Mario Arturo Lerma Estrada - Academia.edu (original) (raw)

Papers by Mario Arturo Lerma Estrada

Biotecnologia Aplicada, Dec 1, 2012

The highly pathogenic H5N1 avian infl uenza virus (AIV) has caused important economic losses and ... more The highly pathogenic H5N1 avian infl uenza virus (AIV) has caused important economic losses and public health problems, mainly in Asia, Africa and Europe. Counteracting this virus by vaccination of poultry is crucial. In our study, recombinant antigens based on the fusion of the extracellular segments of both molecules, hemagglutinin H5 of AIV and the chicken CD154, were tested to enhance the immune response in chickens. For this purpose, chickens were immunized with recombinant adenoviral vectors carrying the nucleotide sequence of the hemagglutinin H5 alone (AdHA) or fused to the CD154 recombinant protein (AdHACD). Also, these two proteins (rHA and rHACD) were produced and assayed as antigens. Both, the adenoviral vector AdHACD and the recombinant protein rHACD, induced hemagglutination-inhibiting antibody titers signifi cantly higher than their counterparts carrying HA alone. Similar results were observed when the cellular response was measured by real time PCR. AdHACD and rHACD signifi cantly increased the production of IFN-γ transcripts, which were lower when AdHA or rHA were used. To obtain a higher quality antigen, rHACD was purifi ed by size exclusion chromatography, resulting in the preservation of its immunogenic properties. However, rHACD did not work as immunogen when an immunoaffi nity chromatography was performed by eluting at acidic pH or with a chaotropic agent. These results demonstrate that chicken CD154 can signifi cantly enhance humoral and cellular responses against hemagglutinin H5 of AIV when both molecules are administered as a fusion protein in chickens. Therefore, AdHACD or rHACD could become promising vaccine candidates against H5N1 virus.

Biotecnologia Aplicada

Small interfering RNAs can be introduced into cells and cause silencing of specific genes. This c... more Small interfering RNAs can be introduced into cells and cause silencing of specific genes. This can be used to study the effect of the gene on cellular function. The small interfering RNAs can be chemically prepared in an ordinary DNA/RNA synthesizer of a suitable quality for RNA interference. Here we report how these molecules are obtained at the Center for Genetic Engineering and Biotechnology (CIGB), Cuba, and their evaluation in the knowdown of green fluorescent protein in mammalian cells. In HEK293 cells, the eGFP expression was visualized at 24 and 48 h post-transfection under a fluorescence microscope. We observed that one RNA duplex (named RNA duplex B) silenced eGFP expression at 48 h post-transfection at a dose of 120 nM. No evident silencing effects were observed with the other RNA duplex (RNA duplex A). These results were corroborated by Northern blot analysis.

Chemometrics and Intelligent Laboratory Systems, 2015

In this work, we performed a quantitative structure activity relationship (QSAR) model for a fami... more In this work, we performed a quantitative structure activity relationship (QSAR) model for a family of 5lipoxygenase (5-LOX) inhibitors using k-means clustering and linear discriminant analysis (LDA) for the selection of training and test sets and multivariate linear regression (MLR) for the independent variable selection. With the k-means clustering method, the total set of compounds (58 derivatives of 5-Benzylidene-2phenylthiazolinones) was divided in two clusters according to a simple discriminant function. We found that piID (conventional bond order ID number) molecular descriptor discriminates correctly 100% of the compounds of each clusters. Thirty different models divided in three series were analyzed and the series with representative training and test sets (series 3) had the most predictive models. The statistical parameters of the best model are R train = 0.811 and R test = 0.801. We found that a rational selection in the setting-up of training and test sets allows to obtain the most predictive models and the random selection is sometimes unsuitable, especially, when the total set of compounds can be classified in different clusters according to structural features.

Antioxidant capacity of garlic has been attributed to organic sulfur compounds such us allyl meth... more Antioxidant capacity of garlic has been attributed to organic sulfur compounds such us allyl methyl disulfide. Using quantum chemical calculations at B3LYP/6-31+G (d) and G3MP2B3/6-31+G (d) levels of theory, we study three possible oxidation reactions of this compound against hydrogen peroxide, a reactive oxygen species, from a thermodynamic point of view. Because these reactions are supposed to occur in biological media, solvent effect was taken into consideration. Oxidation over the double bond that leads to the formation of an epoxide is more thermodynamically feasible, limiting the antioxidant capacity of this compound.

