Percorrer por autor "Diallo, Moustapha"
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- Chemical characterization and bioactivity of poplar, green and red propolis: a screening study with a food preservation purposePublication . Diallo, Moustapha; Falcão, Soraia; Vilas-Boas, MiguelPropolis is a resin made by honeybees from multiple plant sources surrounding the hive. Therefore, each type of propolis from different regions has intrinsic characteristics related to their chemical composition, such as antifungal, antioxidative properties, and extrinsic such as color, both specific to their botanical origin. Thus, propolis can be regarded as a functional food with preservative properties offering an alternative to the concern of the global and growing use of synthetic preservatives considerably harming human health. The aim of this work was to study three types of propolis, namely, Portuguese propolis (from Populus sp.), Brazilian red propolis (from Dalbergia ecastophyllum), and Brazilian green propolis (from Baccharis dracunculifolia) in order to evaluate the antifungal potential for its application as a preservative in food. For that, the chemical composition was characterized by LC/DAD/ESI-MSn. Also, the total phenolic content, flavonoids and antioxidant activity was evaluated through UV-Vis spectrophotometry. Concerning the antifungal properties, the values differed in relation to the types of fungi, to the inoculating concentration and mode of action. With this in mind, an analysis of their antifungal activities at two levels of concentration (0.5-1.5 g/L and 5-15 g/L) was previously evaluated in vitro, with the aim of selecting the best concentration of inhibition of the rotting diameter of two types of grapes, namely, red and white. Subsequently, different fungi were used to test the activity of the aforementioned propolis, namely, Alternaria sp., Botrytis cinerea, Cladosporium sp., Penicillium sp. 2, Aspergillus carbonarius MUM04.46, and Aspergillus carbonarius MUM04.52. This last experiment made it possible to measure the rotting diameter of each grape and to evaluate the antifungal capacity of each type of propolis, with the final aim of using it to design an effective product that can extend the shelf life of food.
- Improvement of the in vitro cytotoxic effect on HT-29 colon cancer cells by combining 5-fluorouacil and fluphenazine with green, red or brown propolisPublication . Falcão, Soraia; Duarte, Diana; Diallo, Moustapha; Santos, Joana B.; Ribeiro, Eduarda; Vale, Nuno; Vilas-Boas, MiguelCancer is regard as one of the key factors of mortality and morbidity in the world. Treatment is mainly based on chemotherapeutic drugs that, when used in targeted therapies, have serious side effects. 5-fluorouracil (5-FU) is a drug commonly used against colorectal cancer (CRC), despite its side effects. Combination of this compound with natural products is a promising source in cancer treatment research. In recent years, propolis has become the subject of intense pharmacological and chemical studies linked to its diverse biological properties. With a complex composition rich in phenolic compounds, propolis is described as showing positive or synergistic interactions with several chemotherapeutic drugs. The present work evaluated the in vitro cytotoxic activity of the most representative propolis types, such as green, red and brown propolis, in combination with chemotherapeutic or CNS drugs on HT-29 colon cancer cell lines. The phenolic composition of the propolis samples was evaluated by LC-DAD-ESI/MSn analysis. According to the type of propolis, the composition varied; green propolis was rich in terpenic phenolic acids and red propolis in polyprenylated benzophenones and isoflavonoids, while brown propolis was composed mainly of flavonoids and phenylpropanoids. Generally, for all propolis types, the results demonstrated that combing propolis with 5-FU and fluphenazine successfully enhances the in vitro cytotoxic activity. For green propolis, the combination demonstrated an enhancement of the in vitro cytotoxic effect compared to green propolis alone, at all concentrations, while for brown propolis, the combination in the concentration of 100 mu g/mL gave a lower number of viable cells, even when compared with 5-FU or fluphenazine alone. The same was observed for the red propolis combination, but with a higher reduction in cell viability. The combination index, calculated based on the Chou-Talalay method, suggested that the combination of 5-FU and propolis extracts had a synergic growth inhibitory effect in HT-29 cells, while with fluphenazine, only green and red propolis, at a concentration of 100 mu g/mL, presented synergism.