Joel Alderete

Joel Alderete
Universidad de Talca · Insitute of Chemestry of Natural Resources

PhD in Chemical Science

About

130
Publications
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1,857
Citations
Citations since 2016
39 Research Items
886 Citations
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150

Publications

Publications (130)
Article
Non-silica-based metal oxide nanomaterials, especially those possessing significant porosity, are emerging as good candidates for the delivery of a range of chemotherapeutic drugs providing an enhanced biocompatibility in compares with silica-based nanocarriers. Herein, mesoporous materials were synthesized from hard-templated lanthanum-manganese (...
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Dendrimer‐based nanoconjugates play a key role as functional polymers for biomedical applications. In this work, the one‐pot conjugation of polyamidoamine dendrimers of the third generation (PAMAM‐G3) with the photosensitizer chlorin e6 (Ce6) is presented using 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) and N‐hydroxysuccinimide (NHS) to me...
Article
E-selectin is a cell-adhesion receptor with specific recognition capacity toward sialo-fucosylated Lewis carbohydrates present in leukocytes and tumor cells. E-selectin interactions mediate the progress of inflammatory processes and tumor metastasis, which aroused the interest in using this protein as a biomolecular target to design glycomimetic in...
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Nanoscale molecularly imprinted polymers (nanoMIPs) are powerful molecular recognition tools with broad applications in the diagnosis, prognosis, and treatment of complex diseases. In this work, fully atomistic molecular dynamics (MD) simulations are used to assist the design of nanoMIPs with recognition capacity toward l-fucose and d-mannose as pr...
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Gold nanoparticles (Au-NPs) stabilized with PEGylated Poly(amidoamine) (PEG-PAMAM) dendrimers were successfully prepared in mild aqueous conditions; they were evaluated as efficient and recyclable catalysts for the cleaner reduction of 4-morpholinonitrobenzenes (MNBs) to 4-morpholinoanilines (MANs), which have pharmaceutical significance. Transmiss...
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Copper nanoparticles (Cu NPs) were synthesized using NaBH4 as reducing agent and increasing molar ratios of 50 % PEGylated polyamidoamine dendrimer of the third generation (PEG-PAMAM-G3) as a capping agent. The dendrimer-stabilized Cu NPs were evaluated as novel catalysts for the reduction of poorly soluble nitrocompounds in aqueous media. The nano...
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The purpose of this study was to design a polyamidoamine (PAMAM)-based nanovector for the efficient delivery of methotrexate to U87 glioma cells. To this end, 0–100% acetylated PAMAM dendrimers of the fourth generation were synthesized and evaluated using drug encapsulation measurements, molecular dynamics simulations, neurotoxicity assays and neur...
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The use of nanomaterials in photodynamic therapy (PDT) has emerged as a promising alternative to enhance the efficacy and overcome the limitations of conventional photosensitizers. A major challenge in this regard is the development of novel cheap, synthetically convenient and biocompatible photoresponsive nanomaterials for visible-light-driven PDT...
Article
Microtubules (MT) are cytoskeletal polymers of αβ-tubulin dimers that play a critical role in many cellular functions. Diverse antimitotic drugs bind to MT and disrupt their dynamics acting as MT stabilizing or destabilizing agents. The occurrence of undesired side effects and drug resistance encourages the search for novel MT binding agents with c...
Article
The transmembrane glycoprotein mucin 1 (MUC1) is an attractive tumor marker for cancer therapy and diagnosis. The nine amino acid extracellular epitope APDTRPAPG of this protein is selectively recognized by the S2.2 single-stranded DNA anti-MUC1 aptamer, which has emerged as a promising template for designing novel targeting agents for MUC1-directe...
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In the present work, the chemical composition of the Chilean freshwater crab Aegla cholchol exoskeleton was studied for the first time. α-Chitin was isolated from three main body parts (pincers, legs, carapace), and its content ranged from 9.0-10.4% (w/w). Moreover, chitosan was extracted by alkaline treatment at different temperature and time regi...
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In this work, Molecular Dynamics and QM/MM calculations were employed to examine structural and catalytic features of the retaining glucosyltransferase GTF-SI from GH70 family, which participates in the process of caries formation. Our goal was to obtain deeper understanding on the role of the R475 in the mechanism of sucrose breakage. This residue...
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Microtubules (MT) are dynamic cytoskeletal components that play a crucial role in cell division. Disrupting MT dynamics by MT stabilizers is a widely employed strategy to control cell proliferation in cancer therapy. Most MT stabilizers bind to the Taxol (TX) site located at the luminal interface between protofilaments, except Laulimalide (LAU) and...
