Post-anthesis thermal stress induces differential accumulation of bioactive compounds in field-grown barley.

BACKGROUND: Barley (Hordeum vulgare L.) is a healthy grain because of its high content of dietary fibre and phenolic compounds. It faces periods of high temperature during grain filling, frequently reducing grain weight. Heat stress may also affect some of the bioactive compounds present in the grain. To produce quality grains that provide nutritional and health benefits, it is important to understand the effect of environmental stresses on the quantity and quality of bioactive compounds. RESULTS: We have studied the effect of post-anthesis thermal stress on barley bioactive compounds and antioxidant capacity under Mediterranean field conditions during two consecutive growing seasons in four barley genotypes. Thermal stress affected grain weight and size and changed the relative composition of bioactive compounds. The relationship between heat stress and grain ß-glucans and arabinoxylans content was indirect, as the resulting increases in concentrations were due to the lower grain weight under stress. Conversely, heat stress had a significant direct impact on some phenolic compounds, increasing their concentrations differentially across genotypes, which contributed to an improvement in antioxidant capacity of up to 30%. CONCLUSION: Post-anthesis thermal stress had a significant effect on ß-glucans, arabinoxylans, phenolic compound concentration and antioxidant capacity of barley grains. Final grain quality could, at least partially, be controlled in order to increase the bioactive concentrations in the barley grain, by cultivation in growing areas prone to heat stress. Late sowings or late flowering genotypes could also be considered, should a premium be implemented to compensate for lower yields. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bioactive Compounds and Antioxidant Capacity in Pearling Fractions of Hulled, Partially Hull-Less and Hull-Less Food Barley Genotypes.

Three food barley genotypes differing in the presence or absence of husks were sequentially pearled and their fractions analyzed for ash, proteins, bioactive compounds and antioxidant capacity in order to identify potential functional food ingredients. Husks were high in ash, arabinoxylans, procyanidin B3, prodelphinidin B4 and p-coumaric, ferulic and diferulic bound acids, resulting in a high antioxidant capacity. The outermost layers provided a similar content of those bioactive compounds and antioxidant capacity that were high in husks, and also an elevated content of tocols, representing the most valuable source of bioactive compounds. Intermediate layers provided high protein content, ß-glucans, tocopherols and such phenolic compounds as catechins and bound hydroxybenzoic acid. The endosperm had very high ß-glucan content and relative high levels of catechins and hydroxybenzoic acid. Based on the spatial distribution of the bioactive compounds, the outermost 30% pearling fractions seem the best option to exploit the antioxidant capacity of barley to the full, whereas pearled grains supply ß-glucans enriched flours. Current regulations require elimination of inedible husks from human foods. However, due to their high content in bioactive compounds and antioxidant capacity, they should be considered as a valuable material, at least for animal feeds.

Impact of Rising Temperature in the Deposition Patterns of Bioactive Compounds in Field Grown Food Barley Grains.

High temperatures at the end of the season are frequent under Mediterranean conditions, affecting final grain quality. This study determined the deposition patterns throughout grain filling of dry matter, dietary fiber, phenolic compounds and antioxidant capacity for four barley genotypes under two contrasting temperatures. Deposition pattern for dietary fiber followed that of grain weight. Genotypic differences for duration were more significant than for rate. Anthocyanins followed a second-degree polynomial pattern, reaching a maximum before grain maturation. Free and bound phenols decreased as grain developed, suggesting that they are synthesized in early stages. Rate of bound phenols deposition was more sensitive to genotypic changes. Overall, antioxidant capacity decreased over time; the decay being less steep under stress for all genotypes. Heat stress negatively affected grain weight. It did not alter the profile of ß-glucans and arabinoxylans deposition but positively changed the accumulation of some phenolic compounds, increasing the antioxidant capacity differentially across genotypes. These results support the growing of food barley in high-temperature stress-prone areas, as some bioactive compound and antioxidant capacity will increase, regardless of the smaller grain size. Moreover, if a market develops for food-barley ingredients, early harvesting of non-mature grain to maximize antioxidant capacity should be considered.

Biparametric potentiometric analytical microsystem for nitrate and potassium monitoring in water recycling processes for manned space missions.

The construction and evaluation of a Low Temperature Co-fired Ceramics (LTCC)-based continuous flow potentiometric microanalyzer prototype to simultaneously monitor the presence of two ions (potassium and nitrate) in samples from the water recycling process for future manned space missions is presented. The microsystem integrates microfluidics and the detection system in a single substrate and it is smaller than a credit card. The detection system is based on two ion-selective electrodes (ISEs), which are built using all-solid state nitrate and potassium polymeric membranes, and a screen-printed Ag/AgCl reference electrode. The obtained analytical features after the optimization of the microfluidic design and hydrodynamics are a linear range from 10 to 1000 mg L(-1) and from 1.9 to 155 mg L(-1) and a detection limit of 9.56 mg L(-1) and 0.81 mg L(-1) for nitrate and potassium ions respectively.

Neuroinmunología de la meningoencefalitis por citomegalovirus en pacientes inmunocompetentes / Neuroimmunology of meningoencephalitis caused by cytomegalovirus in immunocompetent patients

Se sabe que la infección humana por citomegalovirus (CMV) ha ganado en importancia en la medicina moderna, por el gran número de enfermedades que produce, en dependencia del estado inmunológico del individuo. En pacientes inmunocompetentes, la meningoencefalitis por CMV es excepcional. Se hizo una revisión general del tema que incluyó el reporte de un adulto joven sin antecedentes de patologías inmunosupresoras con meningoencefalitis a CMV al que se le realizó estudio neuroinmunológico. Se observó marcada disfunción de la barrera sangre-LCR y síntesis intratecal de las clases IgA e IgM. La razón (LCR/suero) IgG se encontró por debajo de la razón IgA y los niveles de ácido láctico fueron elevados. La detección de antígenos de CMV por técnicas de reacción en cadena de la polimerasa confirmó el diagnóstico. Se concluyó que el estudio neuroinmunológico mostró características atípicas de acuerdo con lo reportado en la literatura por lo que puede ayudar al diagnóstico de otros casos con igual presentación

Neuroinmunología de la meningoencefalitis por citomegalovirus en pacientes inmunocompetentes / Neuroimmunology of meningoencephalitis caused by cytomegalovirus in immunocompetent patients

Se sabe que la infección humana por citomegalovirus (CMV) ha ganado en importancia en la medicina moderna, por el gran número de enfermedades que produce, en dependencia del estado inmunológico del individuo. En pacientes inmunocompetentes, la meningoencefalitis por CMV es excepcional. Se hizo una revisión general del tema que incluyó el reporte de un adulto joven sin antecedentes de patologías inmunosupresoras con meningoencefalitis a CMV al que se le realizó estudio neuroinmunológico. Se observó marcada disfunción de la barrera sangre-LCR y síntesis intratecal de las clases IgA e IgM. La razón (LCR/suero) IgG se encontró por debajo de la razón IgA y los niveles de ácido láctico fueron elevados. La detección de antígenos de CMV por técnicas de reacción en cadena de la polimerasa confirmó el diagnóstico. Se concluyó que el estudio neuroinmunológico mostró características atípicas de acuerdo con lo reportado en la literatura por lo que puede ayudar al diagnóstico de otros casos con igual presentación(AU)