[Methodological problems and possibilities at the standardization of flavonoid containing extracts]

Flavonoid containing extracts may be divided into two groups regarding to the possibilities of their standardization. If known compound/s are responsible for the pharmacological effects, their selective determination is recommended. Extracts with unknown compositions are usually characterized by their flavonoid content. The latter may be carried out according to several methods official in pharmacopoeias. However the applicability of these methods for each plant material is in question. We have determined the flavonoid content of plant materials with various flavonoid composition following spectroscopic methods from pharmacopoeias official in Hungary. Comparing the measured results significant differences could be observed. Because these couldn't be explained even taking account of applying different evaluation methods, we have decided to study at large the possible parameters which may be responsible for the differences. The effect of the extraction, the hydrolisation, the cleaning steps, building up complexes and the flavonoid composition were proved in model experiments. Using the method of the VII. Hungarian Pharmacopoeia we experienced that this method wasn't applicable in case of the plant materials examined in our experiments.