Vibrational assignments of two polymorphic forms of metaxolone by using DFT calculations and the SQM methodology

A theoretical study has been performed on the musclerelaxant 5-[(3, 5-dimethylphenoxy)methyl]-1,3-oxazolidin-2-one, of generic name metaxolone (MTX), by using the hybridB3LYP/6-31G calculations in the gas phase and theexperimental available infrared and Raman spectra in thesolid phase. Three C1, C2 and C3 isomers were found in thepotential energy surface (PES) but only two of them, C1 andC2 correspond to those experimentally reported polymorphicforms A and B, respectively. The absence of C3 isomer couldbe easily explained by the quite high values in the dihedralC5-C7-O2-C9 and O1-C5-C7-O2 angles different from thoseexperimental structures reported for the two polymorphicforms A and B of MTX. On the other hand, the higher bondorders values together with the high topological propertiesobserved for the oxazolidinone ring of C1 could possiblysupport their existence despite this isomer has highest energythan C2 and C3. The natural bond orbital (NBO) analysesreveal the high stabilities of C1 and C2 while the atoms inmolecules(AIM) study suggests that the ringdimethylphenoxy-methyl practically do not have influence onthe properties of MTX. The frontier orbitals show that theisomers of MTX have reactivities and electrophilicity indexessimilar to antiviral thymidine while their nucleophilicityindexes present values closer to antimicrobial thione. Inaddition, the complete vibrational assignments of those twostable isomers were performed by using the experimentalavailable FT-IR and FT-Raman spectra, their normal internalcoordinates,the scaled quantum mechanical force field(SQMFF) methodology and the Molvib program.Theharmonic force fields for the two isomers and theircorresponding force constants were also reported. The forceconstants values are in agreement with values reported in theliterature for species with similar groups.Fil: Iramain, Maximiliano Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica; ArgentinaFil: Márquez, María J.. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica; ArgentinaFil: Ledesma, Ana Estela. Universidad Nacional de Santiago del Estero. Facultad de Cs.exactas y Tecnologías. Departamento de Física y Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brandan, Silvia Antonia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica; Argentin

Analizando the effects of halogen on properties of a halogenated series of R and S enantiomers analogues alkaloid cocaine-X, X=F, Cl, Br, I.

The volumes and weight molecular of all members of both series are relationed with the Van der Waals radius X distances with the electronegativities and R of X suggesting that these two properties have influence on the positions of the CO CH groups of VdW 2 3 both series. The NBO calculations have evidenced that the F and Cl derivatives of both series present the higher variations in the total energies while the AIM analyses reveal that the presence of halogen X in the benzyl rings generate a new H bonds no observed in the free base of cocaine whose topological properties are strongly dependent from the electronegativity of the halogen. Hence, the properties for the F derivatives are higher than the observed for the other ones. The NBO calculations also show clearly that the presence of the halogen X generates variations in the bond orders related to the inter-rings C-C bonds formed between the piperidine and benzyl rings and, in the C atoms that contain the CO CH groups. The frontier orbitals 2 3 demonstrate that the effects of halogen X on the halogenated series are to increase the gaps values and, as consequence decrease the reactivities of all members of both series. Finally, the higher dipole moment values observed for the Cl derivatives of both R and S series could be clearly explained by the higher Merz-Kollman (MK) charges values observed on all C atoms belong to the benzyl rings that contain the halogen X.Fil: Iramain, Maximiliano Alberto. Universidad Nacional de Tucuman. Facultad de Bioquimica, Quimica y Farmacia. Instituto de Quimica Inorganica. Cátedra de Química General.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ledesma, Ana Estela. Universidad Nacional de Santiago del Estero. Facultad de Cs.exactas y Tecnologías. Departamento de Física y Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brandan, Silvia Antonia. Universidad Nacional de Tucuman. Facultad de Bioquimica, Quimica y Farmacia. Instituto de Quimica Inorganica. Cátedra de Química General.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Structural, Electronic, Topological and Vibrational Properties of Isomers of Thymidine ? A Study Combining Spectroscopic Data with DFT Calculations