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High-risk strains of human papillomavirus (HPV) have been identified as the etiologic agent of some anogenital tract, head, and neck cancers. Although prophylactic HPV vaccines have been approved; it is still necessary a drug-based treatment against the infection and its oncogenic effects. The E6 oncoprotein is one of the most studied therapeutic t...
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Understanding the molecular features responsible for the plasma kinetics of surface-modified polyamido amine (PAMAM) dendrimers is critical to explore novel biomedical applications for these nanomaterials. In this report, polyethylene glycol (PEG) and folic acid (FA) were employed to obtain partially-substituted PAMAM dendrimers as model biocompati...
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Upconversion nanoparticles (UCNPs) have been used as biolabels for cancer cells due to their ability to absorb near-infrared photons and upconvert them into visible radiation. We reported the synthesis of UCNPs Y2O3/Yb³⁺, Er³⁺ (1, 1 mol%), which upon excitation with infrared photons (λ = 980 nm) emit green color with a maximum peak centered at λ =...
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In this work, QM/MM calculations were employed to examine the catalytic mechanism of the retaining glucosyltransferase GTF-SI enzyme, which participates in the process of caries formation. Our goal was to characterize, with atomistic details, the mechanism of sucrose hydrolysis and the catalytic factors that modulate this reaction. Our results sugg...
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Gold nanoparticles supported on titania nanotubes (TiO2NT) were synthesized and employed as an efficient catalysts for the selective hydrogenation of nitrobenzenes. Materials characterization by N2 adsorption-desorption isotherms, XRD, HRTEM, DRS UV-vis, and XPS revealed that structured materials with high metal dispersion were obtained. The cataly...
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Absorption spectroscopy experiments were carried out to examine the 1:1 supramolecular interaction between Eosin Y (EOS) and low generation G0-G3 poly(amido amine) (PAMAM) dendrimers at neutral and basic media, aimed at gaining insight about the role of pH and dendrimer generation on EOS-PAMAM binding. Our results revealed that EOS complexation is...
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Luminescent biolabels are being eagerly investigated as a means of detecting cancer cells by bioimaging. Upconversion nanoparticles are a promising option to be used as biolabels for cancer cell detection. This process uses a near infrared beam (NIR λ = 980 nm) as the excitation source to upconvert the energy into light in the visible region. The p...
Article
Laulimalide (LAU) and Peloruside A (PLA) are non-taxane microtubule stabilizing agents with promising antimitotic properties. These ligands promote the assembly of microtubules (MTs) by targeting a unique binding site on β-tubulin. The X-ray structure for LAU/PLA-tubulin association was recently elucidated but little information is available regard...
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One of the most studied nanocarriers for drug delivery are polyamidoamine (PAMAM) dendrimers. However, the alterations produced by PAMAM dendrimers in neuronal function have not been thoroughly investigated, and important aspects such as effects on synaptic transmission remain unexplored. We focused on the neuronal activity disruption induced by de...
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This work reports the synthesis of surface-modified iron oxide magnetic nanotubes (Fe3O4NT) with poly(amido amine) dendrimers of the third generation (PAMAM-G3) as novel nanomaterials for potential drug-delivery applications. Fe3O4NT were obtained by reduction of α-Fe2O3 nanotubes, which were synthesized following a hydrothermal strategy using SO42...
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Peloruside A (PLA) and Laulimalide (LAU) are novel microtubule-stabilizing agents with promising properties against different cancer types. These ligands share a non-taxoid binding site at the outer surface of β-tubulin and promote microtubule stabilization by bridging two adjacent αβ-tubulin dimers from parallel protofilaments. Recent site-directe...
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Molecular dynamics (MD) simulations were employed to study the tubulin-binding modes of 20 epothilone derivatives spanning a wide range of antitumor activity. Trajectory analysis revealed that active ligands shared a common region of association and similar binding poses compared to the high-resolution crystal structure of the tubulin complex with...
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PEGylated PAMAM-G4 dendrimers with substitution percentages of 50% and intermediate size PEG chains (0.55 and 2.0?kDa) were synthesized and evaluated as solubility enhancers and potential supramolecular carriers for the poorly soluble drug Silybin (SIL). Aqueous solubility profiles revealed that the PEGylated system with 2.0?kDa chains induced a fi...
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This contribution reports a novel preparation of gold nanoparticles on polymer/metal oxide hybrid materials (Au/P[VBTACl]-M metal: Al, Ti or Zr) and their use as heterogeneous catalysts in liquid phase hydrogenation of p-chloronitrobenzene. The support was prepared by in situ radical polymerization/sol gel process of (4-vinyl-benzyl)trimethylammoni...
