title: The cardioprotective effect of an aqueous extract of fermented rooibos (Aspalathus linearis) on cultured cardiomyocytes derived from diabetic rats.
abstract: 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 40 mg/kg of STZ. Two weeks after STZ injection, cardiomyocytes were isolated and cultured. Cultured cardiomyocytes were treated with FRE (1 and 10 μg/ml), vitamin E (50 μg/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.
authors.affiliation: Diabetes Discovery Platform, South African Medical Research Council, Tygerberg 7505, South Africa; Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa.
authors.forename: P V
authors.initials: PV
authors.lastname: Dludla
authors.affiliation: Diabetes Discovery Platform, South African Medical Research Council, Tygerberg 7505, South Africa.
authors.forename: C J F
authors.initials: CJ
authors.lastname: Muller
authors.affiliation: Diabetes Discovery Platform, South African Medical Research Council, Tygerberg 7505, South Africa.
authors.forename: J
authors.initials: J
authors.lastname: Louw
authors.affiliation: Post-Harvest and Wine Technology Division, Agricultural Research Council (ARC) Infruitec-Nietvoorbij, Stellenbosch 7599, South Africa; Department of Food Science, Stellenbosch University, Stellenbosch 7602, South Africa.
authors.forename: E
authors.initials: E
authors.lastname: Joubert
authors.affiliation: Diabetes Discovery Platform, South African Medical Research Council, Tygerberg 7505, South Africa; Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg 7505, South Africa.
authors.forename: R
authors.initials: R
authors.lastname: Salie
authors.affiliation: Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa.
authors.forename: A R
authors.initials: AR
authors.lastname: Opoku
authors.affiliation: Diabetes Discovery Platform, South African Medical Research Council, Tygerberg 7505, South Africa. Electronic address: rabia.johnson@mrc.ac.za.
authors.forename: R
authors.initials: R
authors.lastname: Johnson
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D036903:Aspalathus; D002478:Cells, Cultured; D058065:Diabetic Cardiomyopathies / Q000188:drug therapy*; D004353:Drug Evaluation, Preclinical; D005285:Fermentation; D005978:Glutathione / Q000378:metabolism; D008297:Male; D017202:Myocardial Ischemia / Q000188:drug therapy; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000032:analysis
chemical_list: D010936:Plant Extracts; D017382:Reactive Oxygen Species; D005978:Glutathione
keywords: Aspalathus linearis; Diabetic cardiomyopathy; Hyperglycemia; Oxidative stress; Rooibos