A comparative kinetic study on the singlet molecular oxygen‐mediated photoxidation of α‐ and β‐chymotrypsins

Kinetic aspects of the sensitized photooxidation of a- and b-chymotrypsins have been studied at pH 6 and 8. The sensitization, employing classical O2(1Dg)-photogenerators, such as xanthene dyes, is a kinetically intricate process because of the presence of ground state dye?protein associations and to the simultaneous participation of superoxide ion and singlet molecular oxygen [O2(1Dg)].Both proteins, that possess the same distribution pattern of photooxidizable amino acids, suffer a pure O2(1Dg)- mediated photodynamic attack, using the carbonylic sensitizer Perinaphthenone. Overall and reactive rate constants for the O2(1Dg)-quenching (in the order of 108 and 107/M/s, respectively), and rates of oxygen consumption determined by time-resolved, spectroscopic and polarographic methods indicate that a- and b-chymotrypsins are less photooxidizable at pH 6, as a result of an enhancement of the O2(1Dg)-physical quenching component. In general terms, b-chymotrypsin exhibits the greater overall proclivity to interact with O2(1Dg), whereas structural factors, possibly evidenced by a higher exposure of the reactive tryptophan residues, impart an increased photooxidation degree to the proteins at pH 8, specially to the a-chymotrypsin.Fil: Biasutti, Maria Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto; ArgentinaFil: Posadaz, Ariana. Universidad Nacional de Río Cuarto; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: García, N. A.. Universidad Nacional de Río Cuarto; Argentin

Oregano Essential Oil Interactions with Photogenerated Singlet Molecular Oxygen

Essential oils are a mixture of volatile compounds, products of the secondary metabolism of plants. Once extracted, they can be deteriorated losing their organoleptic and therapeutic properties due to various environmental factors, being light exposure in aerobic conditions the main cause. In this work, the oregano essential oil extraction and characterization from Origanum vulgare plants grown in the experimental field of the FTU-UNSL and its photodegradation in MeOH:H2O 60:40 v/v solvent were studied. Characterization by EIMS and NIST Mass Spectrometry indicates the main compounds of oregano essential oil, quantified in the extracted oil by GC-MS, are carvacrol (7.14%) and thymol (47.37%). Degradation of essential oil and its two major components can be caused by reactive oxygen species photogenerated from endogenous sensitizers as riboflavin. Our results suggest degradation occurs involving singlet molecular oxygen. Interaction of carvacrol and thymol with singlet oxygen is mainly a physical process, while essential oil has an important reactive component, which indicates there might be other constituents which could contribute to reactive photoprotection. The effect of simultaneous presence of oregano essential oil and tryptophan amino acid—used as a photooxidizable model under riboflavin-photosensitizing conditions—was studied in order to evaluate the possible photoprotection exerted by the essential oil.Fil: Dimarco Palencia, Frida Claudia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Muñoz, Vanesa Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Posadaz, Ariana C.. Universidad Nacional de San Luis. Facultad de Turismo y Urbanismo; ArgentinaFil: Cifuente, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Miskoski, Sandra. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ferrari, Gabriela Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: García, Norman Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; ArgentinaFil: Montaña, Maria Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Caracterización in situ de poblaciones de Aloysia gratissima var. gratissima recolectadas del noreste de la provincia de San Luis, Argentina

The aerial part of Aloysia gratissima (Gillies & Hook. ex Hook.) Tronc., "Usillo", is used as aromatic and medicinal. It is a shrub of up to 3 meters, distributed in North America, from the south of the USA to the north of Mexico, and in South America up to the 37th parallel. As in other native species, the demand is covered by harvesting in wild populations, which brings about the deterioration of the resource and lack of homogeneity of the harvested product. The variability was characterized in nine populations of A. gratissima var. gratissima from the northeast of San Luis, Argentina, based on morphological and phytochemical characters. It was found that the species in the region presents considerable heterogeneity. Diversity was detected in the chemical characteristics of the essential oils analyzed and the prevalence of mono and sesquiterpenes was related to the olfactory identities identified. The main components were the sesquiterpene spatulenol and the monoterpene 1,8 cineole.La parte aérea de Aloysia gratissima (Gillies & Hook. ex Hook.) Tronc., “usillo”, es utilizada como aromática y medicinal. Es un arbusto de hasta 3 metros, distribuido en Norteamerica, desde el sur de EEUU hasta el norte de México, y en Sudamerica hasta el paralelo 37°. Al igual que en otras especies nativas, la demanda es cubierta por recolección en poblaciones silvestres, lo cual trae aparejado el deterioro del recurso y falta de homogeneidad del producto cosechado. Se caracterizó la variabilidad en nueve poblaciones de A. gratissima var. gratissima del noreste de San Luis, Argentina, en base a caracteres morfológicos y fitoquímicos. Se encontró que la especie en la región presenta una considerable heterogeneidad. Se detectó diversidad en las características químicas de los aceites esenciales analizados y se relacionó la prevalencia de mono y sesquiterpenos con las identidades olfativas identificadas. Los componentes mayoritarios fueron el sesquiterpeno espatulenol y el monoterpeno 1,8 cineol

