Claire Kevers

Bilberry extract (Antho 50) selectively induces redox-sensitive caspase 3-related apoptosis in chronic lymphocytic leukemia cells by targeting the Bcl-2/Bad pathway

Defect in apoptosis has been implicated as a major cause of resistance to chemotherapy observed in B cell chronic lymphocytic leukaemia (B CLL). This study evaluated the pro-apoptotic effect of an anthocyanin-rich dietary bilberry extract (Antho 50) on B CLL cells from 30 patients and on peripheral blood mononuclear cells (PBMCs) from healthy subjects, and determined the underlying mechanism. Antho 50 induced concentration- and time-dependent pro-apoptotic effects in B CLL cells but little or no effect in PBMCs. Among the main phenolic compounds of the bilberry extract, delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside induced a pro-apoptotic effect. Antho 50-induced apoptosis is associated with activation of caspase 3, down-regulation of UHRF1, a rapid dephosphorylation of Akt and Bad, and down-regulation of Bcl-2. Antho 50 significantly induced PEG-catalase-sensitive formation of reactive oxygen species in B CLL cells. PEG-catalase prevented the Antho 50-induced induction of apoptosis and related signaling. The present findings indicate that Antho 50 exhibits strong pro-apoptotic activity through redox-sensitive caspase 3 activation-related mechanism in B CLL cells involving dysregulation of the Bad/Bcl-2 pathway. This activity of Antho 50 involves the glucoside and rutinoside derivatives of delphinidin. They further suggest that Antho 50 has chemotherapeutic potential by targeting selectively B CLL cells.

Sample Dilution Influences the Determination of Antioxidant Capacity in Food: How to Minimize It?

The influence of sample dilution on the measurement of antioxidant capacity was analyzed. To ensure the reproducibility of results, it is necessary to realize such scarce investigations. This study focuses on different antioxidant capacity assays commonly used for the analysis of pure substances and food extracts. For all compounds and foods tested in most of the four assays (Trolox equivalent antioxidant capacity, 2,2-diphenyl-1-picrylhydrazyl, and oxygen radical absorbance capacity), effects of sample dilution on the measured (and recalculated) antioxidant capacity were observed, with differences up to 28xa0% between dilutions. An extrapolation method was proposed to obtain a “real value” thus to minimize the effects of the sample dilution. This extrapolation method is relatively simple, based on a linear regression of 4 or 5 appropriate dilutions of the sample and applicable to the various assays. The use of such a method will improve the consistency of interlaboratory antioxidant capacity data and thus permit better comparisons. In contrast, there was no dilution problem with ferric reducing antioxidant power assays.

Antioxidant capacity of small dark fruits. Influence of cultivars and harvest time

BACKGROUND: Small dark fruits represent one of the most important sources of bioactive compounds with antioxidant capacity in the human diet. The content of health-promoting antioxidants in these fruits may be important information to take into account when a fruit producer has to choose which cultivar to grow. OBJECTIVE: It is important to know how antioxidant capacity and antioxidant compounds as total phenolics and ascorbic acid vary between 9 small dark fruit species and for each species among cultivars (2 to 10 per species). METHODS: The antioxidant capacity (ORAC assay), total phenolic (Folin-Ciocalteu) and ascorbic acid content were measured in 9 fruits (plums, blackcurrants, blackberries, blueberries, cherries, redcurrants, raspberries, white currants and gooseberries) / 42 cultivars harvested at maturity during their high production period. RESULTS: The comparison of the average of the various cultivars of each small fruits showed that blackcurrants had the best antioxidant capacity (with plums), the highest ascorbic acid content and the highest total phenolic content (with blackberries). The present study shows that total phenolic compounds, ascorbic acid and antioxidant capacity strongly differed between genotypes of each small dark fruits. Other parameters as harvest time, culture conditions and maturity degree at the harvest may also influence the antioxidant capacity of small fruits. CONCLUSIONS: Among small dark fruits, blackcurrants have high qualities. Choices of variety, harvest time and maturity degree are important for all fruits.

