title: New nitrogen-containing bromophenols from the marine red alga Rhodomela confervoides and their radical scavenging activity.
abstract: In addition to nine known bromophenol derivatives, five new nitrogen-containing bromophenols were isolated from an ethyl acetate extract of the marine red alga Rhodomela confervoides. By using spectroscopic methods, the structures of the new compounds were identified as 3-(2,3-dibromo-4,5-dihydroxybenzyl)pyrrolidine-2,5-dione (1), methyl 4-(2,3-dibromo-4,5-dihydroxybenzylamino)-4-oxobutanoate (2), 4-(2,3-dibromo-4,5-dihydroxybenzylamino)-4-oxobutanoic acid (3), 3-bromo-5-hydroxy-4-methoxybenzamide (4), and 2-(3-bromo-5-hydroxy-4-methoxyphenyl)acetamide (5). All of these bromophenols showed potent scavenging activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals, with IC(50) values ranging from 5.22 to 23.60μM. These compounds also displayed moderate activity against ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonate) radicals, with Trolox Equivalent Antioxidant Capacity values (TEAC) ranging from 2.11 to 3.58mM. The results obtained in this study demonstrate that the bromophenols obtained from R. confervoides may have potential application in food and/or pharmaceutical fields as natural antioxidants.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China.
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Li
authors.forename: James B
authors.initials: JB
authors.lastname: Gloer
authors.forename: Bin-Gui
authors.initials: BG
authors.lastname: Wang
mesh_terms: D016166:Free Radical Scavengers / Q000737:chemistry* / Q000302:isolation & purification; D015394:Molecular Structure; D009584:Nitrogen / Q000032:analysis; D010636:Phenols / Q000737:chemistry* / Q000302:isolation & purification; D000461:Rhodophyta / Q000737:chemistry*
chemical_list: D016166:Free Radical Scavengers; D010636:Phenols; D009584:Nitrogen