Vaios T. Karathanos

Thermal Stability of Anthocyanin Extract of Hibiscus sabdariffa L. in the Presence of β-Cyclodextrin

The thermal stability of anthocyanin extract isolated from the dry calyces of Hibiscus sabdariffa L. was studied over the temperature range 60-90 degrees C in aqueous solutions in the presence or absence of beta-cyclodextrin (beta-CD). The results indicated that the thermal degradation of anthocyanins followed first-order reaction kinetics. The temperature-dependent degradation was adequately modeled by the Arrhenius equation, and the activation energy for the degradation of H. sabdariffa L. anthocyanins during heating was found to be approximately 54 kJ/mol. In the presence of beta-CD, anthocyanins degraded at a decreased rate, evidently due to their complexation with beta-CD, having the same activation energy. The formation of complexes in solution was confirmed by nuclear magnetic resonance studies of beta-CD solutions in the presence of the extract. Moreover, differential scanning calorimetry revealed that the inclusion complex of H. sabdariffa L. extract with beta-CD in the solid state was more stable against oxidation as compared to the free extract, as the complex remained intact at temperatures 100-250 degrees C where the free extract was oxidized. The results obtained clearly indicated that the presence of beta-CD improved the thermal stability of nutraceutical antioxidants present in H. sabdariffa L. extract, both in solution and in solid state.

Deployment of response surface methodology to optimise recovery of grape (Vitis vinifera) stem polyphenols

A 2(3)-full factorial design and response surface methodology were deployed to assess some basic factors (time, % ethanol and pH) affecting profoundly the extractability of polyphenolic phytochemicals from grape (Vitis vinifera) stems. In an effort to obtain a thorough insight into the applicability of the models established, stem extracts from three different varieties were tested, by determining several indices of the polyphenolic composition, such as total polyphenol (TP), total flavanol (TFl), total flavone (TFn) and proanthocyanidin (PC) concentration. It was shown that the models generated can adequately predict the recovery levels for each polyphenol group, but the optimal conditions predicted for TP, TFl, TFn and PC recovery varied significantly. Notable differences were also seen among the different varieties. Correlation of the polyphenol indices with the antiradical activity and reducing power of the extracts indicated that the PC fraction might exert strong effects, while the influence of other groups was not apparent. Examination of the optimally obtained extracts using liquid chromatography-mass spectrometry revealed that the most prominent compounds were caftaric acid, flavanols and derivatives thereof, as well as dehydroflavonols and flavonols.

Encapsulation of complex extracts in β-cyclodextrin: An application to propolis ethanolic extract

Propolis ethanolic extracts (PE) are rather complicated mixtures of bioactive compounds belonging to several chemical classes. The potential use of β-cyclodextrin (β-CD) cavity for the incorporation of specific PE components, aiming to increase their solubility in water, was studied in a Greek propolis, which was rich in polyphenols and terpenes. The PE/β-CD inclusion complexes were prepared by sonication of PE suspensions in aqueous solutions of β-CD, followed by filtration and freeze-drying. The aqueous solubility of PE in the presence of β-CD was studied by the construction of solubility diagrams and by determining the fraction of PE constituents that was dissolved in water. Encapsulation efficiencies were found to be higher (9.4–23.3%) for relatively small aromatic molecules like cinnamic and benzoic acid derivatives and lower for terpenic acids (5.0–6.7%), anthraquinones (3.6–8.4%) and flavonoids (4.0–10.7%). The respective in vitro solubilities in simulated gastric fluid followed an opposite trend, being lower for the relatively small aromatic molecules. It is concluded that the encapsulation in β-CD may increase the solubility of PE constituents in a manner related to their structure, while the amount of substances released will depend both on their chemical properties and on their relative abundance in the matrix.

