Determination of the conversion factor for silymarin - a solution for the problems associated with new assay methods in the pharmacopoeia.

In pharmacopoeial monographs for herbal drugs and herbal preparations, conventional assay methods such as colorimetry or spectophotometric assays are often replaced by modern, more specific and reliable methods, e.g. liquid chromatography (LC). However, existing dosage recommendations in the monographs on efficacy and safety of herbal medicinal products which are an important basis for licensing procedures do not refer to the mandatory new methods but to the existing photometric methods. The laboratory comparison of the determination of silymarin of Milk Thistle extract shows that a conversion factor can be calculated which allows a correlation between the new and the existing method. It is suggested that this factor should be included in the Ph. Eur. monograph on Milk Thistle extract, allowing reference to dosages given in official monographs (e.g. ESCOP, HMPC). The solution to use a conversion factor should also be applied to other herbal drugs and herbal preparations, especially for standardised extracts.

The role of triterpenoids in the topical anti-inflammatory activity of Calendula officinalis flowers.

By means of a bioassay-oriented fractionation of the CO2 extract of Calendula flowers, the triterpenoids are shown as the most important anti-inflammatory principles of the drug. Among them, the faradiol monoester appears to be the most relevant principle for the activity of the drug, due to its quantitative prevalence. The unesterified faradiol, not present in the extract, is the most active of the tested compounds and equals indomethacin in activity, whereas the monools psi-taraxasterol, lupeol, taraxasterol, and beta-amyrin are less active than the free diol. The anti-inflammatory activity of different CO2 extracts is proportional to their content of faradiol monoester, which can be taken as a suitable parameter for the quality control of Calendula preparations.