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Pharmacologic activity of proanthocyanidins in Ginkgo biloba leaf extract has recently been reported. The objective of the present study was to screen proanthocyanidin contents in herbal medicinal products containing Ginkgo extracts. A recently published HPLC method for quantification of proanthocyanidins in G. biloba leaf extract EGb 761 was adopted to also be suitable for finished herbal medicinal products. The method was applied to 14 products from the German market. For each product, a set of three individual batches was purchased and analyzed. Substantial differences in proanthocyanidins contents were found among distinct products, ranging from 0.30 to 5.86%. The batch-to-batch variability within each product was low. The highest concentrations are in a similar range as, for example, the amount of Ginkgo terpene trilactones specified in the monograph for G. biloba leaf extract in the European Pharmacopeia. Although it has not yet been established whether and to what extent proanthocyanidins contribute to the overall pharmacological or clinical efficacy of Ginkgo extracts, a potential impact on the purported benefits of different contents in proanthocyanidins cannot be ruled out. Quality assessment of different Ginkgo extracts in the future may include proanthocyanidins. [ABSTRACT FROM AUTHOR]

Several studies indicate that the terpene trilactones (TTL) of EGb 761® are responsible for most of its pharmacological action in the brain [1]. Therefore, we investigated the ability of the TTL to cross the blood brain barrier in rats after a single oral administration (600 mg/kg) of EGb 761® and compared it with the plasma levels. In addition, we checked the pharmacokinetic characteristics of an application of EGb 761® against a similar amount of pure substances. For this purpose, we developed a sensitive HPLC-(APCI)-MSmethod for the determination of the Ginkgo biloba TTL (ginkgolide A [GA], B [GB], C [GC] and bilobalide [Bb]) in plasma as well as in brain tissue. The following animal study shows that the oral application of 600 mg/kg EGb 761® results in significant GA, GB, and Bb concentrations in plasma as well as in the CNS of the rodents, while the GC concentration was below the detection limit of the analytical method in both matrices. GA, GB, and Bb brain concentrations showed a rapid increase up to 55 ng/g, 40 ng/g, and 98 ng/g with no difference of the characteristic after extract or pure substance application. Regarding the plasma levels, significant higher Cmax and AUC values were detected after application of the extract EGb 761®. These results allow for the first time a discussion of pharmacological effects with the knowledge of the pharmacokinetic behavior of the TTL in target tissues. [ABSTRACT FROM AUTHOR]