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- Natural antioxidants in emulsions O/WPublication . EL-GEUNDOUZ, Soukaina; Azza, S.; Dandlen, Susana Anahi; MAJDOUB, Nesrine; Lyoussi, Badiaa; Raposo, Sara; Gomes, Vera; Bankova, Vassya; Popova, Milena; Antunes, Maria Dulce; Miguel, Maria GracaThis study compared the capacity of propolis extract (PE) and thyme waste extract (TWE) to prevent the oxidation of oil in water (O/W) emulsion, as well as their impact on emulsion apparent viscosity (AV) in the presence of wheat germ and almond oils as lipid phase. For this, central composite design (CCD) and principal component analysis (PCA) were performed. Oxidation process was monitored by evaluating the formation of primary and secondary lipid oxidation products, at the same time the AV behavior was determined evaluating consistency index and flow behavior index. The results revealed that the increase of PE% and TWE% decreases TBARS (Thiobarbituric Acid Reactive Substances) and hydroperoxides formation. Viscosity increases with the rise of TWE% over (0.04%), whereas lower concentrations of PE% decreases it. Those results have been confirmed in the PCA analysis. TWE showed higher resistance to oxidation, although PE was more effective as antioxidant than TWE.
- Characterization of volatiles from Moroccan propolis samplesPublication . EL-GEUNDOUZ, Soukaina; Lyoussi, Badiaa; Miguel, Maria Graca; Figueiredo, A. CristinaThe volatiles from 24 propolis samples collected from different geographical locations in Morocco were evaluated. Propolis volatiles isolated by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). Cluster analysis based on propolis samples’ volatile chemical composition defined two main uncorrelated clusters. Cluster I, with 23 of the 24 samples analyzed, included three subgroups, Ia, Ib1 and Ib2, dominated by βeudesmol (11–30%), cedrol (7–40%) and n-tricosane (6–34%), respectively. Cluster II included just one sample, with ar-curcumene (32%) as the main component. The results obtained contributed to increase the knowledge on the chemical composition and variability of Moroccan propolis samples. The volatile profile of these samples was distinct from those of Algeria, Canary Islands and Ethiopia, the sole African propolis volatiles studied so far.
- Growth, photosynthetic pigments, phenolic content and biological activities of Foeniculum vulgare Mill., Anethum graveolens L. and Pimpinella anisum L. (Apiaceae) in response to zincPublication . MAJDOUB, Nesrine; EL-GEUNDOUZ, Soukaina; Rezgui, Marwa; Carlier, Jorge; Clara Costa, Maria; Ben Kaab, Leila Bettaieb; Miguel, Maria GracaThe effect of zinc (Zn) on phenols, antioxidant activities (free radicals' scavenging activities, inhibition of lipid peroxidation, chelating activity and reducing power), and enzyme inhibition activities of acetylcholinesterase, lipoxygenase and tyrosinase of anise, dill and two cultivars of fennel [Latina" (F-L) and "Doux de Florence" (F-DF)] aqueous extracts was evaluated for the first time. At the same time, growth and photosynthetic pigment contents were also estimated. A significant decrease in all growth parameters, such as plant height, fresh and dry weights of aerial parts and roots was statistically proved in the presence of 2 mM Zn. An enhancement of Zn accumulation was observed, particularly in aerial part. Exposure to 2 mM Zn induced quantitative changes in the phenols of all tested extracts. In fennel extracts, a decrease of phenol content was observed when treated with Zn, whereas an increase was found in dill and anise extracts submitted to Zn treatment. All samples, either in the presence or absence of Zn, showed antioxidant activity, independent on the tested assay, with the exception of the cultivar F-DF (treated and non-treated), which was unable to scavenge NO radicals. Zn-treated dill and anise presented usually higher antioxidant activity. Concerning inhibitory activities against acetylcholinesterase, lipoxygenase and tyrosinase enzymes, both treated and non-treated F-DF did not inhibit acetylcholinesterase activity. Zinc-treated F-DF was also unable to inhibit lipoxygenase activity. The remaining species presented capacity for inhibiting those enzymes and tyrosinase as well, but their abilities varied in response to Zn excess.
- Impact of fifteen combinations of the main components of rosemary, lavender and citrus essential oils on in vitro biological activitiesPublication . Kharraf, Sara El; EL-GUENDOUZ, Soukaina; Farah, Abdellah; Mateus, Maria Da Conceição; Hadrami, El Mestafa El; Miguel, Maria GracaSince ancient times, essential oils or their volatiles have been used in food, health and aromatherapy. Essen-tial oils are complex mixtures constituted by dozens of compounds, which makes it difficult to attribute their biological properties to this or that compound or compound combinations. Moreover, the quantification of the volatiles is generally made through their relative percentage abundances. In the present study, the major volatiles isolated from Rosmarinus officinalis, Lavandula angustifolia, and Citrus aurantium essential oils extracted by simultaneous hydrodistillation-steam distillation were quantified through the external standard calibration method. Fifteen volatile mixtures were made using individual volatiles identified in the essential oils (EOs) to better find their role in the biological activities (antioxidant, anti-glucosidase, anti-inflammatory, anti-tyrosinase and anti-acetylcholinesterase activities). For almost mixtures assayed, the in vitro biological activities were generally poorer than those obtained for crude EOs, with the exception of the inhibitory effect on the a-glucosidase activity. In this case, 1,8-cineole and a-terpineol seem to have a positive role in inhibit-ing a-glucosidase activity, in contrast to camphor and borneol, which had the opposite action. Therefore there was a possible antagonist effect of both camphor and borneol in the volatile mixtures assayed on inhibiting the a-glucosidase activity. This approach also permitted us to conclude that there were several other factors not determined in the present work that were responsible for the activities found in the EOs,(c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.