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To compare the potential erosive effect of a prototype carbohydrate-electrolyte drink (PCE) with a neutral control (water) and a commercially available carbohydrate-electrolyte drink (CCE) during exercise.: Nineteen healthy adults (male, N = 16; female, N = 3) took part in this single blind, three-way crossover study. Subjects were given each of the three drinks according to a randomization schedule, approximately balanced for first-order carryover effects. At the beginning of each of the three study periods, the volunteers were fitted with an intraoral appliance containing two human enamel blocks. During each study period, volunteers exercised for 75 min.d(-1) (5 repetitions of 15 min of exercise, with 5-min rests between exercise repetitions), 5 d.wk(-1) for 3 wk. Each day, drink aliquots of 200 mL were consumed during a 5-min period before exercise and after every 15-min bout of exercise, followed by a final 400-mL aliquot ingested over a 10-min period: a total of 1400 mL per study day. Dental erosion was measured as tissue loss from the enamel blocks by profilometry at the end of each study period.Water, PCE, and CCE produced 0.138 microm (SD 0.090 microm), 0.138 microm (SD 0.038 microm), and 4.238 microm (SD 3.872 microm) of enamel loss, respectively. A Wilcoxon t statistic showed a significant statistical difference between the PCE and CCE drinks (P0.001), whereas no significant difference could be detected between the PCE drink and water (P = 0.740).The PCE solution showed minimal erosion compared with the commercially available drink, and was statistically indistinguishable from water under the conditions of this study. Use of CE solutions formulated to minimize erosion during exercise may provide significant dental benefits.

The antioxidant activity during storage at 30 degrees C of quercetin, myricetin and alpha-tocopherol in small unilamellar liposomes has been investigated. Myricetin was more effective than alpha-tocopherol as an antioxidant in liposomes under all conditions studied. At pH 5.4 with a concentration of 10(-2) mol/mol phospholipid, myricetin has been shown to be the strongest antioxidant followed by quercetin and alpha-tocopherol. Cupric chloride and ferric chloride strongly reduced the antioxidant activity of myricetin and quercetin with cupric chloride causing a stronger reduction in activity than ferric chloride. At a pH of 7.4, quercetin was less effective than alpha-tocopherol at a concentration of 10(-2) mol/mol phospholipid, but it's activity increased more strongly with concentration and it was very effective at a concentration of 5 x 10(-2) mol/mol phospholipid.

The effect of quercetin and myricetin on the stability of sunflower oil and oil-in-water emulsions was studied by storage experiments monitored by measurement of peroxide values, conjugated dienes, and headspace volatile analysis. Myricetin showed strong antioxidant activity in oils stored at 60 or 30°C and in oil-in-water emulsions stored at 30°C, whether tocopherols or citric acid were present or not; however, quercetin showed similar antioxidant activity in stripped sunflower oil but no activity in oils that contained tocopherols and citric acid. This showed that myricetin is effective owing to strong radical scavenging and metal-chelating properties, whereas quercetin has weaker radical scavenging activity, although it is also active by metal-chelation. The effects of copper and iron salts on the antioxidant activity of myricetin and quercetin were studied in sunflower oil and oil-in-water emulsions. Quercetin and myricetin enhanced the prooxidant effect of cupric chloride in oil-in-water emulsions (pH 7.4), but this effect was not observed with cupric stearate. The addition of myricetin to emulsions that contained ferric chloride at pH 5.4 also produced a strong prooxidant effect, and small prooxidant effects of flavonols were also detected in the presence of cupric chloride under these conditions. However, myricetin and quercetin reduced the prooxidant effect of ferric palmitate in oils. Myricetin also showed a strong antioxidant effect in oil that contained cupric stearate, although quercetin had no significant effect on the oxidative stability of this system. It therefore appears that flavonols may exert a prooxidant effect in the presence of metal salts, but the nature of the metal salt is important in determining whether a prooxidant effect occurs.

Extraction of green tea with hot water provided an extract that was highly effective as an antioxidant for an oil-in-water emulsion at pH 5.5 during prolonged storage (40 days). Other components besides epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) made important contributions to the antioxidant activity of the extract in an oil-in-water emulsion, since ECG, when pure, had no significant antioxidant activity (p > 0.05) and EGCG was completely oxidized within 15 days. Myricetin had a greater antioxidant effect in this system than EGCG or ECG at a concentration of 10-4 M in the absence of ferric ions, but all three flavonoids exhibited prooxidant effects in the presence of ferric ions. Keywords: Antioxidants; epigallocatechin gallate; epicatechin gallate; green tea; emulsions

Berry extracts rich in anthocyanins have been linked to protective effects including the modulation of age-related neurological dysfunction and the improvement of the resistance of red blood cells against oxidative stress in vitro. In this study the bioavailability, metabolism and elimination of polyphenols from blackcurrant juice, rich in anthocyanins, flavonols, and hydroxycinnamates, were investigated. The four major native anthocyanidin glycosides of blackcurrant juice, delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside and cyanidin-3-rutinoside, were detected and identified in low amounts by HPLC and LC-MS in plasma and urine post-ingestion. Elimination of the anthocyanins was fast (maximum excretion after 1 h) and plasma levels (0-128.6 nmol/l) and total urinary exretion (0.07-1.35 mg; 0.007-0.133% of the dose ingested) were low. Most significantly, of the hydroxycinnamates, conjugated and free ferulic, isoferulic, p-coumaric, sinapic and vanillic acids were identified in plasma and urine, using GC-MS techniques. Quercetin and kaempferol (as glucuronides) and the proposed colonic metabolite of quercetin, 3-hydroxyphenylacetic acid, were detectable in a minority of subjects. Increased daily urinary hippuric, 4-hydroxyhippuric and 3-hydroxyhippuric acid levels were also observed post-ingestion in all volunteers.