Juliano C.R. Freitas

Synthesis and evaluation of (−)-Massoialactone and analogues as potential anticancer and anti-inflammatory agents

(-)-Massoialactone, an α,β-unsaturated δ-lactone isolated from Cryptocarya massoia, and five analogues were synthesized and their antiproliferative and anti-inflammatory activities were evaluated. The lactones were able to mimic the core functional group required for the biological activity of their parent natural compounds suggesting that substantially altered analogues may retain their properties.

Differentiation and assignment of vinyl telluride regioisomers by 1H-125Te gHMBC

Complete 1H, 13C, and 125Te NMR spectral data for some vinyl tellurides are described. The 1H–125Te gHMBC experiment was used for the complete chemical shift assignment and structure elucidation of a mixture of regioisomers. The assignment (125Te NMR) and coupling constants (JH,H) for all regioisomers are described for the first time. Copyright

Stereoselective synthesis of 2,3-unsaturated-O-Glycosides promoted by TeBr4

The use of a catalytic amount of tellurium(IV) tetrabromide to promote the O-glycosylation of glycals to yield 2,3-unsaturated-O-glycosides is described. The desired compounds were obtained in good yields and high α-selectivity.

Effects of α,β-unsaturated lactones on larval survival and gut trypsin as well as oviposition response of Aedes aegypti.

Lactones are organic cyclic esters that have been described as larvicides against Aedes aegypti and as components of oviposition pheromone of Culex quinquefasciatus. This work describes the effect of six α,β-unsaturated lactones (5a-5f) on survival of A.u2009aegypti fourth instar larvae (L4). It is also reported the effects of the lactones on L4 gut trypsin activity and oviposition behavior of A.u2009aegypti females. Five lactones were able to kill L4 being the lactones 5a (LC50 of 39.05u2009ppm), 5e (LC50 of 36.30u2009ppm) and 5f (LC50 of 40.46u2009ppm) the most promising larvicides. Only the lactone 5a inhibited L4 gut trypsin activity, with an IC50 of 115.15u2009µg/mL. Lactones 5a, 5c, 5d and 5e did not exert deterrent or stimulatory effects on oviposition, whereas lactone 5b exhibited a strong deterrent oviposition activity. In conclusion, this work introduces new α,β-unsaturated lactones as promising alternatives to control A.u2009aegypti dissemination. The larvicidal mechanism of the lactone 5a can involve the disruption of proteolysis at larval gut.

Investigando cinza da casca do arroz como fase estacionária em cromatografia: uma proposta de aula experimental nos cursos de graduação

This article describes an experiment that involves the extraction and separation of the pigments of spinach extract by column chromatography using the silica obtained from rice husk ash as a stationary phase. The experimental procedure is very simple to apply in the chemistry laboratory, and allowed to illustrate some concepts of organic chemistry: structure of organic molecules, solubility, polarity, extraction, partition coefficient, adsorption and retention factor (Rf), as well as objectives and fundamentals of chromatographic methods. The experiment can be carried out in a 4 h period.