Antioxidant and anti-cholinesterase activity of Sargassum wightii

Abstract

Context. Sargassum has been used in traditional Chinese medicine since the eighth century AD to treat goiter. Sargassum wightii Greville (Sargassaceae) is a major source of alginic acid used widely in food and drug industries. Objective: To evaluate the anti-Alzheimer potential of S. wightii through evaluation of antioxidant and cholinesterase inhibitory activities. Materials and methods: Successive extraction was done using solvents of varying polarity. Solvent extracts (100-500μg/mL) were employed for all the antioxidant assays. Free radical scavenging activity was evaluated by 2,2-diphenyl-1- picrylhydrazyl, OH•, H2O2 radical scavenging assay. The reducing power of the seaweed was evaluated by ferric reducing antioxidant power and reducing power assay. Cholinesterase (ChE) inhibitory activity was evaluated and the Km, Vmax and Ki were calculated. Further, compound characterization was done by GC-MS analysis. Results: The non-polar extracts were found to possess significant antioxidant activity. At 100μg/mL, petroleum ether, hexane, benzene and dichloromethane extracts showed significant ChE inhibitory activity with IC50 values of 19.33±0.56, 46.81±1.62, 27.24±0.90, 50.56±0.90μg/mL, respectively, for AChE, and 17.91±0.65, 32.75±1.00, 12.98±0.31, 36.16±0.64μg/mL, respectively, for BuChE. GC-MS reveals that 1,2-benzenedicarboxylic acid, diisooctyl ester is the major compound present in dichloromethane extract of S. wightii. The mode of inhibition exhibited by dichloromethane extract against the cholinesterases was found to be competitive type. Discussion and conclusion: The presence of high amount of terpenoids could be the possible reason for its potential antioxidant and ChE inhibitory activity. © 2013 Informa Healthcare USA, Inc.