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Abstract(s)
A crescente valorização de produtos naturais na alimentação tem ganho importância na comunidade científica, cada vez mais a investigação se tem direcionado para o desenvolvimento de conceitos inovadores sustentáveis ao nível alimentar e não só. Esta tendência generalizada pela sociedade de procurar, usar e consumir o que é natural deve-se não só à partilha do conhecimento científico para a sociedade, como também à urgente preocupação em mudarmos os nossos hábitos a nível alimentar, mas também à sustentabilidade dos processos industriais. As plantas aromáticas e medicinais (PAM) têm ganho especial atenção, a importância dos seus usos tradicionais tem vindo a ser confirmada, na maioria das vezes, em estudos de caracterização das propriedades biológicas. Os extratos e óleos essenciais (OEs) de PAM têm apresentado bons resultados em termos de atividades antioxidante e antimicrobiana, sendo a sua potencial aplicação na conservação de alimentos perecíveis, como é o caso de frutas e vegetais frescos, apresentando resultados promissores na substituição de conservantes químicos sintéticos e na redução do desperdício alimentar, devido à extensão de conservação dos alimentos.
A Lavandula stoechas subsp. luisieri (Rozeira) Rozeira (Lsl) e a Pterospartum tridentatum L. Willk (Pt) são dois endemismos da flora portuguesa, sendo bastante referenciados em estudos etnobotânicos. Os seus extratos e OEs têm revelado resultados importantes na caracterização das suas propriedades biológicas.
O presente estudo procura desenvolver protocolos de propagação in vitro destas espécies por sistemas de biorreatores de imersão temporária (BIT) e caracterizar os compostos fenólicos e voláteis dos extratos de plantas silvestres, recolhidas nas diferentes fases fenológicas e com origem em BIT. Nestes subprodutos, pretende-se avaliar as suas propriedades biológicas, nomeadamente a atividade antioxidante, antimicrobiana e a citotoxicidade. Foram realizados ensaios de conservação pós-colheita de medronho e cereja, onde, neste último, em cerejas, foram também elaboradas e caracterizadas formulações de revestimentos edíveis com incorporação de OE de Lsl.
Os resultados dos ensaios de micropropagação de Lsl e Pt revelaram boas propriedades biométricas e morfológicas, obtendo taxas de multiplicação próximas ou superiores às obtidas no sistema convencional. A caracterização de extratos aquosos de Lsl revelou a presença maioritária de ácido rosmarínico em todas as fases fenológicas da planta, sendo que no extrato de BIT os compostos maioritários foram os ácidos cafeico e rosmarínico. Nos extratos aquosos de Pt os compostos fenólicos maioritários foram a rutina e quercetina, enquanto o extrato de BIT foi caracterizado por ácido elágico e rutina como compostos maioritários. Os resultados dos constituintes voláteis dos OEs de Lsl permitiram observar uma variação no perfil volátil nas diferentes fases fenológicas, sendo a fase da floração caracterizada por possuir maior teor de acetato de trans-α-necrodilo, nomeadamente no OE das folhas. Neste trabalho foi possível obter OE com origem em plantas no tratamento de BIT, sendo que o perfil volátil do OE apresentou como composto maioritário o acetato de trans-α-necrodilo, revelando alguns constituintes com maior teor comparativamente às plantas silvestres, como o α- e β-pineno, a cânfora, o acetato de lavandulilo e o viridiflorol.
Os resultados permitiram concluir que os extratos aquosos e OE de Lsl e o extrato aquoso de Pt apresentaram atividade antioxidante pelos métodos testados, conferindo-lhes propriedades de potencial de aplicação como conservante. O OE de Lsl revelou potencial citotóxico em todas as concentrações testadas, enquanto nas concentrações mais baixas testadas o extrato aquoso de Pt não revelou citotoxicidade em células de fibroblastos. A atividade antimicrobiana foi confirmada no OE de Lsl, apresentando um largo espectro de ação antibacteriano e antifúngico. Foram isolados leveduras e fungos filamentosos de medronho no ensaio de conservação, permitindo a identificação de 57% dos isolados ao nível do género e espécie, destacando os géneros mais representativos como Alternaria, Cladosporium, Penicillium, Aspergillus, Aureobasidium e Saccothecium. No ensaio de conservação de cereja as formulações de revestimentos à base de quitosano e OE de Lsl apresentaram propriedades mecânicas adequadas, assim como a sua aplicação em frutos permitiu reduzir a carga microbiana inicial, contribuindo para a sua conservação e tempo de vida útil.
