Antihypertensive and Vasorelaxant effects of Cistanche phelypaea leaves through inhibition of Receptor-Operated Calcium Channels in Rats

The study aimed to assess the antihypertensive and vasorelaxant effects of Cistanche phelypaea leaves (family: Orobanchaceae) and their impact on angiotensin-converting enzyme 2 (ACE-2). The aqueous leaf extract of Cistanche phelypaea (CPAE) was prepared and its antihypertensive effect (200 mg/kg) was examined using a hypertensive rat model induced by oral administration of L-NAME (60 mg/kg bw), additionally, we assessed its vasorelaxant potential and its impact on the stimulation or inhibition of ACE-2 in isolated rat thoracic aorta. The results indicate that CPAE significantly lowered systolic (p<0.0001), diastolic (p<0.01), and mean arterial pressure (p<0.01) without affecting normotensive rats. The data showed that CPAE mediates its antihypertensive effect via vasodilatory properties. Furthermore, the vasorelaxant activity of CPAE seems to be mediated through receptor-operated calcium channels (ROCCs). However, CPAE had no effect on ACE-2. In conclusion, the study reveals that the aqueous leaf extract of Cistanche phelypaea possesses a powerful antihypertensive and vasorelaxant effect through the inhibition of Ca2+ entry.