In vitro ACE-inhibitory activity and in vivo antihypertensive effects of water-soluble extract by Parmigiano Reggiano and Grana Padano cheeses

Angiotensin converting enzyme (ACE)-inhibitory activity and the anti-hypertensive effect of naturally formed bioactive peptides in a lyophilised water-soluble extract (WSE) from 32-month-aged Parmigiano Reggiano (PR) and Grana Padano (GP) cheeses were assessed. ACE-inhibitory activity was evaluated on undigested and in vitro digested WSE: consistent ACE-inhibitory activity in both hard cheeses was found. Twenty spontaneously hypertensive rats were used to test the hypotensive action of lyophilised WSEs from PR and GP cheeses; systolic (SBP) and diastolic (DBP) blood pressures were recorded by a non-invasive tail-cuff method. In vivo administration of GP and PR WSE did not induce a reduction of SBP and DBP after ten weeks of treatment. These results clearly indicate that in vitro ACE-inhibitory activity cannot be used as an exclusive criterion to evaluate potential anti-hypertensive substances. Therefore, in vivo testing of the anti-hypertensive effects of bioactive peptides is necessary to confirm beneficial effects.