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Sodium selenite is used to prevent selenium deficiency known as nutritional muscular dystrophy or white muscle disease. In ruminants, selenium supplements are transformed partiality in insoluble form by ruminal microorganisms and its process decrease the selenium absorption in digestive gastrointestinal. However, the objective in this research was focused in encapsulated sodium selenite to be release into of a pH less than four, similarity to an intestinal environment. It was encapsulated by nanoprecipitation and emulsion–evaporation methods, within polymeric nanoparticles. The effect of these methods, polymer proportion (Eudragit RL and RS) and solvent (ethanol and acetone) on the physicochemical (drug entrapment, polidispersity index (PDI) and z potential) and morphological characteristics (particle morphology and particle size) were evaluated. Particle size from each nanoparticles, formulation ranged from 36.64 to 213.86 nm. Particle size, z potential and PDI increased (P ≤ 0.01) when nanoprecipitation and ethanol were used. No significant differences (P > 0.05) were observed when different polymeric proportions were used. Selenium entrapment was 26% when emulsion–evaporation method was used and 78% with nanoprecipitation. Nanoparticles produced by nanoprecipitation were spherical and had a great variation in particle size; on the other hand, nanoparticles produced by emulsion–evaporation were spherical as well as amorphous and presented a homogeneous nanopartcicle size distribution. The release of selenium from nanoparticles was higher in acid pH (less than 4), this condition may represent a better availability of the mineral in the small intestine.

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During a pathogen attack, cells triggers the overproduction of reactive oxygen species causing oxidative stress and physiological damage. Plants develop strategies using these reactive molecules for protection against pathogen attack. Phytoplasma are bacteria lacking cell walls that inhabit plant phloem and reduce yield, tuber quality, and commercial harvest value. Sprayed salicylic acid (SA) activated plant defense response against phytoplasma attack and reduced infection symptoms, favored photosynthate translocation, and improved tuber quality. Low levels of exogenous SA (0.001 mM) induced higher biological activity. Damage reduction was associated with high hydrogen peroxide and ascorbic acid contents together with reduction of peroxidase activity, suggesting an important SA role regulating these molecules counteracting pathogen effects.Resumen Durante un ataque patogénico las células presentan una sobreproducción de especies reactivas de oxígeno. Esto provoca estrés oxidativo y daño fisiológico. Las plantas aprovechan éstas moléculas reactivas para desarrollar estrategias que conducen a la autoprotección contra el patógeno atacante. Los fitoplasmas son bacterias sin pared celular que habitan el floema de las plantas y disminuyen el rendimiento, la calidad de los tubérculos y el valor comercial de las cosechas, entre otros daños. El ácido salicílico (SA) asperjado activó la respuesta de defensa de la planta contra el ataque del fitoplasma, redujo los síntomas de la infección, favoreció la translocación de fotosintetizados e incrementó la calidad de los tubérculos. Bajos niveles de SA exógeno (0.001 mM) mostraron mayor actividad biológica. La reducción de daño estuvo asociada a altos contenidos de peróxido de hidrógeno y ácido ascórbico acompañada de reducción de la actividad peroxidasa, lo que sugiere un papel importante del SA en la regulación de éstas moléculas contrarrestando los efectos dañinos del patógeno.