Characterizing Eckol as a Therapeutic Aid: A Systematic Review

Manandhar, Bandana; Paudel, Pradeep; Seong, Su Hui; Jung, Hyun Ah; Choi, Jae Sue

Because the oxidation of LDL is one of the causative agent of atherosclerosis, the inhibitory effects of E. stolonifera, its fractions, the phlorotannins isolated from them, and the conjugated diene formation of the methanolic extract was investigated on in vitro Cu 2+ -induced human LDL oxidation. The thiobarbituric acid reactive substances (TBARS) assay revealed that the methanolic extract had concentration-dependent inhibitory activity against LDL oxidation induced by Cu 2+ , with an IC 50 value of 5.66 ± 0.05 µg/mL, while the EtOAc fraction of E. stolonifera showed very high inhibition, with an IC 50 value of 3.04 ± 0.13 µg/mL. Among the isolated phlorotannins (phloroglucinol, dioxinodehydroeckol, eckol, phlorofucofuroeckol -A, dieckol, and 7-phloroeckol), phlorofucofuroeckol-A and dieckol were found to be potent Cu 2+ -induced LDL oxidation inhibitors. Eckol showed moderate inhibition exhibiting an IC 50 value of 7.47 µM. Because the production of conjugated dienes indicates the start of LDL oxidation, the lag time can be used as a measure of LDL oxidation resistance. Eckol extended the lag time to 54 min at 1 µM, 97 min at 5 µM, and 117 min at 10 µM. Probucol, the positive control, increased the lag time to 55 min at 1 µM, 74 min at 5 µM, and 91 min at 10 µM, thus, eckol was more effective than probucol at inhibiting conjugated diene formation [81] .