Effect of light intensity on steviol glycosides production in leaves of Stevia rebaudiana plants.

Stevia rebaudiana leaf extracts contain stevioside and rebaudioside A, two steviol glycosides (SGs) used as natural sweeteners because of their non-toxic, thermally stable and non-caloric properties. Indeed, leaf extracts can be up to 300 times sweeter than sucrose. Stevioside and rebaudioside A have organoleptic differences, the first one having an undesirable bitterness and the second one a higher sweetener capacity. Selection of the S. rebaudiana varieties and the best environmental conditions that elicit higher SGs content and the appropriate composition is an important goal. In this study we quantified and compared the amount of stevioside and rebaudioside A in two of the most used S. rebaudiana cultivars, Morita II and Criolla. Our results show a strong differential ratio of stevioside and rebaudioside A accumulated in the leaf between these cultivars. The Criolla cultivar showed about 3 times more stevioside per mg of dry weight than Morita II, whereas the Morita II accumulated almost 10 times more rebaudioside A than that produced in Criolla. We observed an enhanced expression in Morita II of three genes (SrKA13H, SrUGT74G1 and SrUGT76G1) known to encode three enzymes that participate in SGs biosynthesis, likely contributing to the differences in the stevioside and rebaudioside A accumulation. Not only genetic variation can affect SGs composition, but also environmental factors and crop management. Numerous studies have shown that the light regime in which S. rebaudiana cultivars grow can affect SGs accumulation. However, the optimal light regime to increase total SGs content is currently controversial. By applying various light intensities, we detected an increase of expression of these three biosynthetic genes at higher light intensity, accompanied by higher levels of stevioside and rebaudioside A, demonstrating that light intensity influences the synthesis of SGs.

Comparative Study of Metabolomic Profile and Antioxidant Content of Adult and In Vitro Leaves of Aristotelia chilensis.

This work aimed to identify the bioactive compounds present in adult maqui (Aristotelia chilensis) leaves from different stages of development and seasons of the year and compare them with leaves obtained from maqui plants grown in vitro. The qualitative and quantitative analysis of maqui leaf extracts by HPLC-DAD-ESI-MSn showed the presence of different polyphenolic compounds classified into galloyl and caffeoyl quinic acids, ellagitannins and ellagic acid- and flavonoid-derivatives. In general, the total phenolic content of the in vitro samples was higher than that of ex vitro samples, whereas the total flavonoid content was higher in winter basal leaves. Additionally, the analysis by HPLC-MS showed that the extract from spring basal leaves was enriched in quercetin, catechin, kaempferol and 3-caffeoyl quinic acids, while in the in vitro leaves extract, quercetin was not present. As regards lipophilic compounds identified by GC/MS, the samples of in vitro leaves showed a high presence of α-tocopherol and ß-sitosterol. In contrast, the samples of adult leaves presented a hight level of linolenic and linoleic acids. These results suggest that maqui leaves could be an excellent source of antioxidants and lipophilic compounds for many industries, such as the nutraceutical and pharmaceutical industries.

Efecto antibacteriano in vitro de exudados foliares de tabaco contra dos bacterias fitopatógenas / In vitro antibacterial effect of tobacco leaf exudates against two bacterial plant pathogens

Los productos naturales son una alternativa para el control de microorganismos que ocasionan enfermedades en los cultivos. Este trabajo tuvo como objetivo evaluar diferentes solventes para la obtención de extractos crudos a partir de exudados foliares de líneas de tabaco, y el efecto in vitro de estos extractos contra dos bacterias fitopatógenas: Xanthomonas campestris (Xc) y Pectobacterium carotovorum (Pc). Se evaluaron solventes con polaridades entre 3.1 y 6.2 (diclorometano, n-butanol, acetato de etilo, metanol y etanol 90 %). El etanol 90 % se seleccionó como mejor solvente y como sustituto del diclorometano por su mayor rendimiento. Los extractos etanólicos crudos se obtuvieron a partir de exudados foliares de diez líneas de tabaco seleccionadas. La diversidad de la composición química de los extractos etanólicos se reveló por cromatografía en capa delgada. La actividad antibacteriana se evaluó por el método de difusión en agar con discos de papel de filtro y la medición del diámetro del halo de inhibición. Se observó inhibición para todos los extractos contra Xc destacándose los correspondientes a las líneas Nic 1061 "TI 1738" y Nic 1016 "Incekara" hasta 5 µg de extracto crudo seco /disco, con un mayor rendimiento para la línea Nic 1061. El extracto de la línea Nic 1015 fue el único con actividad contra Pc hasta 5 µg de extracto crudo seco por disco. Estos resultados sugieren un uso potencial de los extractos crudos de las líneas Nic 1061 y Nic 1015 "TI 1341" como un agente efectivo para la protección de cultivos contra estas bacterias.