Expert Opinion on Drug Discovery, 2014

Quantitative structure-activity relationships (QSAR and 3D-QSAR) have been applied in the last de... more Quantitative structure-activity relationships (QSAR and 3D-QSAR) have been applied in the last decade to obtain a reliable statistical model for the prediction of the anticonvulsant activities of new chemical entities. However, despite the large amount of information on QSAR, no recent review has published and discussed this data in detail. In this review, the authors provide a detailed discussion of QSAR studies that have been applied to compounds with anticonvulsant activity published between the years 2003 and 2013. They also evaluate the mathematical approaches and the main software used to develop the QSAR and 3D-QSAR model. QSAR methodologies continue to attract the attention of researchers and provide valuable information for the development of new potentially active compounds including those with anticonvulsant activity. This has been helped in part by improvements in the size and performance of computers; the development of specific software and the development of novel molecular descriptors, which have given rise to new and more predictive QSAR models. The extensive development of descriptors, and the way by which descriptor values are derived, have allowed the evolution of the QSAR methods. This evolution could strengthen the QSAR methods as an important tool in research and development of new and more potent anticonvulsant agents.

Current Computer Aided-Drug Design, 2014

Lacosamide is an anticonvulsant drug which presents carbonic anhydrase inhibition. In this paper,... more Lacosamide is an anticonvulsant drug which presents carbonic anhydrase inhibition. In this paper, we analyzed the apparent relationship between both activities performing a molecular modeling, docking and QSAR studies on 18 lacosamide derivatives with known anticonvulsant activity. Docking results suggested the zinc-binding site of carbonic anhydrase is a possible target of lacosamide and lacosamide derivatives making favorable Van der Waals interactions with Asn67, Gln92, Phe131 and Thr200. The mathematical models revealed a poor relationship between the anticonvulsant activity and molecular descriptors obtained from DFT and docking calculations. However, a QSAR model was developed using Dragon software descriptors. The statistic parameters of the model are: correlation coefficient, R=0.957 and standard deviation, S=0.162. Our results provide new valuable information regarding the relationship between both activities and contribute important insights into the essential molecular requirements for the anticonvulsant activity.

Journal of Molecular Structure: THEOCHEM, 2005

Enaminones are chemical compounds consisting of an amino group linked through a CaC to a carbonyl... more Enaminones are chemical compounds consisting of an amino group linked through a CaC to a carbonyl group. They combine the ambident nucleophility of enamines with the ambident electrophility of enones. Open-ring enaminones probed to be excellent prodrugs of model primary amines because their transportation ability trough biological membranes, while some cyclic enaminones have been reported as effective anti-epiletic agents. Selected open-ring enaminones, has been subjected to quantum chemical studies with the assumption that their flexibility wills allow more precise complexation with the corresponding receptor. Various conformers were investigated in a search for structural coincidences with the anti-convulsants cyclic enaminones.

Journal of Molecular Structure: THEOCHEM, 2005

Cinnoline (1) and Phthalazine (2), diazanaphthalenes involved in certain biological reactions, ha... more Cinnoline (1) and Phthalazine (2), diazanaphthalenes involved in certain biological reactions, have been studied computational with the purpose of comparing their protonation and covalent hydration mechanisms. Geometry optimizations of neutral, mono-and di-protonated cations and hydrated products were performed at HF, DFT/B3LYP levels of theory using 6-311G* basis set and single points energies were calculated at the MP2 level of theory using the same basis set. In agreement with experimental results, calculations predict a two-step mechanism resulting in a hydrated cation in which the OH of the water is located depending on the position of both nitrogen in the diazanaphthalene molecule.

Journal of Molecular Structure: THEOCHEM, 2005

... diazanaphthalenes. César A. Spedaletti a , Corresponding Author Contact Information , E-mail ... more ... diazanaphthalenes. César A. Spedaletti a , Corresponding Author Contact Information , E-mail The Corresponding Author , Mario R. Estrada a , Graciela N. Zamarbide a , Juan C. Garro a , Carlos A. Ponce a and Francisco Tomas Vert b. ...

Journal of Molecular Structure: THEOCHEM, 2003

... Theoretical study of a hydration mechanism in an enaminone pro-drug prototype. Juan C. Garro ... more ... Theoretical study of a hydration mechanism in an enaminone pro-drug prototype. Juan C. Garro a , Corresponding Author Contact Information , E-mail The Corresponding Author , Graciela N. Zamarbide a , Mario R. Estrada a , Francisco Tomás Vert b and Carlos A. Ponce a. ...

Journal of Molecular Structure: THEOCHEM, 2003

Captopril can interact regio- and stereo-specifically with various functional groups present at t... more Captopril can interact regio- and stereo-specifically with various functional groups present at the active site of angiotensin converting enzyme (ACE). Since no X-ray structure of ACE is available, Captopril, as an ACE inhibitor may be used as a ‘molecular caliper’, to estimate upper and lower bound values for separation d, where the mercaptidic terminal group of the molecule is linked

Journal of Molecular Structure: THEOCHEM, 2009

Ab initio methods were utilized in a gas-phase systematic conformational search of bilirubin conf... more Ab initio methods were utilized in a gas-phase systematic conformational search of bilirubin conformers. The whole molecule was divided into four fragments. Most stable conformers of them were employed to build 196 conformers of the complete bilirubin molecule. Initial geometries were optimized using HF/3-21G level of theory and the minimum energy conformers were then reoptimized at B3LYP/6-31G(d) level. Ridge-tile conformer was the most stable one, in perfect agreement with X-ray data. We found that while tetrapyrrole backbone shows some flexibility, propionic acid side chains have a greater influence in bilirubin conformation because they can interact through different hydrogen bond patterns with the backbone and between them.

