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 analyzed.

PMID: 15493659 [PubMed - indexed for MEDLINE]