Relationship between Hammett's parameters and in silico density functional with tandem mass ESI-CID fragmentation: Dihydropyridines as prototypes.

Over the years, with the instrumental analysis evolution, the relationships between the carried-out results with the data of theoretical analysis in silico and the Hammett's parameters have been reported. They have been very useful for chemical characterization of small organic molecules. Thus, this work aims at showing the feasibility and limitations for Hammett's and density functional theory applications in electrospray ionization-collision-induced dissociation (ESI-CID) fragmentation provision. For this, 13 dihydropyrimidinones para, meta, and orto monosubstituted were studied using ESI and CID in positive mode. As a result, it was observed that the main fragmentation includes the isocyanate and ethanol loses at low energy. Nevertheless, at higher energies, radical ions formed by McLafferty rearrangement were observed. The Hammett plots were correlated fragmentation profiles, showing good linearity for the [M + H]+ , which does not occur to radical ions and carbocation's. These tendencies had demonstrated that the stability of protonate and activation energy of secondary ions changes with the pKa. The density functional theory studies indicated that, both nitrogen atoms in the dihydropyrimidinone's prototypes are capable of being protonated. However, the activation energy of fragmentation products is not changed. Therefore, this work has shown information, which can be useful to understand tandem mass spectrometry in ESI-CID conditions for small organic molecules series. This is the first step for normalization of fragmentation pathway.

Essential oil analysis of 10 Piperaceae species from the Brazilian Atlantic forest.

The volatile composition of ten Piperaceae species, comprising three genera (Ottonia, Piper and Peperomia) has been studied. The species were collected in a typical fragment of the Brazilian Atlantic forest, constantly being damaged by human action. The essential oils were obtained by hydrodistillation in a modified Clevenger-type apparatus and their analyses were performed by GC and GC/MS. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. A great number of non-oxygenated monoterpenes and sesquiterpenes were identified. Most of these sesquiterpenes are derived from E,E-farnesyl-PP, suggesting a preference of these species to synthesize metabolites from this pathway. Arylpropanoids, although being common compounds produced by Piperaceae species, were not found in these oils.

[Diagnostic of the estimated time of ovulation by ultrasounds (author's transl)]. / Daignosyico do dia provavel da ovulacao pela ultra-sonografia.

PIP: Recent experiments have demonstrated that it is possible to detect ovulation by ultrasounds; the examination, which is totally safe and lasts about 5 minutes, should be done during the early follicular phase and daily during the preovulatory period. The diameter of the follicle is usually 2.0-2.5 cm. between day 1 and day 0, which registers the maximum LH (luteinizing hormone) peak, i.e. is the estimated time of ovulation. After day 0 one can either observe the disappearance of the follocular image, or the appearance of the corpus luteum, which can be identified during 24-48 hours.^ieng