title: Antioxidant and anti-cholinesterase activity of Sargassum wightii.
abstract: BACKGROUND
  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.
  
  
  METHODS
  Successive extraction was done using solvents of varying polarity. Solvent extracts (100-500 µg/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 100 μg/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 ± 0.90 µg/mL, respectively, for AChE, and 17.91 ± 0.65, 32.75 ± 1.00, 12.98 ± 0.31, 36.16 ± 0.64 µg/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.
  
  
  CONCLUSIONS
  The presence of high amount of terpenoids could be the possible reason for its potential antioxidant and ChE inhibitory activity.
authors.affiliation: Department of Biotechnology, Alagappa University , Karaikudi 630 003, Tamil Nadu , India.
authors.forename: Arif Nisha
authors.initials: AN
authors.lastname: Syad
authors.forename: Karutha Pandian
authors.initials: KP
authors.lastname: Shunmugiah
authors.forename: Pandima Devi
authors.initials: PD
authors.lastname: Kasi
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000737:chemistry; D002091:Butyrylcholinesterase / Q000378:metabolism; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D010851:Picrates / Q000737:chemistry; D044647:Sargassum; D012997:Solvents / Q000737:chemistry; D013729:Terpenes / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D002800:Cholinesterase Inhibitors; D010851:Picrates; D012997:Solvents; D013729:Terpenes; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase