Antioxidantes em frutos e vegetais

O oxigénio é um elemento necessário à sobrevivência da maioria dos seres vivos. Contudo, este pode revelar-se tóxico, provocando a oxidação e a destruição celular. Em consequência desta oxidação formam–se, a partir do oxigénio molecular (O2), grupos de átomos extremamente reactivos – os radicais livres. A oxidação, tanto dos tecidos animais como dos tecidos vegetais, pode ocorrer tanto como resultado do simples metabolismo celular aeróbio formando os designados radicais livres endógenos, como também pelas agressões externas ao organismo que levam à formação dos radicais livres exógenos (Plummer, 1989).

Novas fontes de antioxidantes e inibidores de enzimas relevantes para o tratamento da diabetes mellitus tipo 2 e doença de Alzheimer

Dissertação de mest., Engenharia Biológica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

Evaluation of the in vitro biological activities of extracts from carob tree and mediterranean oaks

Dissertação mest., Engenharia Biológica, Universidade do Algarve, 2009

Protecção e avaliação de marcadores do stress foto-oxidativo em Ceratonia siliqua L. e Tuberaria major (Willk) P. Silva & Rozeira sob altas temperaturas e défice hídrico

Dissertação mest., Engenharia Biológica, Universidade do Algarve, 2009

Polycyclic aromatic hydrocarbons and oxidative stress markers in the clam Ruditapes decussatus from the Ria Formosa (Portugal)

Tese dout., Ciências e Tecnologias do Ambiente, Universidade do Algarve, 2007

Avaliação das propriedades anti-radicalares de frutos e legumes

Dissertação de mest., Engenharia Biológica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

Estudo do efeito de contaminantes na espécie sentinela, a amêijoa Ruditapes decussatus, por intermédio da análise da expressão proteica: aplicação à monitorização do meio marinho

Tese dout., Ciências e Tecnologias do Ambiente, 2009, Universidade do Algarve

Antioxidant properties and phenol content of Portulaca oleracea L. leaf, stems and flowers infusions: health benefits

Dissertação de mest., Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Univ. do Algarve, 2011

Efeitos a posteriori dos défices hídricos sobre a actividade fotossintética: mecanismos de fotoprotecção e sistema enzimático antioxidante

Tese de dout., Biologia (Fisiologia Vegetal), Faculdade de Engenharia dos Recursos Naturais, Univ. do Algarve, 2005

Effects of nanoparticles exposure in the mussel Mytilus Galloprovincialis

Tese de dout., Ciências do Mar, Terra e Ambiente (Ecotoxicologia), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012

Study of transcripts and reactive oxygen species involved in the defence responses of Quercus suber against Phytophthora cinnamomi

