title: Quantitative analysis of the major constituents of St John's wort with HPLC-ESI-MS.
abstract: A method was developed to profile the major constituents of St John's wort extracts using high-performance liquid chromatography-electrospray mass spectrometry (HPLC-ESI-MS). The objective was to simultaneously separate, identify and quantify hyperforin, hypericin, pseudohypericin, rutin, hyperoside, isoquercetrin, quercitrin and chlorogenic acid using HPLC-MS. Quantification was performed using an external standardisation method with reference standards. The method consisted of two protocols: one for the analysis of flavonoids and glycosides and the other for the analysis of the more lipophilic hypericins and hyperforin. Both protocols used a reverse phase Luna phenyl hexyl column. The separation of the flavonoids and glycosides was achieved within 35 min and that of the hypericins and hyperforin within 9 min. The linear response range in ESI-MS was established for each compound and all had linear regression coefficient values greater than 0.97. Both protocols proved to be very specific for the constituents analysed. MS analysis showed no other signals within the analyte peaks. The method was robust and applicable to alcoholic tinctures, tablet/capsule extracts in various solvents and herb extracts. The method was applied to evaluate the phytopharmaceutical quality of St John's wort preparations available in the UK in order to test the method and investigate if they contain at least the main constituents and at what concentrations.
authors.affiliation: Centre for Pharmacognosy and Phytotherapy, School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
authors.forename: Dhammitha H
authors.initials: DH
authors.lastname: Chandrasekera
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Welham
authors.forename: David
authors.initials: D
authors.lastname: Ashton
authors.forename: Richard
authors.initials: R
authors.lastname: Middleton
authors.forename: Michael
authors.initials: M
authors.lastname: Heinrich
mesh_terms: D000873:Anthracenes; D001643:Bridged Bicyclo Compounds / Q000032:analysis / Q000592:standards; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D020902:Hypericum / Q000737:chemistry*; D010569:Perylene / Q000031:analogs & derivatives* / Q000032:analysis / Q000592:standards; D010696:Phloroglucinol / Q000031:analogs & derivatives* / Q000032:analysis / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013729:Terpenes / Q000032:analysis* / Q000592:standards
chemical_list: D000873:Anthracenes; D001643:Bridged Bicyclo Compounds; D013729:Terpenes; D010569:Perylene; C004965:hypericin; D010696:Phloroglucinol; C001654:hyperforin