Jessica Tabart

Influence of Cultivar, Harvest Time, Storage Conditions, and Peeling on the Antioxidant Capacity and Phenolic and Ascorbic Acid Contents of Apples and Pears

Apple and pear fruits are important sources of secondary plant metabolites and one of the major sources of dietary phenolics consumed all year round. The aim of this work was to identify the main variables influencing phenolic content and antioxidant capacity in apples. Higher phenolic and antioxidant contents were observed in some varieties (such as the Delbar Estival apple and Durondeau pear). Storage conditions were important. Our results also showed that fruits should be consumed rapidly after purchase and with their peel. After one week of domestic storage, the ascorbic acid content was found to decrease by 75%. Peeling led to a more than 25% decrease in total phenolics and ascorbic acid. The harvest time (at normal ripeness) had only a limited impact, but significant year-to-year variations were observed. In conclusion, well-chosen and well-stored apples and pears may contribute to an antioxidant-rich diet if consumed rapidly and with their peel.

Ascorbic Acid, Phenolic Acid, Flavonoid, and Carotenoid Profiles of Selected Extracts from Ribes nigrum

Small fruits such as berries have low energy contents, but high contents of vitamins, micronutrients, and dietary fibers and constitute a good source of natural antioxidant compounds that are important constituents of the human diet. This study identified a large number of compounds in an extract of black currant showing high antioxidant activity and compared their profile in various parts of the plants (leaves, buds, and berries). If it was known that berries contained very high levels of natural phenolic compounds, this study showed that leaves and buds could also be considered good sources of natural antioxidants. Indeed, they contained high amounts of phenolic acids, flavonoids, and carotenoids. An acetone mixture can extract several classes of phenolic compounds with a good yield of flavonols, flavan-3-ols, and anthocyanins.

Antioxidant potential of different plum cultivars during storage

Plums, the most commonly consumed fruits from Romania, are fruits rich in bioactive compounds, such as antioxidants. This research work was carried out to investigate the antioxidant potential of twelve plum cultivars, fresh and stored during 10days at 4°C by using different methods (DPPH, ORAC and erythrocyte resistance to haemolysis). The contents of total phenolic compounds and total anthocyanins were also determined by specific spectrometric methods. Significant differences between fresh and stored plum cultivars (p<0.05) were found. Storage at 4°C resulted in an increase in antioxidant potential and anthocyanins content of the autumn plum varieties. Autumn plum varieties also showed a higher antioxidant capacity than summer varieties, as assessed by the ORAC and the haemolysis resistance assays. Our results suggest that, even after storage, plums could be a good source of antioxidants, which may provide health-promoting effects for humans.

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’.

IN VITRO CHARACTERIZATION OF ANTIOXIDANT PROPERTIES OF CUBAN ENDEMIC VARIETIES OF Erythroxylum alaternifolium A. Rich. ISOLATION OF TWO FLAVONOL GLYCOSIDES

The total antioxidant capacity from leaves of three Cuban endemic varieties of Erythroxylum alaternifolium was measured using three techniques: 2,2-diphenyl1-picrylhydrazyl (DPPH∙), 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS∙+) and Oxygen radical absorbance capacity (ORAC). The highest values of antioxidant capacity and total phenols were measured in polar n-butyl alcohol extracts. Among the varieties of E. alaternifolium assayed, the var. parvifolium showed the strongest antioxidant capacity: ABTS (6.49 ± 0.05 mg TE/g dw); DPPH (11.16 ± 0.01 mg TE/g dw) and ORAC (35.1 ± 1.5 mg TE/g dw). Additionally, n-butyl alcohol extract of E. alaternifolium var. parvifolium also showed the highest content in phenolics with 284.2 ± 7.3 mg CAE/g dw and in flavonols with skeleton quercetin, kaempferol and myricetin with 471 µg/g dw. Moreover, two flavonol glycosides: ombuin-3- O-rutinoside and quercetin-3-O-rutinoside were isolated for the first time from n-butyl alcohol extract of E. alaternifolium var. alaternifolium.

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.

Phytochemical composition and antioxidant activities of different aerial parts extracts of Ferula communis L.

Abstract The present study aimed to assess antioxidant activities of three organs (flower, fruit, and stem) extracts of Tunisian Ferula (F.) communis. Various experimental models were used to characterize the antioxidant activities in vitro as well as on ROS-induced fluorescence using dichlorofluorescein technique from phorbol myristate acetate (PMA)-stimulated human myeloid cell line HL-60. 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. Also, 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 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.

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

OBJECTIVE Polyphenol-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. METHODS Six 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. RESULTS The 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. 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.

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.

Deriving a Global Antioxidant Score for Commercial Juices by Multivariate Graphical and Scoring Techniques

Abstract Blackcurrants constitute an important source of potential health-promoting phytochemicals (e.g., phenolic compounds, ascorbic acid) due to their antioxidant properties. Only small portions of berries are consumed fresh, most of their intake coming from processed foods, such as juices. Seven techniques were used to measure antioxidant capacity and antioxidant compounds of 10 juices. This yielded a large disparity in the results. No single test, even the most popular ORAC assay, is able to compare the antioxidant capacity of similar food matrices such as blackcurrant juices. By combining tests from a large battery of antioxidant assays, it is possible to improve the discrimination of a food matrix by establishing a global antioxidant score (GAS) that correlates well with graphical representations like Chernoff faces or stars. The latter approaches may help food industry managers and authorities to compare their antioxidant products with similar products on the market.