Quantitative analysis of the active components and the by‐products of eight dry extracts of Hypericum perforatum L. (St John's wort)

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Abstract
The major components of eight different batches of commercially available dry extracts of Hypericum perforatum L. were quantified. Hyperforin (1), hypericin (2) and flavonoids, which are considered to play key roles in the treatment of mild and moderate depressive disorders, were determined by HPLC methods. The contents of 1, 2 and flavonoids were found to be in the range of 1.3–3.9%, 0.19–0.30%, and 4.8–11.4%, respectively. Generally extracts contained, besides the so‐called active components, a wide variety of by‐products which may act partially as co‐effectors and affect the technological properties of the extracts. Water‐soluble sugars form one of the main groups of these by‐products, and a procedure for the purification and quantification of such sugars in H. perforatum using HPLC with refractive index detection has been established. Native fructose, glucose and sucrose, as well as lactose added during the processing of the extracts, were determined. The total sugar content in the dry herbal extracts varied from 19 to 25% by weight. Further, citric acid (0.9–2.3%) and malic acid (2.3–3.1%) were determined by HPLC, tannins (6.2–9.0%) and total ash (4.9–8.4%) were quantified according to the methods described in the European Pharmacopoeia, and the content of the total protein (3.9–8.3%) was estimated by elemental analysis. Thus, 60–70% of the compounds of the H. perforatum dry extracts have been quantified. Copyright © 2002 John Wiley & Sons, Ltd.