Antihypertensive and Antioxidant Effects of Safflower Ethanolic Extract in Renovascular Hypertensive Rats

Abstract

Background and Objectives: Previous studies demonstrated that safflower extract had antihypertensive effect in chronic NO synthase inhibition induced hypertensive rats. The aim of the present study was to investigate whether safflower extract could reduce blood pressure and oxidative stress in 2K-1C hypertensive rats and mechanism involved.

Methods: Male Sprague-Dawley rats were induced hypertension using two-kidney one-clip (2K-1C) model. Hypertensive rats were fed with safflower extract (500 mg/kg BW per day) or captopril (5 mg/kg BW per day) for four weeks while sham-operated control group and 2K-1C untreated group received distilled water. Systolic blood pressure (SBP) and heart rate (HR) were measured once a week using tail cuff method. At the end of experiment, vascular superoxide (O₂^•-) production and plasma malondialdehyde (MDA) concentration were evaluated.

Results: 2K-1C hypertensive rats had high blood pressure (SBP = 222.83  ± 11.85 mmHg) comparing to those of control (SBP = 134.80  ± 2.16 mmHg). There was no significant difference of HR between control and 2K-1C hypertensive rats. Increases in vascular superoxide production and plasma MDA were observed in 2K-1C hypertensive rats. Interestingly, the safflower extract significantly reduced blood pressure, vascular superoxide production and plasma MDA concentration (p < 0.05). Furthermore, captopril also reduced SBP and oxidative stress markers in 2K-1C hypertensive rats.

Conclusion: These findings suggested that the safflower extract exhibited an antihypertensive effect in renovascular hypertensive rats. This was associated with reducing oxidative stress.