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- Comparison between the phytochemical and antioxidant properties of plants used in plant infusions for medicinal purposesPublication . Ferreira da Vinha, Ana; Barreira, Sérgio; Castro, Ana; Machado, MarisaIt has already been acknowledged among the medical community that plant based treatments represent an interesting contribution to modern therapeutics due to the presence in their composition of molecules with pharmacological and antioxidant action. The aim of this study was to evaluate the contents of total phenolics, flavonoids, and caffeine in six plants used traditionally by healers in Portugal and usually consumed as tea or infusion namely: Camellia sinensis, Melissa officinalis, Lippia citriodora, Cymbopogon citratus, Matricaria chamomilla, and Tilia cordata. Total phenolics ranged from 32.05 mg GAE/100g for aqueous extracts obtained from leaves of L. citriodora to 145.28 mg GAE/100g for aqueous extracts of C. sinensis. Significant variations in the flavonoid content were also found among analyzed plants and depending on the nature of the extract, with C. sinensis standing out again with the highest values (78.31 mg CE/100g) and the ethanolic extract obtained from the flowers of T. cordata exhibiting the lowest content (25.15 mg CE/100g). The concentration of caffeine was also very diverse and followed the sequence M. officinalis < T. cordata < C. citratus < M. chamomilla < L. citriodora < C. sinensis. The antioxidant activity of each plant was evaluated in vitro using a standard model system, the DPPH assay, and was found to vary according to C. citratus (90.9%) > C. sinensis (87.8%) > M. officinalis (50.7%) > M. chamomilla (45.3%) > T. cordata (32.2%) > L. citriodora (28.0%). The aqueous extracts presented lower antioxidant activity than the corresponding ethanolic ones.
- Effect of extraction methodology on the phytochemical composition for camelia sinensis “Powdered tea extracts” from different provenancesPublication . Barreira, Sérgio; Silva, André M. N.; Moutinho, Carla; Seo, Ean-Jeong; Hegazy, Mohamed-Elamir F.; Efferth, Thomas; Gomes, Lígia RebeloBackground: beverages based on extracts from Camellia sinensis are popular worldwide. Due to an increasing number of processed teas on the market, there is a need to develop unified classification standards based on chemical analysis. Meanwhile, phytochemical characterizations are mainly performed on tea samples from China (~80%). Hence, data on teas of other provenances is recommended. (2) Methods: in the present investigation, we characterized lyophilised extracts obtained by infusion, maceration and methanolic extraction derived from tea samples from China, Japan, Sri Lanka and Portugal by phytochemistry (catechins, oxyaromatic acids, flavonols, alkaloids and theanine). The real benefits of drinking the tea were analysed based on the bioavailability of the determined phytochemicals. (3) Results: the infusions revealed the highest total phenolic contents (TPC) amounts, while methanolic extracts yielded the lowest. The correlation matrix indicated that the levels of phenolic compounds were similar in the infusions and methanolic samples, while extractions made by maceration were significantly different. The differences could be partially explained by the different amounts of (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and gallic acids (GA). The catechin percentages were significantly lower in the macerations, especially the quantity of EGCG decreases by 4- to 5-fold after this process. (4) Conclusions: the results highlight the importance of the processing methodology to obtain “instant tea”; the composition of the extracts obtained with the same methodology is not significantly affected by the provenance of the tea. However, attention should be drawn to the specificities of the Japanese samples (the tea analysed in the present work was of Sencha quality). In contrast, the extraction methodology significantly affects the phytochemical composition, especially concerning the content of polyphenols. As such, our results indicate that instant tea classification based on chemical composition is sensible, but there is a need for a standard extraction methodology, namely concerning the temperature and time of contact of the tea leaves with the extraction solvent.
- Controlo de qualidade de medicamentos - aulas prático-laboratoriais: protocolos laboratoriais (2024/2025)Publication . Lopes, Carla Martins; Barreira, SérgioProtocolos dos trabalhos PL
- Physicochemical parameters, phytochemical composition and antioxidant activity of the algarvian avocado (Persea americana Mill.)Publication . Ferreira da Vinha, Ana; Moreira, Joana; Barreira, SérgioThe physical, chemical and nutritional properties of Persea americana fruits variety ‘Hass’ produced in the Algarve region were studied. Edible and non-edible parts of the fruits (pulp, seeds and peel) were compared considering their possible contribution to improve the sustainability of the food and pharmaceutical industries. The nutritional contents evaluated were moisture, ash, proteins, fat, total soluble solids and acidity. It were also evaluated the contents of bioactive compounds (phenolics, flavonoids, carotenoids, ascorbic acid and vitamin E) and their influence in the antioxidant activity exhibited by the fruit material. The results of the analysis demonstrated that the Algarvian avocado has physical and chemical characteristics comparable or superior to avocados from other growing regions around the world namely, Mexico and California. With regard to the contents of bioactive compounds, the pulp of the Algarvian avocado proved to be rich in carotenoids (0.815±0.201 mg/100g), phenolic compounds (410.2±69.0 mg/100g) and flavonoids (21.9±1.0 mg/100g). The skin was superior to the pulp in the contents of all these compounds with 2.585±0.117 mg/100g of carotenoids, 679.0±117.0 mg/100g of total phenolics and 44.3±3.1 mg/100g of flavonoids. The seed, in turn, was the part of the fruit with the highest total phenolic content (704.0±130.0 mg/100g) and flavonoids (47.97±2.69 mg/100g). Regarding the concentration of vitamins C and E, the highest values were found in the pulp (5.36±1.77 mg/100g of vitamin E) and skin (4.1±2.7 mg/100g of vitamin C). The extracts obtained from the seeds demonstrated higher in vitro DPPH· assay antioxidant activity (43%) than those obtained from the skin (35%) and the fruit pulp (23%). The contents of carotenoids, phenolic compounds and flavonoids found in the non-edible parts of the Algarvian avocado demonstrated that these byproducts could be an interesting inexpensive raw material for the food and cosmetic industries.
