Urinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract as film-coated tablets and aqueous solution in healthy humans.

Bearberry leaves and preparations made from them are traditionally used for urinary tract infections. The urinary excretion of arbutin metabolites was examined in a randomized crossover design in 16 healthy volunteers after the application of a single oral dose of bearberry leaves dry extract (BLDE). There were two groups of application using either film-coated tablets (FCT) or aqueous solution (AS). The urine sample analysis was performed by a validated HPLC coolarray method (hydroquinone) and a validated capillary electrophoresis method (hydroquinone-glucuronide, hydroquinone-sulfate). The total amounts of hydroquinone equivalents excreted in the urine from BLDE were similar in both groups. With FCT, 64.8% of the arbutin dose administered was excreted; with AS, 66.7% was excreted (p = 0.61). The maximum mean urinary concentration of hydroquinone equivalents was a little higher and peaked earlier in the AS group versus the FCT group, although this did not reach statistical significance (Cur max = 1.6893 micromol/ml vs. 1.1250 micromol/ml, p = 0.13; tmax (t midpoint) = 3.60 h vs. 4.40 h, p = 0.38). The relative bioavailability of FCT compared to AS was 103.3% for total hydroquinone equivalents. There was substantial intersubject variability. No significant differences between the two groups were found in the metabolite patterns detected (hydroquinone, hydroquinone-glucuronide, and hydroquinone-sulfate).

Determination of ginsenosides from Panax ginseng using micellar electrokinetic chromatography.

A method for determination of ginsenosides in herbal medicinal products (HMPs) was developed using micellar electrokinetic chromatography (MEKC). Within 22 minutes 7 major ginsenosides were well separated. In order to demonstrate the accuracy, precision and robustness for the main target analyte the method was exemplarily validated for the determination of Rb1 according to ICH guidelines. Compared to chromatographic analysis, several benefits of capillary electrophoresis (CE) could be demonstrated such as high separation efficiency in an aqueous buffer without any organic solvent and shorter run time per assay.