Decoction of Isoflavone Content and Its Acid Hydrolysis Conversion Rate in the Flower of Pueraria lobata / 中国药房

ABSTRACT

OBJECTIVE:To establish a method for the decoction of isoflavone content and its acid hydrolysis conversion rate in the flower of Pueraria lobata. METHODS:Using the flowers of Pueraria lobata as raw material,the isoflavone with main com-ponent of tectoridin in the flower of P. lobata was prepared with ethanol,ethyl acetate extracted,ethanol recrystallized and puri-fied,and it was converted to tectorigenin with hydrolysis in hydrochloric acid. By screening the solvent and wavelength,UV spec-trophotometry was established to determine tectovidin and tectorigenin,and calculate the isoflavone content and acid hydrolysis con-version rate of tectoridin(expressed by the relative percentage of tectorigenin). It was compared with HPLC detection results,the accuracy of UV method was evaluated. RESULTS:The solvent was 70％ethanol solution containing 1％triethylamine,and the iso-flavone content was detected at wavelength of 339,274 nm. The linear range of tectoridin was 8.80-29.33 nmol/mL(r=0.9999). RSDs of precision(n=6),stability(n=5)and reproducibility(n=6)tests were lower than 1.94％;average recovery was 99.7％(RSD=1.77％,n=9). There were no statistical significances in the contents of total flavonoids (UV17.64-25.55 nmol/mL vs. HPLC17.39-24.40 nmol/mL) and the relative percentage of tectorigenin (UV57.65％-87.59％ vs. HPLC55.62％-91.14％). CONCLUSIONS:The established method is accurate,reliable,and can be used for the rapid determination of acid hydrolysis con-version rate of tectoridin.