Optimisation et caractérisation d’un extrait de cassis riche en antioxydants utilisable comme complément alimentaire et étude de ses effets sur la vasorelaxation dépendante de l’endothélium

Parmi les fruits les plus riches en antioxydants figure le cassis (Ribes nigrum) appartenant à la famille desSaxifragacées. Cet arbrisseau est très connu pour ses fruits, fortement aromatiques. Il est largement utilisé dansla production industrielle de sirops et de concentrés, contient des quantités très élevées en composés phénoliques,particulièrement des anthocyanes. Les bourgeons et les feuilles de cassis sont également utilisés en tant quecomplément alimentaire conseillé comme adaptogène tonique, diurétique ainsi que dans le traitementd’affections rhumatismales. Un objectif de ce travail était d’évaluer le cassis en tant que source d’antioxydantsen comparant différents organes (fruits, feuilles et bourgeons) prélevés sur différentes variétés à différentessaisons. Un autre but était de développer une procédure d’extraction permettant l’obtention de hauts rendementsen composés antioxydants et garantissant la stabilité de ceux-ci. Enfin, outre la caractérisation de l’extrait, unobjectif était aussi de démontrer certaines de ses activités biologiques.Dans un premier temps, le matériel végétal ainsi que la méthode d’extraction ont été optimisés. Les extraits lesplus riches en antioxydants stables ont été obtenus à partir de feuilles de cassis lyophilisées, par extraction dansle mélange acétone-eau-acide acétique (70 :28 :2) .Dans un second temps, nous avons caractérisé ces extraits au niveau de diverses classes de moléculesantioxydantes. Les feuilles et les bourgeons présentent un contenu plus élevé en flavonols, en flavanols et encomposés phénoliques totaux, par rapport aux baies. Par contre, les fruits présentent des teneurs plus élevées enacide ascorbique et en anthocyanes.Dans un troisième temps, nous avons analysé certaines propriétés-santé (la capacité antioxydante, la capacitéanti-inflammatoire et les propriétés vasorelaxantes) des extraits de cassis en utilisant tant des méthodes in vitroque des modèles sur culture de cellules et sur organe isolé. Notre étude a mis en évidence, tant au niveauintracellulaire qu’extracellulaire, des propriétés de piégeurs de radicaux libres, une activité inhibitrice de lamyéloperoxydase chez les neutrophiles, ainsi qu’une stimulation de la relaxation des vaisseaux sanguins(production de NO, modulation de l’expression de l’ARNm eNOS dans les cellules endothéliales et mise enévidence de l’effet relaxant sur organe isolé), et ce, sans présenter d’effets toxiques.En conclusion, l’extrait de feuilles de cassis obtenu par une extraction au mélange acétone-eau-acide acétiquepossède de nombreuses qualités tant au niveau nutritionnel qu’au niveau de la protection santé. Cet extrait, richeen composés phénoliques et possédant une haute activité antioxydante, peut également interagir sur l’activité decertaines enzymes impliquées dans les processus d’inflammation et de motricité vasculaire./Blackcurrant (Ribes nigrum, family Saxifragaceae) produces fruits with a high antioxidant content. This shrub ismuch known for its strongly aromatic fruits. It is largely used in the industrial production of syrups and ofconcentrates, it contains very high quantities of phenolic compounds, particularly anthocyanins. Blackcurrantbuds and leaves are also used as a food complement for their tonic and diuretic properties, as well as for thetreatment of rheumatic affections. With this plant, we tried to develop, on a laboratory scale, a flavonoid-richextract, stable in time and to show several biological activities.Initially, different plant materials were compared (fruits, leaves, buds, from different cultivars harvested atdifferent times) and the method of extraction were optimized. Lyophilised-leaf extracts obtained with theacetone-water-acetic acid mixture (70: 28: 2) show an excellent yield in antioxidant compounds. These freezedriedextracts have also the advantage of being stable for several months.We characterized these extracts for their content in various classes of antioxidant molecules. The leaves and thebuds yielded extracts containing mainly flavonols, flavanols and total phenolic compounds, as compared toberries. On the other hand, these fruits showed higher contents of ascorbic acid and anthocyanins.In a third part, we analyzed certain health-properties (antioxidant capacity, anti-inflammatory capacity and theproperties in vasorelaxation process) of the blackcurrant extracts by using in vitro methods as well as cellularand isolated organ models. Our study highlighted the intracellular and the extracellular properties of theblackcurrant extract as radical scavenger. We also showed an inhibition of the myeloperoxydase activity in theactivated neutrophils, and an activation of the vasorelaxation process of the blood-vessels (production of NO,modulation of the expression of ARNm eNOS in the endothelial cells and relaxing effect in isolated organ), andthis, without presenting any toxic effects.In conclusion, the black currant leaf extract obtained through extraction in acetone-water- acetic acid mixture hasmany interesting properties for health-protection. This extract, rich in phenolic compounds and having a highantioxidant activity, can also modulate the activity of several enzymes involved in inflammation or in vascularmotricity

