Percorrer por autor "Estevinho, Letícia M."
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- Chemical characterization and biological properties assessment of Euphorbia resinifera and Euphorbia officinarum Moroccan PropolisPublication . Boutoub, Oumaima; El-Guendouz, Soukaina; Matos, Isabel; El Ghadraoui, Lahsen; Costa, Maria Clara; Carlier, Jorge; Faleiro, Maria Leonor; Figueiredo, Ana Cristina; Estevinho, Letícia M.; Miguel, MariaAlthough the plants of the genus Euphorbia are largely exploited by therapists in Morocco, the composition and antibacterial activities of propolis from these plants are still unknown. To address this gap, this study aimed to characterize the pollen type, the volatile compounds, and the phenolic and mineral profiles of three Euphorbia propolis samples collected in Morocco and evaluate their antimicrobial activities. The minimum inhibitory concentration of the propolis samples was determined by the microdilution method, and the anti-adherence activity was evaluated by the crystal violet assay. The examination of anti-quorum-sensing proprieties was performed using the biosensor Chromobacterium violaceum CV026. Pollen analysis revealed that Euphorbia resinifera pollen dominated in the P1 sample (58%), while E. officinarum pollen dominated in the P2 and P3 samples (44%). The volatile compounds were primarily composed of monoterpene hydrocarbons, constituting 35% in P1 and 31% in P2, with α-pinene being the major component in both cases, at 16% in P1 and 15% in P2. Calcium (Ca) was the predominant mineral element in both E. resinifera (P1) and E. officinarum (P2 and P3) propolis samples. Higher levels of phenols, flavonoids and dihydroflavonoids were detected in the E. officinarum P2 sample. The minimum inhibitory concentration (MIC) value ranged from 50 to 450 µL/mL against Gram-positive and Gram-negative bacteria. Euphorbia propolis displayed the ability to inhibit quorum sensing in the biosensor C. violaceum CV026 and disrupted bacterial biofilm formation, including that of resistant bacterial pathogens. In summary, the current study evidences the potential use of E. officinarum propolis (P2 and P3) to combat important features of resistant pathogenic bacteria, such as quorum sensing and biofilm formation.
- Comparative study of the antioxidant and enzyme inhibitory activities of two types of Moroccan Euphorbia entire honey and their phenolic extractsPublication . Boutoub, Oumaima; EL-GUENDOUZ, Soukaina; Manhita, Ana; Dias, Cristina Barrocas; Estevinho, Letícia M.; Paula, Vanessa B.; Carlier, Jorge; Costa, Maria Clara; Rodrigues, Brígida; Raposo, Sara; Aazza, Smail; El Ghadraoui, Lahsen; Miguel, Maria GraçaHoney is a natural food product very famous for its health benefits for being an important source of antioxidant and phenolic compounds. Euphorbia honeys obtained from different regions of Morocco were evaluated for their ability to inhibit acetylcholinesterase, lipoxygenase, tyrosinase and xanthine oxidase activities. Their antioxidant properties were evaluated using the: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity, nitric oxide scavenging activity (NO) and scavenging ability of superoxide anion radical. Then, the phenolic extracts of the same entire honey samples were evaluated by liquid chromatography coupled to diode array detection and mass spectrometry (LC-DAD-MS) and tested for the biological activities previously evaluated on the entire honeys, in order to conduct a comparative study between both (honey and phenolic extracts). The chromatographic profiles for the studied Euphorbia honey extracts were different. Phenolic compounds gallic acid, 4-hydroxybenzoic acid and p-coumaric acid were detected in all samples, whereas kampferol was only present in two samples. Physicochemical parameters and total phenolic content were also determined. Entire honey that recorded the highest rate of phenols was sample M6 (E. resinifera) = 69.25 mg GAE/100 g. On the other hand, the phenolic extracts had better antioxidant and enzyme inhibitory activities than the entire honeys, regardless the monofloral honey type. In conclusion, the studied Euphorbia honeys may have a great potential as antioxidant, anti-inflammatory and anti-tyrosinase sources for pharmaceutical and cosmetic applications.
