title: Natural bromophenols from the marine red alga Polysiphonia urceolata (Rhodomelaceae): structural elucidation and DPPH radical-scavenging activity.
abstract: Three new natural occurring bromophenols, 3-(3-bromo-4,5-dihydroxyphenyl)-2-(3,5-dibromo-4-hydroxyphenyl)propionic acid (1), (E)-4-(3-bromo-4,5-dihydroxyphenyl)-but-3-en-2-one (2), and (3,5-dibromo-4-hydroxyphenyl) acetic acid butyl ester (3), together with one known bromophenol, 1,2-bis(3-bromo-4,5-dihydroxyphenyl)ethane (4), were isolated and identified from the marine red alga Polysiphonia urceolata. The structures of these compounds were elucidated by extensive analysis of 1D and 2D NMR and IR spectra and MS data. Each of the isolated compounds was evaluated for scavenging alpha, alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical activity and all of them exhibited significant activity with IC(50) values ranging from 9.67 to 21.90 microM, compared to the positive control, a well-known antioxidant butylated hydroxytoluene (BHT), with IC(50) 83.84 microM.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, PR China.
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Li
authors.forename: Nai-Yun
authors.initials: NY
authors.lastname: Ji
authors.forename: Bin-Gui
authors.initials: BG
authors.lastname: Wang
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000302:isolation & purification; D006834:Hydrazines / Q000737:chemistry*; D006842:Hydrocarbons, Brominated / Q000737:chemistry* / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008386:Marine Biology; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry* / Q000302:isolation & purification; D010851:Picrates; D000461:Rhodophyta / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D006834:Hydrazines; D006842:Hydrocarbons, Brominated; D010636:Phenols; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl