Sesquiterpenoids with free-radical-scavenging properties from marine macroalga Ulva fasciata Delile

Free-radical-scavenging activities of various solvent extracts of Viva fasciata, a chlorophytan marine macroalga with significance as a food ingredient, from the southwestern coast of the Indian peninsula, were evaluated using in vitro tests, including 1,1-dipheny1-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonate) (ABTS) scavenging assays. Ethyl acetate (EtOAc) extract of Viva fasciata displayed markedly stronger DPPH (89.8 +/- 4.2%) and ABTS(+) scavenging (82.6 +/- 3.7%) activities at 0.1 mg/ml than dichloromethane and n-hexane extracts. Radical scavenging assay-guided chromatographic separation of the EtOAc extract, using a step gradient of petroleum ether/EtOAc yielded five major sesquiterpenoids. After 8 min of incubation the ABTS.* scavenging activity of one of these sesquiterpenoids was higher (71.4 1.5%) than that of Trolox (44.1 1.5%), and therefore may have potential as a natural antioxidant in the food industry. (C) 2010 Elsevier Ltd. All rights reserved.