Aflatoxines : Toxiques redoutables dans nos aliments

Les aflatoxines sont des métabolites produits par des moisissures du genre Aspergillus et plus particulièrement A. flavus et A. parsiticus se développant sur différents produits alimentaires. Ainsi, on les trouve dans les céréales, le maïs, le riz et aussi dans les graines de coton, les épices et le lait. Ces mycotoxines sont connues pour leur grande toxicité et leurs effets mutagéniques, tératogéniques et carcinogéniques. C’est ainsi que de nombreux pays ont instauré une législation stricte quand aux quantités maximales admissibles des aflatoxines dans les aliments. La protection contre d’éventuelles aflatoxicoses reste évidente. Seul le contrôle continu des aliments assure leur innocuité. Des techniques performantes et sensibles sont largement utilisées pour ces fins sécuritaires

LE TRAITEMENT THERMIQUE DETRUIT – IL LA VALEUR NUTRITIVE DU LAIT COMMERCIALISE AU MAROC ?

Milk is as a nutrient-rich liquid which provides an ideal environment for microbial growth. The heat treatment ensure its safety et enhance his shelf life. Severe heat treatment of milk caused substantial damage to several vitamins and proteins components especially essential amino-acids. International Dairy Federation recommends the use of lactulose measurement as an indicator of heat treatment severity in milk and consequently the nutritional quality loss. In this study, more than 100 milk samples were collected from different regions in Morocco between 1999 and 2013. These samples were analyzed and the lactulose was quantified by Seliwannoff spectrophotometric method. Results showed that more than 47% and more than 62%, of respectively pasteurized and UHT milk samples, contain more than 600 mg/L of lactulose. Consequently these samples could be classified as sterilized products which mean that are of low nutritional value. Enzymatic activity and HMF (hydroxy Methyl Furfural) measurements on some milk samples prove the high amounts of lactulose found. Results and reasons of high lactulose levels occurrence in processed milk is discussed.Le lait est considéré comme vecteur de contaminants microbiologiques. Son traitement thermique assure sa salubrité et augmente sa durée de vie. Cependant, des traitements intenses sont à l’origine de perte de vitamines et d’acides aminés essentiels à la vie humaine. La Fédération International de Laiterie (FIL) et l’Union Européenne ont recommandé la mesure du lactulose comme indicateur de la sévérité du traitement thermique et par conséquent de la dégradation de la qualité nutritionnelle du lait. Plus de 100 échantillons de lait collectés sur différentes régions du royaume au cours de la période 1999 - 2013 ont été analysés par une méthode spectrophotométrique dite Seliwannoff afin d'y quantifier le lactulose. Les résultats montrent que plus de 47% des échantillons de lait pasteurisé et plus de 62% des échantillons de lait UHT contiennent plus de 600 mg/L de lactulose ce qui les classent dans la catégorie des laits stérilisés c'est-à-dire de faible valeur nutritive. Des mesures d’activité enzymatique et de concentration de l’hydroxy Méthyl Furfural (HMF) confirment les teneurs élevés de lactulose. Les raisons de la dégradation de la valeur nutritive du lait sont discutées

Enzyme inhibition-based biosensors for food safety and environmental monitoring

Analytical technology based on sensors is an extremely broad field which impacts on many major industrial sectors such as the pharmaceutical, healthcare, food, and agriculture industries as well as environmental monitoring. This review will highlight the research carried out during the last 5 years on biosensors that are based on enzyme inhibition for determination of pollutants and toxic compounds in a wide range of samples. Here the different enzymes implicated in the inhibition, different transducers forming the sensing devices, and the different contaminants analyzed are considered. The general application of the various biosensors developed, with emphasis on food and environmental applications, is reviewed as well as the general approaches that have been used for enzyme immobilization, the enzyme catalysis, and the inhibition mechanism. © 2005 Elsevier B.V. All rights reserved

Recent Advances in Electrochemical Biosensors Based on Enzyme Inhibition for Clinical and Pharmaceutical Applications

A large number of enzyme inhibitors are used as drugs to treat several diseases such as gout, diabetes, AIDS, depression, Parkinson’s and Alzheimer’s diseases. Electrochemical biosensors based on enzyme inhibition are useful devices for an easy, fast and environment friendly monitoring of inhibitors like drugs. In the last decades, electrochemical biosensors have shown great potentials in the detection of different drugs like neostigmine, ketoconazole, donepezil, allopurinol and many others. They attracted increasing attention due to the advantage of being high sensitive and accurate analytical tools, able to reach low detection limits and the possibility to be performed on real samples. This review will spotlight the research conducted in the past 10 years (2007–2017) on inhibition based enzymatic electrochemical biosensors for the analysis of different drugs. New assays based on novel bio-devices will be debated. Moreover, the exploration of the recent graphical approach in diagnosis of reversible and irreversible inhibition mechanism will be discussed. The accurate and the fast diagnosis of inhibition type will help researchers in further drug design improvements and the identification of new molecules that will serve as new enzyme targets

Extraction and detection of pesticides by cholinesterase inhibition in a two-phase system: a strategy to avoid heavy metal interference

Abstract: A novel method of extraction has been developed to avoid the presence of heavy metals during the measurement of pesticides based on acetylcholinesterase (AchE) inhibition. Heavy metals have been in fact demonstrated in this article to interfere when the assay is performed by using the classic spectrophotometric Ellman's method. We present the results obtained with an assay system using two different phases, one organic and the other aqueous, in which the pesticide and the enzyme are, respectively, solubilized. In a first step, the concentration of the substrate acetylthiocholine (1 mM), of the enzyme (7 mU mL 21 ), and the reaction time (20 min) for measurement of enzyme activity were optimized in aqueous solution. Next, the effect of an organic phase on the enzyme activity was studied by the addition of various solvents with the activity being evaluated after 10 min of mixing. It was found that by using hexane, the enzyme retained almost 100% of its 1703 activity, and this solvent was chosen for further development of the pesticide assay. Hexane was spiked with different concentrations of pesticides and then added to the enzyme aqueous phase. The pesticides were shown to be able to inhibit the enzyme by interaction at the interface between the two solutions. The degree of inhibition obtained with increasing amounts of pesticide was evaluated. A 50% inhibition was observed for a paraoxon solution of 9 Â 10 27 M

Phytochemistry, Biological Activities, Therapeutic Potential, and Socio-economic Value of Caper (Capparis spinosa L.)

Capparis spinosa L., known as caper, is an aromatic plant growing in most of the Mediterranean basin and some parts in the west of Asia. C. spinosa L. has been utilized as a medicinal plant for quite a long time in conventional phytomedicine. Polyphenols and numerous bioactive chemicals extracted from C. spinosa L. display various therapeutic properties that have made this plant a target for further research as a health promoter. This review is meant to systematically summarize the traditional uses, the phytochemical composition of C. spinosa L., and the diverse pharmacological activities, as well as the synthetic routes to derivatives of some identified chemical components for the improvement of biological activities and enhancement of pharmacokinetic profiles. This review also addresses the benefits of C. spinosa L. in adapting to climate change and the socio-economic value that C. spinosa L. brings to the rural economies of many countries