Planta Med 2018; 84(02): 75-82
DOI: 10.1055/s-0043-117415
Biological and Pharmacological Activity
Original Papers
Georg Thieme Verlag KG Stuttgart · New York

Myocardial Glucose Clearance by Aspalathin Treatment in Young, Mature, and Obese Insulin-Resistant Rats

Sybrand Engelbrecht Smit
Division of Medical Physiology, Stellenbosch University, Cape Town, South Africa
,
Rabia Johnson
Division of Medical Physiology, Stellenbosch University, Cape Town, South Africa
Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa
,
Mignon Alberta Van Vuuren
Division of Medical Physiology, Stellenbosch University, Cape Town, South Africa
,
Barbara Huisamen
Division of Medical Physiology, Stellenbosch University, Cape Town, South Africa
Biomedical Research and Innovation Platform, South African Medical Research Council, Cape Town, South Africa
› Author Affiliations
Further Information

Publication History

received 10 February 2017
revised 10 July 2017

accepted 17 July 2017

Publication Date:
03 August 2017 (eFirst)

Abstract

Rooibos, an indigenous South African plant ingested as herbal tea, is well known for its antioxidant effects. This in vitro study investigated aspalathin (C21H24O11), a dihydrochalcone unique to rooibos, for hypoglycemic effects in the context of age- and obesity-induced insulin resistance and the mechanisms involved. Male Wistar rats were allocated into three groups: 16 – 30 weeks feeding with either standard rat chow or a high-caloric diet, or 6 – 10 weeks feeding with standard rat chow. Ventricular cardiomyocytes were isolated by collagenase perfusion digestion, and glucose uptake was determined by 2-[3H]-deoxyglucose accumulation. Viability was tested by trypan blue exclusion or propidium iodide staining. The high-caloric diet significantly increased body weight gain (508.5 ± 50.0 vs. 417.3 ± 40.0 g), visceral adiposity (42.30 ± 10.1 vs. 21.75 ± 7.0 g), and fasting blood glucose (5.7 ± 0.4 vs. 4.7 ± 0.1 mM). Aspalathin (10 µM for 90 min) induced 2-[3H]-deoxyglucose uptake in young cardiomyocytes (37.2 ± 13.9 vs. 25.7 ± 2.5 pmol 2-[3H]-deoxyglucose/mg protein) and enhanced insulin-mediated 2-[3H]-deoxyglucose uptake in control cells (32.4 ± 6.4 vs. 23.5 ± 10.0 pmol 2-[3H]-deoxyglucose/mg protein), but failed to induce 2-[3H]-deoxyglucose uptake in high-caloric diet cells. Aspalathin induced glucose uptake in insulin-sensitive cardiomyocytes from young and aged rats, but not in high-caloric diet animals and enhanced the actions of insulin through a PI3K-dependent mechanism, resulting in an additive response.

Supporting Information