title: UV/Vis spectra and solubility of some naphthoquinones, and the extraction behavior of plumbagin from Plumbago scandens roots in supercritical CO2.
abstract: The solubility of 1,4-naphthoquinone, plumbagin, lawsone, and juglone in supercritical carbon dioxide was determined spectroscopically at 40 degrees C, and in the pressure range 8-18 MPa. Their solubilities at 12 MPa were between 0.3 and 10 g L(-1). Plumbagin from Plumbago scandens L. roots was extracted at 40 degrees C and 20 MPa. The extracted plumbagin mass fraction was up to 0.2% in fresh roots but down to about 0.006% in aged roots. n-Hexane and chloroform extraction of such aged roots indicates that the older and dryer the roots are, the stronger they bind plumbagin. Reversed-phase HPLC indicated a relatively pure plumbagin extract with supercritical carbon dioxide.
authors.affiliation: Departamento de Química Analítica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista S/N, 24020-150 Niterói, Brazil. silvana@vm.uff.br
authors.forename: S V
authors.initials: SV
authors.lastname: Rodrigues
authors.forename: L M
authors.initials: LM
authors.lastname: Viana
authors.forename: W
authors.initials: W
authors.lastname: Baumann
mesh_terms: D002245:Carbon Dioxide; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D015394:Molecular Structure; D009285:Naphthoquinones / Q000032:analysis* / Q000737:chemistry* / Q000302:isolation & purification; D018517:Plant Roots / Q000737:chemistry; D029606:Plumbaginaceae / Q000737:chemistry*; D012995:Solubility; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D009285:Naphthoquinones; D002245:Carbon Dioxide; C014758:plumbagin