In this work, the structural, electronic, topological and vibrationalproperties of six Cis and Trans isomers of Thymidine (THY) in gasand aqueous solution phases were studied combining the hybridB3LYP/6-31G* method with the Polarized Continuum Model(PCM) model and the available experimental infrared, Raman, 1HNMR,13C-NMR and UV spectra. Hence, theoretical molecularstructures of two Cis isomers and one Trans isomers of THY weredetermined in the two media for first time. The population analysessuggest the presence in solution of a Trans isomer and of two Cisisomers in accordance with the experimental structures reported byX-ray diffraction by different authors. The study of the charges showclearly the differences between the Cis and Trans isomers where thecharges on the O atoms belonging to the ribose rings in all thestructures, on the N atoms belonging to the glycosidic bond and onthe two chiral C atoms show the higher modifications. TheMolecular Electrostatic Potential (MEP) surface mapped evidenceclearly that the group´s acceptors of H bonds in all the isomers arethe two C=O groups of the pyrimidine rings while the OH groups ofthe ribose rings and the NH group of the pyrimidine rings are donorsof H bonds showing their surfaces colorations red and blue in thosesites, respectively. Natural Bond Orbital (NBO) and QuantumAtoms in Molecules (QAIM) calculations clearly reveal the highstabilities of those three isomers of THY in both media. The frontierorbitals show that in gas phase the decreasing of the gap values aredifferent than those in solution. The vibrational analyses show thepresence of different isomers in both media and confirm that thedifferent positions of the bands are characteristic of their differentstructures. Here, the 1H-NMR, 13C-NMR and UV spectra present areasonable concordance with the corresponding experimental ones.Finally, the spectroscopic studies support the presence of more of anisomer of THY in solution.Fil: Iramain, Maximiliano Alberto. Universidad Nacional de Santiago del Estero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ledesma, Ana Estela. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Romani, Davide. No especifíca;Fil: Brandan, Silvia Antonia. Universidad Nacional de Santiago del Estero; Argentin

Spectroscopic studies on the potassium 1-fluorobenzoyltrifluoroborate salt by using the FT-IR, Raman and UV–Visible spectra and DFT calculations

Potassium 1-fluorobenzoyltrifluoroborate (FBTFB) salt was characterized using Fourier Transformed Infrared (FT-IR) and Raman solid-state spectroscopies as well as ultraviolet–visible spectroscopy in aqueous solution. The functional hybrid B3LYP with the 6-311++G** basis set have optimized the structures of salt in gas phase and in aqueous solution with CS symmetries. In solution, the influence of solvent was studied at the same level of theory with the integral equation formalism variant polarised continuum method (IEFPCM) and the universal solvation model. FBTFB has evidenced the lower solvation energy (−81.54 kJ/mol), as compared with other trifluoroborate salts probably due to the presence of F in the 1st position of phenyl ring that decreases the solubility of this salt. NBO studies clearly support the ionic characteristics of K+F− and K+O− bonds and the high energy values of LPF17→ LP*B14 transitions (ΔΕn→n*) while AIM analyses suggest a high stability of salt in both media due to three ionic and one C–H⋅⋅⋅F interactions. Analyses of frontier orbitals have suggested that the FBTFB salt is more reactive in solution than in gas phase and, than 2-phenylacetyl-trifluoroborate (PTFB) in the two media possibly because FBTFB presents higher global electrophilicity (ω) and nucleophilicity indexes (E) in both media than PTFB. Here, the calculated harmonic force fields, scaled force constants and complete assignments of all vibration normal modes expected for FBTFB in both media are reported. Predicted IR, Raman and UV–Visible spectra have shown good concordance when they are compared with the corresponding experimental ones.Fil: Iramain, Maximiliano Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica. Cátedra de Química General; ArgentinaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Imbarack, Elizabeth. Pontificia Universidad Católica de Valparaíso; ChileFil: Bongiorno, Patricio Leyton. Pontificia Universidad Católica de Valparaíso; ChileFil: Brandan, Silvia Antonia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica. Cátedra de Química General; Argentin

Tuning surface interactions on MgFe2O4 nanoparticles to induce interfacial hyperactivation in Candida rugosa lipase immobilization

