A relationship between elevated blood pressure and oxidative stress has been suggested in hypertensive animals as well in humans. Rosmarinic acid, the predominant phenolic compound of thyme extract (TE- Thymus serpyllum L.) possesses a broad spectrum of biological activities and is known as antiviral, antibacterial, antioxidant, antinflammatory and immunostimulating agent. The objective of this study was to exemine the effects of bolus injection of TE on sistolic, diastolic, and puls pressure and oxidative stress in the model of essential hypertension.
Design and Method:
Adult male spontaneously hypertensive rats (SHR), and age/sex match normotensive Wistar rats (WR) were divided in 4 groups: SHR-TE and WR-TE received TE, 100 mg/kg b.w. dissolved in 0.2 ml saline. Control SHR-C and WR-C groups received vehicle. After pentobarbital anesthesia systolic (SAP), diastolic (DAP), and pulse pressure (PP) were measured directly. Blood samples were taken for oxidative stress (thiobarbituric acide reactive substances-TBARS).
SAP and DAP decreased significantly in hypertensive rats after bolus of TE (SHR-TE: 147.43 ± 8.99 mmHg vs. SHR-C 243.67 ± 7.17 mmHg, p < 0.001, and SHR-TE: 79.43 ± 7.27 mmHg vs. SHR-C 161.50 ± 6.29 mmHg, p < 0.001) without effects on those parameters in normotesive rats (WR-TE: 105.67 ± 6.23 mmHg vs. WR-C 122.83 ± 7.20 mmHg, and WR-TE: 58.17 ± 5.64 mmHg vs. WR-C 76.33 ± 5.10 mmHg). There was no difference between PP in SHR and WR, however, bolus of TE induced the decline of PP by 17.24 % in hypertensive rats. Plasma TBARS level was significantly higher in SHR than in WR (6.47 ± 0.86 nmol/ml vs. 4.35 ± 0.66 nmol/ml, p < 0.05), and TE significantly reduces its value to a level of normotensive rats (SHR-TE: 4.04 ± 0.52 nmol/ml, p < 0.05).
Our results showed that in SHR, TE induces a normalization of arterial blood pressure and circulating level of TBARS, thus promoting rosmarinic acid, as an antihypertensive and antioxidant agent.