Development of the methods for spectrophotometric determination of the flavonoid concentration in solution to study bioavailability of the amount of bioactive substances in capsules containing the powder of Scutellaria baikalensis roots and rhizomes

Abstract

Development of the methods for spectrophotometric determination of the flavonoid concentration in solution to study bioavailability of the amount of bioactive substances in capsules containing the powder of Scutellaria baikalensis roots and rhizomesRecently, the test "Dissolution", which allows evaluating bioavailability of active ingredients, has become one of the most important tools in the quality control of new and generic drugs development ("biowaiver" procedure). However, for some drugs the use of classical pharmacopoeia buffer solutions in vitro does not always completely adequately reflect their behavior in vivo. As a solution of this problem the group of biorelevant media, which allow simulating dissolution and adsorption of drugs in the gastrointestinal tract of a patient, has been developed.Aim. To develop the methods of spectrophotometric determination of the flavonoid concentration in 0.1 M hydrochloric acid solution and biorelevant media FaSSIF and FeSSIF with pH 6.5 and 6.8 calculated with reference to baicalin for further study of bioavailability of hard gelatine capsules containing a finely divided powder of Scutellaria baicalensis roots and rhizomes.Materials and methods. For the studies on bioavailability determination of pharmacologically active substances of a finely divided powder of Scutellaria baicalensis roots and rhizomes the method of absorption spectrophotometry in the ultraviolet and visible regions of the spectrum calculated with reference to baicalin was chosen.Results and discussion. Adsorption spectra of baicalin solutions in 0.1 M hydrochloric acid solution and biorelevant media FaSSIF (pH 6.5) and FeSSIF (pH 6.8) in the range from 230 to 370 nm consist of two absorption bands. The band with the maximum at 276 nm is more intense, while the band in the near ultraviolet region is less intensive, but broader. The use of this maximum for quantification will allow increasing the specificity of the analysis. The analysis of adsorption spectra of the solutions obtained during extraction of the powder from Scutellaria baicalensis roots and rhizomes with 0.1 M hydrochloric acid solution and biorelevant media FaSSIF and FeSSIF with pH 6.5 and pH 6.8 has shown that their structure is virtually the same as the spectral structure of baicalin solutions. In order to test the possible impact of the dissolution media on the total optical density at the analytical wavelength the adsorption spectra of the biorelevant media FaSSIF and FeSSIF with pH 6.5 or 6.8 have been studied. The analysis of the data obtained has shown that the media are really nontransparent in ultraviolet light and have quite intensive absorption in the range of 230-290 nm. The absorbance testing of baicalin solutions in 0.1 M hydrochloric acid solution and biorelevant media FaSSIF and FeSSIF with pH 6.5 and pH 6.8 has shown that the dependence is linear and obeys the Beer-Lambert law in the range of the concentration from 0.4 to 3.6-4.0 · 10 -3 %.Conclusions. To develop the method for determining the concentration of solutions...