References of "Kevers, Claire"
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See detailPhytochemical studies, antioxidant activity and total phenolic content of Ferula communis L. organ extracts
Rahali, Fatma Zohra; Kefi, Sarra; Rebey, Iness Bettaieb et al

in Plant Biosystems (in press)

The present study aimed to assess antioxidant activities of three organs (flower, fruit and stem) extracts of Tunisian Ferula (F.). Various experimental models were used for the characterization of ... [more ▼]

The present study aimed to assess antioxidant activities of three organs (flower, fruit and stem) extracts of Tunisian Ferula (F.). Various experimental models were used for the characterization of antioxidant activities, in vitro and using dichlorofluorescein (DCF) induced fluorescence techniques from phorbol myristate acetate (PMA ) stimulated human myeloid cell line HL-60communis. Results showed that the antioxidant activities varied considerably with organs. Thus, flower exhibited higher DPPH• scavenging ability, reducing and chelating power than stem and fruit. Moreover antioxidant capacities using ORAC method and a cell based-assay showed that fruit and stem exhibited statistically similar antioxidant activities. Moreover, F. communis contains high amounts of flavonoids with various health benefits as antioxidant properties attributed to their antioxidant potential. Likewise, to obtain biologically relevant information, the antioxidant activities of the extracts were evaluated on cellular models implicating the antioxidant activities; this test generally showed that F. communis flower extracts have the highest antioxidant capacities correlated to the highest total phenolic content. The identification of phenolic compounds in F. communis extracts using RP-HPLC revealed that resorcinol, ferulic and syringic acids together with coumarin were the major molecules. [less ▲]

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See detailThe potency of commercial blackcurrant juices to induce relaxations in porcine coronary artery rings is not correlated to their antioxidant capacity but to their anthocyanin content
Tabart, Jessica ULiege; Auger, Cyril; Kevers, Claire ULiege et al

in Nutrition (2018), 51-52

Objective: Polyphenol-rich products such as fruit juices have been shown to have strong antioxidant capacities and to induce potent endothelium-dependent relaxations. We have evaluated whether the ... [more ▼]

Objective: Polyphenol-rich products such as fruit juices have been shown to have strong antioxidant capacities and to induce potent endothelium-dependent relaxations. We have evaluated whether the commercial blackcurrant juices induced endothelium-dependent relaxation of isolated coronary arteries can be related to their antioxidant capacity and/or phenolic content. Research Methods & Procedures: Six different commercial blackcurrant juices were selected. Their main phenolic compounds were measured by UPLC and antioxidant capacity was evaluated by spectrometric methods. Vascular reactivity studies with these juices were done using isolated porcine coronary arteries. Results: The six different commercial blackcurrant juices induced relaxations ranging from 21 to 100 % at the concentration of 0.5% v/v. The relaxation induced at 0.5 % v/v was not correlated to their antioxidant capacity measured by either ORAC or DPPH assays, and also not to the ascorbic acid, total polyphenols, total flavonols and total phenolic acid contents. In contrast, the amplitude of the relaxation was correlated to the total anthocyanins content and the individual anthocyanin concentration. Conclusions: Correlations between relaxation amplitude and total anthocyanin or individual anthocyanin contents are of interest for the development of functional blackcurrant beverages with the potential to promote vascular protection. [less ▲]

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See detailFacteurs permettant d’améliorer la réussite au greffage des clones GT1 et PB217 d’Hevea brasiliensis (H.B.K.) (Muell.Arg) dans les conditions climatiques du nord Gabon
ONDO OVONO, Paul; KEBANGOYE, Held-Stéphane; MEDZA MVE, Samson Daudet et al

in Journal of Animal and Plant Sciences (2018), 35(3), 5749-5762

This work was undertaken in 2013, at the nursery in Baturi, to determine the main factors that influence the success of Hevea brasiliensis transplant in climatic conditions in northern Gabon. The study ... [more ▼]

This work was undertaken in 2013, at the nursery in Baturi, to determine the main factors that influence the success of Hevea brasiliensis transplant in climatic conditions in northern Gabon. The study was conducted by ten grafters, during four months (June- September) according to a factorial device comprising 4 treatments and 4 replications. Two rubber clones (GT1 and PB 217) were used with two methods of rootstocks transplanting: in polyethylene bags and in the ground. Assessed parameters were the number of successful transplants and the graft success rate, by clones and by transplanting method, the grafting period and the origin of grafting wood. The results of the trial showed that, on the number of successful grafts and the clone graft success rate, by clones, by grafting method and by month, there are highly significant differences (P<0.0001) at the threshold of 5%. As for the success rate, the clone GT1 gives better results (57.1%) compared to the clone PB 217 (40.9%). Transplanting into a polyethylene bag is better (57.2%) compared to the nursery in the ground (40.8%). Over the grafting period, the good results are obtained in September. The origin of the graft wood also has a highly significant effect (P<0.0001) at the threshold 5%. However, the grafted wood from the Olam Rubber graft garden gives better results. A significant interaction clone*seedbed, clone*month was also determined at the 5% level. The results also show that the technicality of the grafters has no influence on the outputs obtained regardless of the method of rootstock transplanting. [less ▲]

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See detailPolyphenol content and antioxidant capacity in various commercial juices
Matute Matute, Alexis Fernando ULiege; Tabart, Jessica; CHERAMY-BIEN, Jean-Paul ULiege et al

Poster (2016, November 16)

Antioxidants are enzymes, non-enzymatic proteins, minerals micronutrients, vitamins, phenolic compounds, pigments and others. Polyphenols have the ability to reduce or prevent damage caused by free ... [more ▼]

Antioxidants are enzymes, non-enzymatic proteins, minerals micronutrients, vitamins, phenolic compounds, pigments and others. Polyphenols have the ability to reduce or prevent damage caused by free radicals promoting positive effects on human health due to their antioxidant capacity. In this study we evaluated the content of polyphenols from several commercial biological (n = 6) and conventional juices (n = 6 ) (orange, blackcurrant, apple, grapes, tomato, carrot, pomegranate, lemon, grapefruit juices) and we determined the antioxidant effect by inhibition of the superoxide anion production measured by chemiluminescence technology. Conventional juices (orange, apple, tomato, pomegranate, lemon, grapefruit juices) showed more total polyphenolics (+ 32%), more flavan-3-ols (+ 67%) and more flavonols (+ 42%) than the same biological juices. The presence of anthocyanins was reported in juices made with blackcurrant, pomegranate and grapes only, with values above 50 µg/mL, regardless of their nature. Surprisingly, chemiluminescence results showed an inhibition in superoxide anion production by 51% for biological juices vs 23% in conventional ones. The correlation between total polyphenol content and antioxidant capacity of all the juices was r = 0.83 (r2 = 0.7). The fact that there is less polyphenols and higher antioxidant activity in bio juices could be related to the concentration and the type of polyphenol present. [less ▲]

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See detailMonitoring of anatabine release by methyl jasmonate elicited BY-2 cells using surface-enhanced Raman scattering
De Bleye, Charlotte ULiege; Dumont, Elodie ULiege; Dispas, Amandine ULiege et al

in Talanta (2016), 160

A new application of surface-enhanced Raman scattering (SERS) in the field of plant material analysis is proposed in this study. The aim was to monitor the release of anatabine by methyl jasmonate (MeJa ... [more ▼]

A new application of surface-enhanced Raman scattering (SERS) in the field of plant material analysis is proposed in this study. The aim was to monitor the release of anatabine by methyl jasmonate (MeJa) elicited Bright Yellow-2 (BY-2) cells. Gold nanoparticles (AuNps) were used as SERS substrate. The first step was to study the SERS activity of anatabine in a complex matrix comprising the culture medium and BY-2 cells. The second step was the calibration. This one was successfully performed directly in the culture medium in order to take into account the matrix effect, by spiking the medium with different concentrations of anatabine, leading to solutions ranging from 250 to 5000 µg L-1. A univariate analysis was performed, the intensity of a band situated at 1028 cm-1, related to anatabine, was plotted against the anatabine concentration. A linear relationship was observed with a R2 of 0.9951. During the monitoring study, after the MeJa elicitation, samples were collected from the culture medium containing BY-2 cells at 0, 24h, 48h, 72h and 96h and were analyzed using SERS. Finally, the amount of anatabine released in the culture medium was determined using the response function, reaching a plateau after 72h of 82 µg of anatabine released / g of fresh weight (FW) MeJa elicited BY-2 cells. [less ▲]

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See detailEffect of Ribes nigrum leaf extracts on endothelium-dependent vasorelaxation
Tabart, Jessica; Shini-Kerth, Valérie; PINCEMAIL, Joël ULiege et al

Poster (2016, April 22)