The present work has the merit of exploring an insight into the activation of defence genes of Quercus suber during response to infection by Phytophthora cinnamomi. Thus, cDNA-AFLP methodology was used to identify gene fragments differentially present in the mRNA profiles of host cells of micropropagated Q. suber plantlets roots infected with zoospores of P. cinnamomi at different post challenge time points. Six candidate genes were selected based on their interesting cDNA-AFLP expression patterns and homology to genes known to play a role in defence. These six genes encode a cinnamyl alcohol dehydrogenase 2 (QsCAD2), a protein disulphide isomerase (QsPDI), a CC-NBS-LRR resistance protein (QsRPc), thaumatin-like protein (QsTLP), chitinase (QsCHI) and a 1,3-beta glucanase (QsGLU). The current work has been successful in evaluation of the expression of these genes by qRT-PCR. Data analysis revealed that transcript levels of QsRPc, QsCHI, QsCAD2 and QsPDI increased during the early hours of inoculation, while transcript profiles of thaumatin-like protein showed decreasing. No expression was detected for 1,3-beta-glucanase (QsGLU). Furthermore, the choice of suitable reference genes in any new experimental system is absolutely crucial in qRT-PCR; for this reason in this study and for the first time a set of potential reference genes were analyzed and validated for qRT-PCR normalization in the patho-system Phytophthora-Q. suber. Four candidate reference genes polimerase II (QsRPII), eukaryotic translation initiation factor 5A(QsEIF-5A), b-tubulin (QsTUB) and a medium subunit family protein of Clathrin adaptor complexes (QsCACs) were evaluated to determine the most stable internal references in Q. suber. Analysis of stability of genes was carried out using Genex software. Results indicated all these four potential reference genes assumed stable expression. Data analysis revealed that QsRPII and QsCACs were the two most stable genes, while genes QsTUB and QsEIF-5A were the third and the fourth most stable gene, respectively. In this study, a plasmid-based quantitative PCR method was developed to measure P. cinnamomi colonization during infection process of Q. suber. Plasmid-based detection of P. cinnamomi showed a gradual accumulation of the pathogen DNA in cork oak root tips up to 24 h post infection. The higher increase in P. cinnamomi/plasmid DNA ratio occurred between 18 and 24 h. One of the primary objectives of this research was to study the effect of cinnamomins (elicitins secreted by P. cinnamomin) on inducing defence mechanism against the pathogen, as recent histological and ultra-structural studies showed that P. cinnamomi was restricted to the outer cortex root fragments pre-treated with capsicien and cryptogein, suggesting that elicitins can stimulate plant defence reactions against P. cinnamomi. To complement these studies and to have a clear view of the nature of the interaction, the role of cinnamomins in the production of the oxidative burst [ROS and ROS scavenging enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)] and in the defence responses was evaluated. Cork oak seedlings were pretreated with alpha-cinnamomin and then inoculated with P. cinnamomi mycelia. Results showed a significant higher production of reactive oxygen species (ROS) (H2O2 and O2•-) in elicitin and non-elicitin treated roots in interaction with P. cinnamomi in comparison to the corresponding control. The plant group inoculated with the pathogen after cinnamomin treatment showed an earlier increase in H2O2 production but this was lower as compared with that group inoculated with P. cinnamomi alone. Also, in elicitin pre-treated group generally, a lower level of O2•− production during infection was observed as compared with inoculated roots with P. cinnamomi alone without elicitin treatment. Furthermore, in this study, we evaluated activities of antioxidant enzymes upon challenge with P. cinnamomi, with and without pretreatment with alpha cinnamomin. Results indicated that the activities of defense enzymes POD, SOD and CAT increased after P. cinnamomi inoculation when compared with those in the control group. Also, in the group treated with alpha-cinnamomin followed by P. cinnamomi inoculation, a higher level of enzymatic activities was detected as compared with elicitin non-treated group, which suggest the protective effect of alpha-cinnamomin against the pathogen due to higher elevated levels of defense enzymes POD, SOD and CAT during the infection period. Furthermore, a sensitive qPCR method was applied to measure the pathogen biomass in elicited and non-elicited Q. suber roots challenged with P. cinnamomi to elucidate the effect of cinnamomins on the colonization of P. cinnamomi. Plasmid-based quantification of P. cinnamomi showed a significant decrease in accumulation of the pathogen DNA in cork oak roots after treatment with alpha and beta-cinnamomins which attest the role of cinnamomins in promoting defense responses in cork oak against P. cinnamomi invasion.

Screening for biological activities with application in aquaculture in halophytes from the Algarve coastline

Infectious diseases often hamper the production of aquatic organisms in aquaculture systems, causing economical losses, environmental problems and consumer safety issues. The conventional way aquaculture producers had to control pathogens was by means of synthetic antibiotics and chemicals. This procedure had consequences in the emergence of more resilient pathogens, drug contamination of seafood products and local ecosystems. To avoid the repercussions of antibiotic use, vaccination has greatly replaced human drugs in western fish farms. However there is still massive unregulated antibiotic use in third world fish farms, so less expensive therapeutic alternatives for drugs are desperately needed. An alternative way to achieve disease control in aquaculture is by using natural bioactive organic compounds with antibiotic, antioxidant and/or immunostimulant properties. Such diverse biomolecules occur in bacteria, algae, fungi, higher plants and other organisms. Fatty acids, nucleotides, monosaccharides, polysaccharides, peptides, polyphenols and terpenoids, are examples of these substances. One promising source of bioactive compounds are salt tolerant plants. Halophytes have more molecular resources and defence mechanisms, when compared with other tracheophytes, to deal with the oxidative stresses of their habitat. Many halophytes have been used as a traditional food and medical supply, especially by African and Asian cultures. This scientific work evaluated the antibiotic, antioxidant, immunostimulant and metal chelating properties of Atriplex halimus L., Arthrocnemum macrostachyum Moric., Carpobrotus edulis L., Juncus acutus L. and Plantago coronopus L., from the Algarve coast. The antibiotic properties were tested against Listonella anguillarum, Photobacterium damselae piscicida and Vibrio fischeri. The immunostimulant properties were tested with cytochrome c and Griess assays on Sparus aurata head-kidney phagocytes. J. acutus ether extract inhibited the growth of P. damselae piscicida. A. macrostachyum, A. halimus, C. edulis, Juncus acutus and P. coronopus displayed antioxidant, copper chelating and iron chelating properties. These plants show potential as sources of bioactive compounds with application in aquaculture and in other fields.