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This paper describes the synthesis and characterization of porous polymeric materials as a support for rhodium(I) cationic coordination compounds and their use as heterogeneous catalysts for alkene hydrogenation. The synthetic strategy was the insertion of a vinyl-moiety in a bis(2-chloroethyl)amine precursor to provide highly porous resins with an...
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Polyamidoamine (PAMAM) dendrimers are hyperbranched macromolecules which have been described as one of the most promising drug nanocarrier systems. A key process to understand is their cellular internalization mechanism because of its direct influence on their intracellular distribution, association with organelles, entry kinetics, and cargo releas...
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Alumina nanotubes are surface-conjugated with polyamidoamine (PAMAM) dendrimers of the third generation, aimed at obtaining novel nanomaterials for drug delivery applications. The structure and surface properties of PAMAM-conjugated alumina nanotubes (PAMAM-Al2O3NT) are characterized using Fourier Transform Infrared spectroscopy, solid state 13C-RM...
Article
Molecular dynamics (MD) simulations and binding free energy calculations were employed to examine the interaction between E-selectin and six structurally-related oligosaccharides including the physiological ligand sialyl Lewis x (sLex). MD simulations revealed that sLex and its mimics share a common binding region and similar interactions with E-se...
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Catalytic hydrogenation of maleic anhydride for the production of succinic anhydride can be a viable alternative to the higher energetic demand route based in the dehydration of succinic acid. In this sense, the metallic Ni catalysts supported on mesoporous TiO2 (anatase) substrate demonstrated to be very active and 100% selective in the liquid pha...
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A series of Ti-modified MCM-41 supports and their respective Au catalysts were prepared and characterized to study the effect of titanium into the support and on the characteristics of the Au surface species for heterogeneous hydrogenation of aromatic nitrocompounds. The systems were characterized by X-ray diffraction, Infrared spectroscopy (FT-IR)...
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E-selectin is an endothelial protein that participates in the adhesion of metastatic cancer cells, and is therefore a relevant target for antitumor therapeutic intervention. In this work, virtual screening was used to identify new E-selectin inhibitors from a subset of drug-like molecules retrieved from the ZINC database, including the physiologica...
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Chloroperoxidase (CPO) from Caldariomyces fumago is a versatile enzyme able to catalyze the styrene epoxidation. However, the lack of long-term operational stability is the principal drawback for the industrial applications of this enzyme. In this work, in order to increase the enzyme operational stability, CPO immobilization in TiO2 mesoporous mat...
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Native and PEGylated poly-amidoamine-G4 (PAMAM-G4) dendrimers with PEGylation degrees of 0%, 28%, 34%, 67%, and 100% are evaluated as potential drug carriers for methotrexate (MTX). A maximum complex stoichiometry of 47:1 is obtained for the system with 34% of PEGylation, with an estimated binding constant of 1.2 × 104 mol-1 per binding site, as de...
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Fully atomistic molecular dynamics (MD) simulations have been performed to examine the effect of PEGylation on the structure and drug loading properties of 25%–100% PEGylated poly(amidoamine) (PAMAM)-G4 dendrimers in complex with 5-fluorouracil (5-FU) as a model anticancer compound. Theoretical estimates predict a complex stoichiometry of 23:1 for...
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Using molecular modelling we have investigated the structure and dynamic properties of epothilone B-tubulin complexes with wild-type and mutated tubulin, aimed at identifying the molecular factors involved in the emergence of drug resistance induced by four protein mutations at Phe270Val, Thr274Ile, Arg282Gln and Gln292Glu. Our results revealed tha...
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Fully atomistic molecular dynamics (MD) simulations and NMR spectroscopy were employed to get insights about the molecular details of drug-dendrimer supramolecular association phenomena, using piroxicam (PRX) and the third generation poly(amido amine) (PAMAM-G3) dendrimer as model systems. Theoretical results concerning the complex stoichiometry su...
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Molecular dynamics simulations were employed to analyze the conformational preferences and binding modes of epothilones A and B as a source of structural information regarding the antitumor properties of these species. Our results suggest that the conformation of free and tubulin-bound epothilones is strongly influenced by the presence of a methyl...
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The complexation of mefenamic acid (MA) with poly(amido amine) dendrimers of the second and third generation (PAMAM‐G2 and PAMAM‐G3) at pH 7.0 is studied by aqueous solubility experiments, DOSY and 2D‐NOESY spectroscopy, and fully atomistic molecular dynamics (MD) simulations. Solubility profiles account for the formation of MA:PAMAM complexes of t...
