•Lipase PS has been immobilized on Accurel in less than 1h with a 70% increase in activity.•Irreversible inhibition with D-pNPP suggested the involvement of the open form of the lipase in the ...immobilization process.•The new biocatalyst is much more active that the commercial one in hydrolysis and synthetic reactions.•The resolution of (±)-1,3,4-tri-O-benzyl-myo-inositol (1) has been optimized using RSM.•The new biocatalyst is more efficient in kinetic resolution of 1 than Novozym 435.
Lipase from Burkholderia cepacia (PS) has been immobilized on Accurel MP 1000, and their performance has been compared to that of the most widely used immobilized commercial preparation of this enzyme. The maximum loading was 18mgprotein/g support, and its thermal and solvent stability was much higher than that of the commercial. PS preparations were used in hydrolysis of triacetin and methyl mandelate, in the esterification of oleic acid and ethanol and in the kinetic resolution of 1,3,4-tri-O-benzyl-myo-inositol (DL-1) using vinylacetate as activated acyl donor. For all reactions studied, PS on Accurel was more active than PS-IM. The conversion in the kinetic resolution of racemic DL-1 was optimized using response surface methodology. Optimal conditions were determined to be 2.0mg/mL of substrate, temperature of 40°C, 2.0mL of vinyl acetate and without water addition. Under these conditions, maximum loaded Accurel-PS preparation permitted to improve the activity in this kinetic resolution compared to the PS commercial preparation by a 55-fold factor, and compared to Novozym 435 (the most active described in literature for this reaction) by a 23-fold factor. The conversion attained was 49.9%±0.3 of conversion and ee of 99% after 24h. The reusability studies showed maintenance of conversion and ee during eight cycles.
The Wnt/β-catenin signaling pathway dictates cell proliferation and differentiation during embryonic development and tissue homeostasis. Its deregulation is associated with many pathological ...conditions, including neurodegenerative disease, frequently downregulated. The lack of efficient treatment for these diseases, including Alzheimer’s disease (AD), makes Wnt signaling an attractive target for therapies. Interestingly, novel Wnt signaling activating compounds are less frequently described than inhibitors, turning the quest for novel positive modulators even more appealing. In that sense, natural compounds are an outstanding source of potential drug leads. Here, we combine different experimental models, cell-based approaches, neuronal culture assays, and rodent behavior tests with Xenopus laevis phenotypic analysis to characterize quercitrin, a natural compound, as a novel Wnt signaling potentiator. We find that quercitrin potentiates the signaling in a concentration-dependent manner and increases the occurrence of the Xenopus secondary axis phenotype mediated by Xwnt8 injection. Using a GSK3 biosensor, we describe that quercitrin impairs GSK3 activity and increases phosphorylated GSK3β S9 levels. Treatment with XAV939, an inhibitor downstream of GSK3, impairs the quercitrin-mediated effect. Next, we show that quercitrin potentiates the Wnt3a-synaptogenic effect in hippocampal neurons in culture, which is blocked by XAV939. Quercitrin treatment also rescues the hippocampal synapse loss induced by intracerebroventricular injection of amyloid-β oligomers (AβO) in mice. Finally, quercitrin rescues AβO-mediated memory impairment, which is prevented by XAV939. Thus, our study uncovers a novel function for quercitrin as a Wnt/β-catenin signaling potentiator, describes its mechanism of action, and opens new avenues for AD treatments.
This article describes acetylcholinesterase (AChE), an enzyme involved in parasympathetic neurotransmission, its activity, and how its inhibition can be pharmacologically useful for treating ...dementia, caused by Alzheimer's disease, or as a warfare method due to the action of nerve agents. The chemical concepts related to the irreversible inhibition of AChE, its reactivation, and aging are discussed, along with a relationship to the current international legislation on chemical weapons.
Organophosphorus poisoning caused by some pesticides and nerve agents is a life-threating condition that must be swiftly addressed to avoid casualties. Despite the availability of medical ...countermeasures, the clinically available compounds lack a broad spectrum, are not effective towards all organophosphorus toxins, and have poor pharmacokinetics properties to allow them crossing the blood-brain barrier, hampering cholinesterase reactivation at the central nervous system. In this work, we designed and synthesised novel isatin derivatives, linked to a pyridinium 4-oxime moiety by an alkyl chain with improved calculated properties, and tested their reactivation potency against paraoxon- and NEMP-inhibited acetylcholinesterase in comparison to the standard antidote pralidoxime. Our results showed that these compounds displayed comparable in vitro reactivation also pointed by the in silico studies, suggesting that they are promising compounds to tackle organophosphorus poisoning.
The present work aimed to compare the small, neutral and monoaromatic oxime, isatin-3-oxime (isatin-O), to the commercial ones, pralidoxime (2-PAM) and obidoxime, in a search for a new potential ...reactivator for acetylcholinesterase (AChE) inhibited by the pesticide paraoxon (AChE/POX) as well as a novel potential scaffold for further synthetic modifications. The multicriteria decision methods (MCDM) allowed the identification of the best docking poses of those molecules inside AChE/POX for further molecular dynamic (MD) studies, while Ellman's modified method enabled in vitro inhibition and reactivation assays. In corroboration with the theoretical studies, our experimental results showed that isatin-O have a reactivation potential capable of overcoming 2-PAM at the initial moments of the assay. Despite not achieving better results than obidoxime, this molecule is promising for being an active neutral oxime with capacity of crossing the blood⁻brain barrier (BBB), to reactivate AChE/POX inside the central and peripheral nervous systems. Moreover, the fact that isatin-O can also act as anticonvulsant makes this molecule a possible multipotent reactivator. Besides, the MCDM method showed to be an accurate method for the selection of the best docking poses generated in the docking studies.