- Preliminary characterization of a Moroccan honey with a predominance of Bupleurum spinosum pollenPublication . ELAMINE, Youssef; S, Azza; Lyoussi, Badiaa; Antunes, Maria Dulce; Estevinho, Letícia M.; Anjos, Ofélia; Resende, Mafalda; Faleiro, Maria Leonor; Miguel, MariaHoney with Bupleurum spinosum (zandaz) as a main pollen source has not been the subject of previous detailed study. Therefore, twelve Moroccan samples of this honey were subjected to melissopalynological, physicochemical and microbiological quality characterization, as well as antioxidant activity assessment. From a quality point of view, almost all samples were within the limits established by Codex Alimentarius, and/or the European legislation. All samples presented predominance of B. spinosum pollen (more than 48%). Relatively high levels of trehalose (1.3-4.0 g/100 g) and melezitose (1.5-2.8 g/100 g) were detected. Those sugars, not common in monofloral honeys, could be used as an important factor to discriminate zandaz honey. Flavonoid content correlated positively with the honey color, melanoidin and polyphenol content, and negatively with the IC50 values of scavenging ABTS (2,2' - azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radicals, while proline amount correlated negatively with IC50 values of nitric oxide scavenging activity and chelating power. This correlation supports the use of anti-oxidant activities as important variables for PCA (principal component analysis). Both components explained 70% from the given data, and showed certain homogeneity upon analyzed samples independent of the region, suggesting the importance of B. spinosum nectar in the resulting honey characteristics.
- Propolis influence on erythrocyte membrane disorder (hereditary spherocytosis): a first approachPublication . Moreira, Leandro L.; Dias, Teresa; Dias, Luís G.; Rogão, Mónica; Silva, José P. da; Estevinho, Letícia M.Propolis is a resinous substance collected from plants by bees. Its composition depends on the vegetation, the season, and the source area. It usually contains many chemical compounds such as polyphenols, steroids and amino acids. The hereditary spherocytosis (HS) is a type of anaemia characterized by microcytic and hyperchromic red cells, spherical in shape and without central pallor. Clinically, subjects present from asymptomatic conditions to severe haemolytic anaemia. In this study it was evaluated the effect of two propolis extracts in the osmotic fragility of HS patient red blood cell (RBC) membrane. It was found that propolis decreases the erythrocytes membrane fragility, being the effect of Bornes propolis more pronounced than Fundao propolis'. This effect was related with the higher phenolic content of the former propolis. The results obtained in vitro suggest that the membrane fragility increases under oxidative stress conditions for the patient RBC's and the protection effect of propolis is due to its antioxidant properties. These results open doors for future investigations in order to elucidate the mechanisms, identify the main compounds involved in this fragility protection of the erythrocyte membrane. This is the first work reporting an evaluation of the propolis effect in a blood disease. (C) 2010 Elsevier Ltd. All rights reserved.
- Volatile characterization of honey with dominance of Bupleurum spinosum pollenPublication . Elamine, Youssef; Machado, Alexandra M.; Estevinho, Letícia M.; Lyoussi, Badiâa; Figueiredo, Ana Cristina; Miguel, MariaMoroccan honey with Bupleurum spinosum (Apiaceae/Umbelliferae) as the main pollen source is locally known as Zantaz honey. In the present work, the volatiles from 18 honeys of this type, were isolated by hydrodistillation and analysed by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS), for volatiles quantification and identification. The percentage composition of the volatiles and pollen profiling was used to determine the relationship between the different samples by cluster analysis. Two poorly correlated clusters were defined in volatiles analysis. Cluster A, with 17 out of the 18 samples, included four subgroups dominated by straight-chain hydrocarbons and fatty acids in variable proportions. Cluster B included just one sample, with 1-phenyldodec-1-en-3-one as the main component. Mono- and sesquiterpene hydrocarbons, as well as oxygen-containing mono- and sesquiterpenes occurred always B. spinosum and Populus sp. pollen. The one sample from Cluster B was moderately correlated with Cluster A and showed the lowest percentage of B. spinosum pollen. Pollen volatiles analysis would be relevant in assessing the presence of putative pollen volatile marker compounds and the importance of pollen profile on honey volatiles.