title: Unprecedented antioxidative cyclic ether from the red seaweed Kappaphycus alvarezii with anti-cyclooxygenase and lipoxidase activities.
abstract: An unprecedented non-isoprenoid oxocine carboxylate cyclic ether characterised as (3S, 4R, 5S, 6Z)-3-((R)-hexan-2'-yl)-3,4,5,8-tetrahydro-4-methyl-2H-oxocin-5-yl acetate was isolated from the ethyl acetate-methanol extract of the red seaweed Kappaphycus alvarezii. The structure, as well as its relative stereochemistry, was proposed on the basis of extensive spectral data. The antioxidative activity of the isolated metabolite was found to have significantly greater as determined by 1, 1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid radical scavenging activities (IC50~ 0.3 mg/mL) compared to α-tocopherol (IC50> 0.6 mg/mL) and was comparable to the synthetic antioxidants butylated hydroxytoluene and butylated hydroxyanisole (IC50~ 0.35-0.34 mg/mL). The compound exhibited greater activity against COX-2 (cyclooxygenase-2) than COX-1 (cyclooxygenase-1) isoform, and therefore, the selectivity index remained significantly lesser (anti-COX-1IC50: anti-COX-2IC500.87) than synthetic anti-inflammatory drugs (0.02-0.44). No significant difference of in vivo 5-lipoxidase activity (IC500.95 mg/mL) than ibuprofen (IC500.93 mg/mL) indicated the potential anti-inflammatory properties of the title compound.
authors.affiliation: a Central Marine Fisheries Research Institute , Cochin , India.
authors.forename: Fasina
authors.initials: F
authors.lastname: Makkar
authors.affiliation: a Central Marine Fisheries Research Institute , Cochin , India.
authors.forename: Kajal
authors.initials: K
authors.lastname: Chakraborty
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology*; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D002855:Chromatography, Thin Layer; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004988:Ethers, Cyclic / Q000737:chemistry* / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D010851:Picrates; D012624:Seaweed / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013451:Sulfonic Acids
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D016861:Cyclooxygenase Inhibitors; D004988:Ethers, Cyclic; D016166:Free Radical Scavengers; D016859:Lipoxygenase Inhibitors; D010851:Picrates; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C004931:1,1-diphenyl-2-picrylhydrazyl; D001094:Arachidonate 5-Lipoxygenase
keywords: Kappaphycus alvarezii; anti-inflammatory; antioxidative; oxocine carboxylate cyclic ether; structure–activity relationship