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See detailHigh anthocyanins content of commercial blackcurrant juices induced endothelium-dependent relaxation in isolated porcine coronary arteries
Kevers, Claire ULiege; Shini-Kerth, Valérie; Tabart, Jessica et al

Poster (2016, April 22)

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See detailThe leaf extract of Ribes nigrum L. is a potent stimulator of the endothelial formation of NO in cultured endothelial cells and porcine coronary artery rings
Tabart, Jessica; Schini-Kerth, Valérie; PINCEMAIL, Joël ULiege et al

in Journal of Berry Research (2016), 6

BACKGROUND: Endothelial dysfunction is a major hallmark of most types of cardiovascular diseases. Numerous plant extracts have been shown to cause endothelium-dependent relaxations by increasing the ... [more ▼]

BACKGROUND: Endothelial dysfunction is a major hallmark of most types of cardiovascular diseases. Numerous plant extracts have been shown to cause endothelium-dependent relaxations by increasing the endothelial formation of the potent vasoprotective factor, nitric oxide (NO). OBJECTIVE: The ability of different Ribes nigrum L. extracts (Grossulariaceae) to induce endothelium-dependent relaxation by stimulating the endothelial formation of NO was assesssed. METHODS: Ribes nigrum extracts were prepared from buds, berries and leaves by extraction (Acetone:H2O:Acetic Acid; 70/28/2 (v/v/v)) and lyophilized after acetone evaporation. The ability of the extracts to stimulate the endothelial formation of NO was assessed using cultured endothelial cells and isolated porcine coronary artery rings. RESULTS: The Ribes nigrum leaf extract increased to a greater extent than the bud and the berry extracts the formation of NO, and up-regulated eNOS mRNA expression in cultured endothelial cells (the stimulatory effects amounted to 197 ± 9 %, 134 ± 6 % and 118 ± 5 %, respectively). The leaf extract induced greater relaxations of isolated coronary arteries with endothelium than the bud and the berry extracts whereas no such effects were observed in rings without endothelium. Relaxations to the leaf extract were minimally affected by indomethacin and by inhibitors of endothelium-dependent hyperpolarization response, and markedly reduced by NG-nitro-L-arginine. CONCLUSIONS: The present findings indicate that the Ribes nigrum leaf extract is a more potent inducer of the endothelial formation of NO than the bud and the berry extracts. [less ▲]

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See detailEffects of planting methods and tuber weights on growth and yield of yam cultivars (Dioscorea rotundata Poir.) in Gabon
ONDO OVONO, Paul; Kevers, Claire ULiege; Dommes, Jacques ULiege

in International Research Journal of Agricultural Science and soil Science (2016), 6

A study was conducted to investigate the influence of planting methods and tuber weight on growth and yield of local yam cultivars obtained by the minisett technique from white yam (D. rotundata) in Gabon ... [more ▼]

A study was conducted to investigate the influence of planting methods and tuber weight on growth and yield of local yam cultivars obtained by the minisett technique from white yam (D. rotundata) in Gabon. Trials were carried out in 2014 and 2015 at the experimental ground of the Higher National Institute of Agronomy and Biotechnology, under natural conditions of lightness, temperature and relative humidity. Twenty- four weeks old mini tubers obtained from local cultivar MVA of D. rotundata were harvested, weighed and categorized ( 40-80 g; 100-150 g; 200-300 g), and three planting methods (horizontal, oblique and vertical), arranged in ridges constituted the main factors. The experiment was laid out in Randomized Completely Block Design with eighteen treatments and two replications. Data pertaining to sprouting were recorded for 30, 60, 90 and 180 DAP, for tuber length (cm), tuber weight (Kg) and number of tubers per plant 270 DAP. Significant differences among tuber weight in all variables tested were observed. The larger tubers had better sprouting ability than the rest of the tuber weight. The methods of planting had no effects on yield and its components but they affect the depth and spread of tubers. Vertical planting produced deeper but more compactly arranged tubers while horizontal planting produced tubers which were shallower but more widespread. Slanting was intermediate for both depth and spread. The number and weight of tubers obtained from mini tubers planted out according to slanting method were significantly different (P< 0.05) from other planting methods. The production of seedlings from mini tuber is an improvement of traditional production of seed yam. Mini tubers must have at least 100-300 g and they should be planted slanting or vertically. [less ▲]