Ex Vivo Antioxidant Capacities of Fruit and Vegetable Juices. Potential In Vivo Extrapolation

Background: In support of claims that their products have antioxidant properties, the food industry and dietary supplement manufacturers rely solely on the in vitro determination of the ORAC (oxygen radical antioxidant capacity) value, despite its acknowledged lack of any in vivo relevance. It thus appears necessary to use tests exploiting biological materials (blood, white blood cells) capable of producing physiological free radicals, in order to evaluate more adequately the antioxidant capacities of foods such as fruit and vegetable juices. Materials: Two approaches to as sessing the antioxidant capacities of 21 commercial fruit and vegetable juices were compared: the ORAC assay and the “PMA–whole blood assay,” which uses whole blood stimulated by phorbol myristate acetate to produce the superoxide anion. We described in another paper the total poly phenol contents (TPCs) and individual phenolic compound contents of all the juices investigated here (Matute et al. Antioxidants 2020, 9, 1–18). Results: Ranking of the juices from highest to lowest antioxidant capacity differed considerably according to the test used, so there was no correlation (r = 0.33, p = 0.13) between the two assays when considering all juices. Although the results of the ORAC assay correlated positively with TPC (r = 0.50, p = 0.02), a much stronger correlation (r = 0.70, p = 0.004) emerged between TPC and % superoxide anion inhibition. In the PMA–whole blood as say, peonidin-3-O-glucoside, epigallocatechin gallate, catechin, and quercetin present in juices were found to inhibit superoxide anion production at concentrations below 1 µM, with a strong positive correlation. Conclusions: Associated with the determination of total and individual phenolic com pounds contained in fruit and vegetable juices, the PMA–whole blood assay appears better than the ORAC assay for evaluating juice antioxidant capacit

Characterization of rich-antioxidant blackcurrant extract used as food complement and his effect on the endothelium-dependent relaxation

Blackcurrant (Ribes nigrum, family Saxifragaceae) produces fruits with a high antioxidant content. This shrub is much known for its strongly aromatic fruits. It is largely used in the industrial production of syrups and of concentrates, it contains very high quantities of phenolic compounds, particularly anthocyanins. Blackcurrant buds and leaves are also used as a food complement for their tonic and diuretic properties, as well as for the treatment of rheumatic affections. With this plant, we tried to develop, on a laboratory scale, a flavonoid-rich extract, stable in time and to show several biological activities. Initially, different plant materials were compared (fruits, leaves, buds, from different cultivars harvested at different times) and the method of extraction were optimized. Lyophilised-leaf extracts obtained with the acetone-water-acetic acid mixture (70: 28: 2) show an excellent yield in antioxidant compounds. These freeze-dried extracts have also the advantage of being stable for several months. We characterized these extracts for their content in various classes of antioxidant molecules. The leaves and the buds yielded extracts containing mainly flavonols, flavanols and total phenolic compounds, as compared to berries. On the other hand, these fruits showed higher contents of ascorbic acid and anthocyanins. In a third part, we analyzed certain health-properties (antioxidant capacity, anti-inflammatory capacity and the properties in vasorelaxation process) of the blackcurrant extracts by using in vitro methods as well as cellular and isolated organ models. Our study highlighted the intracellular and the extracellular properties of the blackcurrant extract as radical scavenger. We also showed an inhibition of the myeloperoxydase activity in the activated neutrophils, and an activation of the vasorelaxation process of the blood-vessels (production of NO, modulation of the expression of ARNm eNOS in the endothelial cells and relaxing effect in isolated organ), and this, without presenting any toxic effects. In conclusion, the black currant leaf extract obtained through extraction in acetone-water- acetic acid mixture has many interesting properties for health-protection. This extract, rich in phenolic compounds and having a high antioxidant activity, can also modulate the activity of several enzymes involved in inflammation or in vascular motricity.Parmi les fruits les plus riches en antioxydants figure le cassis (Ribes nigrum) appartenant à la famille des Saxifragacées. Cet arbrisseau est très connu pour ses fruits, fortement aromatiques. Il est largement utilisé dans la production industrielle de sirops et de concentrés, contient des quantités très élevées en composés phénoliques, particulièrement des anthocyanes. Les bourgeons et les feuilles de cassis sont également utilisés en tant que complément alimentaire conseillé comme adaptogène tonique, diurétique ainsi que dans le traitement d’affections rhumatismales. Un objectif de ce travail était d’évaluer le cassis en tant que source d’antioxydants en comparant différents organes (fruits, feuilles et bourgeons) prélevés sur différentes variétés à différentes saisons. Un autre but était de développer une procédure d’extraction permettant l’obtention de hauts rendements en composés antioxydants et garantissant la stabilité de ceux-ci. Enfin, outre la caractérisation de l’extrait, un objectif était aussi de démontrer certaines de ses activités biologiques. Dans un premier temps, le matériel végétal ainsi que la méthode d’extraction ont été optimisés. Les extraits les plus riches en antioxydants stables ont été obtenus à partir de feuilles de cassis lyophilisées, par extraction dans le mélange acétone-eau-acide acétique (70 :28 :2) . Dans un second temps, nous avons caractérisé ces extraits au niveau de diverses classes de molécules antioxydantes. Les feuilles et les bourgeons présentent un contenu plus élevé en flavonols, en flavanols et en composés phénoliques totaux, par rapport aux baies. Par contre, les fruits présentent des teneurs plus élevées en acide ascorbique et en anthocyanes. Dans un troisième temps, nous avons analysé certaines propriétés-santé (la capacité antioxydante, la capacité anti-inflammatoire et les propriétés vasorelaxantes) des extraits de cassis en utilisant tant des méthodes in vitro que des modèles sur culture de cellules et sur organe isolé. Notre étude a mis en évidence, tant au niveau intracellulaire qu’extracellulaire, des propriétés de piégeurs de radicaux libres, une activité inhibitrice de la myéloperoxydase chez les neutrophiles, ainsi qu’une stimulation de la relaxation des vaisseaux sanguins (production de NO, modulation de l’expression de l’ARNm eNOS dans les cellules endothéliales et mise en évidence de l’effet relaxant sur organe isolé), et ce, sans présenter d’effets toxiques. En conclusion, l’extrait de feuilles de cassis obtenu par une extraction au mélange acétone-eau-acide acétique possède de nombreuses qualités tant au niveau nutritionnel qu’au niveau de la protection santé. Cet extrait, riche en composés phénoliques et possédant une haute activité antioxydante, peut également interagir sur l’activité de certaines enzymes impliquées dans les processus d’inflammation et de motricité vasculaire.Optimisation et caractérisation d’un extrait de cassis riche en antioxydants utilisable comme complément alimentaire et Etude de ses effets sur la vasorelaxation dépendante de l’endothéliu

