Biomedical subjects

E S Bento

Publications and source records attributed to E S Bento.

2 recordsLinked to original sources

PubMed2007

Reaction of o-phenylenediamine with diacetyl monoxime: characterisation of the product by solid-state 13C and 15N MAS NMR.

2,3-dimethylquinoxaline (DMQ) and dimethylglyoxime (DMGH2) form a 1:1 hydrogen-bonded complex in the solid state, which is completely dissociated in methanol solution. There are small differences in solid-state 13C shifts between the separated components DMQ and DMGH2 and the complex. The changes in 15N solid-state chemical shifts are more significant: the hydrogen bond imparting a low frequency shift of ca 19 ppm. The effect of direct protonation on the DMQ solid-state 15N shifts was measured, and the experimental 15N data correlated with those from GIAO molecular orbital (MO) calculations.

Journal Article↗

PubMed2006

Larvicidal diterpenes from Pterodon polygalaeflorus.

Ethanolic extract from seeds of Pterodon polygalaeflorus (Benth) has been shown to possess significant larvicidal activity against the mosquito Aedes aegypti. Bioassay-guided fractionation of the extract led to the isolation and characterization of the know diterpenoid furans 6alpha-hydroxyvouacapan-7beta,17beta-lactone (1), 6alpha,7beta-dihydroxyvouacapan- 17beta-oic acid (2) and methyl 6alpha,7beta-dihydroxyvouacapan-17beta-oate (3). The structures were established from infrared (IR), ultraviolet (UV), 1H-nuclear magnetic resonance (NMR), 13C-NMR, and mass spectral data: full NMR assignments are presented for compounds 1-3 and the diacetyl derivative of 3. Compounds 1-3 exhibited LC50 values of 50.08, 14.69, and 21.76 microg/mL against fourth-instar Aedes aegypti larvae.

Aedes↗