International Journal of Molecular Sciences, 2011

Present work employs the QSAR formalism to predict the ED 50 anticonvulsant activity of ringed-en... more Present work employs the QSAR formalism to predict the ED 50 anticonvulsant activity of ringed-enaminones, in order to apply these relationships for the prediction of unknown open-chain compounds containing the same types of functional groups in their molecular structure. Two different modeling approaches are applied with the purpose of comparing the consistency of our results: (a) the search of molecular descriptors via multivariable linear regressions; and (b) the calculation of flexible descriptors with the CORAL (CORrelation And Logic) program. Among the results found, we propose some potent candidate open-chain enaminones having ED 50 values lower than 10 mg•kg −1 for corresponding pharmacological studies. These compounds are classified as Class 1 and Class 2 according to the Anticonvulsant Selection Project.

Vaccine, 2012

Ticks are acaridae ectoparasites that, while taking a blood meal, can transmit viruses, bacteria,... more Ticks are acaridae ectoparasites that, while taking a blood meal, can transmit viruses, bacteria, protozoa and filarial nematodes, which cause a variety of human and animal illnesses. The use of chemical pesticides constitutes the primary measure for control of these ectoparasites. However, the intensive use of these chemicals has drawbacks such as the contamination of food, environmental pollution and development of resistance by ectoparasites. Vaccination is considered a promising alternative for controlling infestations by ectoparasites. Although emerging tick proteins have been identified recently, and have been proposed as potential targets for generating protective molecules, only a limited number of them have been evaluated in vaccine trials. More than 80 proteins are found in eukaryotic ribosomes. The protein P0 is essential for the assembly of the 60S ribosomal subunit. We have identified an immunogenic region of the ribosomal protein P0 from Rhipicephalus sp. ticks that is not very conserved compared to host P0. The efficacy of a 20 amino acid synthetic peptide from this sequence was assayed as a vaccine antigen against Rhipicephalus sanguineus infestations in an immunization and challenge experiment on rabbits. A remarkable diminution in the viability of newly molted nymphs from larvae fed on vaccinated rabbits was observed. The number of adults and the number of eggs hatching were significantly reduced, with an overall efficacy of 90%. Our results demonstrated that immunization with an immunogenic peptide of tick protein P0 greatly reduced survival of ticks, suggesting that it has promise as an effective tick control agent.

Vaccine, 2014

Modern vaccines based on purified recombinant antigens have improved their safety; however they i... more Modern vaccines based on purified recombinant antigens have improved their safety; however they induce a suboptimal immune response without the help of adjuvants. Consequently, the development of new adjuvants to enhance the immunogenicity of purified subunit antigens and modulate resulting immune responses is of great interest. In the present study, we evaluated the ability of antimicrobial peptides Oreochromicins previously isolated from tilapia Oreochromis niloticus to enhance adaptive immune responses in mice and tilapia. When co-administrated with ovalbumin in mice, Oreochromicin-1 induced a TH1 humoral immune response. Oreochromicin-2 and 3 induce a TH1 cellular immune response characterized by the induction of interferon-γ in a dose depend manner. Additionally, co-administration of Oreochromicin-1 with the sea lice my32 from Lepeophtheirus salmonis antigen (my32-Ls) increases the humoral immune response in mice and tilapia. We also tested different combinations of these Oreochromicins with the sea lice antigen my32-Ls in mice. Humoral and cellular TH1 responses were enhanced by co-administration of my32-Ls/Oreochromicin-3 and the combination my32-Ls/Oreochromicin-2/3. In agreement with these results, Oreochromicin-1 and 3 enhanced in vitro TH1 cytokine IFN-γ production in Concanavalin A primed splenocytes from naïve mice after a 48h incubation period. In summary, the results showed that tilapia alpha-helical antimicrobial peptides Oreochromicins are able to boost immune response in mammals and fish, encouraging their use as TH1 molecular adjuvants to subunit antigens.

Vaccine, 2011

Sea lice (Copepoda, Caligidae) are the most widely distributed marine pathogens in the salmon ind... more Sea lice (Copepoda, Caligidae) are the most widely distributed marine pathogens in the salmon industry in the last 30 years. Caligus rogercresseyi is the most important species affecting Chile's salmon industry. Vaccines against caligid copepods have the potential to be a cost-effective means of controlling the infestation and avoid many of the disadvantages of medicine treatments. However, research in the development of such vaccines has begun only recently and approaches used thus far have met with little or no success. In the present study, we characterized a novel gene (denoted as my32) from C. rogercresseyi which has the highest identity with the Lepeophtheirus salmonis gene akirin-2. To assess the function of the gene an RNA interference experiment was developed and a reduction in the number of ectoparasites on fish in the my32-dsRNA treated group was observed. The recombinant my32 protein was used in a vaccinationchallenge trial to evaluate its ability to protect against sea lice infestations. A significant reduction in the number of parasites per fish was observed at 24 days post-challenge. These results, together with the delay observed in the development of parasites from the vaccinated group suggest that the major effect of immunization was on the second parasite generation. The results of these experiments suggest that the my32 protein may be a promising target for vaccine development to control sea lice infestations in fish.

