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Planta Med 2022; 88(01): 62-78
DOI: 10.1055/a-1239-9236
Biological and Pharmacological Activity
Original Papers

Cardioprotective Function of Green Rooibos (Aspalathus linearis) Extract Supplementation in Ex Vivo Ischemic Prediabetic Rat Hearts

Sybrand Engelbrecht Smit 
1   Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Republic of South Africa
,
Claudine Manirafasha
1   Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Republic of South Africa
,
Erna Marais
1   Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Republic of South Africa
,
Rabia Johnson
2   Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, Republic of South Africa
,
Barbara Huisamen
1   Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Republic of South Africa
2   Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, Republic of South Africa
› Author AffiliationsSupported by: Harry Crossley Foundation
Supported by: South African National Research Foundation
Supported by: South African Rooibos Council
Supported by: South African Medical Research Council
› Further Information
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Abstract

Diabetic patients develop ischemic heart disease and strokes more readily. Following an ischemic event, restoration of blood flow increases oxidative stress resulting in myocardial damage, termed ischemia/reperfusion injury. Aspalathus linearis (rooibos), rich in the antioxidant phenolic compound aspalathin, has been implicated as cardioprotective against ischemia/reperfusion injury with undefined mechanism in control rats. Primarily, the therapeutic potential of Afriplex green rooibos extract to prevent ischemia/reperfusion injury in cardiovascular disease-compromised rats was investigated. Additionally, Afriplex Green rooibos extractʼs cardioprotective signaling on metabolic markers and stress markers was determined using western blotting. Three hundred male Wistar rats received either 16-wk standard diet or high-caloric diet. During the final 6 wk, half received 60 mg/kg/day Afriplex green rooibos extract, containing 12.48% aspalathin. High-caloric diet increased body weight, body fat, fasting serum triglycerides, and homeostatic model assessment of insulin resistance – indicative of prediabetes. High-caloric diet rats had increased heart mass, infarct size, and decreased heart function. Afriplex green rooibos extract treatment for 6 wk lowered pre-ischemic heart rate, reduced infarct size, and improved heart function pre- and post-ischemia, without significantly affecting biometric parameters. Stabilized high-caloric diet hearts had decreased insulin independence via adenosine monophosphate activated kinase and increased inflammation (p38 mitogen-activated protein kinase), whereas Afriplex green rooibos extract treatment decreased insulin dependence (protein kinase B) and conferred anti-inflammatory effect. After 20 min ischemia, high-caloric diet hearts had upregulated ataxia–telangiectasia mutated kinase decreased insulin independence, and downregulated insulin dependence and glycogen synthase kinase 3 β inhibition. In contrast, Afriplex green rooibos extract supplementation downregulated insulin independence and inhibited extracellular signal-regulated kinase 1 and 2. During reperfusion, all protective signaling was decreased in high-caloric diet, while Afriplex green rooibos extract supplementation reduced oxidative stress (c-Jun N-terminal kinases 1 and 2) and inflammation. Taken together, Afriplex green rooibos extract supplementation for 6 wk preconditioned cardiovascular disease-compromised rat hearts against ischemia/reperfusion injury by lowering inflammation, oxidative stress, and heart rate.

Key words

Aspalathus linearis - Leguminosae - rooibos - aspalathin - reperfusion injury - ischemia - diabetes - cardiovascular disease

Supporting Information

    The authors added supplementary information beneficial for future research on either GRT or diet-induced prediabetic rat studies, as well as western blot and infarct size methodology. These include rationales for GRT dosage preparation, nutritional certificates of diets and treatment used, serum fatty acid composition, timelines of food and water intake, simplified diagrams of methodology and graphical analysis of all western blots used in this article.

  • Supporting Information


Publication History

Received: 11 April 2020

Accepted after revision: 11 August 2020

Article published online:
07 December 2020

© 2020. Thieme. All rights reserved.

Georg Thieme Verlag KG
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