Myocardial Protection from Ischemia-Reperfusion Damage by the Antioxidant Effect of Hibiscus sabdariffa Linnaeus on Metabolic Syndrome Rats

Abstract

Cardiovascular diseases (CVD) constitute one of the most prevalent health problems worldwide, being strongly associated with metabolic syndrome (MS). Oxidative stress (OS) is present in both CVD and MS. Infusions of Hibiscus sabdariffa Linnaeus (HSL) have antioxidant properties and could therefore decrease the presence of OS in these diseases. The aim of this study was to evaluate myocardial protection during ischemia/reperfusion due to the antioxidant effect of HSL infusion (3%) on a MS rat model induced by the administration of 30% sucrose in drinking water. We determined in control, MS, and MS + HSL rat hearts (n = 6 per group) cardiac mechanical performance (CMP), coronary vascular resistance (CVR), and activities of manganese and copper/zinc superoxide dismutases (Mn and Cu/Zn-SOD), peroxidases, glutathione peroxidase (GPx), catalase (CAT), glutathione s-transferase (GST), glutathione reductase (GR), and glutathione (GSH). We also determined lipoperoxidation (LPO), total antioxidant capacity (TAC), and the nitrate/nitrite ratio (NO₃ ^-/NO₂ ^-). The treatment with the HSL infusion restored the CMP (p = 0.01) and CVR (p = 0.04) and increased the Mn- (p = 0.02), Cu/Zn-SOD (p = 0.05), peroxidases (p = 0.04), GST (p = 0.02) activity, GHS (p = 0.02), TAC (p = 0.04), and NO₃ ^-/NO₂ ^- (p = 0.01) and decreased the LPO (p = 0.02) in the heart of MS rats undergoing ischemia/reperfusion. The results suggest that the treatment with an infusion from HSL calices protects the cardiac function from damage by ischemia and reperfusion through the antioxidant activities of the substances it possesses. It favors antioxidant enzymatic activities and nonenzymatic antioxidant capacity.

Figure 1

Isolated perfused heart in experimental rats. (a) Coronary vascular resistance of hearts with global ischemia (30 min) and reperfusion (60 min) periods (n = 6); ^∗p = 0.01 Ctr vs. MS and ^∗∗p = 0.04 MS vs. MS + HSL. (b) Cardiac mechanical performance of isolated hearts with global ischemia (30 min) and reperfusion (60 min) (n = 6); ^∗p = 0.03 Ctr vs. MS and ^∗∗p = 0.01 MS vs. MS + HSL. Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus.

Figure 2

Densitophotometric analysis of activity of super oxide dismutase isoforms in the heart homogenates of the experimental rats; a native gel representative of the Mn-SOD and Cu/Zn-SOD activities is presented. (a) Manganese isoform and (b) copper/zinc isoform. Native gel electrophoresis with 10% polyacrylamide. Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus. Data are expressed in mean ± SE (n = 6 rats in each group).

Figure 3

(a) Densitophotometric analysis of peroxidase activities. A native gel electrophoresis with 10% polyacrylamide is shown between (a) and (b). Under these conditions, where peroxidases are present, the gel remains transparent and the 3, 3′,5,5′-tetramethylbenzidine is oxidized showing a green coloration. (b) GPx activity has a tendency to increase its activity when comparing MS + HSL vs. MS. However, the change was not statistically significant (p = 0.06 NS). Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus. Data are expressed in mean ± SE (n = 6 rats in each group).

Figure 4

(a) Glutathione S-transferase activity in the experimental groups and (b) effect of the treatment with HSL infusion on glutathione reductase activity in the heart homogenate. There was a tendency to an increase in the activity of GR between MS + HSL and MS; however, it did not reach a statistically significant level (p = 0.06 NS). Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus. Data are expressed in mean ± SE (n = 6 rats in each group).

Figure 5

Effect of treatment with HSL infusion. (a) Reduced GSH concentrations. (b) Densitophotometric analyses of CAT activity in the heart homogenate. In (b), a native representative gel of the CAT activity is shown. Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus. Data are expressed in mean ± SE (n = 6 rats in each group).

Figure 6

(a) Nitrate and nitrite ratio in the heart homogenates from the experimental groups. (b) Lipid peroxidation levels and (c) total antioxidant capacity. Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus. Data are expressed in mean ± SE (n = 6 rats in each group).

Figure 7

(a–c) Representative photomicrographs of heart tissue after of reperfusion from the three experimental groups. 5 fields per sample were analyzed. (a) Ctr, (b) MS, and (c) MS + HSL. Values are the mean ± SE (n = 6). The tissue was processed according to conventional histological procedures, and histological sections were made and stained by hematoxylin-eosin stain at 10x. Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus.

Figure 8

Densitophotometric analysis of myocyte bundle areas in experimental groups. Ctr: control; MS: metabolic syndrome; MS + HSL: metabolic syndrome plus Hibiscus sabdariffa Linnaeus. Values are the mean ± SE (n = 6).