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Advisor(s)
Abstract(s)
A quimioprevenĆ§Ć£o Ć© um conceito muito atual e contempla a utilizaĆ§Ć£o de medicamentos, compostos biolĆ³gicos ou nutrientes como estratĆ©gia de intervenĆ§Ć£o na prevenĆ§Ć£o do cancro (i.e. inibir, retardar ou reverter a carcinogĆ©nese). SĆ£o numerosos os estudos que tĆŖm atribuĆdo efeito quimiopreventivo aos flavonoides, sendo estes os compostos fenĆ³licos maioritĆ”rios em diversas plantas. Levando em conta os benefĆcios que sĆ£o capazes de proporcionar para a saĆŗde humana, estes assumem grande relevĆ¢ncia na indĆŗstria alimentar, apresentando elevado potencial de serem utilizados no desenvolvimento de alimentos funcionais. Contudo uma restriĆ§Ć£o ao seu uso, consiste na sua grande instabilidade podendo sofrer alteraƧƵes durante o processamento dos alimentos onde sĆ£o incorporados. Neste contexto, a microencapsulaĆ§Ć£o possibilita a proteĆ§Ć£o destes quimiopreventivos naturais, permitindo ainda a sua libertaĆ§Ć£o controlada. Assim, este trabalho teve como objetivo selecionar um extrato natural rico em flavonoides, estudar a sua microencapsulaĆ§Ć£o numa matriz polimĆ©rica de origem natural (alginato) e posterior incorporaĆ§Ć£o das microcĆ”psulas produzidas numa matriz alimentar selecionada (iogurte). A capacidade quimiopreventiva do alimento funcional produzido foi avaliada pelo seu potencial anti-angiogĆ©nico. Em especĆfico, foi preparado um extrato hidroetanĆ³lico de Arenaria montana que, apĆ³s caracterizaĆ§Ć£o por HPLC-DAD, mostrou ser rico em derivados de apigenina. O mesmo extrato revelou capacidade de inibiĆ§Ć£o da fosforilaĆ§Ć£o da VEGFR-2, enzima envolvida em processos de angiogĆ©nese. A microencapsulaĆ§Ć£o do referido extrato pela tĆ©cnica de atomizaĆ§Ć£o/coagulaĆ§Ć£o usando alginato como material de encapslaĆ§Ć£o foi aplicada com sucesso obtendo-se eficiĆŖncias de encapsulaĆ§Ć£o prĆ³ximas de 100%. Os iogurtes funcionalizados com extrato de A. montana (livre e encapsulado) mostraram um valor nutricional similar ao controlo (iogurte nĆ£o enriquecido), mas um aumento do potencial anti-angiogĆ©nico (inibiĆ§Ć£o da fosforilaĆ§Ć£o da VEGFR-2) que foi mais preservado no extrato protegido.
Chemoprevention is a very recent concept and refers to the use of medicines, biological compounds or nutrients as a strategy of intervention in cancer prevention (i.e. inhibit, delay or reverse carcinogenesis). Several studies have attributed chemopreventive effect to flavonoids, ascribed as the most abundant phenolic compounds in various plants. Considering their health benefits, these compounds are of great importance in the food industry, namely in the development of functional foods. However, these compounds might possess a remarkable instability, and might change during food processing in which they are incorporated. In this context, microencapsulation provides protection of these natural chemopreventive agents, allowing also their controlled release. This work aimed at selecting a natural extract rich in flavonoids, and to study its microencapsulation in polymeric matrices of natural origin (alginate) and subsequent incorporation of the produced microcapsules in a selected food matrix (yogurt). The chemopreventive capacity of the obtained functional food was evaluated by its antiangiogenic potential. In particular, a hydroethanolic extract of Arenaria montana was prepared, which after HPLC-DAD characterization, proved to be rich in apigenin derivatives. This extract revealed capacity to inhibit the phosphorylation of VEGFR-2, an enzyme involved in the angiogenesis process. The encapsulation of the mentioned extract by an atomization/coagulation technic using alginate as the encapsulation material was carried out successfully by achieving encapsulation efficiencies close to 100%. The yogurts functionalized with A. montana extracts (free and encapsulated) showed a nutritional value similar to the control (non-enriched yogurt), but an increase in the antiangiogenic potential (inhibition of VEGFR-2 phosphorylation), which was more preserved in the protected extract.
Chemoprevention is a very recent concept and refers to the use of medicines, biological compounds or nutrients as a strategy of intervention in cancer prevention (i.e. inhibit, delay or reverse carcinogenesis). Several studies have attributed chemopreventive effect to flavonoids, ascribed as the most abundant phenolic compounds in various plants. Considering their health benefits, these compounds are of great importance in the food industry, namely in the development of functional foods. However, these compounds might possess a remarkable instability, and might change during food processing in which they are incorporated. In this context, microencapsulation provides protection of these natural chemopreventive agents, allowing also their controlled release. This work aimed at selecting a natural extract rich in flavonoids, and to study its microencapsulation in polymeric matrices of natural origin (alginate) and subsequent incorporation of the produced microcapsules in a selected food matrix (yogurt). The chemopreventive capacity of the obtained functional food was evaluated by its antiangiogenic potential. In particular, a hydroethanolic extract of Arenaria montana was prepared, which after HPLC-DAD characterization, proved to be rich in apigenin derivatives. This extract revealed capacity to inhibit the phosphorylation of VEGFR-2, an enzyme involved in the angiogenesis process. The encapsulation of the mentioned extract by an atomization/coagulation technic using alginate as the encapsulation material was carried out successfully by achieving encapsulation efficiencies close to 100%. The yogurts functionalized with A. montana extracts (free and encapsulated) showed a nutritional value similar to the control (non-enriched yogurt), but an increase in the antiangiogenic potential (inhibition of VEGFR-2 phosphorylation), which was more preserved in the protected extract.