A pilot, randomized controlled trial to examine the health outcomes of raisin consumption in patients with diabetes

OBJECTIVES Dried fruits, like their fresh homologues, contain relatively high concentrations of antioxidants. The aim of this study was to determine the health outcomes of raisin consumption on patients with diabetes. METHODS We examined the effects of dried grapes (Vitis vinifera) cultivated in Greece, namely Corinthian Raisins (CR) on blood pressure, fasting glucose, glucated hemoglobin (HbA1c), lipid peroxidation, high-sensitivity C-reactive protein, antioxidant status, and cytokines in patients with type 2 diabetes mellitus (T2DM). Forty-eight well-controlled patients with T2DM from the diabetes outpatient clinic of our hospital were recruited to a two-armed, randomized, controlled, 24-wk prospective intervention trial in order to examine the health outcomes of CR consumption. All participants were reported to consume less fruits and vegetables than the recommended amount of five servings daily. Participants in the intervention were instructed to consume CR equal to two fruit servings (36 g/d), replacing snacks with similar energy density twice during the day. Anthropometric and blood pressure measurements, assessment of dietary intake, and fasting blood draws were conducted at baseline and at week 24. Also, phenolic compounds present in CR were analyzed in plasma of the patients. t Test for parametric data and Mann-Whitney test or Wilcoxon test for non-parametric data were performed. Significance was set at P < 0.05. RESULTS Body weight, glycemic control, and lipid profile were not affected in either arm. Patients in the CR arm reduced their diastolic blood pressure and increased their total antioxidant potential significantly compared with baseline. The differences between the two groups at week 24 were significant. No change in high-sensitivity C-reactive protein was observed. A significant difference in plasma circulating p-hydroxybenzoic acid was observed between groups at the end of the trial. CONCLUSIONS Our study shows that naturally CR may improve health features in patients with well-controlled T2DM.

Implementation of response surface methodology to assess the antiradical behaviour in mixtures of ascorbic acid and α-tocopherol with grape (Vitis vinifera) stem extracts

The efficiency of grape stem extracts to express antiradical activity was assessed using two different approaches and DPPH as the radical probe. In addition, the mixture effects when the extracts were combined with ascorbic acid (AA) and α-tocopherol (α-Tcp) were also evaluated. The approaches included a simple linear regression analysis between the response (antiradical activity) and concentration, but also a response surface methodology, which permitted the monitoring of the response upon simultaneous variation of both the concentration of the total polyphenols of the extracts and either of the antioxidants (AA and α-Tcp). The deployment of linear regression poses important constraints with regard to concentration ranges, whereas response surface methodology might be a valuable statistical tool for similar assessments and credible modelling of binary mixtures of antioxidants. In all combinations tested it was found that an antagonism was manifested, presumably as a result of AA and α-Tcp regeneration by the extract polyphenols, at the expense of the latter.

Anthocyanins content and antioxidant capacity of Corinthian currants (Vitis vinifera L., var. Apyrena).

Corinthian currants are dried vine products used in the Mediterranean diet. Currant is produced almost exclusively in Southern Greece; three commercial subcategories are recognised, i.e. Vostizza, Gulf, and Provincial. Thirty-five batches of Corinthian currants obtained over two crop years and belonging to the several subcategories, were evaluated in terms of total and individual anthocyanins, total phenolics and antioxidant capacity. Variations were observed among batches, cultivation regions, and subcategories with respect to the studied parameters. Up to five anthocyanidin-3-O-glucosides were identified and quantified in currants for the first time. Overall, Vostizza currants presented the higher total anthocyanins content and the lower total phenolics content and antiradical activity; reducing power showed no differentiation among currants subcategories and crop years studied. Though the contribution of currants to the daily anthocyanin intake is rather low, the combined presence of other phenolics as well, makes this product a source of hydrophilic antioxidants.

Effect of a special carbohydrate-protein cake on oxidative stress markers after exhaustive cycling in humans.

Exercise has been associated with oxidative stress that is correlated with muscle fatigue and reduced exercise performance. The aim of this study was to examine the effects of a special cake (consisting of carbohydrate to whey protein 3.5:1) vs an isocaloric carbohydrate cake on biomarkers of oxidative stress in 9 males after exhaustive cycling. A randomized single-blind cross-over study was completed. They performed one trial involving a 2-h exercise on a cycle ergometer at 60-65% VO(2)max followed by a 4-h recovery and then a second trial involved an 1-h exercise at 60-65% VO(2)max which was increased at 95% VO(2)max (time trial). The subjects received 4 experimental or placebo cakes after the first trial (the first immediately after and then one every hour). Blood samples were collected at eight time intervals: pre-exercise, 30 min, 1.5 h and 4 h post-exercise, post time Trial, 1 h, 24 h and 48 h post time Trial. Thiobarbituric Acid Reactive Substances (TBARS), protein carbonyls, total antioxidant capacity (TAC), catalase and glutathione (GSH) were determined spectrophotometrically. The mean time to exhaustion did not differ upon cake consumption. Consumption of the special cake reduced TBARS significantly, but had no effect on other oxidative stress markers.

Nutritional evaluation and health promoting activities of nuts and seeds cultivated in Greece

Abstract Available data suggest that genetic as well as environmental factors may influence nuts and seeds nutrients content. In this context nuts and seeds cultivated in Greece were studied. Macronutrients content was in agreement with that from other areas. Total phenolics content was in the range of 43.0 ± 2.1–1512.7 ± 60.7 mg GAE/100 g for chestnut and walnut, respectively. Thirteen to 22 individual phenolics were identified in the studied species. Oleanolic acid was in the range of 0.10–9.03 mg/100 g. Pumpkin seeds contained the higher squalene content (71.6 mg/100 g). β-Sitosterol predominated in all samples except pumpkin seeds. Tocopherols ranged from 8.9 mg/100 g (chestnut) to 29.3 mg/100 g (almond). Nuts and seeds hydrophilic extracts at quantities corresponding to the estimated daily consumption by the Greeks succeeded in inhibiting LDL oxidation in vitro by increasing lag time 1.1–14.1 times. One serving of nuts or seeds may cover a significant fraction of health promoting microconstituents daily intake.

Mechanical properties of corn-legume based extrudates.

The effect of extrusion conditions, including feed rate (2.52–6.84 kg/h), feed moisture content (13–19% wet basis), screw speed (150–250 rpm), and extrusion temperature (150–260°C) on the mechanical properties of corn/legume-based extrudates was studied. White bean and lentil were used in mixtures with corn flour at a ratio of 10:90 up to 90:10 (corn:legume). Simple power models were used to correlate breaking stress and corresponding strain with extrusion conditions and material characteristics. The influence of feed rate on the extrudates mechanical properties was incorporated in the mean residence time. The breaking stress of extrudates decreased with temperature, residence time, and corn to legume ratio, and it increased with feed moisture content. The corresponding strain showed an opposite trend. Screw speed did not affect the extrudate properties. The use of lentil flour led to a product with higher breaking stress. Furthermore, in a previous work, the porosity of these products was modeled and, now, it was found that breaking stress and porosity of the extrudates could be correlated by an exponential relationship.

The effect of raisins on biomarkers of endothelial function and oxidant damage; an open-label and randomized controlled intervention

Based on the existing data in grapes and wine, the aim of the present study was to investigate the probability that raisins improve clinical features and markers of oxidative stress, inflammation and arterial function in healthy smokers. Thirty-six apparently healthy smokers were recruited to an open-label and randomized, controlled, 4-week prospective intervention. All participants were reported to consume less than the recommended amount of five servings fruits and vegetables daily. Participants in the intervention were instructed to consume raisins equal to five fruit servings (90g/d). Anthropometric and blood pressure (BP) measurements, assessment of dietary intake, and fasting blood draws were conducted at baseline and at week 4. Biochemical (glucose, lipids, liver enzymes), inflammation [C-reactive protein (CRP), leptin], oxidative stress [Malondialdehyde (MDA), Advanced oxidation protein products (AOPPs)] and arterial function markers [Flow-mediated dilatation (FMD), Pulse wave velocity (PWV), Intercellular adhesion molecule-1 (ICAM-1), Nitric oxide (NO)] were assessed pre- and post-intervention. Baseline characteristics did not differ between the intervention and control arm. No effect of daily raisin consumption was observed on markers assessed between baseline and week 4 in either arm. Regarding vegetable consumption, no difference was observed in either group between baseline and post-intervention; however, as expected, a significant increase was reported in the intervention arm in fruit consumption between baseline and end point (p<0.001) and between two arms post-intervention (p<0.001). When analyzing according to age, ICAM-1 levels significantly decreased in subjects >30years (n=8) in intervention arm (390.1±17.6 to 302.2±11ng/mL, p=0.004). After analysis of the data for sex, women in intervention (n=5) decreased significantly diastolic BP (74.6±4.2 to 67.4±2.6mg/dL, p=0.043), total cholesterol (175.8±7 to 166.6±6.6mg/dL, p<0.001) and LDL-cholesterol (96.2±9.6 to 89±10.5mg/dL, p=0.012). However, due to the small sample size in the above, no safe conclusions can be exported.