Natural products are an alternative to control microorganisms that cause diseases in crops. This work aimed to evaluate different solvents for obtaining crude extracts from tobacco leaf exudates and to determine in vitro effect of these extracts against two phytopathogenic bacteria: Xanthomonas campestris(Xc) and Pectobacterium carotovorum(Pc). Crude extracts from ten tobacco lines using solvents with polarities between 3.1 and 6.2 (dichloromethane, n-butanol, ethyl acetate, methanol and ethanol 90%) were obtained. Ethanol 90% was selected as the best solvent for obtaining extracts from tobacco leaf exudates and as a substitute of dichloromethane due to the best yield. The chemical composition diversity of the ethanolic extracts was revealed by thin-layer chromatography. The antibacterial activity was evaluated by agar disk diffusion method recording the inhibition zones. Growth inhibition was observed for all extracts against Xc, and the better activity corresponded to the lines Nic 1061"TI 1738" and Nic 1016 "Incekara" until a minimal amount of 5 µg/ disc, with higher yield in case of the line Nic1061 . Only the extract of the line Nic 1015 was able to inhibit the growth of Pc until a minimal inhibitory concentration of 5 µg/disc. These results suggest a potential use of crude extracts from lines Nic 1061 and Nic 1015 "TI 1341" as an effective agent for the crop protection against Xc and Pc respectively.

Potencial de actividad antioxidante de extractos fenólicos de Theobroma cacao L. (cacao) / Antioxidant potential of phenolic extracts of Theobroma cacao L. (cocoa)

Introducción: Theobroma cacao L. (cacao), familia Sterculiaceae, es una planta rica en fenoles, los cuales en las plantas son de especial interés por su potente actividad antioxidante, dada esencialmente por sus propiedades redox, que pueden desempeñar un papel importante en la absorción y neutralización de los radicales libres. Objetivos: seleccionar un clon promisorio en la producción de compuestos fenólicos, determinar los órganos con mayor contenido de fenoles, establecer el cultivo in vitro a partir de la evaluación del tipo de explante y determinar el contenido de fenoles, así como la potencial actividad antioxidante de extractos de callos y órganos en Theobroma cacao. Métodos: nucelas, pétalos y estaminoides se cultivaron en medio de formación de callos y se midió su crecimiento. Se cuantificó el contenido de fenoles de extractos de hojas, ramas, semillas, flores y raíces, así como de callos de estaminoides, pétalos y nucelas. La actividad antioxidante se determinó para niveles de malondialdehído y otros aldehídos y por la actividad de reducción del radical 1,1-diphenyl-2-picrylhydrazyl. Resultados: se encontró mayor contenido de fenoles en semillas de UF-654. Con estaminoides y pétalos se obtuvo mayor crecimiento de callos y menor fenolización. Menores concentraciones de malondialdehído y otros aldehídos se hallaron en extractos de ramas. Los extractos de callos de estaminoides, pétalos y nucelas mostraron similares valores de malondialdehído, mientras que en el caso de otros aldehídos los menores valores se encontraron en los extractos de callos de nucelas. Todos los extractos mostraron actividad antioxidante, que reducen el 1,1-diphenyl-2-picrylhydrazyl. Se halló menor actividad en los extractos de ramas, callos de estaminoides y nucelas. Conclusiones: estos resultados proporcionan una información básica prometedora para el uso potencial de extractos metanólicos y acuosos de T. cacao L. como antioxidante

