Angiotensin-converting enzyme inhibitory assay

Inhibitory activity of aqueous extracts was analyzed following a method by Hayakari et al. [22] https://dx.doi.org/10.17504/protocols.io.tb4eiqw. Hippuryl-L-histidyl-L-leucine (HHL) (Sigma) was hydrolyzed by ACE to yield hippuric acid and histidyl-leucine. This method relies on the colorimetric reaction of hippuric acid with 2, 4, 6-trichloro-s-triazine (TT) (Sigma). The tests were performed in triplicate and antihypertensive activity was quantified by a regression analysis of ACE inhibitory activity (%) versus phenolic compounds concentration in aqueous extract and defined as an IC₅₀ value, that is, the concentration of phenolic compounds required to produce 50% ACE inhibition under the conditions described. For angiotensin-converting enzyme inhibitory assay, lisinopril (antihypertensive drug) was used as control.