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)

Neurocognitive improvement through plant food bioactives: A particular approach to Alzheimer's disease

Alzheimer’s disease (AD) is currently one of the most prevalent neurodegenerative disorders, directly related to increasing rates of morbidity and autonomy impairment between worldwide citizens. Social and demographical changes are direct contributors; notwithstanding, modern lifestyle, oxidative stress and its related diseases, and, consequently, premature aging are also important triggering factors (Sun et al. 2008; Ngo and Li 2013). Numerous drugs have been developed mainly to act as symptomatic agents, despite the serious side effects and increasing evidences of lack of effectiveness. Most of them were derived from plant-mimetic synthesis, but tenuous differences on their chemical structure and also the occurrence of synergisms in the pool of the whole plant phytochemicals are sufficient to provide considerable influences on the final biological potential (Ngo and Li 2013; Katalini et al. 2014; Ahmed et al. 2015). The use of medicinal plants, mainly through botanical preparations, is a millenary practice, which has been effectively used for a multitude of health conditions (Vanaclocha and Cañigueral 2003; Murray 2004; Murray and Pizzorno 2012). The interest for natural matrices is still increasing, not only to confirm its bioactive potential, but also to deepen knowledge on the modes of action, metabolism, bioavailability, bioefficacy, and active concentrations, aiming to develop upcoming and safer alternatives to the current ones. Among them, plant phytochemicals have shown to have promissory neurocognitive properties. In this sense, the present chapter aims to provide systematic information about the use of plant-food-derived bioactive molecules with evident in vitro and in vivo neuroprotective and neuroregenerative effects.info:eu-repo/semantics/publishedVersio

Stress oxidativo, antioxidantes e fitoquímicos

A manutenção do equilíbrio entre a produção de radicais livres e as defesas antioxidantes (enzimas e moléculas não enzimáticas) é uma condição essencial para o funcionamento normal do organismo. Quando este equilíbrio tende para a produção de radicais livres dizemos que o organismo está em stress oxidativo, e nestas situações os radicais livres em excesso podem oxidar e danificar lípidos celulares, proteínas e DNA, inibindo a sua função normal e conduzindo a várias doenças. Em organismos aeróbios, os radicais livres são constantemente produzidos durante o funcionamento normal da célula, na maior parte sob a forma de espécies reactivas de oxigénio (ROS) e de nitrogénio (RNS). A exposição dos organismos a radicais livres, conduziu ao desenvolvimento de mecanismos de defesa endógenos para os eliminar. Estas defesas são a resposta da evolução à inevitabilidade da existência de ROS em condições aeróbias. Alguns produtos naturais com actividade antioxidante, podem auxiliar o sistema protector endógeno. Nesta perspectiva, os antioxidantes presentes na dieta assumem grande importância como possíveis agentes protectores, reduzindo os danos oxidativos. São aqui descritos alguns desses agentes antioxidantes, os fitoquímicos, compostos bioactivos provenientes de diferentes partes de plantas (sementes, cereais, vegetais, frutos, folhas, raízes, especiarias, ervas) envolvidos na redução do risco de doença, como o cancro. Foram já identificados mais de 5000 fitoquímicos, no entanto, grande parte destes compostos é ainda desconhecida, sendo a sua identificação essencial para a compreensão da sua contribuição na saúde, ao serem incluídos na dieta. Maintenance of equilibrium between free radical production and antioxidant defences (enzymatic and non enzymatic) is an essential condition for normal organism functioning. When this equilibrium has a tendency to the production of free radical we say that the organism is in oxidative stress. In this situation, excess free radicals may damage cellular lipids, proteins and DNA, inhibiting his normal function and leading to various diseases. In aerobic organisms, the free radicals are constantly being produced during the normal cellular functioning, mainly in the form of Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS). Exposition of the organism to free radicals has led to the development of endogenous defence mechanisms to eliminate them. These defences were the response of evolution to the inevitability of ROS production in aerobic conditions. Natural products with antioxidant activity may help the endogenous defence system. In this perspective the antioxidant present on the diet assume a major importance as possible protector agents reducing oxidative damage. Phytochemicals with antioxidant activity, obtained from different plant parts (seeds, cereals, vegetables, fruits, leaves, roots, spices, herbs), and involved in disease risk reduction are review. More than 5000 phytochemicals were already discovered, but most of these compounds remain yet to be discovered. Their identification and the study of their contribution to health is essential

Extraction and detection of mycotoxins in medicinal and aromatic plants: a case studywith Melissa officinalis L.

