|1: J AOAC Int. 2004 Sep-Oct;87(5):1042-8.
Liquid chromatographic determination of St. John's wort components
in functional foods.
de Jager LS, Perfetti GA, Diachenko GW.
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition,
5100 Paint Branch Pkwy, College Park, MD 20740, USA. Ldejager@cfsan.fda.gov
A method was developed for determination of St. John's wort marker
compounds hypericin, pseudohypericin, hyperforin, and adhyperforin in functional
foods. Solid-phase extraction provided analyte extraction and significant
sample cleanup prior to analysis using liquid chromatography (LC) with UV
and fluorescence detection. In addition to quantification using LC-UV, confirmation
was made with electrospray ionization LC mass spectrometry (LC/MS). Several
commercially available tea and drink products claiming to contain St. John's
wort were tested. Recoveries ranged from 51 to 98% for the liquid
samples. Comparison of the concentrations in 4 St. John's wort teas showed
a variation in analyte concentration (1044-10 ng/mL marker compounds in brewed
tea) and composition. No marker compounds were found in the beverages,
indicating possible decomposition of the marker compounds caused by low pH
and/or exposure to light. A solvent extraction procedure was developed
for analysis of the marker compounds from solid samples. Analytes were detected
at low parts per million, with an average recovery of 75%. No St.
John's wort components were found in the 2 solid functional food samples
PMID: 15493659 [PubMed - indexed for MEDLINE]