Characterizing Eckol as a Therapeutic Aid: A Systematic Review

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

Insomnia is currently a widespread sleep disorder worldwide leading to an increase in the use of natural sleep aids containing specific components of foods and herbal plants. Thus, these are becoming popular to enhance sleep quality and refrain side effects as compared to prescription sedative-hypnotics [97] . Gamma-aminobutyric acid (GABA) A -benzodiazepine (BZD) receptor, a well-recognized target for sedative-hypnotics was used to test the binding activity of methanol extracts of 30 seaweeds. Among the seaweeds, the most active ethanol extract of E. cava significantly increased sleep in mice when induced by pentobarbital. Among the four separated solvent fractions, hypnotic activity was related to the content of total phenols and total phlorotannins in the seaweed. The highest activity was exhibited by the EtOAc fraction which constituted of phlorotannins eckol, dioxinodehydroeckol, dieckol, and triphlorethol-A. Eckol (K i 1.070 µM) and dioxinodehydroeckol (K i 1.491 µM) showed better binding at the receptor than triphlorethol-A (K i 4.419 µM) and dieckol (K i 3.072 µM). The hypnotic effects of the ethanol extract and its EtOAc fraction were inhibited by flumazenil which is a specific GABA A -BZD receptor antagonist. Hence, through the positive allosteric modulation of the GABA A -BZD receptor, the phlorotannins from EC, including eckol, induces sleep [55] .