNP/APTS), or with a silica shell followed by the APTS coating (MagNP@SiO2/APTS). In both cases, a great improvement of enzymatic activity has been observed for the ethanol-acetaldehyde conversion. The MagNP@SiO2/APTS-ADH system exhibited the best stability with respect to pH and temperature.

(77)Se and (125)Te NMR spectroscopy on a selectivity study of organochalcogenanes with L-amino acids.

The hypervalent selenium- and tellurium-containing compounds (halo-organoselenuranes and halo-organotelluranes) were treated with amino acids to evaluate their reactivity and chemoselectivity by (1)H, (13)C, (77)Se and (125)Te NMR spectroscopy. The study of forced thermal stability was performed and analyzed by NMR. The organotelluranes remained stable at temperatures around 60 °C but in the case of organoselenuranes, there was formation of new products at 37 °C as a result of halogen loss.

Impact of hydrocarbons, PCBs and heavy metals on bacterial communities in Lerma River, Salamanca, Mexico: Investigation of hydrocarbon degradation potential.

Freshwater contamination usually comes from runoff water or direct wastewater discharges to the environment. This paper presents a case study which reveals the impact of these types of contamination on the sediment bacterial population. A small stretch of Lerma River Basin, heavily impacted by industrial activities and urban wastewater release, was studied.

Continuous flow synthesis of chiral amines in organic solvents: immobilization of E. coli cells containing both ω-transaminase and PLP.

E. coli cells containing overexpressed (R)-selective ω-transaminase and the cofactor PLP were immobilized on methacrylate beads suitable for continuous flow applications. The use of an organic solvent suppresses leaching of PLP from the cells; no additional cofactor was required after setting up the packed-bed reactor containing the biocatalyst (ω-TA-PLP).

20S proteasome as novel biological target for organochalcogenanes.

A series of hypervalent selenium- and tellurium-containing compounds (organoselenuranes and organotelluranes) was evaluated aiming novel inhibitors of a threonine protease, namely the 20S proteasome (20S PT). In vitro assays demonstrated high inhibitory potency and specificity of these compounds toward the β2 catalytic site of the 20S PT. Organotelluranes were identified as more potent inhibitors than organoselenuranes since their IC50 ranged from 3.

Investigating the influence of the interface in thiol-functionalized silver-gold nanoshells over lipase activity.

We employed thiol-funcionalized AgAu nanoshells (AgAu NSs) as supports for the covalent attachment of lipases (BCL, Burkholderia cepacia lipase; PPL, pancreatic porcine lipase). Specifically, we were interested in investigating the effect of the nature/size of the spacer in AgAu NSs-functionalized organic thiols over the covalent attachment of lipases. The catalytic performance of AgAu-lipase systems was measured in the kinetic resolution of (R,S)-1-(phenyl)ethanol via a transesterification reaction.

Lipase-catalyzed kinetic resolution of aryltrimethylsilyl chiral alcohols.

Lipase-catalyzed kinetic resolution of aryltrimethylsilyl chiral alcohols through a transesterification reaction was studied. The optimal conditions found for the kinetic resolution of m- and p-aryltrimethylsilyl chiral alcohols, led to excellent results, high conversions (c = 50%), high enantiomeric ratios (E > 200) and enantiomeric excesses for the remaining (S)-alcohol and (R)-acetylated product (>99%). However, kinetic resolution of o-aryltrimethylsilyl chiral alcohols did not occur under the same conditions applied to the other isomers.

Enzymatic kinetic resolution of tert-butyl 2-(1-hydroxyethyl)phenylcarbamate, a key intermediate to chiral organoselenanes and organotelluranes.

The enzymatic kinetic resolution of tert-butyl 2-(1-hydroxyethyl) phenylcarbamate via lipase-catalyzed transesterification reaction was studied. We investigated several reaction conditions and the carbamate was resolved by Candida antarctica lipase B (CAL-B), leading to the optically pure (R)- and (S)-enantiomers. The enzymatic process showed excellent enantioselectivity (E > 200).

Screening of microorganisms producing cold-active oxidoreductases to be applied in enantioselective alcohol oxidation. An Antarctic survey.

Several microorganisms were isolated from soil/sediment samples of Antarctic Peninsula. The enrichment technique using (RS)-1-(phenyl)ethanol as a carbon source allowed us to isolate 232 psychrophile/psychrotroph microorganisms. We also evaluated the enzyme activity (oxidoreductases) for enantioselective oxidation reactions, by using derivatives of (RS)-1-(phenyl)ethanol as substrates.

Structure-activity relationships of hypervalent organochalcogenanes as inhibitors of cysteine cathepsins V and S.

A new series of organotelluranes were synthesized and investigated, and the structure-activity relationships in cysteine proteases inhibition were determined. It was possible to identify the relevance of structural components linked to the reactivity of these compounds as inhibitors. For example, dibromo-organotelluranes showed to be more reactive than dichloro-organotelluranes towards cysteine cathepsins V and S.

Hypervalent organochalcogenanes as inhibitors of protein tyrosine phosphatases.

A series of organochalcogenanes was synthesized and evaluated as protein tyrosine phosphatases (PTPs) inhibitors. The results indicate that organochalcogenanes inactivate the PTPs in a time- and concentration-dependent fashion, most likely through covalent modification of the active site sulfur-moiety by the chalcogen atom. Consequently, organochalcogenanes represent a new class of mechanism-based probes to modulate the PTP-mediated cellular processes.