Determination of ascorbic acid and uric acid in plasma by high-performance liquid chromatography

Ross, Marion A.

doi:10.1016/0378-4347(94)80087-1

Cited by 147 publications

(73 citation statements)

References 7 publications

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“…The column was in a Dionex STH 585 column thermostat set at 151C and samples within the autosampler were kept at 41C to prevent degradation. Wavelengths of 245 and 285 nm were used to quantify ascorbic acid and uric acid, respectively (Ross, 1994).…”

Section: Methodsmentioning

confidence: 99%

Effects of enhanced consumption of fruit and vegetables on plasma antioxidant status and oxidative resistance of LDL in smokers supplemented with fish oil

2003

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Objective: To determine whether consumption of five portions of fruit and vegetables per day reduces the enhancement of oxidative stress induced by consumption of fish oil. Subjects: A total of 18 free-living healthy smoking volunteers, aged 18-63 y, were recruited by posters and e-mail in The University of Reading, and by leaflets in local shops. Design: A prospective study. Setting: Hugh Sinclair Unit of Human Nutrition, School of Food Biosciences, The University of Reading, Whiteknights PO Box 226, Reading RG6 6AP, UK. Intervention: All subjects consumed a daily supplement of 4 Â 1 g fish oil capsules for 9 weeks. After 3 weeks, they consumed an additional five portions of fruits and vegetables per day, and then they returned to their normal diet for the last 3 weeks of the study. Fasting blood samples were taken at the ends of weeks 0, 3, 6 and 9. Results: The plasma concentrations of ascorbic acid, lutein, b-cryptoxanthin, a-carotene and b-carotene all significantly increased when fruit and vegetable intake was enhanced (Po0.05). Plasma concentrations of a-tocopherol, retinol and uric acid did not change significantly during the period of increased fruit and vegetable consumption. Plasma oxidative stability, assessed by the oxygen radical absorbance capacity (ORAC) assay, also increased from weeks 3-6 (Po0.001) but not in association with increases in measured antioxidants. Lag phase before oxidation of low-density lipoprotein (LDL) significantly decreased in the first 3 weeks of the study, reflecting the incorporation of EPA and DHA into LDL (Po0.0001). Subsequent enhanced fruit and vegetable consumption significantly reduced the susceptibility of LDL to oxidation (Po0.005). Conclusion: Fish oil reduced the oxidative stability of plasma and LDL, but the effects were partially offset by the increased consumption of fruit and vegetables.

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Section: Methodsmentioning

confidence: 99%

Effects of enhanced consumption of fruit and vegetables on plasma antioxidant status and oxidative resistance of LDL in smokers supplemented with fish oil

2003

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“…Acid hydrolysis of plasma was performed in 50% methanol containing 20 mmolal diethyldithiocarbamate and 1.2 M HCl (Aziz et al, 1998). Plasma ascorbic acid levels in metaphosphoric acid-treated samples were determined by reverse-phase HPLC with UV detection at 263 nm (Ross, 1994) Determination of plasma retinol, a-tocopherol, g-tocopherol and six carotenoids was by reverse-phase HPLC with simultaneous UV and¯uorimetric detection (Hess et al, 1991). Extraction ef®ciency was determined by use of an echinone internal standard.…”

Section: Methodsmentioning

confidence: 99%

Bioavailability and efficiency of rutin as an antioxidant: a human supplementation study

