Cardiovascular diseases are the leading cause of death worldwide and exacerbated by the presence of risk factors such as obesity and insulin resistance. Aspalathus linearis (commonly known as rooibos) is a plant indigenous to South Africa containing bioactive phenolic compounds, including aspalathin, implicated for its strong antioxidant potential.
In this study, 60 mg/kg/day Afriplex green rooibos extract (GRT), containing 12% aspalathin, was used as an intervention in treating cardiometabolic disease risk factors induced by a 16-week high-fat, high-caloric diet (HCD) in Wistar rats. Rats received GRT for 6 weeks before the hearts were excised and mounted on a working heart perfusion apparatus and its recovery post-ischemia/reperfusion injury investigated.
HCD led to increased body weight (368.6±6.5g vs 394.4±6.1g = Δ9.6%) and visceral adiposity (14.5g vs 23.1g = Δ59.0%) compared to age-matched control animals. Pre-ischemia, GRT supplementation improved the heart’s total work performance (a measure of pressure power and kinetic power) compared to both untreated controls (13.5±0.4 vs 11.6±0.3) and untreated HCD (11.70±0.3 vs 10.3±0.2). Post-ischemia, HCD hearts had poorer coronary output recovery after reperfusion (60.2±2.6% vs 69.2±2.6%), and GRT treatment restored coronary capacity (72.7±3.7%) to that of controls. Infarct size was also highest in the HCD group (45.9±2.2% vs 35.9±1.4% in controls), with GRT treatment protecting against the damage incurred (HCD: 24.3±1.8%; controls: 26.6±1.0%). Pre-ischemia, HCD hearts presented with low expression of PKB while GRT treatment elevated both PKB and GSK-3β, phospo-p38 and phospho-ERK. During ischemia, GRT treatment further elevated GSK-3β levels in both control and HCD hearts. In early and late reperfusion, low levels of GSK-3β, PKB and JNK in HCD hearts were reversed by GRT treatment. It furthermore increased ERK activity during late reperfusion in the HCD hearts.
This preliminary study shows that GRT supplementation improves heart recovery post-ischemia in rats with elevated risk for cardiovascular disease by improving pro-survival and anti-inflammatory signalling.