Development of chitosan packaging films with carvacrol and grape seed extract as antimicrobial and antioxidant agents

In order to produce packaging films with a broad spectrum of action on microorganisms, the effect of two antimicrobial (AM) to be included in the films, carvacrol and GSE were studied separately on different microorganisms. Carvacrol was more effective against the grampositive bacteria than against the gram-negative bacterium. GSE was not effective against yeast. Subsequently, a search for optimal combinations of carvacrol, GSE and the addition of chitosan (as a third component with film forming properties) was carried out. Response surface analysis showed several synergetic effects and three optimal AM combinations (OAMC) were obtained for each microorganism. The experimental validation confirmed that the optimal solutions found can successfully predict the response for each microorganism. The optimization of mixtures of the three components, but this time, using the same concentration for all microorganisms, was also studied to obtain an OAMC with wide spectrum of activity. The results of the response surface analysis showed several synergistic effects for all microorganisms. Three OAMC, OAMC-1, OAMC-2, OAMC-3, were found to be the optimal mixtures for all microorganisms. The radical scavenging activity (RSA) of the different agents was then compared with a standard antioxidant (AOX) BHT, at different concentrations; as also at the OAMC. The RSA increased in the following order: chitosan

Searching biocompounds in marine natural extracts with potential use in tumor prevention and treatment

Cancer is a multistage process characterized by three stages: initiation, promotion and progression; and is one of the major killers worldwide. Oxidative stress acts as initiator in tumorigenesis; chronic inflammation promotes cancer; and apoptosis inactivation is an issue in cancer progression. In this study, it was investigated the antioxidant, antiinflammatory and antitumor properties of hexane, ether, chloroform, methanol and water extracts of five species of halophytes: A. macrostachyum, P. coronopus, J. acutus, C. edulis and A. halimus. Antioxidant activity was assessed by DPPH• and ABTS•+ methods, and the total phenolics content (TPC) was evaluated by the Folin-Ciocalteau method. The anti-inflammatory activity of the extracts was determined by the Griess method, and by evaluating the inhibition of NO production in LPS-stimulated RAW- 264.7 macrophages. The cytotoxic activity of the extracts against HepG2 and THP1 cell lines was estimated by the MTT assay, and the results obtained were further compared with the S17 non-tumor cell line. The induction of apoptosis of J. acutus ether extract was assessed by DAPI staining. The highest antioxidant activities was observed in C. edulis methanol and the J. acutus ether extracts against the DPPH• radical; and J. acutus ether and A. halimus ether extracts against the ABTS•+ radical. The methanol extracts of C. edulis and P. coronopus, and the ether extract of J. acutus revealed a high TPC. Generally the antioxidant activity had no correlation with the TPC. The A. halimus chloroform and P. coronopus hexane extracts demonstrated ability to reduce NO production in macrophages (> 50%), revealing their anti-inflammatory capacity. The ether extract of J. acutus showed high cytotoxicity against HepG2 cancer cells, with reduced cellular viability even at the lowest concentrations. This outcome was significantly lower than the obtained with the non-tumor cells (S17). This result was complemented by the induction of apoptosis.

Nanotecnologia na dermocosmética: aplicação a formulações antienvelhecimento

Novos e inovadores sistemas de entrega de agentes ativos estão a transformar o desenvolvimento de formulações no campo da dermocosmética. A sociedade em que nos inserimos apresenta-se crescentemente preocupada com a saúde e aparência, o que tem aumentado a procura de formulações antienvelhecimento eficazes. A nanotecnologia aplicada à dermocosmética tem demonstrado potencialidades na entrega de ativos a nível tópico perante partículas de maior escala. Os nanomateriais apresentam caraterísticas muito específicas, destacando-se o fato de apresentarem uma elevada razão área de superfície/volume permitindo um aumento da profundidade de penetração através das camadas da pele, além de permitirem uma libertação controlada do ativo em questão. Uma grande variedade de ativos antienvelhecimento, como antioxidantes, agentes despigmentantes, hidroxiácidos e agentes hidratantes, encontram-se em formulações com sistemas transportadores como lipossomas, nanocápsulas, nanoesferas, nanoemulsões, nanopartículas lipídicas e nanocristais. Estes sistemas de entrega podem atualmente ser encontrados em inúmeros produtos cosméticos, sendo utilizados pelos laboratórios de cosmética de referência. Com esta monografia pretendem-se explorar os vários tipos de nanomateriais utilizados na formulação de cosméticos, as potencialidades de penetração destes através da pele, enfatizando o uso de nanoestruturas em formulações antienvelhecimento.