Nitric Oxide, 2011

Nitric oxide (NO) is a short-lived radical generated by nitric oxide synthases (NOS). NO is invol... more Nitric oxide (NO) is a short-lived radical generated by nitric oxide synthases (NOS). NO is involved in a variety of functions in invertebrates, including host defense. In a previous study, we isolated and sequenced for the first time the NOS gene from hemocytes of Panulirus argus, demonstrating the inducibility of this enzyme by lipopolysaccharide (LPS) in vitro. In the present work, lobster hemocytes and gills exposed to Escherichia coli O55:B5 LPS showed an increase in both NOS activity and NOS gene expression in vivo. This response was dose and time dependent. The 3D NOS structure was predicted by comparative modeling showing the oxygenase and reductase domains. These domains contain the conserved binding motifs of NOS already found in a variety of organisms. The 3D structure prediction analysis allowed the selection of a fragment of 666bp that was cloned and subsequently expressed in E. coli BL21, in which a recombinant product of around 31KDa was obtained. Hyperimmune serum obtained from immunized rabbits was tested and employed to specifically detect the recombinant polypeptide or the endogenous NOS from lobster hemocytes by western blot and immunofluorescence. This study contributes to enlarge the existing knowledge related to NOS structure and NOS participation in the immune response in lobsters. The evaluation of an antibody capable to recognize NOS from lobsters constitutes a novel and interesting tool for the implementation of further studies on NOS functions in crustaceans.

QSAR & Combinatorial Science, 2009

The formalism of the QSAR Theory is employed to establish mathematical relationships that link th... more The formalism of the QSAR Theory is employed to establish mathematical relationships that link the molecular structure of ringed enaminones to their observed antiepileptic activity. The design of predictive linear regression models, solely based on the available experimental information, involved the simultaneous analysis of 1312 theoretical descriptors calculated with Dragon software. This QSAR study that is based both on classic antiepileptics and second-generation anticonvulsant drugs, including compounds of the enaminone type, allowed the proposal of novel ringed enaminone derivatives as possible antiepileptic agents, posing a similar or even better predicted biological activity when compared to other commonly used drugs.

Medicinal Chemistry Research, 2013

A study about the relationship between molecular properties of open-chain enaminones and their an... more A study about the relationship between molecular properties of open-chain enaminones and their anticonvulsant activity is presented in this paper. Geometry optimizations of the enaminones were performed at HF and DFT/B3LYP levels of theory using 6-31 ? G(d) basis set. The HOMO and LUMO energies were obtained at the same level of theory. The solvent effect was studied through IPCM. A natural bond orbital (NBO) analysis was performed to analyze the possible association between the stability and the intramolecular hydrogen bond interaction energies. The stability order of the isomers in gas phase was the following: cis-1 [ trans-4 [ cis-2 [ trans-3. The IPCM method showed that the trans-3 isomers are more stable that the cis-2 when the solvent effect was taken into account. Two important intramolecular hydrogen bonds were found by NBO analysis. According to our findings, these interactions could affect the activity of the two most stable isomers (cis-1 and trans-4). By contrast, trans-3 isomers did not present this type of interaction. Therefore, the latter isomers have a large flexibility and can adopt a conformation similar to the conformation of active ringed enaminones. In addition, HOMO and LUMO energies suggested that the trans-3 isomers could be the most reactive species. Keywords Open-chain enaminones Á Anticonvulsant activity Á Structure-activity relationship Á Active conformation Á Ab initio Á NBO analysis Electronic supplementary material The online version of this article (

Journal of Physical Organic Chemistry, 2008

Allyl methyl disulfide, a peroxide scavenger, was studied together with three isomeric (two sulfo... more Allyl methyl disulfide, a peroxide scavenger, was studied together with three isomeric (two sulfoxides and one epoxide) forms of its mono-oxidized products. After a full conformational study of the reactant and three isomeric oxidized forms, the geometries were optimized at B3LYP/6-31G (d) level of theory. The epoxide form turned and to be more stable than either one of the two isomeric sulfoxides. Changes for Thermodynamic functions of oxidation reactions were calculated and from the DG reaction values the equilibrium constant for the interconversions of the oxidized products were estimated. Bader-type AIM analyses were performed on the electron density, computed at the B3LYP/6-311þþG (d,p) level of theory. In several of the sulfoxide conformations C-HÁÁÁO-S< secondary interactions were observed.

