Anti-hepatotoxic activities of Hibiscus sabdariffa L. in animal model of streptozotocin diabetes-induced liver damage

Abstract

Background: Flavonoid-rich aqueous fraction of methanolic extract of Hibiscus sabdariffa calyx was evaluated for its anti-hepatotoxic activities in streptozotocin-induced diabetic Wistar rats.

Methods: Diabetes Mellitus was induced in Wistar rats by a single i.p injection of 80 mg/kg b.w. streptozotocin (STZ) dissolved in 0.1 M citrate buffer (pH 6.3).

Results: The ameliorative effects of the extract on STZ-diabetes induced liver damage was evident from the histopathological analysis and the biochemical parameters evaluated in the serum and liver homogenates. Reduced levels of glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) (3.76 ± 0.38 μM, 0.42 ± 0.04 U/L, 41.08 ± 3.04 U/ml, 0.82 ± 0.04 U/L respectively) in the liver of diabetic rats were restored to a near normal level in the Hibiscus sabdariffa-treated rats (6.87 ± 0.51 μM, 0.72 ± 0.06 U/L, 87.92 ± 5.26 U/ml, 1.37 ± 0.06 U/L respectively). Elevated levels of aspartate amino transferase (AST), alanine amino transferase (ALT) and alkaline phosphatase (ALP) in the serum of diabetic rats were also restored in Hibiscus sabdariffa -treated rats. Examination of stained liver sections revealed hepatic fibrosis and excessive glycogen deposition in the diabetic rats. These pathological changes were ameliorated in the extract-treated rats.

Conclusion: The anti-hepatotoxic activity of Hibiscus sabdariffa extract in STZ diabetic rats could be partly related to its antioxidant activity and the presence of flavonnoids.

Figure 1

Photomicrographs showing the liver of the experimental rats (A - normoglycaemic rats, B – test group I, C – diabetic negative control, D – test group II and E – diabetic positive control) stained with H & E. Note the hepatocytes (H) arranged in plates around the central vein (CV) with sinusoids (arrow) in between the plates. Architecture of groups A B and D liver appeared normal. Distortion of architecture and signs of inflammation were observed in group C liver while group E liver section revealed a disheveled pattern of liver architecture with poorly defined hepatocytes and sinusoids except those in the immediate vicinity of the central vein. Vascular congestion of the central vein was also observed in the liver of group C and E rats.

Figure 2

Photomicrographs showing the liver of the experimental rats (A - normoglycaemic rats, B – test group I, C – diabetic negative control, D – test group II and E – diabetic positive control) stained with Gordon and Sweets reticulin stain. Note the reticular fibres (stained black) lining the sinusoids (arrow) where they are between plates of liver cells (stained yellow) and also form a dense network (star) around the central vein (CV). The reticular fibres are well stained in the liver section of groups A, B and D rats. However, in groups C and E liver, the reticular fibres are poorly stained except where they form dense network around the central vein.

Figure 3

Photomicrographs showing the liver of the experimental rats (A - normoglycaemic rats, B – test group I, C – diabetic negative control, D – test group II and E – diabetic positive control) stained with Masson trichrome stain. Note extensive area of collagen staining (black star) around the CV as well as the intercellular matrix around the hepatocytes of the liver groups C and E rats.

Figure 4

Photomicrographs showing the liver of the experimental rats (A- normoglycaemic rats, B- test group I, C-diabetic negative control, D test group II, E-diabetic positive control) stained with PAS (arrow) with diastase control (star). The liver section of group C was deeply stained with PAS while liver sections of other groups were moderately stained with PAS. Diastase negative control was negative to PAS staining in all groups.