Flavonoids inhibit the oxidative modification of low density lipoproteins by macrophages

Whalley, Catherine V. de; Rankin, Sara M.; Hoult, J.R.S.; Jessup, Wendy; Leake, David S.

doi:10.1016/0006-2952(90)90120-a

Cited by 562 publications

(252 citation statements)

References 38 publications

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“…Catechins have strong antioxidant effect and they are known to lower low density lipoprotein (LDL) oxidation in vitro (de Whalley et al, 1990;Luo et al, 1997). The in vivo effects are controversial in that some argue that it suppress the oxidation of LDL (Ishikawa et al 1997), while others report that there are no signi®cant effects (van het Hof et al, 1997(van het Hof et al, , 1999.…”

Section: Antioxidant Effect Of Green Tea H Sung Et Almentioning

confidence: 99%

In vivo antioxidant effect of green tea

et al. 2000

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Objective: The object of this study was to investigate the in vivo antioxidant effect of green tea and dosage effect of green tea on antioxidant effect. Design: We tested 10 healthy subjects (aged 23 ± 25 y, ®ve women and ®ve men) with overnight fasting. The total antioxidant capacity of plasma was measured at baseline and 60 min and 120 min after ingestion of 150 ml green tea. Green tea was prepared by infusing 2.5 g of dried green tea leaves for 2 min at 80 C in 150 ml of water. In the second week, they took 300 ml of tea (5.0 g of green tea leaves) and, in the third week, 450 ml of tea (7.5 g of green tea leaves). The total antioxidant capacities of plasma were determined with a Total Antioxidant Kit (Randox Laboratories Ltd, UK) using a Cobas Mira analyser (Roche Diagnostic Systems Inc., Switzerland). The mean intra-assay coef®cient of variation was 1.2%. Results: The total antioxidant capacity of plasma increased by 1.1% at 60 min and 2.1% at 120 min over baseline value in subjects consuming 150 ml of green tea, which was statistically not signi®cant. However, total antioxidant capacity of plasma after consuming 300 ml of green tea showed a signi®cant increase of 7.0% after 60 min and 6.2% after 120 min (P`0.0001), and after consuming 450 ml 12.0% after 60 min and 12.7% after 120 min over baseline value (P`0.0001). Conclusions: Total antioxidant capacity of plasma was signi®cantly increased after taking green tea in amounts of 300 and 450 ml. A positive increment according to green tea dosage was also observed. Sponsorship: This work was funded by the Paci®c Corporation (Korea).

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Section: Antioxidant Effect Of Green Tea H Sung Et Almentioning

confidence: 99%

In vivo antioxidant effect of green tea

et al. 2000

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“…A number of mechanisms are likely to contribute to inhibition of LDL oxidation by¯avonoids. Flavonoids may directly scavenge some radical species by acting as chain-breaking antioxidants (de-Whalley et al, 1990). In addition, they may recycle other chain-breaking antioxidants such as atocopherol by donating a hydrogen atom to the tocopheryl radical (Frankel et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, they may recycle other chain-breaking antioxidants such as atocopherol by donating a hydrogen atom to the tocopheryl radical (Frankel et al, 1993). Transition metals such as iron and copper are important pro-oxidants, and some¯avo-noids can chelate divalent metal ions, hence preventing free radical formation (de-Whalley et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Extensive in vitro studies have found most of the main dietary¯avonoids to be effective in protecting against the oxidative modi®cation of LDL (de-Whalley et al, 1990;Laughton et al, 1991;Morel et al, 1993;Rankin et al, 1993;Igarashi & Ohmuma, 1995;Fuhrman et al, 1995). The ability of quercetin, and the quercetin glycosides, to protect LDL against oxidative modi®cation has been extensively studied, in every case showing a signi®cant protective effect (de-Whalley et al, 1990;McAnlis et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…The ability of quercetin, and the quercetin glycosides, to protect LDL against oxidative modi®cation has been extensively studied, in every case showing a signi®cant protective effect (de-Whalley et al, 1990;McAnlis et al, 1997). It is therefore plausible that the consumption of¯avonoid-rich foods could reduce LDL oxidation and atherogenesis in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Absorption and antioxidant effects of quercetin from onions, in man