- Capsicum annuum L. with different colors provide bioavailable phytochemicals with health benefitsPublication . Madeira, Ana; Silva, Carla Sousa e; Barreira, Sérgio; Ferreira da Vinha, Ana
- Soap formulation with coffee grounds - a new concept of food by-products valorization and health promotionPublication . Silva, Carla Sousa e; Castro, Bárbara T.; Barreira, Sérgio; Ferreira da Vinha, Ana
- Evaluation of antioxidant and antimicrobial properties of the Angolan Cymbopogon Citratus essential oil with a view to its utilization as food biopreservativePublication . Soares, Marta O.; Ferreira da Vinha, Ana; Barreira, Sérgio; Coutinho, Filipe; Aires-Gonçalves, Sérgio; Oliveira, Maria B.P.P.; Pires, Pedro C.; Castro, AnaIt was studied the chemical composition, antioxidant, antibacterial and antifungal properties of the essential oil obtained from the Cymbopogon citratus of Angolan origin. Its major constituents analyzed by GC-MS were α-citral (40.55%), β-citral (28.26%), myrcene (10.50%) and geraniol (3.37%). The essential oil antioxidant capacity was statistically identical to that of synthetic antioxidants (DPPH IC50 of 41.7 μg/ml) and superior to that of extracts obtained from fresh leaves of the plant (DPPH IC50 of 55.7 μg/ml). The oil also demonstrated to possess high antibacterial activity even against multidrug resistant strains of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Klebsiella pneumoniae and antifungal activity against Candida albicans and Non-Candida albicans, Candida parapsilosis and Candida tropicalis. The results of this study, in conjunction with already published data on the properties of other Cymbopogon citratus oils, provide evidence that it could have a potential application as food preservative.
- Síntese de sistemas nanoscópicos para veicular um inibidor da apoptosePublication . Barreira, SérgioConceberam-se sistemas para veicular um inibidor da apoptose utilizando partículas coloidais com um micrómetro de diâmetro, produzidas através de montagem camada-a-camada com base em interacções electrostáticas. Foram investigadas duas alternativas: a utilização de partículas revestidas com o inibidor e cápsulas para funcionar como contentores. Os resultados de testes in vitro revelaram que as partículas funcionalizadas têm capacidade de inibir a apoptose indicando que esta estratégia poderá ser promissora. A utilização de cápsulas, por seu lado, ainda não foi testada. O seu processo de produção ainda está sendo optimizado. Two innovative vehicles to deliver an apoptosis inhibitor are presented. Both utilize colloidal particles approximately one micrometer in diameter produced by electrostatic layer-by- -layer assembly. One consists on particles coated with layers of a polyelectrolyte derivatized with the inhibitor, the other on capsules filled with the inhibitor. Preliminary in vitro tests revealed that the coated microparticles are capable of inhibiting the apoptosis process, indicating that this strategy could be promising. The capsules were not yet tested since their production process is still being optimized.
- Effect of conventional heat treatment on phenolic contents and free radical scavenging activity of green leafy vegetablesPublication . Ferreira da Vinha, Ana; Castro, A.; Barreira, Sérgio; Alves, R.C.; Oliveira, M.B.P.P.Vegetables represent a higly significant source of functional substances, which might benefit physiological functions in the human metabolism.
- Effect of extraction methodology on the phytochemical composition for camelia sinensis “powdered tea extracts” from different provenancesPublication . Barreira, Sérgio; Silva, André M. N.; Moutinho, Carla; Seo, Ean-Jeong; Hegazy, Mohamed-Elamir F.; Efferth, Thomas; Gomes, Lígia Rebelo(1) Background: beverages based on extracts from Camellia sinensis are popular worldwide. Due to an increasing number of processed teas on the market, there is a need to develop unified classification standards based on chemical analysis. Meanwhile, phytochemical characterizations are mainly performed on tea samples from China (~80%). Hence, data on teas of other provenances is recommended. (2) Methods: in the present investigation, we characterized lyophilised extracts obtained by infusion, maceration and methanolic extraction derived from tea samples from China, Japan, Sri Lanka and Portugal by phytochemistry (catechins, oxyaromatic acids, flavonols, alkaloids and theanine). The real benefits of drinking the tea were analysed based on the bioavailability of the determined phytochemicals. (3) Results: the infusions revealed the highest total phenolic contents (TPC) amounts, while methanolic extracts yielded the lowest. The correlation matrix indicated that the levels of phenolic compounds were similar in the infusions and methanolic samples, while extractions made by maceration were significantly different. The differences could be partially explained by the different amounts of (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and gallic acids (GA). The catechin percentages were significantly lower in the macerations, especially the quantity of EGCG decreases by 4- to 5-fold after this process. (4) Conclusions: the results highlight the importance of the processing methodology to obtain “instant tea”; the composition of the extracts obtained with the same methodology is not significantly affected by the provenance of the tea. However, attention should be drawn to the specificities of the Japanese samples (the tea analysed in the present work was of Sencha quality). In contrast, the extraction methodology significantly affects the phytochemical composition, especially concerning the content of polyphenols. As such, our results indicate that instant tea classification based on chemical composition is sensible, but there is a need for a standard extraction methodology, namely concerning the temperature and time of contact of the tea leaves with the extraction solvent.