Lipase adsorption on solid supports can be mediated by a precise balance of electrostatic and hydrophobic interactions. A suitable fine-tuning could allow the immobilized enzyme to display high catalytic activity. The objective of this work was to investigate how pH and ionic strength fluctuations affected protein-support interactions during immobilization via physical adsorption of a Candida rugosa lipase (CRL) on MgFe2O5. The highest amount of immobilized protein (IP) was measured at pH 4, and an ionic strength of 90 mM. However, these immobilization conditions did not register the highest hydrolytic activity (HA) in the biocatalyst (CRLa@MgFe2O4), finding the best values also at acidic pH but with a slight shift towards higher values of ionic strength around 110 mM. These findings were confirmed when the adsorption isotherms were examined under different immobilization conditions so that the maximum measurements of IP did not coincide with that of HA. Furthermore, when the recovered activity was examined, a strong interfacial hyperactivation of the lipase was detected towards acidic pH and highly charged surrounding environments. Spectroscopic studies, as well as in silico molecular docking analyses, revealed a considerable involvement of surface hydrophobic protein-carrier interactions, with aromatic aminoacids, especially phenylalanine residues, playing an important role. In light of these findings, this study significantly contributes to the body of knowledge and a better understanding of the factors that influence the lipase immobilization process on magnetic inorganic oxide nanoparticle surfaces.Fil: Morales, Andrés Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Hero, Johan Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Martinez, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Navarro, María C.. Universidad Nacional de Tucuman. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorganica. Cátedra de Química Inorganica; ArgentinaFil: Gómez, María I.. Universidad Nacional de Tucuman. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorganica. Cátedra de Química Inorganica; ArgentinaFil: Romero, Cintia Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Biosynthesized ZnO-NPs from Morus indica attenuates methylglyoxal-induced protein glycation and RBC damage: In-vitro, in-vivo and molecular docking study

The development of advanced glycation end-products (AGEs) inhibitors is considered to have therapeutic potential in diabetic complications inhibiting the loss of the biomolecular function. In the present study, zinc oxide nanoparticles (ZnO-NPs) were synthesized from aqueous leaf extract of Morus indica and were characterized by various techniques such as ultraviolet (UV)-Vis spectroscopy, Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Further, the inhibition of AGEs formation after exposure to ZnO-NPs was investigated by in-vitro, in-vivo, and molecular docking studies. Biochemical and histopathological changes after exposure to ZnO-NPs were also studied in streptozotocin-induced diabetic rats. ZnO-NPs showed an absorption peak at 359 nm with a purity of 92.62% and ~6–12 nm in size, which is characteristic of nanoparticles. The images of SEM showed agglomeration of smaller ZnO-NPs and EDS authenticating that the synthesized nanoparticles were without impurities. The biosynthesized ZnO-NPs showed significant inhibition in the formation of AGEs. The particles were effective against methylglyoxal (MGO) mediated glycation of bovine serum albumin (BSA) by inhibiting the formation of AGEs, which was dose-dependent. Further, the presence of MGO resulted in complete damage of biconcave red blood corpuscles (RBCs) to an irregular shape, whereas the morphological changes were prevented when they were treated with ZnO-NPs leading to the prevention of complications caused due to glycation. The administration of ZnO-NPs (100 mg Kg−1) in streptozotocin(STZ)-induced diabetic rats reversed hyperglycemia and significantly improved hepatic enzymes level and renal functionality, also the histopathological studies revealed restoration of kidney and liver damage nearer to normal conditions. Molecular docking of BSA with ZnO-NPs confirms that masking of lysine and arginine residues is one of the possible mechanisms responsible for the potent antiglycation activity of ZnO-NPs. The findings strongly suggest scope for exploring the therapeutic potential of diabetes-related complications.Fil: Anandan, Satish. University of Mysore; IndiaFil: Mahadevamurthy, Murali. University of Mysore; IndiaFil: Ansari, Mohammad Azam. Imam Abdulrahman Bin Faisal University; Arabia SauditaFil: Alzohairy, Mohammad A.. Al Qassim University; Arabia SauditaFil: Alomary, Mohammad N.. King Abdulaziz City For Science And Technology; Arabia SauditaFil: Siraj, Syeda Farha. University of Mysore; IndiaFil: Nagaraja, Sarjan Halugudde. University of Mysore; IndiaFil: Chikkamadaiah, Mahendra. University of Mysore; IndiaFil: Ramachandrappa, Lakshmeesha Thimappa. University of Mysore; IndiaFil: Krishnappa, Hemanth Kumar Naguvanahalli. University of Mysore; IndiaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Nagaraj, Amruthesh Kestur. University of Mysore; IndiaFil: Urooj, Asna. University of Mysore; Indi