et al. 1999

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Objective: To investigate the in vivo effects of quercetin following the ingestion of fried onions. Design: Five healthy volunteers, three males and two females aged between 25 and 39 y, ingested 225 g of fried onions after an overnight fast and peripheral venous blood was collected 0, 2, 4, 24 and 48 h after consumption. Quercetin in the plasma, total antioxidant capacity and susceptibility of low density lipoproteins (LDL) to oxidation were measured. Results: Following the onion meal, quercetin levels increased from baseline values (28.4AE 1.9 ngaml) to peak after 2 h (248.4 AE 103.9 ngaml), decreasing to baseline again after 24 h (P b 0.05). This was accompanied by an increase in the total antioxidant activity of the plasma from baseline (1.70AE 0.04 mmolal trolox equivalents) to 1.75 AE 0.10 mmolal trolox equivalents after 2 h and 1.76AE 0.08 mmolal trolox equivalents after 4 h. There was no signi®cant change in the susceptibility of the plasma or the isolated LDL to oxidation over the 48 h period after consumption of the fried onions. In view of these negative ®ndings, we isolated LDL and other lipoproteins from plasma at each time point. Quercetin was not detected in either LDL or VLDL, but was present in the HDL fraction, although this fraction also contains other proteins including albumin. Conclusions: Quercetin can be absorbed in humans from dietary sources to high enough concentrations to increase the overall antioxidant activity of the plasma. Quercetin, however, has a strong af®nity for protein and provides no direct protective effect during LDL oxidation. Sponsorship: This work was funded by the Department of Agriculture for Northern Ireland.

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Tea Flavonoids May Protect Against Atherosclerosis

Geleijnse¹,

Launer²,

Hofman³

et al. 1999

Arch Intern Med

211

102

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Background: Epidemiological studies have indicated a protective role of dietary flavonoids in cardiovascular disease, but evidence is still conflicting. Tea is the major dietary source for flavonoids in Western populations. We studied the association of tea intake with aortic atherosclerosis in a general population. Methods:The present analysis formed part of the Rotterdam Study, a prospective study of men and women 55 years and older. Dietary intakes were assessed at baseline by a trained dietician who used a semiquantitative food frequency questionnaire. Calcified plaques in the abdominal aorta were radiographically detected after 2 to 3 years of follow-up. Aortic atherosclerosis was classified as "mild," "moderate," or "severe," according to the length of the calcified area (Ͻ1 cm, 1-5 cm, and Ͼ5 cm, respectively). The association of tea intake with severity of aortic atherosclerosis was studied in 3454 subjects who were free of cardiovascular disease at baseline. Data were analyzed by logistic regression, adjusting for age, sex, body mass index (calculated as weight in kilograms divided by the square of height in meters), smoking, education, and intake of alcohol, coffee, vitamin antioxidants, total fat, and total energy.Results: Multivariable analyses showed a significant, inverse association of tea intake with severe aortic atherosclerosis. Odds ratios decreased from 0.54 (95% confidence interval [CI], 0.32-0.92) for drinking 125 to 250 mL (1-2 cups) of tea to 0.31 (CI, 0.16-0.59) for drinking more than 500 mL/d (4 cups per day). The associations were stronger in women than in men. The association of tea intake with mild and moderate atherosclerosis was not statistically significant. Conclusion:This study indicates a protective effect of tea drinking against ischemic heart disease.

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Flavonoids inhibit the oxidative modification of low density lipoproteins by macrophages

Cited by 562 publications

References 38 publications

In vivo antioxidant effect of green tea

In vivo antioxidant effect of green tea

Absorption and antioxidant effects of quercetin from onions, in man

Tea Flavonoids May Protect Against Atherosclerosis

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