Em suma, os extratos e OE das plantas estudadas revelaram propriedades interessantes para possível aplicação como agentes conservantes em formulações alimentares e/ou como componentes de embalagens, no entanto, validações futuras serão necessárias de forma a complementar estes resultados para o desenvolvimento de produtos bioativos na conservação de alimentos.
The scientific community has come to recognize the increased importance of natural products in food, and an increasing amount of research is being focused on creating innovative and sustainable food concepts and beyond. This widespread tendency in society to look for, use, and consume natural products is caused by the dissemination of scientific knowledge and an urgent desire to modify our eating patterns and the sustainability of industrial processes. Aromatic and medicinal plants (AMP) have received particular attention, and studies characterizing their biological properties have confirmed the significance of their traditional uses. AMP essential oils (EOs) and extracts have demonstrated promising outcomes regarding their antimicrobial and antioxidant properties. Lavandula stoechas subsp. luisieri (Rozeira) Rozeira (Lsl) and Pterospartum tridentatum L. Willk (Pt) are two endemisms of the Portuguese flora that are frequently mentioned in ethnobotanical studies. Its extracts and EOs have revealed significant results in characterizing its biological properties. The present study aimed to develop protocols for the in vitro propagation of these species by temporary immersion bioreactor systems (TIB) and to characterize the phenolic and volatile compounds of extracts of wild plants collected in the different phenological phases and obtained by TIB. These by-products are intended to evaluate their biological properties, namely antioxidant and antimicrobial activities, and cytotoxicity. Post-harvest conservation trials were carried out on the strawberry tree and sweet cherry, where, in the last one, formulations of edible coatings with the incorporation of EOs of Lsl were developed and characterized. Concerning the results, the Lsl and Pt micropropagation in the TIB system showed good biometric and morphological properties, with multiplication rates equal to or higher than those of the conventional system. Characterization of aqueous extracts of Lsl revealed the presence of rosmarinic acid in all phenological phases of the plant, and the main phenolic compounds in the extract of TIB were caffeic and rosmarinic acids. In Pt aqueous extracts, rutine and quercetin were the main phenolics, whereas their TIB extract was characterized by ellagic acid and rutine. The results of the volatile constituents of the EOs allowed us to observe a variation in the volatility profile of the Lsl EOs in the different phenological phases, with the flowering phase being characterized by having a higher content of trans-α-necrodyl acetate, particularly in the EO of the leaves. In this work, it was possible to obtain EO from plants obtained by TIB, with the volatile profile of this EO presented as the majority compound trans-α-necrodyl acetate, revealing some constituents with a higher content compared to wild plants, such as α- and β-pinene, camphor, lavandulyl acetate, and viridiflorol. The results allow us to conclude that the aqueous extracts and EO of Lsl, as well as the aqueous extract of Pt, exhibited antioxidant activity using the tested methods, making them suitable for use as a preservative. EO of Lsl exhibited cytotoxic potential in all concentrations tested in fibroblasts, whereas aqueous extracts of Pt did not exhibit cytotoxicity in fibroblasts cells at lower concentrations tested. Lsl EO has also shown antimicrobial activity with a broad spectrum of antibacterial and antifungal properties. In the strawberry tree conservation assay, the main representative yeasts and filamentous fungi were isolated, allowing 57% of the isolates to be identified at the genus and species level, highlighting Alternaria, Cladosporium, Penicillium, Aspergillus, Aureobasidium e Saccothecium. The coating formulations demonstrated adequate mechanical properties in the cherry conservation assay, and their application on fruits reduced the initial microbial load, contributing to their conservation and shelf life. In summary, the extracts and EO of the plants studied revealed interesting properties for potential use as preservatives in food formulations. However, future validations to complement these findings should be considered to develop bioactive products in food conservation.
