Maria Helena Florêncio

Acetylcholinesterase inhibition, antioxidant activity and toxicity of Peumus boldus water extracts on HeLa and Caco-2 cell lines.

This work aimed to study the inhibition on acetylcholinesterase activity (AChE), the antioxidant activity and the toxicity towards Caco-2 and HeLa cells of aqueous extracts of Peumus Boldus. An IC(50) value of 0.93 mg/mL, for AChE inhibition, and EC(50) of 18.7 μg/mL, for the antioxidant activity, was determined. This activity can be attributed to glycosylated flavonoid derivatives detected, which were the main compounds, although boldine and other aporphine derivatives were also present. No changes in the chemical composition or the biochemical activities were found after gastrointestinal digestion. Toxicity of P. boldus decoction gave an IC(50) value 0.66 mg/mL for HeLa cells, which caused significant changes in the cell proteome profile.

Synthesis and Characterization of the New Nano Flowers Lead(II) Coordination Polymer with Hemidirected Coordination Sphere

Nano flowers of a new polymeric lead(II) complex containing the azide anions, [Pb(baea)(N3)·(N3)]n (“baea” is the abbreviation of bis(2-aminoethyl)amine), has been synthesized by a sonochemical method. The new nano-structure was characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, elemental analyses, and IR spectroscopy. Single crystalline material was obtained using a heat gradient applied to a solution of the reagents. Single-crystal X-ray diffraction analyses show that the coordination number for PbII ions is five, PbN5 and hold hemidirected coordination geometry. To the best of our knowledge, the 1D coordination polymer interact with each other via supramolecular and weak Pb···N interactions to create 2D supramolecular frameworks.

Evidence of the Presence of Dimethylated, Trimethylated and "Refractory' Arsenic Compounds in Estuarine Salt‐marsh Halophytes

Five species of halophytes were sampled in the salt marshes of the Tagus estuary, dried, ground and digested. They were further extracted with ethanol and the extracts passed through weak and strong cationic ion-exchange resins, purified through TLC and submitted to pyrolysis mass spectrometry and HPLC–ICP/MS. Arsenic content and hydride-forming arsenic species were verified, in each step, by GF–AA and HG–QFAA. A high content of arsenic was found in the samples of halophytes studied, both di- and tri-methylated arsenic compounds being present. A considerable fraction of this arsenic content seems to be refractory to hydride generation. Moreover, the arsenic fraction found seems to have the same ion-exchange behaviour as the refractory fractions formerly studied in estuarine water. A partial characterization of these structures by pyrolysis–GC–MS suggests the presence of arsenobetaine and arsenocholine compounds. Furthermore, HPLC–ICP/MS data seem to confirm the presence of these compounds. In addition, the latter hyphenated technique strongly suggests the presence of a number of other organoarsenicals including tetramethylarsonium (TMAs), trimethylarsine oxide (TMAO), cacodylate (DMA) and possibly an arsenosugar-type compound.

Improvement of speciation analysis in environmental matrices. Identification of refractory arsenicals—some analytical difficulties

Arsenic species that do not form hydrides have been recently put in evidence in coastal seawater. This paper describes the procedures used in the first attempts to concentrate, purify and identify these forms as well as the difficulties that make this identification problematic. The rationale behind a new scheme under investigation based on solvent extraction/high-performance liquid chromatography/dynamic-flow-fast-atom-bombardment mass spectrometry is presented. Some alternatives that seem promising for the future are indicated.

Antiacetylcholinesterase activity and docking studies with chlorogenic acid, cynarin and arzanol from Helichrysum stoechas (Lamiaceae)

This work was aimed at the study of the chemical composition in phenolic compounds responsible for the high antiacetylcholinesterase activity of aqueous extracts (decoctions) from Helichrysum stoechas aerial parts. Chlorogenic acid, cynarin, and arzanol were the main components of decoctions, detected by high-performance liquid chromatography with diode-array detection and liquid chromatography-mass spectrometry/mass spectrometry. Flowers and stems/leaves extracts inhibited antiacetylcholinesterase with IC50 values of 260.7 and 654.8 μg/mL, respectively. The biological activity of these extracts was maintained after in vitro gastrointestinal digestion, indicating that the active compounds present in the extracts were not enzymatically modified by the gastrointestinal system used to simulate the digestion. Molecular docking studies with the main components were carried out in order to obtain information, at the molecular level, as to how these compounds access the enzyme’s active site. The docking study showed for the first time that chlorogenic acid, cynarin, and arzanol fit nicely in the antiacetylcholinesterase active site channel, blocking all access to the catalytic triad. This explained the high inhibitory activity determined during in vitro experiments.

Correction to: Antiacetylcholinesterase activity and docking studies with chlorogenic acid, cynarin and arzanol from Helichrysum stoechas (Asteraceae)

The original version of this article unfortunately contained an error in the article title. There is a incorrect term Lamiaceae inadvertently appeared in the title, instead it should be Asteraceae.

Porous Graphitic Carbon Liquid Chromatography–Mass Spectrometry Analysis of Drought Stress-Responsive Raffinose Family Oligosaccharides in Plant Tissues

Drought is a major limiting factor in agriculture and responsible for dramatic crop yield losses worldwide. The adjustment of the metabolic status via accumulation of drought stress-responsive osmolytes is one of the many strategies that some plants have developed to cope with water deficit conditions. Osmolytes are highly polar compounds, analysis of whcih is difficult with typical reversed-phase chromatography. Porous graphitic carbon (PGC) has shown to be a suitable alternative to reversed-phase stationary phases for the analysis of highly polar compounds typically found in the plant metabolome. In this chapter, we describe the development and validation of a PGC-based liquid chromatography tandem mass spectrometry (LC-MSn) method suitable for the target analysis of water-soluble carbohydrates, such as raffinose family oligosaccharides (RFOs). We present detailed information regarding PGC column equilibration, LC-MSn system operation, data analysis, and important notes to be considered during the steps of method development and validation.