Antioxidant capacity of hydrophilic food matrices: optimization and validation of ORAC assay.

It is widely accepted that ORAC is a useful method for assessing food extracts that contain various antioxidants. The principal aim of this study was to validate the ORAC assay. We first identified parameters that can interfere with the ORAC assay and we optimized it. Then, experiments were conducted to determine the limits of linearity and response function, to determine the accuracy profiles to circumvent some of the drawbacks of traditional validation procedures. Trueness, selectivity and limits of quantification of the method were also determined. Our objective of ORAC method validation is thus to give guarantees that most of the results generated during use of this method will be close enough to unknown true value of antioxidant capacity of food matrices. The validation results indicate that the described method will give accurate and reliable results for Trolox equivalent values ranging from 50 to 200xa0μmol/L.

Determination of total phenolic compound content and antioxidant activity in cherry species and cultivars

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’.

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

The present research work describes the effects of 2,4-dichlorophenoxyacetic acid (2,4-d)/Benzylaminopurine (BAP) ratio on callus induction, total phenolic and ascorbic acid production, and antioxidant activities in leaf-derived calli of Crataegus azarolus (hawthorn). The supplementation of 1.0xa0mg/L 2,4-d and 1.0xa0mg/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 phenolic contents were obtained in callus cultured on MS medium supplemented with 2.0xa0mg/L 2,4-d and 1.0xa0mg/L BAP (52xa0±xa00.56xa0mg GAE/g DM) and were significantly lower than those of intact leaves (76xa0±xa01.72xa0mg GAE/g DM). However, the highest ascorbic acid contents were found in callus cultured on MS medium supplemented with 1.0xa0mg/L 2,4-d and 0.5xa0mg/L BAP (0.96xa0±xa00.13xa0mg AAE/g DM) and these amounts were statistically similar to those found in leaf tissues (0.74xa0±xa00.07xa0mg 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 2.0xa0mg/L 2,4-d and 1.0xa0mg/L BAP have the greatest antiradical activities against DPPH (124xa0±xa02.92xa0mg TE/g DM) and ABTS (0.19xa0±xa00.02xa0mg 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.

Monitoring of anatabine release by methyl jasmonate elicited BY-2 cells using surface-enhanced Raman scattering

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 5000µgL(-1). A univariate analysis was performed, the intensity of a band situated at 1028cm(-1), related to anatabine, was plotted against the anatabine concentration. A linear relationship was observed with a R(2) 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 analysed using SERS. Finally, the amount of anatabine released in the culture medium was determined using the response function, reaching a plateau after 72h of 82µg of anatabine released/g of fresh weight (FW) MeJa elicited BY-2 cells.

The 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

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.

The 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

OBJECTIVEnPolyphenol-rich products such as fruit juices have been found to have strong antioxidant capacities and to induce potent endothelium-dependent relaxation. We 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.nnnMETHODSnSix different commercial blackcurrant juices were selected. Their main phenolic compounds were measured by ultra-performance liquid chromatography and antioxidant capacity was evaluated by spectrometric methods. Vascular reactivity studies with these juices were done using isolated porcine coronary arteries.nnnRESULTSnThe six different commercial blackcurrant juices induced relaxation ranging from 21% to 100% at the concentration of 0.5% volume per volume (v/v). The relaxation induced at 0.5% v/v was not correlated to their antioxidant capacity measured by either oxygen radical antioxidant capacity or DPPH (2,2-diphenyl-1-picrylhydrazyl) assays and also not to the ascorbic acid, total polyphenols, total flavanols, and total phenolic acid contents. In contrast, the amplitude of the relaxation was correlated to the total anthocyanins content and the individual anthocyanin concentration.nnnCONCLUSIONSnCorrelations 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.

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

The 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 four or six times during the first minute of microwaving in the two vegetables.