Extract from Opuntia ficus-indica cladode delays the Aedes aegypti larval development by inducing an axenic midgut environment.

This study evaluated the effects of acute exposure of Aedes aegypti third instar (L3 ) larvae to the saline extract of Opuntia ficus-indica cladodes on the biological cycle and fertility of the emerging adults. For this, larvae were treated for 24 h with the extract at » LC50 (lethal concentration to kill 50% of larvae), ½ LC50 or LC50 ; the development and reproduction of the emerged adults were evaluated after a recovery period of 9 days. The resistance of proteins in the extract to hydrolysis by L3 digestive enzymes and histomorphological alterations in the larval midgut were also investigated. The extract contained lectin, flavonoids, cinnamic derivatives, terpenes, steroids, and reducing sugars. It showed a LC50 of 3.71% for 48 h. The data indicated mean survival times similar in control and extract treatments. It was observed development delay in extract-treated groups, with a lower number of adults than in control. However, the females that emerged laid similar number of eggs in control and treatments. Histological evaluation revealed absence of bacterial and fungal microorganisms in the food content in midguts from larvae treated with cladode extract. Electrophoresis revealed that three polypeptides in the extract resisted to hydrolysis by L3 digestive proteases for 90 min. The lectin activity was not altered even after 24-h incubation with the enzymes. In conclusion, the extract from O. ficus-indica can delay the development of Ae. aegypti larvae, which may be linked to induction of an axenic environment at larval midgut and permanence of lectin activity even after proteolysis.

Schinus terebinthifolia Raddi leaf lectin is an antiangiogenic agent for Coturnix japonica embryos.

Angiogenesis (budding of new blood vessels) is involved in several processes, including the development of embryos and growth of tumors. Schinus terebinthifolia leaves express an antitumor lectin (SteLL). This work hypothesized that SteLL can interfere with the formation of a vascular network from preexisting vessels. To test this hypothesis, the effect of SteLL on the angiogenesis process was assessed using an in vivo model of yolk sac membrane of Coturnix japonica embryos. SteLL was isolated with purification factor of 46.6. As expected, polyacrylamide gel electrophoresis (PAGE) for native basic proteins confirmed the homogeneity and PAGE in presence of dodecyl sodium sulphate revealed a single 14-kDa polypeptide band. The fractal analysis by box counting and information dimension measurements indicated that SteLL at 1.35 mg/mL significantly decreased by ca. 12% the angiogenesis within the C. japonica yolk sac membrane regarding the control. The inhibition of the vascular network formation in the yolk sac membrane resulted in decreased blood supply to the embryos. Consequently, the area of embryos was significantly reduced by 9.2% regarding the control, which corroborated with the antiangiogenic activity of SteLL. The findings implicate SteLL as an antiangiogenic agent and add to the panel of biological activities of this lectin.

Caseinolytic and milk-clotting activities from Moringa oleifera flowers.

This work reports the detection and characterization of caseinolytic and milk-clotting activities from Moringa oleifera flowers. Proteins extracted from flowers were precipitated with 60% ammonium sulphate. Caseinolytic activity of the precipitated protein fraction (PP) was assessed using azocasein, as well as α(s)-, ß- and κ-caseins as substrates. Milk-clotting activity was analysed using skim milk. The effects of heating (30-100°C) and pH (3.0-11.0) on enzyme activities were determined. Highest caseinolytic activity on azocasein was detected after previous incubation of PP at pH 4.0 and after heating at 50°C. Milk-clotting activity, detected only in the presence of CaCl(2), was highest at incubation of PP at pH 3.0 and remained stable up to 50°C. The pre-treatment of milk at 70°C resulted in highest clotting activity. Enzyme assays in presence of protease inhibitors indicated the presence of aspartic, cysteine, serine and metallo proteases. Aspartic proteases appear to be the main enzymes involved in milk-clotting activity. PP promoted extensive cleavage of κ-casein and low level of α(s)- and ß-caseins hydrolysis. The milk-clotting activity indicates the application of M. oleifera flowers in dairy industry.