Effect of polyamines or precursors on the hyperhydricity process in micropropagated apple trees.

peer reviewedHyperhydricity is a physiological disorder affecting tissue-culture-generated plants. It is associated with excessive hydration and poor lignification. The effects of exogenous polyamines (spermidine and putrescine) and polyamine precursors (arginine and ornithine) were studied on ‘Jonagold’ apple shoots subjected to hyperhydric conditions for one in vitro multiplication cycle (28 days) on a culture medium containing gelrite as gelling agent. Supplementation of the gelrite-containing medium with 10-5 M spermidine, ornithine, or arginine reduced the percentage of hyperhydricity by at least 50%. Exogenous supplementation with spermidine or a polyamine precursor also caused total phenolics and the antioxidant capacity (measured by ORAC and DPPH assays) to decrease in shoots during the first two weeks. These results suggest an important role of spermidine and its precursor ornithine in countering hyperhydricity. Supplementation could help to maintain high endogenous levels of polyamines and phenolamides necessary for cell osmoregulation, antioxidant protection, cell wall cross-linking, and plant growth regulation

Processing effects on antioxidant, glucosinolate and sulforaphane contents in broccoli and red cabbage

peer reviewedThe objective of this study is to investigate the effects of three home cooking methods traditionally used all around the world (boiling, steaming and microwaving) in two vegetables: broccoli and red cabbage. Their effects on phytochemical content (i.e., polyphenols, ascorbic acid, anthocyanins, glucosinolates and sulforaphane) and on total antioxidant capacity were investigated. Steaming and microwaving were explored to understand the effect of cooking time and/or cooking power. Nutrient and health-promoting compounds in broccoli and red cabbage are significantly affected by domestic cooking. The boiling seems to result in a very significant loss of nutritional compounds by leaching in cooking water. However, steaming and microwaving allowed the preservation of the higher quantities of bioactive compounds such as antioxidant compounds and glucosinolates. Microwave cooking significantly influenced the concentrations of bioactive compounds such as ascorbic acid, anthocyanins and sulforaphane. Sulforaphane content increased 4 or 6 times during the first minute of microwaving in the two vegetables

The Total Antioxidant Capacity of Foods: a reappraisal. Application to commercial orange juices

