Absorbance data of hypericin and pseudohypericin used as reference compounds for medicinal plant analysis
Wirz, A.; Meier, B.; Sticher, O.
Die Pharmazie 56(1): 52-57
2001
ISSN/ISBN: 0031-7144 PMID: 11210670 Document Number: 536596
Evaluation of the absorbance data of hypericin and pseudohypericin revealed the molar/specific coefficients of absorbacne in methanol-pyridine (99:1, v/v) at the maximum of the longest wavelength to be 51 936/1030 and 43 486/836, 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, indicating that both compounds exhibit the same homoassociation behaviour.