Effect of phlorotannins isolated fromEcklonia cavaon angiotensin I-converting enzyme (ACE) inhibitory activity

Abstract

Inhibition of angiotensin I-converting enzyme (ACE) activity is the most common mechanism underlying the lowering of blood pressure. In the present study, five organic extracts of a marine brown seaweed Ecklonia cava were prepared by using ethanol, ethyl acetate, chloroform, hexane, and diethyl ether as solvents, which were then tested for their potential ACE inhibitory activities. Ethanol extract showed the strongest ACE inhibitory activity with an IC50 value of 0.96 mg/ml. Five kinds of phlorotannins, phloroglucinol, triphlorethol-A, eckol, dieckol, and eckstolonol, were isolated from ethanol extract of E. cava, which exhibited potential ACE inhibition. Dieckol was the most potent ACE inhibitor and was found to be a non-competitive inhibitor against ACE according to Lineweaver-Burk plots. Dieckol had an inducible effect on the production of NO in EAhy926 cells without having cytotoxic effect. The results of this study indicate that E. cava could be a potential source of phlorotannins with ACE inhibitory activity for utilization in production of functional foods.

Anticancer effects of seaweed compounds fucoxanthin and phloroglucinol, alone and in combination with 5-fluorouracil in colon cells

“…For example, a study conducted by Wijesinghe and colleagues, showed that extracts of Ecklonia cava are able to inhibit angiotensin I-converting enzyme (ACE) activity. This inhibition is essential in the treatment of hypertension (Wijesinghe et al, 2011). …”

Angiotensin I-converting enzyme (ACE) inhibition and nitric oxide (NO)-mediated antihypertensive effect of octaphlorethol A isolated from Ishige sinicola: In vitro molecular mechanism and in vivo SHR model

“…Among these marine bioresources, brown algae are known to provide an abundance of bioactive materials with valuable pharmaceutical and biomedical potential (Ko, Cha, Heo, Lee, & Jeon, 2011). Wijesinghe, Ko, and Jeon (2011) reported that phlorotannins isolated from the brown alga, Ecklonia cava, have potential to regulate blood pressure because of their ACE inhibitory activity. OPA, a type of phlorotannin, is the marine algal compound isolated from I. sinicola.…”

“…The ACE inhibition by phlorotannins may be closely associated with their protein-binding abilities. Furthermore, it has been demonstrated that the hydroxyl groups in compounds may have a crucial function in promoting the inhibitory effects of enzymes (Wijesinghe et al, 2011). Therefore, OPA could bind to the active or binding sites of ACE, resulting in the inhibition of ACE activity.…”

Comparison of different extraction techniques for obtaining extracts from brown seaweeds and their potential effects as angiotensin I-converting enzyme (ACE) inhibitors

“…However, other molecules that affect the actions of this enzyme include carbohydrates (Endringer et al 2014), chitooligosaccharides (Park et al 2003;Je et al 2006;Ngo et al 2008), and polyphenolic compounds, such as flavonoids, gallic acid (Cerpa-Calderón and Kennedy 2008; Eriz et al 2011;Godoy et al 2012), and phlorotannins (Kim and Himaya 2011;Thomas and Kim 2011;Wijesinghe et al 2011).…”

“…Chemically, phlorotannins are oligomeric or polymeric derivatives of phloroglucinol (1,3,5-trihydroxybenzene) and present variable molecular sizes between 162 Da (phloroglucinol unit) and 650 kDa (Breton et al 2011). Due to their chemical characteristics, these compounds can be used as antioxidants (Li et al 2009;Breton et al 2011;Vijayabaskar and Shiyamala 2012;Rengasamy et al 2013), anti-allergics (Li et al 2011;Vo et al 2012), and anti-inflammatories (Thomas and Kim 2011;Wijesinghe et al 2013), and they exhibit inhibitory effects on enzymes (Lordan et al 2013;Rengasamy et al 2013), particularly ACE inhibitory effects (Wijesekara and Kim 2010;Wijesinghe et al 2011). Another main component present in brown algae is polysaccharides ( Marinho-Soriano et al 2006;Percival and McDowell, 1967;Westermeier et al 2012), and the potential of carbohydrates and its derivatives as ACE inhibitors has also been demonstrated (Lohith et al 2006;Endringer et al 2014).…”