Abstract
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.
Highlights
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.
Saringosterol, 24-methylenecholesterol and fucosterol showed strong LPO inhibitory activity.
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.
Abbreviations
- 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