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Flavonoids, which have many biological activities and have been widely used in nature, can be artificially synthesized. However, regioselective cyclization of chalcones is difficult by chemical methods. In this study, we demonstrated that Aspergillus niger is capable of cyclizing chalcones to flavanones, affording a mimic of plant biosynthetic proc...
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a b s t r a c t Cytochrome c has been extensively used as model of peroxidase reaction. The peroxidase activity and stability of a triple mutant CYC-3 (N52I, Y67F and M80A) were studied and compared to those of wild type protein (Wt-16). The CYC-3variant showed ten-fold increased activity in styrene oxidation. An interme-diary specie that resembles...
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A Structure Activity Relationship (SAR) study for laccase mediator systems was performed in order to correctly classify different natural phenolic mediators. Decision tree (DT) classification models with a set of five quantum-chemical calculated molecular descriptors were used. These descriptors included redox potential (ɛ°), ionization energy (E(i...
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Aqueous solution diffusion coefficients for G0–G3 PAMAM dendrimers were determined from DOSY-NMR spectroscopy at high and neutral pH. The study was performed in a dilute regime and diffusion coefficients at infinite dilution (D 0) were estimated from the variation of diffusion coefficients with dendrimer concentration. Hydrodynamic radii (R h) for...
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Abstract The structure and diffusion behavior of the neutral and charged first-generation polyamidoamine (PAMAM-G1) dendrimer and its β-cyclodextrin (β-CD) conjugate in aqueous solutions were studied by molecular dynamics (MD) simulations. Diffusion coefficients were obtained from mean square displacement data, considering 500-ps intervals of norma...
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The immobilization of enzymes in inorganic materials has been widely used because it can produce an enhancement of the catalytic stability and enzymatic activity. In this article, the effect of the immobilization of iso-1-cytochrome c (CYC-Sc) from Saccharomyces cerevisiae and chloroperoxidase (CPO) from Caldariomyces fumago on the enzyme stability...
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The study's aims were to evaluate the antimycobacterial activity of 13 synthetic neolignan analogues and to perform structure activity relationship analysis (SAR). The cytotoxicity of the compound 2-phenoxy-1-phenylethanone (LS-2, 1) in mammalian cells, such as the acute toxicity in mice, was also evaluated. The extra and intracellular antimycobact...
Article
Levansucrases from Bacillus subtilis (BS-LVS) and Leuconostoc mesenteroides ssp. mesenteroides ATCC 8293 (LevC), inulosucrase from Leuconostoc citreum (IslA) and an invertase from Saccharomyces cerevisiae (Inv) were evaluated in acceptor reactions with non-sugar acceptors. Among them, BS-LVS was selected for the fructosylation of aromatic or alipha...
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The acetohydroxyacid synthase (AHAS) is a thiamin diphosphate dependent enzyme that participates in the biosynthetic pathway of branched-chain amino acids. The catalytic cycle of AHAS consists of five steps and the first three steps are analogues to other thiamin diphosphate dependent enzymes, but some mechanism aspect of the last two steps of the...
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The equilibria among the various ionization and tautomeric states involved in the activation of ThDP is addressed using high level density functional theory calculations, X3LYP/6-311++G(d,p)//X3LYP(PB)/6-31++G(d,p). This study provides the first theoretically derived thermodynamic data for the internal equilibria in the activation of ThDP. The role...
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A new series of intermolecular hydrogen-bonded complexes has been obtained using mesogenic 4-n-nonyloxybenzoic acid and mesogenic 5-(4-pyridyl)-2-(4-n-alkoxy) benzylideneamino-1,3,4-thiadiazole moieties. The thermal and phase behaviour of these complexes were studied by thermal microscopy and differential scanning calorimetry. Intermolecular hydrog...
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Acetohydroxyacid synthase (AHAS) is a thiamin diphosphate dependent enzyme that catalyses the decarboxylation of pyruvate to yield the hydroxyethyl-thiamin diphosphate (ThDP) anion/enamine intermediate (HEThDP(-)). This intermediate reacts with a second ketoacid to form acetolactate or acetohydroxybutyrate as products. Whereas the mechanism involve...
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Bioreduction of several prochiral carbonylic compounds such as acetophenone (1), ethyl acetoacetate (2) and ethyl phenylpropionate (3) to the corresponding optically active sec-alcohols 1a-3a was performed using wild-type strains of Pichia pastoris UBB 1500, Rhodotorula sp., and Saccharomyces cerevisiae. The reductions showed moderate to excellent...
