title: Continuous hot pressurized solvent extraction of 1,1-diphenyl-2-picrylhydrazyl free radical scavenging compounds from Taiwan yams (Dioscorea alata).
abstract: This study investigates a semicontinuous hot pressurized fluid extraction process and the scavenging activity on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical of the extract from Taiwan yams (Dioscorea alata). Liquid-liquid extractions were preliminarily employed to generate six fractions, initially extracted by ethanol. Then, the aqueous solution of dried crude ethanol extract was sequentially fractionated by hexane, chloroform, ethyl acetate, and n-butanol. The EC50 value was defined as the UV absorption of DPPH concentrations sufficiently decreased to 50% of the original value. It was found that all peel portions have a better effect on scavenging of the DPPH free radical than meat portions, especially for the ethyl acetate partition of the peel portion of Tainung #2 yam. Its EC50 value (14.5 microg mL(-1)) was even lower than that of ascorbic acid (21.4 microg mL(-1)). Furthermore, semicontinuous hot pressurized ethanol was superior to hot pressurized water in extracting the compound scavenging the DPPH radical from the Purpurea-Roxb peel. The recovery of four unknown compounds corresponded to the scavenging ratio of DPPH free radical in the hot pressurized ethanol extract. Finally, three-level and four-factor experimental design revealed that ethanol ratio and temperature were the most effective factors in order. Conditions of 80% of aqueous ethanol, 20.0 kg/kg solid ratio, 180 psig (1.342 MPa), and 100 degrees C were preferred to extract those antioxidants from the yam peel.
authors.affiliation: Department of Chemical Engineering, National Chung Hsing University, 250 Kuokuang Road, Taichung, Taiwan, Republic of China.
authors.forename: Po-Yen
authors.initials: PY
authors.lastname: Chen
authors.forename: Yu-Xun
authors.initials: YX
authors.lastname: Tu
authors.forename: Cheng-Tar
authors.initials: CT
authors.lastname: Wu
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Jong
authors.forename: Chieh-Ming J
authors.initials: CM
authors.lastname: Chang
mesh_terms: D001205:Ascorbic Acid; D001713:Biphenyl Compounds; D027742:Dioscorea / Q000737:chemistry*; D000431:Ethanol; D016166:Free Radical Scavengers / Q000302:isolation & purification*; D006358:Hot Temperature; D010851:Picrates / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D018514:Plant Structures / Q000737:chemistry; D011312:Pressure; D014867:Water
chemical_list: D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; D010936:Plant Extracts; D014867:Water; D000431:Ethanol; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid