Osmoregulatory disturbance in Neotropical fish exposed to the crude extracts of the cyanobacterium, Radiocystis fernandoi.

Blooms of cyanobacteria, a common event in eutrophic environments, result in the release of potentially toxic substances into the water. The cyanobacterium Radiocystis fernandoi produces microcystin (MC) and other peptides that may disturb homeostasis. This study evaluated the effect of intraperitoneal injections containing the crude extract (CE) of R. fernandoi strain R28 on the gills and kidneys of neotropical fish, Piaractus mesopotamicus, 3, 6 and 24 h post-injection. CE contained MC-RR, MC-YR and minor other oligopeptides. Plasma ions and the activities of the enzymes PP1 and PP2A, Na+/K+-ATPase (NKA), H+-ATPase (HA) and carbonic anhydrase (CA) were determined and morphological changes in both the gills and kidneys were characterized. Compared to controls, the concentration of Na+ within the plasma of P. mesopotamicus decreased after treatment with CE 3 h post treatment and increased after 24 h; the concentration of K+ decreased after 6 h. The activity of the endogenous PP1 and PP2A was unchanged in the gills and was inhibited in the kidneys 6 h after i.p. injection. In the gills, NKA activity increased after 3 h and decreased 6 h post i.p. exposure. Further, NKA activity did not differ from the controls 24-h post injection. In the kidneys, NKA, HA and CA activities were unaffected by treatment. The mitochondria-rich cell (MRC) density in the gills decreased after 3 h in the filament and 3 and 6 h in the lamellae and was restored to the control levels 24 h post-exposure. Filament epithelial hyperplasia and hypertrophy, lamellar atrophy and rupture of the lamellar epithelium were the most common effects of treatment in the gills. No histopathological changes occurred in the kidneys. This study demonstrates that a single dose of toxic CE from R. fernandoi can cause a transitory ion imbalance in P. mesopotamicus which is related to the changes in MRC levels and NKA activity. Ionic balance was recovered 24 h post i.p. injection, however, morphological changes that occurred in the gills took a longer amount of time to return to normal. To conclude, the effects of components contained within the CE of R. fernandoi may be harmful to P. mesopotamicus. In particular, the recovery of ionic regulation depends on MRC responses and histopathological changes produced by CE may affect gas exchange and other gill functions.

Structural effects on the hesperidin properties obtained by chelation to magnesium complexes.

The magnesium complex [Mg(hesp)2(phen)] (1), where hesp=hesperidin and phen=1,10'-phenanthroline, was synthesized and characterized by Elemental Analysis (C,H,N), atomic absorption and spectroscopic (FTIR, UV-visible, (1)H NMR) techniques. The congested structure facilitates the tilting and contact of the two hesperidin ligands by hydrogen bonding interactions having a stabilizer effect on the hesperidin. The hydrogen bonds are strongly affected by the solvent used which can lead to changes in the physical-chemical, luminescence and biologic properties of complex 1. Complex 1 is more hydrosoluble (S=472±3.05µgmL(-1)) and liposoluble (log P=-0.15±0.01) than free hesperidin (S=5.92±0.49µgmL(-1), log P=0.30). Oxidation of the complex in an aqueous solution and room temperature investigated by cyclic voltammetry resulted in a very stable two-electron cyclic process to form the phenoxonium neutral, cation and dication radicals. The stability of the voltammetric process indicates that the species produced are never exhausted and does not lead to changes in the coordination sphere composition. The complex was found to be a better radical scavenger for superoxide radical (IC50=68.3µM at pH7.8) than free hesperidin (IC50=116.68µmolL(-1)) and vitamin C (IC50=852µmolL(-1)). The strong blue fluorescence of complex 1 switches through loss of luminescence in pure water/protic organic solvents or when protected from water (in octanol for example as a model of phospholipid membranes). These features provide an opportunity to map the reactivity of hesperidin in the physiologic medium. In this context, a high uptake of complex into HeLa cells was detected by fluorescence microscopy. The blue fluorescence was uniformly distributed mainly in per nucleic region.

Transformações químicas de lignanas isoladas de Virola sebifera em análogos de podofilotoxina

The chloroform extract of leaves of Virola sebifera was fractioned leading to isolation of lignans (2R, 3R) -2, 3-Di- (3', 4' -dimethoxybenzyl) -butirolactone (1) (2R, 3R) -2, 3- Di- (3', 4' -methylenedioxybenzyl) -butyrolactone (2), (2R, 3R) -3- (3'', 4'' -dimethoxybenzyl) -2- (3', 4' -methylenedioxybenzyl) -butyrolactone (3). Transformation of these lignans intopodophyllotoxin analogs (4) was tested experimentally with negative results. In the proposed transformation (2R, 3R) -2, 3-Di- (5-bromo-3', 4' -dimethoxybenzyl) -butyrolactone (5) was obtained.

0 fracionamento do extrato clorofórmico das folhas de Virola sebifera levou ao isolamento da lignanas (2R, 3R) -2, 3-Di- (3', 4'-dimetoxibenzil) -butirolactona (1), (2R, 3R) -2, 3-Di (3'', 4'' -dimetoxibenzil) -butirolactona(3). Tentativa de transformações da lignana(1) em ánalogo de Podofilotoxina (4) foram realizadas com resultados parciais negativos. Um dos produtos obtidos nas transformações propostas foi (2R, 3R) -2, 3Di- (5'-bromo-3', 4' -Dimetoxibenzil) -butirolactona (5).