The edible seaweed Laminaria japonica contains cholesterol analogues that inhibit Lipid Peroxidation and Cyclooxygenase Enzymes

In this study, 5 sterols were isolated and purified from Laminaria japonica , commonly known as edible brown seaweed, and their structures were identified based on detailed chemical methods and spectroscopic analyses. Spectroscopic analyses characterized 5 sterols as 29-Hydroperoxy-stigmasta-5,24(28)-dien-3β-ol, saringosterol (24-vinyl-cholest-5-ene-3β,24-diol), 24-methylenecholesterol, fucosterol (stigmasta-5,24-diene-3β-ol), and 24-Hydroperoxy-24-vinyl-cholesterol. The bioactivities of these sterols were tested using lipid peroxidation (LPO) and cyclooxygenase (COX-1 and −2) enzyme inhibitory assays. Fucosterol exhibited the highest COX-1 and −2 enzyme inhibitory activities at 59 and 47%, respectively. Saringosterol, 24-methylenecholesterol and fucosterol showed higher LPO inhibitory activity at >50% than the other compounds. In addition, the results of molecular docking revealed that the 5 sterols were located in different pocket of COX-1 and −2 and fucosterol with tetracyclic skeletons and olefin methine achieved the highest binding energy (−7.85 and −9.02 kcal/mol) through hydrophobic interactions and hydrogen bond. Our results confirm the presence of 5 sterols in L. japonica and its significant anti-inflammatory and antioxidant activity. ![Figure][1] Highlights 1. Sterols 29-hydroperoxy-stigmasta-5,24(28)-dien-3β-ol and 24-hydroperoxy-24-vinyl-cholesterol are identified for the first time in L. japonica . 2. Saringosterol, 24-methylenecholesterol and fucosterol showed strong LPO inhibitory activity. 3. Fucosterol showed highest binding affinity for COX-1 and −2 enzymes through hydrophobic interactions. ### Competing Interest Statement The authors have declared that no competing interests exist. * HRESITOFMS : high-resolution electrospray ionization mass spectrometry NMR : nuclear magnetic resonance LPO : lipid peroxidation COX : cyclooxygenase MPLC : medium-pressure liquid chromatography VLC : vacuum liquid chromatography Prep-TLC : preparative thin-layer chromatography HPLC : high pressure liquid chromatography TBHQ : t-butylhydroquinone BHA : butylated hydroxyanisole BHT : butylated hydroxytoluene NSAIDs : nonsteroidal anti-inflammatory drugs SLPC : 1-stearoyl-2-linoleoyl-sn-glycerol-3-phosphocholine LUVs : large unilamellar vesicles AA : arachidonic acid [1]: pending:yes