The cardioprotective effect of an aqueous extract of fermented rooibos (Aspalathus linearis) on cultured cardiomyocytes derived from diabetic rats

• Published in: Phytomedicine (Stuttgart) Vol. 21; no. 5; pp. 595 - 601
• Main Authors: Dludla, P.V., Muller, C.J.F., Louw, J., Joubert, E., Salie, R., Opoku, A.R., Johnson, R.
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 15.04.2014; Urban & Fischer Verlag
• Subjects: Animals; Apoptosis - drug effects; Aspalathus; Aspalathus linearis; Cardiomyopathy; Care and treatment; Cells, Cultured; Diabetes; Diabetic Cardiomyopathies - drug therapy; Diabetic cardiomyopathy; Drug Evaluation, Preclinical; Fermentation; Glutathione - metabolism; Health aspects; Heart diseases; Hyperglycemia; Male; Materia medica, Vegetable; Myocardial Ischemia - drug therapy; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - metabolism; Oxidative stress; Oxidative Stress - drug effects; Pharmacology, Experimental; Phytotherapy; Plant extracts; Plant Extracts - pharmacology; Plant Extracts - therapeutic use; Rats; Rats, Wistar; Reactive Oxygen Species - analysis; Rooibos; Rooibos tea; NaHCO3; Oxidative stress; PPAG; HFABP; DM; H2O2; DMEM; Hyperglycemia; Aspalathus linearis; KCl; CaCl2; FBS; STZ; Diabetic cardiomyopathy; MgCl2·6H2O; Rooibos; GSH; PBS; HPLC-DAD; T2D; NaH2PO4·2H2O; DCM; CVD; DCFH-DA; NAC; FFAs; ROS; FRE; NaCl; PI; SGLT; HBSS; ATP
• ISSN: 0944-7113; 1618-095X
• DOI: 10.1016/j.phymed.2013.10.029

Diabetic cardiomyopathy (DCM) is a disorder of the heart muscle that contributes to cardiovascular deaths in the diabetic population. Excessive generation of free radicals has been directly implicated in the pathogenesis of DCM. The use of antioxidants, through dietary supplementation, to combat increased cellular oxidative stress has gained popularity worldwide. Aspalathus linearis (rooibos) is a popular herbal tea that contains a novel antioxidant, aspalathin. Literature has reported on the antidiabetic, anti-inflammatory and free radical scavenging effects of rooibos. However, its protective effect against DCM has not been established. Therefore, this study investigated whether chronic exposure to an aqueous extract of fermented rooibos (FRE) has an ex vivo cardioprotective effect on hearts obtained from streptozotocin (STZ) induced diabetic rats. Adult Wistar rats were injected with 40mg/kg of STZ. Two weeks after STZ injection, cardiomyocytes were isolated and cultured. Cultured cardiomyocytes were treated with FRE (1 and 10μg/ml), vitamin E (50μg/ml), and n-acetyl cysteine (1mM) for 6h, before exposure to either hydrogen peroxide (H2O2) or an ischemic solution. Cardiomyocytes exposed to H2O2 or an ischemic solution showed a decrease in metabolic activity and glutathione content with a concomitant increase in apoptosis and intracellular reactive oxygen species. Pretreatment with FRE was able to combat these effects and the observed amelioration was better than the known antioxidant vitamin E. This study provides evidence that an aqueous extract of fermented rooibos protects cardiomyocytes, derived from diabetic rats, against experimentally induced oxidative stress and ischemia.