A new approach for the preparation of palladium nanoparticles in water from a renewable source, 2‐hydroxypropyl‐α‐cyclodextrin (α‐HPCD), which acts both as a reductant and capping agent, is ...presented. The palladium nanoparticles were characterized by using dynamic light scattering (DLS), transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS), which revealed the formation of spherical particles in the size range of 2–7 nm. Further analysis by Fourier‐transform infrared spectroscopy (FT‐IR) and 1H NMR did not show covalent bonds between cyclodextrins and palladium nanoparticles, suggesting that α‐HPCD is only physically adsorbed on the nanoparticle surface, presumably through hydrophobic interactions which limit the mutual coalescence of nanoclusters. The catalytic activity was tested in Suzuki, Heck and Sonogashira reactions in neat water, providing good yields and selectivities of coupling products under very low Pd loadings (0.5–0.01 mol%). Remarkably, the nanocatalyst showed significant stability hence the aqueous phase remained active for four subsequent runs. The combination of a binding site for substrates (the HPCD cavity) and a reactive centre (Pd core) provides a potential to explore functional catalysis in aqueous medium.
Casualties caused by nerve agents, potent acetylcholinesterase inhibitors, have attracted attention from media recently. Poisoning with these chemicals may be fatal if not correctly addressed. ...Therefore, research on novel antidotes is clearly warranted. Pyridinium oximes are the only clinically available compounds, but poor penetration into the blood-brain barrier hampers efficient enzyme reactivation at the central nervous system. In searching for structural factors that may be explored in SAR studies, we synthesized and evaluated neutral aryloximes as reactivators for acetylcholinesterase inhibited by NEMP, a VX surrogate. Although few tested compounds reached comparable reactivation results with clinical standards, they may be considered as leads for further optimization.
•A practical method for synthesis of neutral aryloximes is presented.•A VX surrogate was used as inhibitor for Electrophorus eel Acetylcholinesterase.•Neutral aryloximes retrieved promising predicted properties for use as reactivators.•Seven compounds were identified as potential leads for further optimization.
Chiral myo‐inositol derivatives play key roles in cell‐signaling processes. Despite the relevance of these compounds, few syntheses of them rely on enantioselective catalytic reactions. Even fewer ...reports describe the use of desymmetrization of myo‐inositol derivatives. In fact, most routes involve resolution by derivatization. Thus, a symmetrical partially protected myo‐inositol derivative, 1,3‐di‐O‐benzyl‐myo‐inositol (1), was used as a substrate in fast lipase‐catalyzed desymmetrization reactions. Among the lipases tested, both Lipozyme RM‐IM and Lipozyme TL‐IM were effective in catalyzing the formation of the chiral acetate l‐(+)‐6‐O‐acetyl‐1,3‐di‐O‐benzyl‐myo‐inositol l‐(+)‐2 with high conversion (98–99 %) and ee (>99 %). Conversely, Novozyme 435 and Lipomod 34P as biocatalysts showed different regioselectivity, leading to the formation of the symmetrical 5‐O‐acetylated product. We were able to reuse TL‐IM lipase seven times without any noticeable decrease in the conversion. Acetate l‐(+)‐2 is a potential precursor of biologically active myo‐inositol derivatives and other relevant materials for cell biology studies.
Depending on the choice of lipase, 1,3‐di‐O‐benzyl‐myo‐inositol (1) either undergoes desymmetrization to form l‐(+)‐6‐O‐acetyl‐1,3‐di‐O‐benzyl‐myo‐inositol (with Lipozyme RM‐IM or Lipozyme TL‐IM), or is transformed into the meso 5‐O‐acetyl derivative 3 (with Novozym 435).
This paper shows the production of lipase B from Candida antarctica (LIPB) after cloning the gene that encoded it in Pichia pastoris using PGK as a constitutive promoter. The production of the lipase ...is lower using this strategy but it avoids the use of inducers like methanol. The performance of this enzyme was compared with that of the commercial enzyme (CALB) after immobilization on different supports in different reactions. As supports, we used Accurel 1000, and three core-shell supports (poly(methyl methacrylate) on the core and on the shell - PMMA/PMMA; poly(methyl methacrylate-co-divinylbenzene) on the core and on the shell - PMMA-co-DVB/PMMA-co-DVB; and poly(styrene-co-divinylbenzene) on the core and on the shell - PS-co-DVB/PS-co-DVB). The popular Novozym 435 was also utilized to assess the features of the new biocatalysts. All these supports adsorbed lipases via interfacial activation of the open form of the lipase on the hydrophobic surface of the supports. The studied reactions were esterification of oleic acid and ethanol in a solvent-free medium, resolution of ( plus or minus )-1,3,5-O-benzyl-myo-inositol via acylation using vinyl acetate in hexane and resolution of ( plus or minus )-1,2-O-isopropylidene-3,6-di-O-benzyl-myo-inositol via acylation using vinyl acetate (solvent free system). The results varied depending on the employed supports and on the studied reactions, but some general trends may be observed, pointing to better behavior of LIPB compared to CALB. The use of 4 different supports gave more strength to these differences, as it did not depend on a specific difference between a single support/enzyme pair, but it is more general. Thus, LIPB seems to have some advantages compared to the commercial enzyme on all the reactions assayed in this paper. PS-co-DVB/PS-co-DVB-LIPB is in general the most active preparation (even 50% higher activity was observed). Further investigations are in development to determine the structural reasons for these differences.
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