Antihypertensive activity of natural antioxidant, olive leaf extract (OLE) is
known, but its influence on cardiovascular system when administered in a high
dose has not been investigated yet. Our aim was to determine the acute
effects of excessive intake of standardized OLE on blood pressure, heart rate
and oxidative status in both spontaneously hypertensive rats and normotensive
Wistar rats. Systolic arterial pressure and heart rate were measured using a
tail-cuff, pneumatic pulse detector, before, 60 and 120 minutes after
intragastric OLE administration. Activities of catalase, glutathione
peroxidase, superoxide dismutase (SOD) and glutathione reductase in
erythrocytes, as well as lipid peroxidation in plasma (pTBARS) were measured
at the same time points, spectrophotometrically. High-dose OLE did not
influence blood pressure, heart rate and pTBARS in normotensive rats, while
SOD, catalase, and glutathione reductase activities significantly increased.
The same dose significantly decreased blood pressure in hypertensive rats,
but increased pTBARS and SOD activity. Excessive oral intake of OLE induced
moderate hypotensive effects in spontaneously hypertensive rats only,
suggesting absence of harmful haemodynamic effects after oral overdose in
both rats strain. However, its prooxidative role when given in high dose in
hypertensive organism should not be neglected.
Effects of high dose olive leaf extract on haemodynamic and oxidative stress parameters in normotensive and spontaneously hypertensive rats