Hypertension is a major risk factor for the development of cardiovascular disease including stroke and may also play a role in the development of vascular cognitive impairment and vascular dementia [1, 2]. Angiotensin I-converting enzyme (EC 3.4.15.1; ACE) plays an important role in the renin-angiotensin system and is a carboxy-terminal dipeptidyl exopeptidase that catalyzes the conversion of angiotensin I to angiotensin II [3-6] . ACE also converts an inactive form of decapeptide, angiotensin I, into a potent vasoconstrictor, the octapeptide, angiotensin II; since ACE is a multifunctional enzyme, it also catalyzes the degradation of bradykinin, known as a vasodilator [4, 7]. Therefore, inhibition of ACE activity leads to a decrease in the concentration of angiotensin II and an increase in the level of bradykinin; consequently reduce blood pressure [8]. The discovery of captopril as a potent ACE inhibitor has led to the recent development of many series of new structures with similar biological activity [9]. To date, a wide variety of ACE inhibitors have been reported from various terrestrial and marine food sources, such as milk [10], cheese [11], egg white [12], rapeseed [13], peanuts [14], rapeseed [15], deer horn [16], fish muscle [17], seaweed [18] and tuna [2]. Many academic, scientific and regulatory organizations are evaluating ways to establish the scientific basis to further support and validate claims about functional components or foods containing them. Consumer interest in the relationship between diet and health has increased the demand for information on functional foods. More recently, the food industry, agricultural community and now consumers have shown increasing interest in the field... of paper media... dependent on the conversion of yellow tetrazolium bromide to its purple formazan derivative by mitochondrial succinate dehydrogenase in viable cells [34]. In conclusion, E. cava is a very interesting resource, thanks to the presence of unique phlorotannin derivatives with special bioactivities including ACE inhibitory activity. Ethanol improves the extraction of phlorotannins, especially dieckol, from the brown algae E. cava. In contrast, in this study, the phloroglucinol derivative dieckol showed the strongest activity against ACE. With the results of this study we can suggest that the brown algae E. cava could be used in the development of promising and potential functional food products. Furthermore, these findings are expected to help develop interest in basic research and potential applications of phlorotannins in relevant fields..