Since a few years, more and more attention has been specifically given to dietary antioxidants as agents promoting health and preventing the incidence of diseases. As part of these efforts, analytical methods and assays have been developed to measure the antioxidant content in food substances. In this paper, the antioxidant capacity of 17 orange juices is determined by various assays (DPPH, ORAC, heamolysis, xanthine/xanthine oxidase) as the content in ascorbic acid and total phenolics. The results evidence all the complexity to evaluate the in vitro antioxidant capacity of foods. In very general terms, in spite of the wide utilization in these tests (FRAP, TAC, ORAC TRAP and others), their significance remains obscure. The discrepancy of the results and the absence of good correlation between the assays clearly highlight all the importance of understanding the strengths and weakness of assays evaluating antioxidant potential of a food at the risk of giving erroneous information to the consumer. It is clear that the use of "total antioxidant capacity" assays for the in vitro assessment of antioxidant quality of food does not be employed by food industrials as a marketing argument or for the assessment of the "wholesomeness" of a food

Effects of 2,4-dichlorophenoxyacetic acid combined to 6-Benzylaminopurine on callus induction, total phenolic and ascorbic acid production, and antioxidant activities in leaf tissue cultures of Crataegus azarolus L. var. aronia

peer reviewedThe present research work describes the effects of 2,4-dichlorophenoxyacetic acid (2,4-D)/6-Benzylamino-purine (BAP) ratio on callus induction, total phenols and ascorbic acid production and antioxidant activities in leaf-derived calli of Crataegus azarolus (hawthorn). The supplementation of 1.0 mg/L 2,4-D and 1.0 mg/L BAP to MS medium was found to be the most efficient for callus induction (as percentage and fresh weigh). The results of biochemical analysis showed that the highest total phenols contents were obtained in callus cultured on MS medium supplemented with 2.0 mg/L 2,4-D and 1.0 mg/L BAP (52 ± 0.56 mg GAE/g DM) and were significantly lower than those of intact leaves (76 ± 1.72 mg GAE/g DM). However, the highest ascorbic acid contents were found in callus cultured on MS supplemented with 1.0 mg/L 2,4-D and 0.5 mg/L BAP (0.96 ± 0.13 mg AAE/g DM) and these amounts were statistically similar to those found in leaves tissues (0.74 ± 0.07 mg AAE/g DM). Antioxidant activities of callus extracts were determined using two TEAC assays and results showed that extract of callus cultured on MS medium supplemented with 2.0 mg/L 2,4-D and 1.0 mg/L BAP have the greatest antiradical activities against DPPH (124 ± 2.92 mg TE/g DM) and ABTS (0.19 ± 0.02 mg TE/g DM) compared to the leaves of field-grown plant. Thus, the use of high level of 2,4-D over BAP can be suitable to enhance the quality more than the quantity of bioactive compounds in leaf callus culture of hawthorn

Antioxidant capacity of black currant varies with organ, season, and cultivar

Small berries such as black currant constitute one of the important sources of potential health-promoting phytochemicals because these fruits are rich sources of compounds with high antioxidant properties. In this work, antioxidant capacities of different parts (buds, leaves, fruits) of various black currant cultivars were compared throughout the growing season with the aim to prepare extracts with high antioxidant capacity. Buds (opened, at the end of March) and leaves (in June) had a higher content in phenolics and antioxidants than fully ripened berries (in July) and the best yield (per branch) was obtained with the leaves collected in June due to their higher biomass. The differences observed among the eight cultivars tested were small. Concerning flavonols, quercetin was dominant in all organs and cultivars, myricetin varied widely among the cultivars, and kampferol was very low

Comparative antioxidant capacities of phenolic compounds measured by various tests

The purpose of this study was to compare the antioxidant capacities of standard compounds (phenolic compounds, ascorbic acid, and glutathione) as measured by various assays. Five methods were selected so as to span a diversity of technical approaches: TEAC (radical 2,2′-azino-bis(3-ethylbenzothiazoline)-6 sulphonic acid), DPPH (radical 2,2-diphenyl-1-picryhydrazyl used to measure reducing capacity), ORAC (oxygen radical scavenging capacity), red blood cell haemolysis (protection of biological sample), and ESR (electron spin resonance for direct free radical evaluation). Most compounds showed significant differences in free radical scavenging activity according to the method used. Of the 25 tested compounds, only a few, such as myricetin and gallocatechin, gave comparable activities in the various tests. To standardise reporting on antioxidant capacity, it is proposed to use a weighted mean of the values obtained using the DPPH, ORAC, resistance to haemolysis, and ESR assays. This strategy was used to test the antioxidant capacity of several beverages. The highest antioxidant capacity was observed for red wine, followed by green tea, orange juice, grape juice, vegetable juice, and apple juice