Influence of bioflavonoids from the radix extract of Scutellaria baicalensis on the level of serum lipids, and the development of laboratory rats fed with fresh and oxidized fats Boz ˙ena Regulska-Ilow, Jadwiga Biernat, Halina Grajeta, RafalIlow and Maria Drzewicka 1 Introduction Thermally altered fats are one of the risk factors in arterio- sclerosis, which is one of the most serious diseases of the civi- lized world. Interest in the role of oxidized fats in the pathogen- esis of this disease arose in 1965, when Kannitz et al. [1] demonstrated that feeding laboratory animals a diet containing repeatedly reheated fat led to atheriosclerotic changes in their organisms; such changes were not observed in animals fed a diet with fresh oil, even when the oil had added cholesterol [2]. Arteriosclerosis was caused in rabbits by giving them 400 lmol of thermally altered fatty acids – significant, bearing in mind that servings of chips containing 15 g fat have been found to contain up to 8000 lmol of thermally altered fatty acids [3]. In vitro experiments have shown that the harmful activity of oxidized fats is the result of their initiation of free-radical reac- tions; when antioxidants were given along with the fats, their toxic activity was reduced [4]. Compounds like flavonoids and antioxidant vitamins play a significant role in the prevention of arteriosclerosis. It was found that the bioflavonoids present in many plants display a stronger antioxidant activity than vita- mins C and E [5]. In the epidemiological Seven Countries Study [6], researchers observed a negative correlation between the consumption of flavonoids and the mortality rate due to coronary heart disease. Bioflavonoids are characterized by a very broad range of activity. They have various mechanisms of medicinal activity, mainly related to their antioxidant properties [7–9] and their influence on enzymes [10, 11] and the concentration of lipids in the blood [12, 13]. The main sources of bioflavonoids in the human diet are vegetables, fruit, tea and red wine [14]. Due to the health benefits of flavonoid activity, new sources of these compounds are always being sought. One promising source of “flavonoid raw material” is the radix of Scutellaria baicalen- sis, of the Lamiaceae (Labiatae) family, a plant used in Chi- nese medicine, which has been adapted to the climate of Eu- rope [15]. The most important biologically active chemical components of the material are lipophilic flavones, such as bai- calein, baicalin, vogonin and their glycosides. The flavonoid content of the material is very high – A 20%, of which 12–17% is baicalin, and 3-4% is vogonin. After oral administration of baicalein in rats, absorption of baicalein itself was negligible, whereas the glucuronides and sulfates of baicalein were predominant in the plasma. When baicalin was administrated orally, glucuronides and sulfates of baicalein were exclusively circulating in the plasma. The abso- lute absorption of baicalein was 40%. Profound differences of serum profile and pharmacokinetics were observed between oral baicalein and baicalin. Baicalin was absorbed more slowly and to a lesser extent then baicalein [16]. Ten lmol/L of baica- lein and baicalin effectively inhibited lipid peroxidation of rat brain cortex mitochondria induced by Fe 2+ -ascorbic acid, AAPH or NADPH, while wogonin showed significant effects only on NADPH-induced lipid peroxidation [17]. The extract from the radix of S. baicalensis is above all a source of bioflavonoids, compounds of antioxidative activity which are able to neutralize free radicals in the organism. This extract was added to the fodder of some of the experimental groups, with the expectation that it would have a beneficial antioxidative effect neutralizing the toxic effects of the oxi- dized fats in the animals’ diets, and that it would reduce the hyperlipemic effect of their high fat diet. The antioxidative activity of bioflavonoids related to the protection of the low- density lipoprotein (LDL)-cholesterol fraction, as the high- density lipoprotein (HDL) fraction is resistant to oxidation. The aim of this study was to assess the influence of an extract from the radix of S. baicalensis on the plasma concen- i 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/food.200300382 Nahrung/Food 48 (2004) No. 2, pp. 123 – 128 123 The aim of this study was to assess the influence of bioflavonoids from the radix of Scutellaria baicalensis on the level of lipids, via the determination of the concentrations of triglycerides, total cholesterol and high-density lipoprotein (HDL) cholesterol in the plasma of labora- tory rats fed high-fat and high-cholesterol diets, and via the calculation of their atherogenic index. We also studied the influence of bioflavo- noids on their physical development by measuring the increase in their body mass and liver mass. The rats were fed a diet with a 15% content of fresh or oxidized lard or sunflower oil, along with 0.5% added choles- terol. 0.05% S. baicalensis radix extract was added to the diet of half of the rats as the source of bioflavonoids. In the group of rats fed a diet con- taining oxidized oil we observed a significantly lower increase in body mass (15.5 l 7.6 g/4 weeks/rat) than that observed for the control rats (77.0 l 15.7 g/4 weeks/rat). The addition of S. baicalensis radix extract to the diet raised the increase in body mass in the groups receiving oil as the source of fat; those receiving fresh oil had a 40% increase, and those receiving oxidized oil showed a 300% increase relative to the appropri- ate controls. In all the groups of rats fed a diet with bioflavonoids added, a beneficial decrease in the plasma triglyceride content was observed relative to the appropriate controls. In the plasma of rats on a diet con- taining the extract and fresh or oxidized oil or fresh lard, we observed a beneficial reduction in the total cholesterol level relative to the appro- priate controls. The atherogenic index was higher for the group of ani- mals fed with fresh lard than for those fed with fresh oil, and higher for those fed with oxidized oil than for those fed with oxidized lard. The addition of bioflavonoids to the diet beneficially reduced the athero- genic index value in the group fed with fresh oil, and increased its value in the group fed with oxidized lard. Correspondence: Dr. Boz ˙ena Regulska-Ilow, Wroclaw Medical Uni- versity, Department of Food Science and Nutrition, pl. Nankiera 1, PL-50-140 Wroclaw, Poland E-mail: regulska@bf.uni.wroc.pl Fax: +48-71-7840206 Abbreviations: HDL, high-density lipoprotein; LDL, low-density li- poprotein Keywords: Atherogenic index / Bioflavonoids / Lipids / Oxidized fats / Rats /