The standardized extract of Nigella sativa and its major ingredient, thymoquinone, ameliorates angiotensin II-induced hypertension in rats.

Background This study investigated the effect of hydroalcoholic extract of Nigella sativa (N. sativa) and its active component, thymoquinone (TQ) on hypertension induced by angiotensin II (AngII), the main product of renin-angiotensin system (RAS). Methods Seven animal groups (n=7 for each group) were used as follows: (1) control, (2) AngII (300 ng/kg), (3) AngII+losartan (Los; 10 mg/kg), (4) TQ (40 mg/kg)+AngII, and (5-7) three doses of N. sativa (200, 400, and 600 mg/kg)+AngII. Los and AngII were injected intravenously; TQ and extracts were injected intraperitoneally. In TQ and N. sativa-treated groups, 30 min after injection of the extract and TQ, AngII was injected. Cardiovascular parameters were recorded by power lab system after cannulation of femoral artery. The maximum changes (∆) of systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) were calculated and used for statistical analysis. Results AngII significantly increased maximal ∆SBP, ∆MAP, and ∆HR compared with the control (p<0.001), and these effects significantly were blunted by Los. TQ and two higher doses (400 and 600 mg/kg) of N. sativa significantly could antagonize effect of AngII on ∆SBP, ∆MAP (p<0.05 to p<0.001). AngII-induced changes of HR are also significantly decreased by TQ and dose 600 mg/kg of extract (p<0.01 and p<0.05, respectively). Conclusions The N. sativa and its component TQ have the beneficial effect on hypertension probably due to attenuation cardiovascular effects of AngII.