Analysis of Forsythia suspensa, for the purpose of establishing a monograph draft proposal for the German Pharmacopoeia

The development of appropriate analytical procedures is proposed for the TCM-herbal drug Forsythia suspensa, which is planned for an implementation in the German Pharmacopoeia DAB. The quantification method described by the respective monograph of the Chinese Pharmacopoeia (English Edition) [1], suggesting a HPLC method for the quantification of forsythoside A, was improved by a more simple methanol reflux extraction.

As a first step for the implementation of an appropriate quantification with HPLC, the method suggested by Wagner [2] for the fingerprint analysis of Forsythia was investigated. We propose the use of a H₂O/acetonitrile/acetic acid gradient on a RP-18 column (Purospher Star, 5µm, 250×4) which allows the quantification of the forsythoside A at a detection wavelength 325nm within 35 minutes. In a second step we developed a completely new densitometric HPTLC method for the quantification of forsythoside A, using fully wettable RP18 plates and a mixture of H₂O/acetonitrile/acetic acid.

For the densitometric TLC and the HPLC quantification method a validation protocol is established.

In addition, identification methods for this herbal drug (macroscopic, microscopic, TLC/HPTLC) and appropriate tests for purity are proposed [2].

All the newly developed and controlled methods will be the basis of a monograph draft suitable for the DAB.

Acknowledgements: The BfArM (Kurt-Georg-Kiesinger-Allee3, 53175 Bonn, Germany) is gratefully acknowledged for financial support.

References: [1] Anonymous, Pharmacopoeia of the People's Republic of China Engl. Edit. 2005.

[2] Wagner, Chinese Drug Monographs and Analysis, Fructus Forsythiae 2004.

[3] Anonymous, (2005) European Pharmacopoeia 5th Edit.