Inhibition of angiotensin I-converting enzyme (ACE-I) by aqueous extracts prepared from edible and non-edible parts of lotus root

Angiotensin I-converting enzyme (ACE) is known to catalyze the conversion of angiotensin-I to angiotensin-II, which is the biologically active peptide elevating blood pressure, thereby being implicated in the pathogenic process of hypertension. Therefore, ACE inhibitory substances are expected to reduce the blood pressure in hypertensive patients. Then, the aqueous extracts were prepared from the edible and non-edible joint parts of lotus root (a rhizome of Nelumbo nucifera), and the effects of these extracts on ACE activity were examined in vitro to search for potentially effective substances against hypertension. The extracts of both edible and joint parts caused their inhibitory effects on ACE activity, similar in their properties and different in their potencies. Thus, the aqueous extracts prepared from lotus root are suggested to contain novel substances inhibiting ACE activity, thereby reducing blood pressure by inhibiting the production of active hypertensive peptide.