A review on antioxidants, prooxidants and related controversy: natural and synthetic compounds, screening and analysis methodologies and future perspectives

Many studies have been conducted with regard to free radicals, oxidative stress and antioxidant activity of food, giving antioxidants a prominent beneficial role, but, recently many authors have questioned their importance, whilst trying to understand the mechanisms behind oxidative stress. Many scientists defend that regardless of the quantity of ingested antioxidants, the absorption is very limited, and that in some cases prooxidants are beneficial to human health. The detection of antioxidant activity as well as specific antioxidant compounds can be carried out with a large number of different assays, all of them with advantages and disadvantages. The controversy around antioxidant in vivo benefits has become intense in the past few decades and the present review tries to shed some light on research on antioxidants (natural and synthetic) and prooxidants, showing the potential benefits and adverse effects of these opposing events, as well as their mechanisms of action and detection methodologies. It also identifies the limitations of antioxidants and provides a perspective on the likely future trends in this field.Fundação para a Ciência e a Tecnologia (FCT, Portugal) and COMPETE/QREN/EU for financial support to CIMO (strategic project PEst-OE/AGR/UI0690/2011)

The role of phenolic compounds in the fight against cancer – a review

Cancer is a worldwide scourge; it’s the leading cause of death in developed countries and is increasing in developing countries. Mankind has been trying with effort to find better and cheaper treatments with fewer side effects, to reduce the incidence of the disease and its consequent mortality. For many years, phenolic compounds have been intensely studied for their antitumor, proapoptotic and antiangiogenic effects. In recent years, the usage of these compounds has increased considerably. This manuscript intends to structurally characterize the different phenolic compounds (flavonoids, hydroxycinnamates, hydroxybenzoates, coumarins, xanthones, chalcones, stilbenes, lignins and lignans) and their metabolic pathways as well as review the most important results regarding these compounds and their derivatives in cancer treatment and prevention both in tumor cell lines in vitro, in murine models in vivo and finally some results regarding human trials.Fundação para a Ciência e a Tecnologia (FCT, Portugal) and COMPETE/QREN/EU for research project PTDC/AGR-ALI/110062/2009 and to CIMO (strategic project PEst-OE/AGR/UI0690/2011)

Caracterização química de fungos micorrízicos e plantas de Pinus pinaster ao longo dos primeiros estádios de simbiose

A simbiose ectomicorrízica entre fungos e as raízes de algumas espécies de plantas pode ter efeitos importantes a nível da produção de compostos antioxidantes em ambos os simbiontes, como resultado de um processo de reconhecimento mútuo e como resposta à interacção. Neste trabalho, estudaram-se os efeitos do período de co-cultura entre germinantes da espécie florestal Pinus pinaster e as espécies de fungos ectomicorrízicos Pisolithus arhizus e Paxillus involutus nas propriedades antioxidantes e na produção de compostos com igual actividade (fenóis, tocoferóis e açúcares) dos simbiontes. Assim, avaliaram-se os primeiros estádios do processo de micorrização (6, 24 e 72h), testando-se todos os elementos (raízes, micélio e meio de cultura) de modo a compreender a resposta de cada um dos parceiros à simbiose. As propriedades antioxidantes foram determinadas através da realização de ensaios de avaliação da actividade captadora de radicais livres 2,2-difenil-1-picril-hidrazilo (DPPH), poder redutor, inibição da descoloração do β-caroteno e inibição da peroxidação lipídica pela diminuição da formação de espécies reactivas do ácido tiobarbitúrico (TBARS). As concentrações em fenóis, tocoferóis e açúcares foram obtidas pelo ensaio colorimétrico Folin Ciocalteus, por cromatografia líquida de alta eficiência (HPLC) acoplada a um detector de fluorescência e por HPLC acoplada a um detector de índice de refracção (RI), respectivamente. Os efeitos observados foram interpretados do ponto de vista ecológico (compreensão dos efeitos da associação micorrízica na produção de antioxidantes, nomeadamente a percepção se este mutualismo potencia a actividade antioxidante ou se, por outro lado, a inibe), mas também do ponto de vista medicinal (utilização das associações simbióticas para obtenção de antioxidantes). O fungo Pisolithus arhizus provou ser mais compatível com Pinus pinaster do que o Paxillus involutus, dado que a actividade antioxidante deste aumentou entre as 48 e as 72h, enquanto no Pisolithus arhizus essa actividade decresceu no mesmo período de tempo (podendo evidenciar menos stresse oxidativo). Apesar da espécie Paxillus involutus parecer ser menos indicada para programas de reflorestação que envolvam processos de micorrização, esta poderá ser uma fonte de compostos bioactivos pois revelou uma maior produção de compostos antioxidantes nos primeiros estádios da simbiose. De facto, a concentração máxima de fenóis foi obtida após as 6h. Desta forma, caso a finalidade seja a produção de compostos bioactivos, a co-cultura deverá ser interrompida neste período.Ectomycorrhizal symbiosis between fungi mycelia and the roots of some plants could have important effects in the levels of antioxidants of both parts. In the present work, the effects of co-culture period (6, 24 and 72h) in the antioxidant properties and antioxidants (phenolics, tocopherols and sugars) production during early steps of in vitro mycorrhization (Pisolithus arhizus-Pinus pinaster and Paxillus involutus-Pinus pinaster) were evaluated. The studied parameters were determined in each culture element (root, mycelium and medium) in order to understand the response of each partner to the symbiotic association. The antioxidant properties were determined by assays evaluating the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging activity, reducing power, β-carotene bleaching inhibition and lipid peroxidation inhibition by the decrease in tiobarbituric acid reactive substances (TBARS). The concentrations in phenolics, tocopherols and sugars were obtained by Folin Ciocalteus colorimetric assay, high performance liquid chromatography (HPLC) coupled to a fluorescence detector and HPLC coupled to a refraction index detector (RI), respectively. The observed effects were analyzed in the ecological (comprehension of the mycorrhizal association effects in the antioxidants production, understanding if the mutualism stimulates or inhibits the antioxidant activity) and medicinal (use of symbiotic associations to obtain antioxidants) perspectives. Pisolithus arhizus proved to be more compatible with Pinus pinaster than Paxillus involutus, since the antioxidant activity in the latter species increased from 48 to 72h, while Pisolithus arhizus antioxidant properties decreased at the same period (indicative of less oxidative stress). Although Paxillus involutus proved to be less suitable to be included in forestation programs using mycorrhization processes, it revealed a higher potential for bioactive compounds production in the early steps of symbiosis. A maximal value of phenolics content was obtained after the first 6h, and, therefore, considering bioactive compounds production purposes, the co-culture should be stopped at that time.Este trabalho insere-se no projecto de investigação PTDC/AGR-ALI/110062/2009, financiado pela Fundação para a Ciência e Tecnologia (FCT, Portugal) e pelo Programa COMPETE/QREN/EU

Natural food additives: Quo vadis?

In a time where the public is more aware and interested with what they eat, natural additives have been gaining interest both from the food industries and the consumers. Some studies show that consumers prefer food prepared with natural additives rather than chemical ones, due to health reasons. Although quite promising, natural additives still face some drawbacks and limitations as well as conflicting information. In this manuscript, the most important natural additives are overviewed, as well as their use, benefits and risks. The future of these molecules along with new types of additives are also summarized.The authors are grateful to the PRODER project No. 46577-PlantLact., and the Foundation for Science and Technology (FTC, Portugal) for financial support to the research centre CIMO (Pest-OE/AGR/UI0690/2014)

Aditivos antioxidantes

La química entre los radicales libres y antioxidantes se fundamenta en un equilibrio entre ambos. Los radicales libres son compuestos muy reactivos que tienden a captar un electrón de moléculas biológicas estables con el fin de alcanzar su estabilidad electroquímica. Una vez que el radical libre ha conseguido sustraer el electrón que necesita, la molécula estable que se lo cede se convierte, a su vez, en un radical libre al quedarse con un electrón desapareado, iniciándose así una verdadera reacción en cadena. La vida media biológica dei radical libre es de microsegundos, pêro tiene la capacidad de reaccionar con todo lo que este a su alrededor provocando dano molecular en membranas celulares y tejidos. Los radicales libres se pueden definir como "cualquier espécie química con un número impar de electrones, con uno o más electrones desapareados, que se encuentra de forma libre en el médio".info:eu-repo/semantics/publishedVersio

Antioxidants: Reviewing the chemistry, food applications, legislation and role as preservatives

Food antioxidants play a critical role in the food industry, and have become one of the most widespread methods of conserving food. Their cheapness and ease of use have made them a part of virtually all foodstuffs. Although different, all groups of food antioxidants have a same common objective, to conserve food for the longest possible time without altering it, conferring taste or color. Consumer trends have shifted the industry to find natural antioxidants for conservation, and although synthetic additives have been the mainstream, their natural counterparts have been gaining interest. Scope and approach This review focuses of the different antioxidant groups, describing their properties, function and applicability, as well as indexing the relevant legislation in order to be a guide for academia and industry. Key findings and conclusions The wide number of antioxidant additives allowed by the different countries if of synthetic origin, and consist of pure molecules. Although consumers are leaning toward natural additives, this offer is still quite limited despite the permission of rosemary extract within the European Union. There is still much work to be done in order to completely demystify the importance and safety of antioxidants as well as to harmonize legislation worldwide.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO ( UID/AGR/00690/2013 ). Author Márcio Carocho also thanks FCT for his post-doctoral grant SFRH/BPD/114650/2016info:eu-repo/semantics/publishedVersio

Manjericão como ingrediente bioativo em queijo da serra da estrela

como conservantes naturais e ingredientes bioativos em alimentos tem ganho cada vez mais interesse por parte das indústrias dada a excelente aceitabilidade por parte dos consumidores. O manjericão (Ocimum basilicum L.) é uma planta utilizada na alimentação humana, fazendo parte de molhos, sopas e outras preparações culinárias. Esta planta é também conhecida por aliviar dores e inflamações, reduzir a tosse e febre, entre outros efeitos benéficos. Assim o objetivo deste trabalho foi a incorporação de material desidratado de manjericão, bem como de extratos aquosos preparados por decocção em queijo da Serra da Estrela. Após a incorporação os queijos, estes foram deixados na unidade de transformação (Queijos Casa Matias, Lda) durante 1 mês para a cura e posteriormente trazidos para"la boratórioo ndef oram sujeitos a ensaiosd e atividade antioxidante à chegada. Ao mesmo tempo, foi também determinada a composição nutricional, bem como os ácidos gordos individuais (cromatografia gasosa) e composição mineral (espectroscopia de absorção atómica). Estes ensaios foram repetictos após 6 meses de maturação, a fim de verificar as alterações nutricionais sofridas durante esse tempo de maturação. Concluiu-se que a nível de bioatividade ambas as incorporações de manjericão conferiram atividade antioxidante ao queijo. Em termos nutricionais, os nutrientes mais abundantes no queijo da Serra da Estrela foram a gordura e as proteínas, enquanto que os ácidos gordos mais predominantes foram os saturados seguidos dos monoinsaturados. Os minerais mais abundantes foram o cálcio e o sódio. A funcionalização com manjericão acabou por conferir um aspeto e sabor distintos ao queijo, podendo ser utilizado como um novo produto no mercado lácteo. Por outro lado, em termos de benefícios para a saúde, as propriedades bioativas do manjericão foram detetadas no queijo através de ensaios de avaliação da atividade antioxidante. Os efeitos de conservação do manjericão foram detetadas através da conservação de alguns ácidos gordos insaturados. Este é mais um exemplo de como a incorporação de plantas em alimentos pode ser benéfica à indústria alimentar em três frentes distintas, na produção de novos produtos, nos benefícios para a saúde e na conservação de alimentos

Aditivos edulcorantes

El poder edulcorante es una de las propiedades más conocidas de los azúcares. Se determina en relación con la sacarosa, el azúcar de referencia (a una solución de 30 g/L a 20°C se lê asigna un poder edulcorante igual a l), y no depende unicamente de su concentración, sino también de la intensidad dei sabor dulce. Se calcula mediante la determinación dei umbral de percepción dei sabor o por comparación con la sustancia de referencia (sacarosa). El umbral de reconocimiento de la sensación dulce es la concentración mínima dei azúcar a la cual es posible percibir el sabor dulce [1-4 mM). La intensidad dei sabor dulce está condicionada a la solubilidad de la sustancia, de manera que, una vez solubilizada en la saliva, esta entra en contacto con el receptor. También depende de otros parâmetros, como son la estructura dei edulcorante, la temperatura, el pH, y de la presencia de otras sustancias que puedan interferir con los receptores dei sabor. Con respecto a la estructura, la intensidad dei sabor dulce suele disminuir a medida que aumenta el número de unidades de monosacáridos que conforme el edulcorante, siendo, por tanto, mucho menor en el caso de los oligosacáridos.info:eu-repo/semantics/publishedVersio

Plants as a source of natural preservatives for food application

One of the main challenges of the food industry has been the substitution of artificial additives for natural ones. In a world increasingly demanding for healthy foods, functional products, clean labels etc., it is urgent to develop safer,healthier altematives to preserve foods. Nature has been a fascinating source of distinct classes of compounds (e.g. phenolics, organic acids), recognizedfor their bioactive properties, namely antioxidants and antimicrobials, two essential attributes to be considered a natural preservative, in addition of having low/no toxicityeffectFoundation for Science and Technology (FCT, Portugal) for financiai support through national funds FCTIMCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LAIP/0007/2021). S. Heleno and M. Carocho thank FCT for their individual employment program- contract (CEECIND/00831/2018, CEECIND/03040/2017), and L. Barros thanks to the national funding by FCT through the institutional scientific employment program-contract for her contract. European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of the projects GreenHealth (Norte-Ol-0145-FEDER-000042) and co-promotion R&D project Bi04Drinks (NORTE-01-0247-FEDER-113508)info:eu-repo/semantics/publishedVersio

Teaching chemistry of natural products to young students: “Verão Ciência no IPB” case study

For some years the BioChemCore research group of School of Agriculture, Polytechnic Institute of Bragança (IPB), has conducted several one-week internships for young students in college, inserted in the program "Verão Ciência no IPB" (science summer in the IPB). These small courses aim to disseminate various aspects of the research conducted by our group, which include chemistry of natural products, nutraceuticals and functional foods, technology of natural products, and medicinal chemistry. In this case study, brief information was provided on all these topics, but highlighting the chemistry of natural products. This manuscript reports the assays, theory and goals achieved by the students enrolled in the internship, covering various aspects of chemistry and biochemistry, antioxidant activity. and finally the research on some bioactive molecules through high performance liquid chromatography. Although the receptiveness and motivation of students was high the details of the explanations were basic and (adjusted to their level of understanding) easy to comprehend. This yearly internship has been very successful over the various editions of the program, with an increasing number of students applying for it