In vitro Antidiabetic Activity of a Polyherbal Tea and Its Individual Ingredients

Aim: To assess the antidiabetic potential of a polyherbal tea, Diabetea, and its individual ingredients; Achillea millefolium L., Agathosma betulina Bartl. & Weidl., Salvia officinalis L., Taraxacum officinalis L., Thymus vulgaris L., Trigonella foenum-graecum L. and Urtica urens L. Study Design: An in vitro laboratory-based study with appropriate positive and negative controls. Place and Duration of Study: Department of Pharmacology, February 2011 to August 2013. Methodology: The alpha-amylase and alpha-glycosidase enzyme inhibitory activity of hot water-and dichloromethane extracts (HWE and DCME) of Diabetea and its constituents were assessed spectrophotometrically and data interpreted using the Michaelis-Menten model. Glucose uptake into C2C12 myotubes was determined using a fluorometric method. Results: A. betulina (DCME) and U. urens (DCME) significantly (p< 0.05) inhibited the activity of aglucosidase (non-competitively) and alpha-amylase (un-competitively). The inhibitory activity of these extracts significantly (p< 0.05) compared with the positive control, acarbose. The DCME of Diabetea, T. officinalis, U. urens, A. millefolium and the HWE of A. betulina, T. officinalis, T. foenum-graecum, S. officinalis, U. urens and T. vulgaris caused a significant (p< 0.05) uptake of glucose into C2C12 myotubes compared to the control. S. officinalis (HWE) and T. vulgaris (DCME) were found to be more active in reducing the blood sugar level than insulin (p< 0.05) at 3 and 20 mu g/ml, respectively. Conclusion: Diabetea, T. officinalis, U. urens, A. millefolium, A. betulina, T. foenum-graecum, S. officinalis and T. vulgaris contain bioactive compounds that act as insulin mimetics. It can be concluded that U. urens (DCME), A. betulina (HWE) and T. vulgaris (HWE and DCME) were the most promising in vitro antidiabetic preparations due to their potent hypoglycaemic activities.