Planta Med 2006; 72 - P_324
DOI: 10.1055/s-2006-950124

Release of soy isoflavones from commercial capsule preparation

J Cvejic 1, I Stepanov 1, M Pocuca 2
  • 1Laboratory for Analysis of Natural and Pharmaceutical Products, Department of Pharmacy, Faculty of Medicine, University of Novi Sad, Serbia and Montenegro
  • 2Laboratory for Biopharmacy, Department of Pharmacy, Faculty of Medicine, University of Novi Sad, Serbia and Montenegro

Herbal medicinal products can be biopharmaceuticaly characterized by dissolution tests, provided that there was identification of the active pharmaceutical ingredient. This study describes the determination of the concentration of released soy isoflavones (dissolution test) for commercial capsules containing soybean extract using an HPLC method.

In analysed preparation four different isoflavones were detected and total of their concentrations was evaluated. Two major compounds were daidzein and genistein glucosides, most probably malonyl-glucosides. Aglycones daidzein and genistein were also present, but in much smaller amounts. Release of isoflavones from commercial capsules (Menosoya, Belgrade) was measured with in 90 minutes (six time-points).

The dissolution tests were performed in a Erweka DT800 multi-bath (n=6) dissolution test system, in accordance with the United States Pharmacopeia (USP) general methods. Conditions applied to carry out the dissolution tests were 900 mL of 0.05M potassium dihydrogen phosphate buffer pH4.5 (KH2PO4) as dissolution medium, basket at 100 rotations per minute (rpm) stirring speed and bath temperature of 37°C. Quantification of isoflavones was performed using gradient reversed phase (150×4mm, 5µm LiChrospher RP-18) high-performance liquid chromatography and detection at 270 nm.

All dissolution profiles obtained for six capsules were similar. Values of standard deviation for all measurements (10, 20, 30, 40, 60 and 90min) were between 3.0 10-4 and 5.3 10-4. Analysis of samples showed that more than 50% of isoflavones were dissolved from capsules after 40 minutes. Approximately 30% of the total is released in the first 10min and 65% after 90 minutes. Individual isoflavones showed slight differences between their dissolution curves. In the first 20min release of glucosides from formulation was more important than of aglycones.