Exploration of Anti-HIV Phytocompounds against SARS-CoV-2 Main Protease: Structure-Based Screening, Molecular Simulation, ADME Analysis and Conceptual DFT Studies

The ever-expanding pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has gained attention as COVID-19 and caused an emergency in public health to an unmatched level to date. However, the treatments used are the only options; currently, no effective and licensed medications are available to combat disease transmission, necessitating further research. In the present study, an in silico-based virtual screening of anti-HIV bioactive compounds from medicinal plants was carried out through molecular docking against the main protease (Mpro) (PDB: 6LU7) of SARS-CoV-2, which is a key enzyme responsible for virus replication. A total of 16 anti-HIV compounds were found to have a binding affinity greater than −8.9 kcal/mol out of 150 compounds screened. Pseudohypericin had a high affinity with the energy of −10.2 kcal/mol, demonstrating amino acid residual interactions with LEU141, GLU166, ARG188, and GLN192, followed by Hypericin (−10.1 kcal/mol). Moreover, the ADME (Absorption, Distribution, Metabolism and Excretion) analysis of Pseudohypericin and Hypericin recorded a low bioavailability (BA) score of 0.17 and violated Lipinski’s rule of drug-likeness. The docking and molecular simulations indicated that the quinone compound, Pseudohypericin, could be tested in vitro and in vivo as potent molecules against COVID-19 disease prior to clinical trials.This was also supported by the theoretical and computational studies conducted. The global and local descriptors, which are the underpinnings of Conceptual Density FunctionalTheory (CDFT) have beenpredicted through successful model chemistry, hoping that they could be of help in the comprehension of the chemical reactivity properties of the molecular systems considered in this study.Fil: Murali, Mahadevamurthy. University Of Mysore; IndiaFil: Gowtham, Hittanahallikoppal Gajendramurthy. Nrupathunga University; IndiaFil: Shilpa, Natarajamurthy. University Of Mysore; IndiaFil: Krishnappa, Hemanth Kumar Naguvanahalli. University Of Mysore; IndiaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Jain, Anisha S.. University Of Mysore; IndiaFil: Shati, Ali A.. King Khalid University; Arabia SauditaFil: Alfaifi, Mohammad Y.. Vacsera Holding Company; EgiptoFil: Elbehairi, Serag Eldin I.. Jss Academy Of Higher Education And Research; IndiaFil: Achar, Raghu Ram. Pirogov Russian National Research Medical University; RusiaFil: Silina, Ekaterina. Universitat de Les Illesbalears; EspañaFil: Stupin, Victor. Centro de Investigaciónen Materiales Avanzados; MéxicoFil: Ortega Castro, Joaquín. Jss Academy Of Higher Education And Research; IndiaFil: Frau, Juan. Universitat de Les Illesbalears; EspañaFil: Flores Holguín, Norma. Centro de Investigaciónen Materiales Avanzados; MéxicoFil: Amruthesh, Kestur Nagaraj. University Of Mysore; IndiaFil: Shivamallu, Chandan. Jss Academy Of Higher Education And Research; IndiaFil: Kollur, Shiva Prasad. University Of Mysore; IndiaFil: Glossman Mitnik, Daniel. Centro de Investigaciónen Materiales Avanzados; Méxic

Characterization of substrate specificity and inhibitory mechanism of bile salt hydrolase from Lactobacillus reuteri CRL 1098 using molecular docking analysis

Objectives: To elucidate the molecular mechanisms involved in the substrate interaction of the bile salt hydrolase of Lactobacillus reuteri CRL 1098 (LrBSH) with bile acids (BAs) and to evaluate potential enzyme inhibitors based on computer and in vitro modeling assays. Results: Asp19, Asn79, and Asn171 participated in the LrBSH interaction with all BAs tested while Leu56 and Glu 222 played an important role in the interaction with glyco- and tauro-conjugated BAs, respectively. A great percentage of hydrophobic and polar interactions were responsible for the binding of LrBSH with glyco- and tauro-conjugated BAs, respectively. Remarkably, the four binding pocket loops participated in the substrate binding site of LrBSH unlike most of the reported BSHs. Inhibition assays showed that ascorbic acid, citric acid, penicillin G, and ciprofloxacin decreased LrBSH activity by 47.1%, 40.14%, 28.8%, and 9%, respectively. Docking analysis revealed that tetracycline and caffeic acid phenethyl ester had the low binding energy (−7.32 and −7.19 kcal/mol, respectively) and resembled the interaction pattern of GDCA (−6.88 kcal/mol) while penicillin (−6.25 kcal/mol) and ascorbic acid (−5.98 kcal/mol) interacted at a longer distance. Conclusion: This study helps to delve into the molecular mechanisms involved in the recognition of substrates and potential inhibitors of LrBSH.Fil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Taranto, Maria Pia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentin

Impact of temperature changes and pH on aqueous solutions of TCAB, a derived propanil contaminant

3,4,3′,4′-tetrachloroazobenzene known as TCAB is an unwanted product derivate from the degradation of propanil herbicide. In this work UV–visible and infrared spectroscopies were used to experimentally explore the impact of pH and temperature changes of TCAB in aqueous and ethanol solutions. Two isomeric forms, cis and trans, are present in solution. The density functional theory (DFT) with PCM methodology was used to analyze the stability of each isomer in solution phase by the evaluation of solvation energy and frontier orbital energies of TCBA at 25 and 40 °C. This compound has been studied from room temperature to 50 °C, revealing the weakening of trans form with an increment of cis form in ethanol and high temperature. Interestingly, under acid conditions the protonated azo compound was evidenced in solution. We found that the cis form is predominant in aqueous solution at 40 °C and 30 min. Finally, FTIR studies show that the increasing of the temperature promote irreversible structural changes via a trans to cis interconversion process. The derivative results from this study may contributed to understanding of transformation of TCAB in aqueous solution by pH and temperature changes.Fil: Alvarez Escalada, Fanny Cecilia. Universidad Nacional de Santiago del Estero. Facultad de Cs.exactas y Tecnologías. Departamento de Física y Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentin

Estudio de la actividad proteolítica de bacterias lácticas aisladas de nichos autóctonos de Santiago del Estero

Las bacterias lácticas capaces de crecer en leche utilizan su sistema proteolítico para hidrolizar la caseína, proteína mayoritaria de la leche, y así obtener los aminoácidos necesarios para su desarrollo. Estas reacciones proteolíticas son aprovechadas en muchos procesos fermentativos involucrados en la elaboración de alimentos con particulares características organolépticas y, en algunos casos, para aumentar el valor nutricional de los mismos. Sin embargo, la actividad proteolítica depende de la cepa y de parámetros fisicoquímicos como el pH. Es por ello, que el objetivo del presente trabajo fue evaluar la actividad proteolítica de 16 cepas lácticas aisladas a partir de quesos de cabra regionales empleando el método de Bradford, para determiner la concentración de proteínas totales, y la técnica del o-ftalaldehído (OPA), para cuantificar aminoácidos libres. Los resultados obtenidos mostraron valores de concentraciones comprendidos entre (4,99 – 12,10) mg de proteínas libres por litro y (122,09 – 169,49) mmoles de glicina por litro; siendo las cepas CB17 y CB8, las de mayor y menor actividad, respectivamente. Potencialmente, estas cepas podrían emplearse para ser incluidas en procesos fermentativos con el propósito de modificar características sensoriales, aumentar el valor nutricional y mejorar la digestibilidad de alimentos fermentados.Lactic acid bacteria capable of growing in milk use their proteolytic system to hydrolyze casein, the major milk protein, and thus obtain the necessary amino acids for their development. These proteolytic reactions are used in many fermentative processes involved in the preparation of foods with particular organoleptic characteristics and, in some cases, to increase their nutritional value. However, the proteolytic activity depends on the strain and physicochemical parameters such as pH. For this reason, the objective of this work was to evaluate the proteolytic activity of 16 lactic strains isolated from regional goat cheeses using the Bradford method, to determine the concentration of total proteins, and the o-phthalaldehyde technique (OPA), to quantify free amino acids. The results obtained showed concentration values between (4.99 – 12.10) mg of free proteins per liter and (122.09 – 169.49) mmols of glycine per liter; being the strains CB17 and CB8, those with the highest and lowest activity, respectively. Potentially, these strains could be used to be included in fermentative processes with the purpose of modifying sensory characteristics, increasing nutritional value and improving digestibility of fermented foods.Fil: Carol Paz, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentin