Antihyperglycemic Effect of the Moroccan Collard Green (Brassica oleracea var. viridis) in Streptozotocin-Induced Diabetic Rats

Aim: The aim of the study was to assess the antihyperglycemic activity of Brassica oleracea. Background: Collard green or Brassica oleracea var. viridis which belongs to Brassicaceae family is ranked at 10th place of “powerhouse” vegetables, and it is commonly used traditionally for the treatment of diabetes in Morocco. Objective: This current investigation aimed to assess the antihyperglycemic capacity of the aqueous extract of Collard green leaves. Methods: The effect of a single (6 hours) and repeated (seven days of treatment) oral administration of Collard green aqueous extract (CGAE) at a dose of 60 mg/kg on glucose and lipid profile was examined in normal and streptozotocin-induced diabetic rats. Additionally, histopathological examination of liver was carried out according to the Hematoxylin-Eosin method. Furthermore, a preliminary phytochemical screening, and the quantification of phenolic, flavonoid and tannins contents as well as the antioxidant activity using DPPH assay were carried out. Results: The results demonstrated that Collard green A.E. (CGAE) exhibited a significant antihyperglycemic effect and positive improvement liver histology in diabetic rats. After a single oral administration of CGAE, blood glucose levels were lowered from 15±2 mM to 4.9±1 mM (p<0.0001) at the sixth hour in diabetic rats but no change was observed in normal rats. Repeated CGAE administration was able to reduce blood glucose levels from 15±2 mM to normal values (5±1 mM at the seventh day, p<0.0001) while the extract had no effect in normal rats. In addition, we revealed that CGAE is rich in several phytochemical compounds and exerts an important antioxidant activity. Conclusion: In conclusion, this study demonstrates that Collard green possesses a beneficial effect against diabetes and can be used in the program diet of diabetic patients.