Oxygen uptake in the vitamin B2-sensitized photo-oxidation of tyrosine and tryptophan in the presence of uracil: Kinetics and mechanism

Considering the significance of visible light-promoted reactions in complex biological media, the photo-oxidation of the amino acids (AAs) tyrosine (tyr) and tryptophan (trp) was studied in the presence of the naturally occurring oxidative scavenger uracil (ur). The involved photoprocesses, studied at pH 7 and 9, are driven through the reactive oxygen species (ROS) singlet molecular oxygen (O2(1Äg)), superoxide radical anion (O2•−) and hydrogen peroxide (H2O2). The effect on the effectiveness of the overall photo-oxidation process due to the presence of an added electron-donating substrate such as ur is not straightforwardly predictable. The addition of the pyrimidine compound, a much lesser photo-oxidizable substrate than the AAs themselves, produced different results: (1) antioxidative for tyr at pH 9, decreasing the overall rate of oxygen uptake; (2) synergistic for tyr at pH 7, increasing the oxidation rate more than the corresponding addition value of the respective individual rates and (3) no effect for trp at both pH values. The final result depends on the respective abilities of the substrates as quenchers of both the long-lived riboflavin triplet excited state and the generated ROS and the pH of the medium. An interpretation for the different cases is attempted through a kinetic and mechanistic analysis.Fil: Montaña, Maria Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Blasich, Néstor Fabian. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Haggi, Ernesto Sergio. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Garcia, Norman Andino. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentin

Establishment of callus-cultures of the Argentinean mistletoe, Ligaria cuneifolia (R. et P.) Tiegh (Loranthaceae) and screening of their polyphenolic content

Ligaria cuneifolia (R. et P.) Tiegh (Loranthaceae), known as liga, muérdago criollo, or Argentinean mistletoe, is a hemiparasitic plant with a broad distribution in central and northern Argentina. Pharmacological studies showed that L. cuneifolia extracts have hypolipemic, antioxidant, antibacterial, and immunomodulatory effects. We have established callus cultures from embryo and haustoria fragments. The highest frequency of callus formation from embryos (85%) was obtained on White medium with 4% (w/v) sucrose and 2.5 µM 1-naphtalene acetic acid and 9.2 µM kinetin as plant growth regulators (PGRs). From haustoria, the best result (35%) was obtained on Gamborg medium with 3% (w/v) sucrose and 0.45 µM 2,4-dichlorephenoxyacetic acid and 0.47 µM zeatin as PGRs. Thin layer chromatography showed that callus methanolic extract (2.5% w/v) had a lower content of flavonoids and proanthocyanins as compared to the wild plant (5% w/v for leaves, stems, and flowers), but a higher content of hydroxycinnamic acids. High performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) showed the presence of quercetin glycosides and phenolic acids in the methanolic extracts both from the parent plant and the callus obtained from embryo.Fil: Ricco, María Valeria. Universidad Maimónides. Facultad de Ciencias de la Salud. Carreras de Farmacia y Bioquímica. Cátedra de Farmacobotánica y Farmacognoscia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bari, Martín León. Universidad Maimónides. Facultad de Ciencias de la Salud. Carreras de Farmacia y Bioquímica. Cátedra de Farmacobotánica y Farmacognoscia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bagnato, Federico. Universidad Maimónides. Facultad de Ciencias de la Salud. Carreras de Farmacia y Bioquímica. Cátedra de Farmacobotánica y Farmacognoscia; ArgentinaFil: Cornacchioli, Carolina. Universidad Maimónides. Facultad de Ciencias de la Salud. Carreras de Farmacia y Bioquímica. Cátedra de Farmacobotánica y Farmacognoscia; ArgentinaFil: Laguía Becher, Melina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico. Departamento de Estudios Biomédicos y Biotecnológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Spairani, Leonardo Ulises. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad Maimónides. Facultad de Ciencias de la Salud. Carreras de Farmacia y Bioquímica. Cátedra de Farmacobotánica y Farmacognoscia; ArgentinaFil: Posadaz, Ariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Turismo y Urbanismo; ArgentinaFil: Dobrecky, Cecilia Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacobótanica; ArgentinaFil: Ricco, Rafael Alejandro. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacobótanica; ArgentinaFil: Wagner, Marcelo Luis. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacobótanica; ArgentinaFil: Alvarez, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Facultad de Ciencias de la Salud. Carreras de Farmacia y Bioquímica. Cátedra de Farmacobotánica y Farmacognoscia; Argentin