Plants frequently suffer contaminations by toxigenic fungi, and their mycotoxins can be produced throughout growth, harvest, drying and storage periods. The objective of this work was to validate a method for detection of toxins in medicinal and aromatic plants, through a fast and highly sensitive method, optimizing the joint eo-extraction of aflatoxins (AF: AFB1, AFB2, AFG1 and AFG2) and ochratoxin A (OTA) by using Aloysia citrodora P. (lemon verbena) as a case study. For optimization purposes, samples were spiked (n=3) with standard solutions of a mix of the four AFs and OTA at 10 ng/g for AFB1, AFG1 and OTA, and at 6 ng/g of AFB2 and AFG2. Several extraction procedures were tested: i) ultrasound-assisted extraction in sodium chloride and methanol/water (80:20, v/v) [(OTA+AFs)1]; ii) maceration in methanol/1% NaHC03 (70:30, v/v) [(OTA+AFs)2]; iii) maceration in methanol/1% NaHC03 (70:30, v/v) (OTA1); and iv) maceration in sodium chloride and methanol/water {80:20, v/v) (AF1). AF and OTA were purified using the mycotoxin-specific immunoaffinity columns AflaTest WB and OchraTest WB (VICAM), respectively. Separation was performed with a Merck Chromolith Performance C18 column (100 x 4.6 mm) by reverse-phase HPLC coupled to a fluorescence detector (FLD) and a photochemical derivatization system (for AF). The recoveries obtained from the spiked samples showed that the single-extraction methods (OTA1 and AF1) performed better than eoextraction methods. For in-house validation of the selected methods OTA1 and AF1, recovery and precision were determined (n=6). The recovery of OTA for metl:lod OTA1 was 81%, and intermediate precision (RSDint) was 1.1%. The recoveries of AFB1, AFB2, AFG1 and AFG2 ranged from 64% to 110% for method AF1, with RSDint lower than 5%. Methods OTA1 and AF1 showed precision and recoveries within the legislated values and were found to be suitable for the extraction of OTA and AF for the matrix under study

Medicinal chemistry from fungi and back: discovery of novel anti-fungal drugs and mycotherapy of cancer and other diseases with fungal metabolites

Fungi are important organisms for human population and could find important applications namely, in many pharmaceutical and food industries. A variety of compounds has been isolated from medicinal and edible mushrooms, and their healthbeneficial effects have been reported. On the other hand, it is important to control microfungi as parasites and contaminants since they can provoke, in some cases, serious issues to human health. The following issue is devoted to recent findings in the fields of novel antifungal drugs, mycotherapy of cancer and other diseases with compounds recently isolated from fungi. It is covered by eight hot topic manuscripts from the mentioned relevant fields. A review on antifungal activity of mushrooms (Basidiomycetes) and their isolated compounds including high (e.g. peptides and proteins) and low (e.g. sesquiterpenes and other terpenes, steroids, organic acids, acylcyclopentenediones and quinolines) molecular weight compounds is presented. Furthermore, antioxidant protective effects of mushroom metabolites is presented covering antioxidant features of numerous compounds isolated from mushrooms, such as phenolic compounds, vitamins, polysaccharides, peptides, proteins, organic acids, carotenoids, alkaloids, and nucleotides. Cyclodextrins are usually used in antifungal formulations as auxiliary substances to improve solubility, stability, or other physicochemical properties of the active compound. Nevertheless, recent research and practical use results indicate that cyclodextrins might also act as active compounds in pharmaceutical formulations. Furthermore, Recent advances in synthesis of compounds and their biological evaluation considering antifungal activity is also presented, covering the broad spectrum of compounds from different chemical classes. Therapeutic properties of mushrooms in managing adverse effects in the metabolic syndrome deeply discusses the use of edible mushrooms, their extracts, polysaccharide fractions and isolated compounds as hypoglycaemic agents, as holders of cholesterol and triglyceride lowering ability, hypotensive agents, as well as weight managing holders. New and highly potent antitumor natural products from marine-derived fungi presents recent finding on cytotoxic activities of fungal compounds. Essential oils for the control of fungi and the production of aflatoxins, especially the most toxic aflatoxins B1 and G1, is essential and decisive, therefore highlighting the possibilities of utilizing essential oils in biological control of aflatoxin contamination. The last paper focuses on recent update of cytotoxic and antitumor activity of mushroom extracts and compounds belonging to the heteropolysaccharides, β-glucans, α-glucans, proteins, complexes of polysaccharides with proteins, fatty acids, nucleoside antagonists, terpenoids, sesquiterpenes, lanostanoids, sterols and phenolic compounds. Molecular mechanisms of cytotoxic and antitumor activities are briefly discussed

Chemical composition of Lactarius sp. mushrooms in different maturity stages.

Wild mushrooms are becoming more and more important in our diet for fheir nutritional value, inciuding high pratein and low fat/energy contenfs [1], Dikeman et 01, [2] reported lhe effects of stage o f maturity and cooking on the chemical composition of mushroom species commonly cultivated and consumed in the United Sfates, Nevertheless, there are no detailed studies on the influence in fatty acid and sugars pro flles, partic ularly on mushrooms from Northeast Portugal