Angiotensin‐converting enzyme I inhibitory activity of phlorotannins from Ecklonia stolonifera
ABSTRACT As part of our study of the isolation of antihypertensive agents derived from natural marine products, the bioactivity of 10 edible Korean seaweeds were screened by angiotensin converting enzyme (ACE) inhibitory and peroxynitrite assays. Among the crude extracts of selected seaweeds, including five Phaeophyta (Ecklonia stolonifera, E. cava, Pelvetia siliquosa, Hizikia fusiforme, and Undaria pinnatifida), four Rhodophyta (Gigartina tenella, Gelidium amansii, Chondria crassicaulis, and Porphyra tenera) and one Chlorophyta (Capsosiphon fulvescens), the ethanol extracts of E. stolonifera, E. cava, P. siliquosa, U. pinnatifida, and G. tenella exhibited significant inhibitory properties against ACE at more than 50% inhibition at a concentration of 163.93 µg/mL. Phloroglucinol 1, eckstolonol 2, eckol 3, phlorofucofuroeckol A 4, and dieckol 5 had been isolated previously, and triphlorethol-A 6 and fucosterol 7 were isolated for the first time from E. stolonifera. Also, the ACE inhibitory and peroxynitrite scavenging properties of phlorotannins 1–6 were evaluated, along with fucosterol 7 obtained from E. stolonifera. Among profound peroxynitrite scavenging compounds 1–6, phlorotannins 3, 4 and 5 were also determined to manifest marked inhibitory activity against ACE, with 50% inhibition concentration (IC50) values of 70.82 ± 0.25, 12.74 ± 0.15, and 34.25 ± 3.56 µM, respectively.
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ABSTRACT: Edible seaweeds were collected from Indonesia, a tropical country that does not show seasonal varia-tions in temperature, to evaluate their health-related activities. Ethanol and acetone extracts were prepared from -green and -brown algae. The ethanol and acetone extracts from Padina australis showed the strongest DPPH radical scavenging activity. These extracts also had the highest concentrations of total phenol and flavonoid. Both the ethanol and acetone extracts of the 0 Indonesian seaweeds decreased Caco-, cell viability when such cells were treated with 0** mM hydrogen peroxide. However, when Caco-, cells were treated with 1** or 2** mM hydrogen peroxide, the ethanol and acetone extracts from P. australis increased cell viability significantly more than those from the other seaweeds. This study indicates that organic extracts of seaweed have useful health-related functions.
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ABSTRACT: Five polyphenols were isolated and purified from a brown alga Ecklonia cava. These compounds showed diverse biological activities such as antioxidative, antiinflammatory, and enzyme inhibitory activities. This led us to investigate the potential of these compounds as Alzheimer's disease drugs. All of the compounds showed moderate acetylcholinesterase inhibitory activity in a micromolar range (IC50 from 16.0 to 96.3 μM). For butyrylcholinesterase, a new target for the treatment of Alzheimer's disease, phlorofucofuroeckol-A (PFF-A), showed a particularly potent inhibitory activity (IC50 0.95 μM), which is over 100-fold greater than for acetylcholinesterase. These compounds inhibited glycogen synthase kinase 3 beta, which is related to the formation of hyperphosphorylated tau and generation Aβ. Bieckol and PFF-A inhibited amyloid precursor protein biosynthesis. PFF-A also showed very strong β-secretase inhibitory activity with IC50 of submicromole. These results render these compounds as interesting potential drug candidates for Alzheimer's disease. Copyright © 2015 John Wiley & Sons, Ltd.Phytotherapy Research 01/2015; DOI:10.1002/ptr.5282 · 2.40 Impact Factor