Angiotensin converting enzyme (ACE) and renin are the two key enzymes in the renin-angiotensin system (RAS) that regulate blood pressure in human beings.Therefore,inhibitors of renin and ACE are good candidates for the formulation of therapeutic products against hypertension.Inhibition of renin reduces the production of angiotensin I,and inhibition of ACE decreases the conversion of angiotensin Ⅰ to angiotensin Ⅱ.