Rational Design, Synthesis and Evaluation of Indole Nitrogen Hybrids as Photosystem II Inhibitors.

We report the synthesis of twelve indole derivatives bearing nitro or amide groups via Fischer indole methodology followed by reduction/acetylation and amidation reactions. After thorough characterization, these indoles were subjected to a number of studies in order to evaluate their bioactive potential as photosynthesis and plant growth inhibitors. Firstly, these molecular hybrids were evaluated as photosystem II (PSII) inhibitors through chlorophyll a (Chl a) fluorescence measurement. In this study, 6-chloro-8-nitro-2,3,4,9-tetrahydro-1H-carbazole (15a) and 5-chloro-2,3-dimethyl-7-nitro-1H-indole (15b) showed the best results by reducing the phenomenological parameters of reaction centers ABS/RC, TR0 /RC and ET0 /RC of PSII. Electron chain blockage by these compounds may lead to diminished ATP synthesis and CO2 fixation which interrupt the plant development. The compounds 15a and 15b both act as postemergent herbicides, reducing the dry biomass of Ipomoea grandifolia and Senna alata weeds by an average of 40% and 37%, respectively, corroborating the fluorescence results. Additionally, the molecular docking study revealed that the presence of strong electron-withdrawing groups at the indole phenyl ring is important for the ligand's interaction with the binding pocket of protein D1 on PSII. The optimization of these molecular features is the goal of our research group in further understanding and development of new potent herbicides.

Digestibilidade de dietas suplementadas com fitase para suínos sob diferentes ambientes térmicos / Digestibility of diets supplemented with phytase for pigs under different thermal environments

Realizou-se um ensaio de digestibilidade com o objetivo de avaliar níveis de fitase sobre a digestibilidade e excreção de nutrientes para suínos submetidos a condições de conforto e estresse térmico. Foram utilizados 24 suínos machos castrados, alojados em gaiolas metabólicas, em câmara climatizada, distribuídos em delineamento de blocos ao acaso em esquema fatorial 2x4, com dois ambientes (23 e 31°C) e quatro níveis de fitase (0, 300, 600 e 900UF kg-1 de ração), com três repetições, sendo cada unidade experimental constituída por um animal. Concluiu-se que as dietas fornecidas aos suínos submetidos ao estresse térmico (31°C) apresentam menores coeficientes de digestibilidade da proteína, fósforo, cálcio, zinco, ferro e magnésio e, portanto, apresentam maior excreção percentual desses nutrientes nas fezes, quando comparadas às dietas fornecidas aos suínos submetidos à termoneutralidade (23°C). A suplementação de fitase não altera o valor energético da dieta e o coeficiente de digestibilidade da proteína, mas aumenta o coeficiente de digestibilidade de fósforo, cálcio e magnésio e reduz a excreção percentual de fósforo e cálcio nas fezes dos suínos. Recomenda-se o nível de inclusão de 300UF kg-1 de ração, independentemente da condição térmica ambiental.

We conducted a digestibility trial with the aim of evaluate phytase levels on digestibility and nutrient excretion for pigs submitted to thermoneutral conditions and heat stress. We used 24 barrows housed in metabolic cages in climatic chamber, distributed in randomized blocks in a 2x4 factorial design, two environments (23 and 31°C) and four phytase levels (0, 300, 600 and 900UF kg-1 diet), with three replicates and each experimental unit consists of one animal. It was concluded that pigs submitted to high ambient temperatures (31°C) have worse digestibility of protein, phosphorus, calcium, zinc, iron and magnesium and therefore have a higher percentage of nutrients excreted in feces when compared to pigs submitted to thermoneutral environment (23°C). Phytase supplementation did not alter the energy value of feed and the digestibility coefficient of protein, but it increases the digestibility coefficient of phosphorus, calcium and magnesium and reduces the percentage of phosphorus and calcium in the faeces of pigs. We recommend the inclusion level of 300UF kg-1 feed, regardless of the environmental thermal condition.