title: Absorbance data of hypericin and pseudohypericin used as reference compounds for medicinal plant analysis.
abstract: The evaluation of the absorbance data of hypericin and pseudohypericin revealed the molar/specific coefficients of absorbance in methanol-pyridine (99:1, v/v) at the maximum of the longest wavelength to be 51936/1030 and 43486/836, respectively. The absorbance data of hypericin were also determined in methanol. They were not significantly different from those in the presence of pyridine. The decrease of the coefficients by water addition was found to be the same for hypericin and pseudohypericin. It was concluded that hypericin and pseudohypericin reveal the same homoassociation behavior.
authors.affiliation: Department of Applied BioSciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Zürich.
authors.forename: A
authors.initials: A
authors.lastname: Wirz
authors.forename: B
authors.initials: B
authors.lastname: Meier
authors.forename: O
authors.initials: O
authors.lastname: Sticher
mesh_terms: D000873:Anthracenes; D002851:Chromatography, High Pressure Liquid; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D012015:Reference Standards; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000873:Anthracenes; D012997:Solvents; D010569:Perylene; C004965:hypericin; C056602:pseudohypericin