Biotecnologia Aplicada, Dec 1, 2012

The highly pathogenic H5N1 avian infl uenza virus (AIV) has caused important economic losses and ... more The highly pathogenic H5N1 avian infl uenza virus (AIV) has caused important economic losses and public health problems, mainly in Asia, Africa and Europe. Counteracting this virus by vaccination of poultry is crucial. In our study, recombinant antigens based on the fusion of the extracellular segments of both molecules, hemagglutinin H5 of AIV and the chicken CD154, were tested to enhance the immune response in chickens. For this purpose, chickens were immunized with recombinant adenoviral vectors carrying the nucleotide sequence of the hemagglutinin H5 alone (AdHA) or fused to the CD154 recombinant protein (AdHACD). Also, these two proteins (rHA and rHACD) were produced and assayed as antigens. Both, the adenoviral vector AdHACD and the recombinant protein rHACD, induced hemagglutination-inhibiting antibody titers signifi cantly higher than their counterparts carrying HA alone. Similar results were observed when the cellular response was measured by real time PCR. AdHACD and rHACD signifi cantly increased the production of IFN-γ transcripts, which were lower when AdHA or rHA were used. To obtain a higher quality antigen, rHACD was purifi ed by size exclusion chromatography, resulting in the preservation of its immunogenic properties. However, rHACD did not work as immunogen when an immunoaffi nity chromatography was performed by eluting at acidic pH or with a chaotropic agent. These results demonstrate that chicken CD154 can signifi cantly enhance humoral and cellular responses against hemagglutinin H5 of AIV when both molecules are administered as a fusion protein in chickens. Therefore, AdHACD or rHACD could become promising vaccine candidates against H5N1 virus.

Biotecnologia Aplicada

Small interfering RNAs can be introduced into cells and cause silencing of specific genes. This c... more Small interfering RNAs can be introduced into cells and cause silencing of specific genes. This can be used to study the effect of the gene on cellular function. The small interfering RNAs can be chemically prepared in an ordinary DNA/RNA synthesizer of a suitable quality for RNA interference. Here we report how these molecules are obtained at the Center for Genetic Engineering and Biotechnology (CIGB), Cuba, and their evaluation in the knowdown of green fluorescent protein in mammalian cells. In HEK293 cells, the eGFP expression was visualized at 24 and 48 h post-transfection under a fluorescence microscope. We observed that one RNA duplex (named RNA duplex B) silenced eGFP expression at 48 h post-transfection at a dose of 120 nM. No evident silencing effects were observed with the other RNA duplex (RNA duplex A). These results were corroborated by Northern blot analysis.

Chemometrics and Intelligent Laboratory Systems, 2015

In this work, we performed a quantitative structure activity relationship (QSAR) model for a fami... more In this work, we performed a quantitative structure activity relationship (QSAR) model for a family of 5lipoxygenase (5-LOX) inhibitors using k-means clustering and linear discriminant analysis (LDA) for the selection of training and test sets and multivariate linear regression (MLR) for the independent variable selection. With the k-means clustering method, the total set of compounds (58 derivatives of 5-Benzylidene-2phenylthiazolinones) was divided in two clusters according to a simple discriminant function. We found that piID (conventional bond order ID number) molecular descriptor discriminates correctly 100% of the compounds of each clusters. Thirty different models divided in three series were analyzed and the series with representative training and test sets (series 3) had the most predictive models. The statistical parameters of the best model are R train = 0.811 and R test = 0.801. We found that a rational selection in the setting-up of training and test sets allows to obtain the most predictive models and the random selection is sometimes unsuitable, especially, when the total set of compounds can be classified in different clusters according to structural features.

Antioxidant capacity of garlic has been attributed to organic sulfur compounds such us allyl meth... more Antioxidant capacity of garlic has been attributed to organic sulfur compounds such us allyl methyl disulfide. Using quantum chemical calculations at B3LYP/6-31+G (d) and G3MP2B3/6-31+G (d) levels of theory, we study three possible oxidation reactions of this compound against hydrogen peroxide, a reactive oxygen species, from a thermodynamic point of view. Because these reactions are supposed to occur in biological media, solvent effect was taken into consideration. Oxidation over the double bond that leads to the formation of an epoxide is more thermodynamically feasible, limiting the antioxidant capacity of this compound.

Expert Opinion on Drug Discovery, 2014

Quantitative structure-activity relationships (QSAR and 3D-QSAR) have been applied in the last de... more Quantitative structure-activity relationships (QSAR and 3D-QSAR) have been applied in the last decade to obtain a reliable statistical model for the prediction of the anticonvulsant activities of new chemical entities. However, despite the large amount of information on QSAR, no recent review has published and discussed this data in detail. In this review, the authors provide a detailed discussion of QSAR studies that have been applied to compounds with anticonvulsant activity published between the years 2003 and 2013. They also evaluate the mathematical approaches and the main software used to develop the QSAR and 3D-QSAR model. QSAR methodologies continue to attract the attention of researchers and provide valuable information for the development of new potentially active compounds including those with anticonvulsant activity. This has been helped in part by improvements in the size and performance of computers; the development of specific software and the development of novel molecular descriptors, which have given rise to new and more predictive QSAR models. The extensive development of descriptors, and the way by which descriptor values are derived, have allowed the evolution of the QSAR methods. This evolution could strengthen the QSAR methods as an important tool in research and development of new and more potent anticonvulsant agents.

Current Computer Aided-Drug Design, 2014

Lacosamide is an anticonvulsant drug which presents carbonic anhydrase inhibition. In this paper,... more Lacosamide is an anticonvulsant drug which presents carbonic anhydrase inhibition. In this paper, we analyzed the apparent relationship between both activities performing a molecular modeling, docking and QSAR studies on 18 lacosamide derivatives with known anticonvulsant activity. Docking results suggested the zinc-binding site of carbonic anhydrase is a possible target of lacosamide and lacosamide derivatives making favorable Van der Waals interactions with Asn67, Gln92, Phe131 and Thr200. The mathematical models revealed a poor relationship between the anticonvulsant activity and molecular descriptors obtained from DFT and docking calculations. However, a QSAR model was developed using Dragon software descriptors. The statistic parameters of the model are: correlation coefficient, R=0.957 and standard deviation, S=0.162. Our results provide new valuable information regarding the relationship between both activities and contribute important insights into the essential molecular requirements for the anticonvulsant activity.

Journal of Molecular Structure: THEOCHEM, 2005

Enaminones are chemical compounds consisting of an amino group linked through a CaC to a carbonyl... more Enaminones are chemical compounds consisting of an amino group linked through a CaC to a carbonyl group. They combine the ambident nucleophility of enamines with the ambident electrophility of enones. Open-ring enaminones probed to be excellent prodrugs of model primary amines because their transportation ability trough biological membranes, while some cyclic enaminones have been reported as effective anti-epiletic agents. Selected open-ring enaminones, has been subjected to quantum chemical studies with the assumption that their flexibility wills allow more precise complexation with the corresponding receptor. Various conformers were investigated in a search for structural coincidences with the anti-convulsants cyclic enaminones.

Journal of Molecular Structure: THEOCHEM, 2005

Cinnoline (1) and Phthalazine (2), diazanaphthalenes involved in certain biological reactions, ha... more Cinnoline (1) and Phthalazine (2), diazanaphthalenes involved in certain biological reactions, have been studied computational with the purpose of comparing their protonation and covalent hydration mechanisms. Geometry optimizations of neutral, mono-and di-protonated cations and hydrated products were performed at HF, DFT/B3LYP levels of theory using 6-311G* basis set and single points energies were calculated at the MP2 level of theory using the same basis set. In agreement with experimental results, calculations predict a two-step mechanism resulting in a hydrated cation in which the OH of the water is located depending on the position of both nitrogen in the diazanaphthalene molecule.

Journal of Molecular Structure: THEOCHEM, 2005

... diazanaphthalenes. César A. Spedaletti a , Corresponding Author Contact Information , E-mail ... more ... diazanaphthalenes. César A. Spedaletti a , Corresponding Author Contact Information , E-mail The Corresponding Author , Mario R. Estrada a , Graciela N. Zamarbide a , Juan C. Garro a , Carlos A. Ponce a and Francisco Tomas Vert b. ...

Journal of Molecular Structure: THEOCHEM, 2003

... Theoretical study of a hydration mechanism in an enaminone pro-drug prototype. Juan C. Garro ... more ... Theoretical study of a hydration mechanism in an enaminone pro-drug prototype. Juan C. Garro a , Corresponding Author Contact Information , E-mail The Corresponding Author , Graciela N. Zamarbide a , Mario R. Estrada a , Francisco Tomás Vert b and Carlos A. Ponce a. ...

Journal of Molecular Structure: THEOCHEM, 2003

Captopril can interact regio- and stereo-specifically with various functional groups present at t... more Captopril can interact regio- and stereo-specifically with various functional groups present at the active site of angiotensin converting enzyme (ACE). Since no X-ray structure of ACE is available, Captopril, as an ACE inhibitor may be used as a ‘molecular caliper’, to estimate upper and lower bound values for separation d, where the mercaptidic terminal group of the molecule is linked

Journal of Molecular Structure: THEOCHEM, 2009

Ab initio methods were utilized in a gas-phase systematic conformational search of bilirubin conf... more Ab initio methods were utilized in a gas-phase systematic conformational search of bilirubin conformers. The whole molecule was divided into four fragments. Most stable conformers of them were employed to build 196 conformers of the complete bilirubin molecule. Initial geometries were optimized using HF/3-21G level of theory and the minimum energy conformers were then reoptimized at B3LYP/6-31G(d) level. Ridge-tile conformer was the most stable one, in perfect agreement with X-ray data. We found that while tetrapyrrole backbone shows some flexibility, propionic acid side chains have a greater influence in bilirubin conformation because they can interact through different hydrogen bond patterns with the backbone and between them.

