The Effect of Ilex × meserveae S. Y. Hu Extract and Its Fractions on Renal Morphology in Rats Fed with Normal and High-Cholesterol Diet

Abstract

Therapeutic properties of Ilex species are widely used in natural medicine. Ilex × meserveae may become a potential substitute for Ilex paraguariensis (Yerba Mate). As a part of the preliminary safety verification of this European Ilex hybrid vs. Yerba Mate, an eight-week study concerning the impact of regular administration of leaves of both species on kidneys was conducted. The standard water infusion and three dominant fractions of Ilex × meserveae leaves' constituents (polyphenols, saponins and less polar terpenoids) were separately tried on 96 male Wistar rats divided into 8-member groups. Animals were divided into two basic nutritional groups: the first one was rats fed standard feed and the second on was rats fed with high-cholesterol diet (20 g of cholesterol per kg of standard feed). Postmortem morphometric evaluation of stained kidney samples concerned the filtration barrier elements, which are crucial in proper diuresis. The results showed that saponins present in the hydroalcoholic dry extract (administered in a dose of 10 mg/kg of body weight/day) as well as in water infusions (1:20) from Ilex × meserveae and Ilex paraguariensis do not demonstrate nephrotoxicity but conversely, have a protective role on kidney status in animals fed with a normal diet and in a high-cholesterol diet.

Keywords: Ilex × meserveae; Yerba Mate; high-cholesterol diet; kidney filtration barrier; polyphenols; saponins; terpenoids.

Figure 1

The structure of the kidneys in the control groups: in normal, I (a) and high-cholesterol diet, II (b); (a) note the lack of the urine in proximal tubules and slightly enlarged distal tubules (black arrow); (b) glomerulus filled with blood (black arrow) hematoxylin and eosin (H&E) staining. Mag. 400×. Bar scale 100 µm.

Figure 2

The changes in the structure of the kidneys in groups: II (a), IIa (b), III (c), IIIa (d). Glomeruli with different urine content (black arrow). Note the presence of leukocytes in the kidney parenchyma in IIa group (b) (red arrow). H&E staining. Mag. 400×. Bar scale 100 µm.

Figure 3

The changes in the structure of the kidneys in groups: IV (a), IVa (b), V(c), Va (d), VI (e), and VIa (f). A glomerulus with different urine and blood content (black arrow). The massive lymphocyte infiltration around the glomerulus in group IVa (b) (white arrow) H&E staining. Mag. 400×. Bar scale 100 µm.

Figure 4

The changes in the kidneys’ structure in the controls group: in I, animals fed with normal (a) and II, high-cholesterol diet (b). Note the high content of proteoglycans (blue color) in the capillary tuft of the glomerulus (black arrow). Alcian blue staining. Mag. 200×. Bar scale 50 µm.

Figure 5

The changes in the structure of the kidneys in animals fed with a normal diet—groups II (a), III (c), and in animals fed with high-cholesterol diet—groups IIa (b), IIIa (d). A glomerulus with different proteoglycan content (arrow). Note the presence of urine in the glomerulus in group III (c). Alcian blue staining. Mag. 200×. Bar scale 50 µm.

Figure 6

The changes in the proteoglycans content in the kidneys from groups IV (a), V (c), and VI (e) fed with normal diet and from groups IVa (b), Va (d), VIa (f) fed with a high-cholesterol diet. A glomerulus with different urine and blood content (black arrow). Noticeable differences in the lumen of proximal and distal tubules result from different levels of diuresis. Alcian blue staining. Mag. 400×, Bar scale 50 µm.

Figure 7

The membrane thickness of the capillary tuft. (a) Differences between the control group—I and groups II, III, IV, V were statistically significant at p = 0.05 (and signed by *); (b) Difference between the control group—Ia and IVa group was statistically significant at p = 0.05 (and signed by *). Vertical scale units expressed in µm.

Figure 8

The capsule’s surface area and capillary tuft in kidneys of animals fed with regular diet (a) and fed with a high-cholesterol diet (b). Differences were statistically significant in respect to the control group at p = 0.05 (and signed by *). Vertical scale units expressed in µm.

Figure 9

The ratio of the capsule surface to the capillary tuft surface in rats fed with regular diet (a). The ratio of the capsule surface to the capillary tuft surface in rats fed with a high-cholesterol diet (b). Differences were statistically significant in respect to the control group at p = 0.05 (and signed by *). Vertical scale units expressed in µm.