Boyle¹,

Dobson²,

Duthie³

et al. 2000

Eur J Clin Nutr

179

107

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Objective: To determine the potential antioxidant effect of rutin (quercetin-3-O-b-rutinoside) supplementation. Design: A 6-week randomized single-blind placebo controlled trial was conducted; 500 mg rutin supplement was compared to an equivalent amount of glucose placebo. In addition, a pharmacokinetic study was carried out. Setting: The Rowett Research Institute, Aberdeen, UK. Subjects: Eighteen healthy non-obese normocholesterolaemic female volunteers in the age range 18 ± 48 y. Main outcome measures: Plasma¯avonoids, ascorbic acid, tocopherols and carotenoids, plasma antioxidant capacity, lymphocyte DNA damage, blood chemistry and haematology, liver function tests, urinary malondialdehyde, 8-hydroxy-2H -deoxyguanosine and 8-iso-prostaglandin F 2a . Results: Eighteen volunteers completed the trial. Rutin supplementation did not induce any adverse changes in blood chemistry or indices of liver function. Plasma¯avonoids were signi®cantly elevated in the rutinsupplemented group. Endogenous oxidation of pyrimidines was signi®cantly decreased in both rutin-and placebo-treated volunteers. There was no signi®cant change in the level of urinary 8-hydroxy-2 H -deoxyguanosine or urinary malondialdehyde in either group. A linear correlation was observed between urinary malondialdehyde and urinary 8-iso-prostaglandin F 2a (R 0.54, P`0.01). Conclusion: Six weeks' rutin supplementation signi®cantly elevated the levels of three plasma¯avonoids (quercetin, kaempferol and isorhamnetin) but there was no signi®cant change in plasma antioxidant status. The decrease in the level of endogenous base oxidation in lymphocyte DNA seen in both the placebo-and rutinsupplemented subjects may re¯ect seasonal changes in other dietary antioxidants.

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“…Total phenols in plasma and urine were also determined with Folin-Ciocalteu reagent, using a modi®cation to remove protein interference in the samples (Sera®ni et al, 1998). Vitamin C concentration in plasma and juice was measured by high pressure liquid chromatography (Ross, 1994). Haematocrit and total haemoglobin were measured by routine procedures to allow correction for any changes in plasma volume (Dill & Costill, 1974) arising from consumption of 500 ml of¯uid.…”

Section: Methodsmentioning

confidence: 99%

Effects of blueberry and cranberry juice consumption on the plasma antioxidant capacity of healthy female volunteers

Pedersen

Kyle²,

Jenkinson³

et al. 2000

Eur J Clin Nutr

155

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Objective: To assess whether consumption of 500 ml of blueberry juice or cranberry juice by healthy female subjects increased plasma phenolic content and antioxidant capacity. Design: Latin square arrangement to eliminate ordering effects. After an overnight fast, nine volunteers consumed 500 ml of blueberry juice, cranberry juice or a sucrose solution (control); each volunteer participated on three occasions one week apart, consuming one of the beverages each time. Blood samples were obtained by venipuncture at intervals up to four hours after consumption of the juices. Urine samples were also obtained four hours after consuming the juice. Results: Consumption of cranberry juice resulted in a signi®cant increase in the ability of plasma to reduce potassium nitrosodisulphonate and Fe(III)-2,4,6-Tri(2-pyridyl)-s-triazine, these measures of antioxidant capacity attaining a maximum after 60 ± 120 min. This corresponded to a 30% increase in vitamin C and a small but signi®cant increase in total phenols in plasma. Consumption of blueberry juice had no such effects. Conclusion: The increase in plasma antioxidant capacity following consumption of cranberry juice could mainly be accounted for by an increase in vitamin C rather than phenolics. This also accounted for the lack of an effect of the phenolic-rich but vitamin C-low blueberry juice. Sponsorship: Funded by the Scottish Executive Rural Affairs Department and the Danish Government.

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Determination of ascorbic acid and uric acid in plasma by high-performance liquid chromatography

Cited by 147 publications

References 7 publications

Effects of enhanced consumption of fruit and vegetables on plasma antioxidant status and oxidative resistance of LDL in smokers supplemented with fish oil

Effects of enhanced consumption of fruit and vegetables on plasma antioxidant status and oxidative resistance of LDL in smokers supplemented with fish oil

Bioavailability and efficiency of rutin as an antioxidant: a human supplementation study

Effects of blueberry and cranberry juice consumption on the plasma antioxidant capacity of healthy female volunteers

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