Characterizing Eckol as a Therapeutic Aid: A Systematic Review

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

The arachidonic acid (AA)-derived lipid-mediator secretory phospholipase A 2 s (sPLA 2 s) are esterases cleaving glycerophospholipids at the sn-2 position, ultimately liberating a fatty acid and a lysophospholipid [141] that are then present in synovial fluid, articular cartilage, and blood in patients suffering from rheumatic diseases [142] . Another lipid mediator derived from arachidonic acid that is involved in inflammation is biosynthesized by pathways that depend on COX and lipoxygenases (LOX) enzymes. An inhibitor of those enzymes could treat inflammatory diseases, atherosclerosis, and cancer. Five phlorotannins (i.e., phloroglucinol, eckol, dieckol, phlorofucofuroeckol-A, and 8,8'-bieckol) purified from E. bicyclis were evaluated for their potential inhibition on bee venom, porcine pancreas secretory phospholipase A 2 , soybean lipoxygenase, 5-LOX, COX-1, and COX-2. In the case of the bee venom sPLA 2 , the phlorotannins eckol, phlorofucofuroeckol-A, dieckol, 8,8'-bieckol, resveratrol , and epigallocatechin gallate demonstrated IC 50 values of 120, 130, 160, 180, 170, and 110 µM, respectively. Eckol, phlorofucofuroeckol-A, dieckol and 8,8'-bieckol showed high activity in comparison to the positive controls resveratrol and epigallocatechin gallate. In porcine pancreas sPLA 2 , eckol, phlorofucofuroeckol-A, dieckol, and 8,8'-bieckol demostrated IC 50 values of 100, 150, 90, and 180 µM, respectively . Eckol showed less inhibition against soybean lipoxygenase (LOX) and 5-LOX than 8,8'-bieckol, which was the potent inhibitor of soybean LOX, showing inhibition of more than 90% at 50 µM, and 5-LOX (IC 50 24 µM). The phlorotannins had negligible inhibitory effects on COX-1 and COX-2, with eckol exhibiting 43.2% inhibition of COX-2 at 100 µM [72] .