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The inhibitory effects of novel prodrugs, inclusion complexes of 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans propenoic acid (GOFA) and auraptene (AUR) with beta-cyclodextrin (CD), on colon carcinogenesis were investigated using an azoxymethane (AOM)/dextran sodium sulfate (DSS) model. Male CD-1 (ICR) mice initiated with a single intraperitoneal inje...
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The oxidation of R-(+)-limonene by chloroperoxidase (CPO) from Caldariomyces fumago is reported. The reaction was performed in 60 mM phosphate buffer at pH 3.0 and 6.0, and in the absence and in the presence of chloride ions. In the absence of chloride ions, at both pH values, the reaction was regio and stereoselective with a diasteromeric excess (...
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Complexation free energies of aliphatic compounds with α- and β-cyclodextrins were analyzed in terms of theoretical and empirical parameters that account for the role of van der Waals, hydrophobic, electrostatic, charge transfer interactions and steric effects. Two multivariate correlations were obtained to describe the inclusion behavior of 73 ali...
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The synthesis, characterisation and mesomorphic properties of new liquid crystals are reported. The goal was to obtain amides starting from 7‐decanoyloxychromone‐3‐carboxylic acid and 4‐n‐alkoxyanilines. However, instead of the expected amides, in each case a mixture of two isomeric E/Z enaminones was isolated, with a ratio 3/1. The mesophase behav...
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Biotransformation of tryptophan to tryptamine and 3-methyl-indole by Psilocybe coprophila was performed. On the other hand, Aspergillus niger was able to transform tryptophan to 5-hydroxy-tryptophan. P. coprophila biotransformed 5-hydroxy-tryptophan to 5-hydroxytryptamine. These results prove once more that fungi are good tools to establish hydroxy...
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Herein, we report the geometry optimization of four conformers of alpha-cyclodextrin (alpha-CD) by means of PM3, HF/STO-3G, HF/3-21G, HF/6-31G(d), B3LYP/6-31G(d), and X3LYP/6-31G(d) calculations. The analysis of several geometrical parameters indicates that all conformers possess bond lengths, angles, and dihedrals that agree fairly well with the c...
Article
Biotransformation of tryptophan to tryptamine and 3-methyl-indole by Psilocybe copro-phila was performed. On the other hand, Aspergillus niger was able to transform tryptophan to 5-hydroxy-tryptophan. P. coprophila biotransformed 5-hydroxy-tryptophan to 5-hydroxy-tryptamine. These results prove once more that fungi are good tools to establish hydro...
Article
5α-Hydroxy-14-eudesm-11-en-3-one (1) was metabolised by the filamentous fungi Rhizopus nigricans, Cunninghamella elegans and Mucor plumbeus to produce four metabolites. Regioselective hydroxylation at C-6 and C-11 were detected. These 11-hydroxylated compounds can be chemically transformed into α-agarofuran.
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A polysaccharide separated from Paecilomyces sp. was determined by gel permeation chromatography to be homogeneous. HPLC showed a monosaccharide containing D-glucose and D-fructose at a ratio of about 2:1. The results obtained from IR, 1H NMR, and 13C NMR analyses confirmed the proposed structure.
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Exopolysaccharide basic was obtained from a submerged culture of a native Paecilomyces sp. strain isolated from Chilean soil.
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Four potential tetradentate ligands of formulae 1,2-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)ethane (H(4)L(1), 1), 1,2-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)propane (H(4)L(2), 2), 1,2-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)benzene (H(4)L(3), 3) and 1,8-bis-(3,5-di-tert-butyl-2-hydroxybenzamido)naphthalene (H(4)L(4), 4) have been prepared an...
Article
Highly accurate methods CBS-4M and CBS-QB3 and standard DFT/B3LYP calculations were employed to study the tautomerism and protonation of triazoles and tetrazole in gas phase. Throughout this analysis, a remarkable agreement between CBS methods and B3LYP/6-311++G(d,p) calculations was observed. To account for solvation effects on tautomer stabilitie...
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Chemical reactions performed by fungi have been used as a modern tool in chemistry. In this work, we show the tryptophan biotransformation with Psilocybe coprophila on liquid culture medium. The results prove once more the versatility of fungi in performing a wide range of industrially attractive chemical reactions.
Article
From a density functional theory (DFT) analysis of solvation and the different components which comprise the free energy of solvation we propose quantitative structure–property relationship (QSPR) models to predict free energy of solvation, , of organic compounds in seven alkane solvents (n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane...
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This paper describes a combined synthesis of b-hydroxy-sesquiterpen eudesmane derivative using a microbiological hydroxylation sesquiterpen eudesmane derivative as the key reaction. The stereochemistry of the biohydroxylation was identified using mono and bi-dimensional 1H-NMR experiments