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See detailDetermination of total phenolic compounds content and antioxidant activity in cherry species and cultivars
Pissard, Audrey; Lateur, Marc; Baeten, V et al

in Journal of Berry Research (2016)

BACKGROUND: Several studies have shown that cherries, especially sour cultivars, contain substantial amounts of phenolic compounds. OBJECTIVE: This study aims to (i) analyze the total phenolic compound ... [more ▼]

BACKGROUND: Several studies have shown that cherries, especially sour cultivars, contain substantial amounts of phenolic compounds. OBJECTIVE: This study aims to (i) analyze the total phenolic compound (TPC) content and the antioxidant capacity (AC) of a large range of cultivars using the same methodology in one laboratory, and (ii) determine the possible relationship between agronomic characteristics and AC. METHODS: A total of 245 samples including sweet, sour and hybrid cultivars from our collections were harvested at their optimum maturity and characterized according to their TPC, DPPH and ORAC values. RESULTS: The TPC content and DPPH and ORAC values varied greatly among the cherries, with the sour cultivars presenting higher levels than the sweet ones. The PCA plot showed a slight grouping by species and confirmed the high TPC content level in sour cultivars. The bi-colored cultivars had lower TPC and antioxidant capacity (AC) values than dark-colored ones, indicating that coloration could give an indication of the AC of fruits. No significant relationship between the agronomic and chemical properties was highlighted. CONCLUSIONS: Cherry fruits, especially from sour cultivars, represent an important source of bioactive compounds and could attract new interest as a ‘functional food’. [less ▲]

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See detailAnthocyanin-rich blackcurrant juice induces a redox-sensitive caspase 3-related pro-apoptotic effect in leukemia Jurkat cells: role of delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside
Leon-Gonzalez; Sharif, T; Kayali, A et al

in 7th International Conference on Polyphenols and Health (2015, October)

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See detailDelphinidin-3-O-glucoside and delphinidin-3-O-rutinoside mediate the redoxsensitive caspase 3-related pro-apoptotic effect of blackcurrant juice on leukaemia Jurkat cells
Leon-gonzalez, Antonio; Sharif, Tanveer; Kayali, Asaad et al

in Journal of Functional Foods (2015), 17

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See detailInduction of antioxidant capacity and hydroxymethylfurfural content variations by modifications of cooked fruit processing.
Kevers, Claire ULiege; brack, François; PINCEMAIL, Joël ULiege et al

in Journal of antioxidant activity (2015), 1(1), 42-54

Liège syrup is a Belgian traditional cooked fruit foodstuff, produced mainly from apples and pears. The process includes several hours of heating at high temperature during which complex chemical ... [more ▼]

Liège syrup is a Belgian traditional cooked fruit foodstuff, produced mainly from apples and pears. The process includes several hours of heating at high temperature during which complex chemical reactions occur, such as Maillard condensation between reducing sugars and amino acids. Aiming at understanding the modifications of the fruit juices during heating, different parameters were monitored throughout the process. It was shown that hydoxymethylfurfural was formed during the first step of concentration by heating. At the end of the process, hydroxymethylfurfural had totally disappeared and the deep brown color of the product suggested that this compound was transformed into melanoidins. A parallel increase in antioxidant capacity was also observed. To determine optimal conditions to reach high melanoidin content and high antioxidant capacity, different in vitro model systems were compared. It was shown that different combinations of an amino acid with glucose or fructose led to different levels of hydroxymethyfurfural, of melanoidins and antioxidant capacity. After heating of apple or pear puree, an increase of the antioxidant capacity and the hydroxymethylfurfural and melanoidin contents was observed when the heating time was doubled. An increase of the pH from 5 to 9 in apple marmalade’s also induced an increase in antioxidant capacity and in hydroxymethylfurfural and melanoidins. However it was not the case in pear marmalade where only the increase in antioxidant capacity was observed. These results suggest that some parameters of the processing could be modified to improve the health-promoting effect of this traditional food (antioxidant properties and composition in hydroxymethylfurfural and melanoidins). The main factors affecting the quality of the final product were the cooking times, the temperature, the pH, the addition of reducing sugars or amino acids. [less ▲]

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See detailThe Total Antioxidant Capacity of Foods: a reappraisal. Application to commercial orange juices
PINCEMAIL, Joël ULiege; Tabart, Jessica; Defraigne, Jean-Olivier ULiege et al

in journal of antioxidant activity (2015), 1

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 ... [more ▼]

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. [less ▲]

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