Evaluation of acetylcholinesterase inhibitory activity of Brazilian red macroalgae organic extracts

Abstract Alzheimer's disease affects nearly 36.5 million people worldwide, and acetylcholinesterase inhibition is currently considered the main therapeutic strategy against it. Seaweed biodiversity in Brazil represents one of the most important sources of biologically active compounds for applications in phytotherapy. Accordingly, this study aimed to carry out a quantitative and qualitative assessment of Hypnea musciformis (Wulfen) J.V. Lamouroux, Ochtodes secundiramea (Montagne) M.A. Howe, and Pterocladiella capillacea (S.G. Gmelin) Santelices & Hommersand (Rhodophyta) in order to determine the AChE effects from their extracts. As a matter of fact, the O. secundiramea extract showed 48% acetylcholinesterase inhibition at 400 μg/ml. The chemical composition of the bioactive fraction was determined by gas chromatography–mass spectrometry (GC–MS); this fraction is solely composed of halogenated monoterpenes, therefore allowing assignment of acetylcholinesterase inhibition activity to them.

Metabolic regulation of pathways of carbohydrate oxidation in potato (Solanum tuberosum) tubers.

In the present article we evaluate the consequence of tuber-specific expression of yeast invertase, on the pathways of carbohydrate oxidation, in potato (Solanum tuberosum L. cv. Desiree). We analysed the relative rates of glycolysis and the oxidative pentose phosphate pathway that these lines exhibited as well as the relative contributions of the cytochrome and alternative pathways of mitochondrial respiration. Enzymatic and protein abundance analysis revealed concerted upregulation of the glycolytic pathway and of specific enzymes of the tricarboxylic acid cycle and the alternative oxidase but invariant levels of enzymes of the oxidative pentose phosphate pathway and proteins of the cytochrome pathway. When taken together these experiments suggest that the overexpression of a cytosolic invertase (EC 3.2.1.26) results in a general upregulation of carbohydrate oxidation with increased flux through both the glycolytic and oxidative pentose phosphate pathways as well as the cytochrome and alternative pathways of oxidative phosphorylation. Moreover these data suggest that the upregulation of respiration is a consequence of enhanced efficient mitochondrial metabolism.

Mild reductions in mitochondrial citrate synthase activity result in a compromised nitrate assimilation and reduced leaf pigmentation but have no effect on photosynthetic performance or growth.

Transgenic tomato (Solanum lycopersicum) plants, expressing a fragment of the mitochondrial citrate synthase gene in the antisense orientation and exhibiting mild reductions in the total cellular activity of this enzyme, displayed essentially no visible phenotypic alteration from the wild type. A more detailed physiological characterization, however, revealed that although these plants were characterized by relatively few changes in photosynthetic parameters they displayed a decreased relative flux through the tricarboxylic acid cycle and an increased rate of respiration. Furthermore, biochemical analyses revealed that the transformants exhibited considerably altered metabolism, being characterized by slight decreases in the levels of organic acids of the tricarboxylic acid cycle, photosynthetic pigments, and in a single line in protein content but increases in the levels of nitrate, several amino acids, and starch. We additionally determined the maximal catalytic activities of a wide range of enzymes of primary metabolism, performed targeted quantitative PCR analysis on all three isoforms of citrate synthase, and conducted a broader transcript profiling using the TOM1 microarray. Results from these studies confirmed that if the lines were somewhat impaired in nitrate assimilation, they were not severely affected by this, suggesting the presence of strategies by which metabolism is reprogrammed to compensate for this deficiency. The results are discussed in the context of carbon-nitrogen interaction and interorganellar coordination of metabolism.