The scientific community has come to recognize the increased importance of natural products in food, and an increasing amount of research is being focused on creating innovative and sustainable food concepts and beyond. This widespread tendency in society to look for, use, and consume natural products is caused by the dissemination of scientific knowledge and an urgent desire to modify our eating patterns and the sustainability of industrial processes. Aromatic and medicinal plants (AMP) have received particular attention, and studies characterizing their biological properties have confirmed the significance of their traditional uses. AMP essential oils (EOs) and extracts have demonstrated promising outcomes regarding their antimicrobial and antioxidant properties. Lavandula stoechas subsp. luisieri (Rozeira) Rozeira (Lsl) and Pterospartum tridentatum L. Willk (Pt) are two endemisms of the Portuguese flora that are frequently mentioned in ethnobotanical studies. Its extracts and EOs have revealed significant results in characterizing its biological properties. The present study aimed to develop protocols for the in vitro propagation of these species by temporary immersion bioreactor systems (TIB) and to characterize the phenolic and volatile compounds of extracts of wild plants collected in the different phenological phases and obtained by TIB. These by-products are intended to evaluate their biological properties, namely antioxidant and antimicrobial activities, and cytotoxicity. Post-harvest conservation trials were carried out on the strawberry tree and sweet cherry, where, in the last one, formulations of edible coatings with the incorporation of EOs of Lsl were developed and characterized. Concerning the results, the Lsl and Pt micropropagation in the TIB system showed good biometric and morphological properties, with multiplication rates equal to or higher than those of the conventional system. Characterization of aqueous extracts of Lsl revealed the presence of rosmarinic acid in all phenological phases of the plant, and the main phenolic compounds in the extract of TIB were caffeic and rosmarinic acids. In Pt aqueous extracts, rutine and quercetin were the main phenolics, whereas their TIB extract was characterized by ellagic acid and rutine. The results of the volatile constituents of the EOs allowed us to observe a variation in the volatility profile of the Lsl EOs in the different phenological phases, with the flowering phase being characterized by having a higher content of trans-α-necrodyl acetate, particularly in the EO of the leaves. In this work, it was possible to obtain EO from plants obtained by TIB, with the volatile profile of this EO presented as the majority compound trans-α-necrodyl acetate, revealing some constituents with a higher content compared to wild plants, such as α- and β-pinene, camphor, lavandulyl acetate, and viridiflorol. The results allow us to conclude that the aqueous extracts and EO of Lsl, as well as the aqueous extract of Pt, exhibited antioxidant activity using the tested methods, making them suitable for use as a preservative. EO of Lsl exhibited cytotoxic potential in all concentrations tested in fibroblasts, whereas aqueous extracts of Pt did not exhibit cytotoxicity in fibroblasts cells at lower concentrations tested. Lsl EO has also shown antimicrobial activity with a broad spectrum of antibacterial and antifungal properties. In the strawberry tree conservation assay, the main representative yeasts and filamentous fungi were isolated, allowing 57% of the isolates to be identified at the genus and species level, highlighting Alternaria, Cladosporium, Penicillium, Aspergillus, Aureobasidium e Saccothecium. The coating formulations demonstrated adequate mechanical properties in the cherry conservation assay, and their application on fruits reduced the initial microbial load, contributing to their conservation and shelf life. In summary, the extracts and EO of the plants studied revealed interesting properties for potential use as preservatives in food formulations. However, future validations to complement these findings should be considered to develop bioactive products in food conservation.
Description
Keywords
Atividade antimicrobiana Atividade antioxidante Carqueja Extratos aquosos Óleo essencial Micropropagação Revestimentos edíveis Rosmaninho-menor