Introduction: Theobroma cacao L. (cocoa), family Sterculiaceae, is a plant rich in phenols. These substances are especially interesting in plants, due to their powerful antioxidant activity, essentially given by their redox properties, and may play an important role in the absorption and neutralization of free radicals. Objectives: select a promising clone from the production of phenolic compounds, determine the organs with the greatest content of phenols, establish the in vitro culture based on evaluation of the explant type, and determine the content of phenols as well as the potential antioxidant activity of callus and organ extracts of Theobroma cacao. Methods: nucelli, petals and staminodes were cultured in a callus forming medium and their growth was measured. Phenolic content was quantified in extracts of leaves, branches, seeds, flowers and roots, as well as calluses of staminodes, petals and nucelli. Antioxidant activity was determined for levels of malondialdehydes and other aldehydes, and based on the reduction activity of the radical 1,1-diphenyl-2-picrylhydrazyl. Results: a greater phenolic content was found in UF-654 seeds. Higher callus growth and lower phenolization was obtained with staminodes and petals. Lower concentrations of malondialdehydes and other aldehydes were found in extracts from branches. Extracts from staminode, petal and nucellus calluses exhibited values similar to malondialdehydes, whereas in other aldehydes the lowest values were found in extracts from nucellus calluses. All extracts showed antioxidant activity, reducing 1,1-diphenyl-2-picrylhydrazyl. Lower activity was found in extracts from branches, staminode calluses and nucelli. Conclusions: these results provide promising basic information for the potential use of methanolic and aqueous extracts of Theobroma cacao L. as antioxidants

Potencial de actividad antioxidante de extractos fenólicos de Theobroma cacao L. (cacao) / Antioxidant potential of phenolic extracts of Theobroma cacao L. (cocoa)

Introducción: Theobroma cacao L. (cacao), familia Sterculiaceae, es una planta rica en fenoles, los cuales en las plantas son de especial interés por su potente actividad antioxidante, dada esencialmente por sus propiedades redox, que pueden desempeñar un papel importante en la absorción y neutralización de los radicales libres. Objetivos: seleccionar un clon promisorio en la producción de compuestos fenólicos, determinar los órganos con mayor contenido de fenoles, establecer el cultivo in vitro a partir de la evaluación del tipo de explante y determinar el contenido de fenoles, así como la potencial actividad antioxidante de extractos de callos y órganos en Theobroma cacao. Métodos: nucelas, pétalos y estaminoides se cultivaron en medio de formación de callos y se midió su crecimiento. Se cuantificó el contenido de fenoles de extractos de hojas, ramas, semillas, flores y raíces, así como de callos de estaminoides, pétalos y nucelas. La actividad antioxidante se determinó para niveles de malondialdehído y otros aldehídos y por la actividad de reducción del radical 1,1-diphenyl-2-picrylhydrazyl. Resultados: se encontró mayor contenido de fenoles en semillas de UF-654. Con estaminoides y pétalos se obtuvo mayor crecimiento de callos y menor fenolización. Menores concentraciones de malondialdehído y otros aldehídos se hallaron en extractos de ramas. Los extractos de callos de estaminoides, pétalos y nucelas mostraron similares valores de malondialdehído, mientras que en el caso de otros aldehídos los menores valores se encontraron en los extractos de callos de nucelas. Todos los extractos mostraron actividad antioxidante, que reducen el 1,1-diphenyl-2-picrylhydrazyl. Se halló menor actividad en los extractos de ramas, callos de estaminoides y nucelas. Conclusiones: estos resultados proporcionan una información básica prometedora para el uso potencial de extractos metanólicos y acuosos de T. cacao L. como antioxidante(AU)

Introduction: Theobroma cacao L. (cocoa), family Sterculiaceae, is a plant rich in phenols. These substances are especially interesting in plants, due to their powerful antioxidant activity, essentially given by their redox properties, and may play an important role in the absorption and neutralization of free radicals. Objectives: select a promising clone from the production of phenolic compounds, determine the organs with the greatest content of phenols, establish the in vitro culture based on evaluation of the explant type, and determine the content of phenols as well as the potential antioxidant activity of callus and organ extracts of Theobroma cacao. Methods: nucelli, petals and staminodes were cultured in a callus forming medium and their growth was measured. Phenolic content was quantified in extracts of leaves, branches, seeds, flowers and roots, as well as calluses of staminodes, petals and nucelli. Antioxidant activity was determined for levels of malondialdehydes and other aldehydes, and based on the reduction activity of the radical 1,1-diphenyl-2-picrylhydrazyl. Results: a greater phenolic content was found in UF-654 seeds. Higher callus growth and lower phenolization was obtained with staminodes and petals. Lower concentrations of malondialdehydes and other aldehydes were found in extracts from branches. Extracts from staminode, petal and nucellus calluses exhibited values similar to malondialdehydes, whereas in other aldehydes the lowest values were found in extracts from nucellus calluses. All extracts showed antioxidant activity, reducing 1,1-diphenyl-2-picrylhydrazyl. Lower activity was found in extracts from branches, staminode calluses and nucelli. Conclusions: these results provide promising basic information for the potential use of methanolic and aqueous extracts of Theobroma cacao L. as antioxidants(AU)