The effect of dried tomato, grape and apple pomace on the cholesterol metabolism and antioxidative enzymatic system in rats with hypercholesterolemia

Abstract

The effect of dried tomato, grape and apple pomace (5% in diet) on the cholesterol levels in serum and selected organs was studied in male Wistar rats fed a cholesterol diet (0.3%) shortly after weaning. Pomace of individual fruits contained 47.2, 67.0 and 46.2 g of total dietary fiber per 100 g of dry matter for tomato, grape and apple pomace, respectively. Corresponding values for the soluble components of the fiber were 10.3, 14.7 and 26.0%. None of the tested products affected the serum cholesterol levels. Tomato and apple pomace significantly reduced cholesterol level in liver by 15% and 11%, respectively, and all tested pomace species reduced cholesterol content in heart (by 18-21%). Triacylglycerol content was affected only by tomato pomace and solely in the heart. Cholesterol absorption measured by dual-isotope ratio method, was not significantly affected by the pomace, however, all products strongly reduced (up to the half of the original value) the activity of HMG-CoA reductase in liver and increased the fractional catabolic rate of plasma cholesterol (by 60-120%). All tested pomace reduced plasma levels of conjugated dienes and tomato and grape pomace exhibited this effect also in the liver. All tested pomace reduced the activities of antioxidant enzymes superoxid dismutase, catalase and glutathione peroxidase in erythrocytes (by 34-56%).

Grape products and cardiovascular disease risk factors

“…So, it cannot be said overall that grapes and derived products present positive effects on plasma cholesterol in animal studies. However, one of these studies (26) did find a reduction in cardiac cholesterol and in the half-times of serum [ 14 C]cholesterol decay curves, while another reported a decrease in aorta total cholesterol (63) .…”

“…The same happened after supplementation to hamsters with different extracts from grapes (52) or to rats with grape pomace. In this last case, there was actually a significant loss of antioxidant capacity in the liver (26) . These differences in results of similar assays may be related to the various limitations that have been reported in the determination of plasma antioxidant capacity (97) , as well as to differences in the designs of the studies (duration of treatment, doses employed).…”

“…Also, an increase in hepatic glutathione peroxidase activity after the intake of grape pomace by rats was observed, although there was no change in any of the other hepatic enzymes, and there was a significant decrease in the activities of these enzymes in the erythrocytes. A similar tendency was observed for tomato and apple pomace (26) .…”

“…Main compositional characteristics of grapes and polyphenol-rich derived products (9,14,28,30,34) (11) Twenty-three ovariectomised guinea-pigs 12 weeks Control treatment or diet with 10 % freeze-dried grapes, 6 % dietary fibre and 0·5 % total polyphenols. Intake ad libitum Ruf et al (1995) (12) 144 rats 4 months Series 1: tap water, ethanol 6 %, red wine diluted in water (6 % ethanol) or white wine diluted in water (6 % ethanol) Series 2: ethanol 6 %, red wine diluted in water (6 % ethanol), ethanol 6 % with 0·2 % glycerol or ethanol 6 % with 0·025 % grape seed extract Series 3: ethanol 6 %, red wine diluted in water (6 % ethanol) or red wine extract added to ethanol 6 % Series 4: water, red wine diluted in water (6 % ethanol) with the same content in glycerol as dealcoholised red wine or dealcoholised red wine Martín-Carró n et al (2000) (13) Twenty-four rats 4 weeks Diet with and without cholesterol, two groups in each: control treatment or product from grapes rich in polyphenols (1·63 %) and fibre (50 %) (10 % diet) Martín-Carró n et al (2000) (13) Eighty rats 42 d Diet with and without cholesterol, three groups in each: control with cellulose, white grape peel or white grape seed (all the groups with 54-59 % dietary fibre) Falchi et al (2006) (14) Rats 30 d Grape seed extract (0·18-0·33 % total polyphenols fresh matter), grape flesh extract (0·03 -0·04 % total polyphenols fresh matter) or water Osman et al (1998) (22) Five (26) Eighty rats 10 weeks Diet with cholesterol supplemented with: cellulose, grape pomace, apple pomace or tomato pomace Diebolt et al (2001) (40) Twenty-four rats 1 week Product with glucose 5 % or two different extracts of polyphenols from red wine (in all cases, 20 mg/kg weight per d) Bernatova et al (2002) (41) Forty-eight rats After taking L-NAME for 3 weeks, three groups:…”

Effect of gala apples (Malus domestica Borkh) on lipidemia of hyperlipidemic rats

“…This result is in accordance with Aprikian et al (2002), who found that when cholesterol-fed rats were supplemented with apples, there was a significant drop in plasma cholesterol and an increase in high-density lipoproteins (HDL). More studies investigated these parameters using apples, pears and peaches, with apples having the greatest effect (BOBEK; OZDÍN; HROMADOVÁ, 1998;LEONTOWICZ et al, 2003). Apples contained more phenolic compounds, suggesting that perhaps the phenolics in apples contribute to this effect ( LEONTOWICZ et al, 2002).…”