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-3{beta}-ol, saringosterol (24-vinyl-cholest-5-ene-3{beta},24-diol), 24-methylenecholesterol, fucosterol (stigmasta-5,24-diene-3{beta}-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. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/463984v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@16c3f43org.highwire.dtl.DTLVardef@1ad7385org.highwire.dtl.DTLVardef@7b3c4borg.highwire.dtl.DTLVardef@b3675a_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISterols 29-hydroperoxy-stigmasta-5,24(28)-dien-3{beta}-ol and 24-hydroperoxy-24-vinyl-cholesterol are identified for the first time in L. japonica. C_LIO_LISaringosterol, 24-methylenecholesterol and fucosterol showed strong LPO inhibitory activity. C_LIO_LIFucosterol showed highest binding affinity for COX-1 and -2 enzymes through hydrophobic interactions. C_LI