Berry juices, teas, antioxidants and the prevention of atherosclerosis in hamsters
Introduction
The postulated involvement of lipid peroxidation in atherogenesis invoked intensive research on antioxidants. Consumption of fruits and vegetables has been linked with lower prevalence of coronary heart disease (Bazzano, 2006, Dauchet et al., 2006, Feldman, 2001, Liu et al., 2000). Drinking tea has also been linked with reduced mortality arising from cardiovascular disease (Kuriyama et al., 2006), although some epidemiological data are inconclusive (Yang & Landau, 2000). Fruits, vegetables and teas contain a wide range of antioxidant compounds, including phenolic compounds and vitamins. Phenolic compounds, such as anthocyanins, flavan-3-ols, flavonols, hydroxycinnamates and tannins, are widespread in fruits and vegetables, with especially high quantities being found in berries and teas. Berries are rich in anthocyanins and can also contain substantial quantities of ellagitannins, while flavan-3-ols and their related derivatives predominate in teas (Crozier, Jaganath, Marks, Saltmarsh, & Clifford, 2006).
Golden Syrian hamsters represent an useful test system because when fed a fat-rich diet they develop dyslipidemia and atherosclerotic plaques, similar in many respects to human atheroma (Auger et al., 2002).
A relatively straight-forward way to evaluate influences on atherosclerosis progression in animal models is to measure the extent of fatty streak development, the continuous accumulation of lipids (due mainly to large accumulations of macrophages) in the sub-endothelial space. Using this approach, we have evaluated the effects of raspberry, strawberry and bilberry juices and green and black tea, sources of potentially anti-atherogenic phenolic compounds, by feeding the beverages to golden Syrian hamsters on a high fat diet for a 12-week period.
Section snippets
Chemicals
5-O-Caffeoylquinic acid, procyanidin B2, (–)-epicatechin (+)-catechin, (–)-gallocatechin, (–)-epicatechin, (–)-epicatechin gallate, (–)-epigallocatechin, (–)-epigallocatechin gallate, gallic acid, caffeine, theobromine, theaflavins and ellagic acid were purchased from Sigma–Aldrich (Poole, UK). Quercetin, myricetin, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, quercetin-3-O-arabinoside, quercetin-3-O-galactoside, kaemperol-3-O-rutinoside, kaemperol-3-O-glucoside, caffeic acid and p
Phenolic compounds in berry juices and teas
Twenty seven phenolic compounds were detected in the bilberry juice (Table 1) with the 13 anthocyanins comprising 599 nmoles/ml of a total flavonoid and phenolic content of 744 nmoles/ml. The juice also contained 76 nmoles/ml of gallic acid and smaller quantities of flavan-3-ols and a number of flavonols in low concentrations. The major components in the raspberry juice were anthocyanins (164 nmoles/ml), principally cyanidin-3-sophoroside and cyanidin-3–2G-glucosylrutinoside, and the ellagitannins,
Discussion
Daily consumption of each of the test beverages for a 12-week period resulted in a substantially lower fatty streak deposition in the arteries of the hamsters compared to water-treated controls, with stronger effects for green tea and raspberry juice (Fig. 1, Fig. 2). This marked limitation of the onset of atherosclerosis was not associated with any significant change in plasma cholesterol profile.
The observation that the plasma cholesterol profile did not change among groups of hamsters (Table
Conflict of interest statement
The authors declare that there are no conflicts of interest.
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