International Journal of Molecular Sciences, 2011

Present work employs the QSAR formalism to predict the ED 50 anticonvulsant activity of ringed-en... more Present work employs the QSAR formalism to predict the ED 50 anticonvulsant activity of ringed-enaminones, in order to apply these relationships for the prediction of unknown open-chain compounds containing the same types of functional groups in their molecular structure. Two different modeling approaches are applied with the purpose of comparing the consistency of our results: (a) the search of molecular descriptors via multivariable linear regressions; and (b) the calculation of flexible descriptors with the CORAL (CORrelation And Logic) program. Among the results found, we propose some potent candidate open-chain enaminones having ED 50 values lower than 10 mg•kg −1 for corresponding pharmacological studies. These compounds are classified as Class 1 and Class 2 according to the Anticonvulsant Selection Project.

Vaccine, 2012

Ticks are acaridae ectoparasites that, while taking a blood meal, can transmit viruses, bacteria,... more Ticks are acaridae ectoparasites that, while taking a blood meal, can transmit viruses, bacteria, protozoa and filarial nematodes, which cause a variety of human and animal illnesses. The use of chemical pesticides constitutes the primary measure for control of these ectoparasites. However, the intensive use of these chemicals has drawbacks such as the contamination of food, environmental pollution and development of resistance by ectoparasites. Vaccination is considered a promising alternative for controlling infestations by ectoparasites. Although emerging tick proteins have been identified recently, and have been proposed as potential targets for generating protective molecules, only a limited number of them have been evaluated in vaccine trials. More than 80 proteins are found in eukaryotic ribosomes. The protein P0 is essential for the assembly of the 60S ribosomal subunit. We have identified an immunogenic region of the ribosomal protein P0 from Rhipicephalus sp. ticks that is not very conserved compared to host P0. The efficacy of a 20 amino acid synthetic peptide from this sequence was assayed as a vaccine antigen against Rhipicephalus sanguineus infestations in an immunization and challenge experiment on rabbits. A remarkable diminution in the viability of newly molted nymphs from larvae fed on vaccinated rabbits was observed. The number of adults and the number of eggs hatching were significantly reduced, with an overall efficacy of 90%. Our results demonstrated that immunization with an immunogenic peptide of tick protein P0 greatly reduced survival of ticks, suggesting that it has promise as an effective tick control agent.

Vaccine, 2014

Modern vaccines based on purified recombinant antigens have improved their safety; however they i... more Modern vaccines based on purified recombinant antigens have improved their safety; however they induce a suboptimal immune response without the help of adjuvants. Consequently, the development of new adjuvants to enhance the immunogenicity of purified subunit antigens and modulate resulting immune responses is of great interest. In the present study, we evaluated the ability of antimicrobial peptides Oreochromicins previously isolated from tilapia Oreochromis niloticus to enhance adaptive immune responses in mice and tilapia. When co-administrated with ovalbumin in mice, Oreochromicin-1 induced a TH1 humoral immune response. Oreochromicin-2 and 3 induce a TH1 cellular immune response characterized by the induction of interferon-γ in a dose depend manner. Additionally, co-administration of Oreochromicin-1 with the sea lice my32 from Lepeophtheirus salmonis antigen (my32-Ls) increases the humoral immune response in mice and tilapia. We also tested different combinations of these Oreochromicins with the sea lice antigen my32-Ls in mice. Humoral and cellular TH1 responses were enhanced by co-administration of my32-Ls/Oreochromicin-3 and the combination my32-Ls/Oreochromicin-2/3. In agreement with these results, Oreochromicin-1 and 3 enhanced in vitro TH1 cytokine IFN-γ production in Concanavalin A primed splenocytes from naïve mice after a 48h incubation period. In summary, the results showed that tilapia alpha-helical antimicrobial peptides Oreochromicins are able to boost immune response in mammals and fish, encouraging their use as TH1 molecular adjuvants to subunit antigens.

Vaccine, 2011

Sea lice (Copepoda, Caligidae) are the most widely distributed marine pathogens in the salmon ind... more Sea lice (Copepoda, Caligidae) are the most widely distributed marine pathogens in the salmon industry in the last 30 years. Caligus rogercresseyi is the most important species affecting Chile's salmon industry. Vaccines against caligid copepods have the potential to be a cost-effective means of controlling the infestation and avoid many of the disadvantages of medicine treatments. However, research in the development of such vaccines has begun only recently and approaches used thus far have met with little or no success. In the present study, we characterized a novel gene (denoted as my32) from C. rogercresseyi which has the highest identity with the Lepeophtheirus salmonis gene akirin-2. To assess the function of the gene an RNA interference experiment was developed and a reduction in the number of ectoparasites on fish in the my32-dsRNA treated group was observed. The recombinant my32 protein was used in a vaccinationchallenge trial to evaluate its ability to protect against sea lice infestations. A significant reduction in the number of parasites per fish was observed at 24 days post-challenge. These results, together with the delay observed in the development of parasites from the vaccinated group suggest that the major effect of immunization was on the second parasite generation. The results of these experiments suggest that the my32 protein may be a promising target for vaccine development to control sea lice infestations in fish.

Nitric Oxide, 2011

Nitric oxide (NO) is a short-lived radical generated by nitric oxide synthases (NOS). NO is invol... more Nitric oxide (NO) is a short-lived radical generated by nitric oxide synthases (NOS). NO is involved in a variety of functions in invertebrates, including host defense. In a previous study, we isolated and sequenced for the first time the NOS gene from hemocytes of Panulirus argus, demonstrating the inducibility of this enzyme by lipopolysaccharide (LPS) in vitro. In the present work, lobster hemocytes and gills exposed to Escherichia coli O55:B5 LPS showed an increase in both NOS activity and NOS gene expression in vivo. This response was dose and time dependent. The 3D NOS structure was predicted by comparative modeling showing the oxygenase and reductase domains. These domains contain the conserved binding motifs of NOS already found in a variety of organisms. The 3D structure prediction analysis allowed the selection of a fragment of 666bp that was cloned and subsequently expressed in E. coli BL21, in which a recombinant product of around 31KDa was obtained. Hyperimmune serum obtained from immunized rabbits was tested and employed to specifically detect the recombinant polypeptide or the endogenous NOS from lobster hemocytes by western blot and immunofluorescence. This study contributes to enlarge the existing knowledge related to NOS structure and NOS participation in the immune response in lobsters. The evaluation of an antibody capable to recognize NOS from lobsters constitutes a novel and interesting tool for the implementation of further studies on NOS functions in crustaceans.

QSAR & Combinatorial Science, 2009

The formalism of the QSAR Theory is employed to establish mathematical relationships that link th... more The formalism of the QSAR Theory is employed to establish mathematical relationships that link the molecular structure of ringed enaminones to their observed antiepileptic activity. The design of predictive linear regression models, solely based on the available experimental information, involved the simultaneous analysis of 1312 theoretical descriptors calculated with Dragon software. This QSAR study that is based both on classic antiepileptics and second-generation anticonvulsant drugs, including compounds of the enaminone type, allowed the proposal of novel ringed enaminone derivatives as possible antiepileptic agents, posing a similar or even better predicted biological activity when compared to other commonly used drugs.

Medicinal Chemistry Research, 2013

A study about the relationship between molecular properties of open-chain enaminones and their an... more A study about the relationship between molecular properties of open-chain enaminones and their anticonvulsant activity is presented in this paper. Geometry optimizations of the enaminones were performed at HF and DFT/B3LYP levels of theory using 6-31 ? G(d) basis set. The HOMO and LUMO energies were obtained at the same level of theory. The solvent effect was studied through IPCM. A natural bond orbital (NBO) analysis was performed to analyze the possible association between the stability and the intramolecular hydrogen bond interaction energies. The stability order of the isomers in gas phase was the following: cis-1 [ trans-4 [ cis-2 [ trans-3. The IPCM method showed that the trans-3 isomers are more stable that the cis-2 when the solvent effect was taken into account. Two important intramolecular hydrogen bonds were found by NBO analysis. According to our findings, these interactions could affect the activity of the two most stable isomers (cis-1 and trans-4). By contrast, trans-3 isomers did not present this type of interaction. Therefore, the latter isomers have a large flexibility and can adopt a conformation similar to the conformation of active ringed enaminones. In addition, HOMO and LUMO energies suggested that the trans-3 isomers could be the most reactive species. Keywords Open-chain enaminones Á Anticonvulsant activity Á Structure-activity relationship Á Active conformation Á Ab initio Á NBO analysis Electronic supplementary material The online version of this article (

Journal of Physical Organic Chemistry, 2008

Allyl methyl disulfide, a peroxide scavenger, was studied together with three isomeric (two sulfo... more Allyl methyl disulfide, a peroxide scavenger, was studied together with three isomeric (two sulfoxides and one epoxide) forms of its mono-oxidized products. After a full conformational study of the reactant and three isomeric oxidized forms, the geometries were optimized at B3LYP/6-31G (d) level of theory. The epoxide form turned and to be more stable than either one of the two isomeric sulfoxides. Changes for Thermodynamic functions of oxidation reactions were calculated and from the DG reaction values the equilibrium constant for the interconversions of the oxidized products were estimated. Bader-type AIM analyses were performed on the electron density, computed at the B3LYP/6-311þþG (d,p) level of theory. In several of the sulfoxide conformations C-HÁÁÁO-S< secondary interactions were observed.