Simultaneous determination of seven alkaloids and three flavonoids in Sophorae Tonkinensis Radix et Rhizoma by HPLC

Abstract

In this study, an HPLC method was developed for simultaneous determination of seven alkaloids (cytosine, oxymatrine, N-oxysophocarpine, N-methylcytisine, sophoranol, matrine, and sophocarpine) and three flavonoids (trifolirhizin, fermononetin, and maackiain) from different samples of Sophorae Tonkinensis Radix et Rhizoma. Samples were analyzed on a Welch XtimateTM C₁₈ column (4. 6 mm× 250 mm, 5 μm) eluted with the mobile phase of acetonitrile (A) and 0.01 mol•L⁻¹ ammonium acetate solution (pH 8.0) (B) in a linear gradient mode as follows: 0-20 min,4%-14% A;20-30 min,14%-25% A;30-45 min,25%-40% A;45-65 min,40%-55% A;65-75 min,55% A. The flow rate of the mobile phase, the column temperature, and the PDA detector wavelength were set at 1.0 mL•min⁻¹, 30 ℃, and 225 nm, respectively. For the method validation, these ten compounds showed good separation and satisfactory linearity (r≥0.999 7) within the concentration ranges tested. The mean recoveries were in the range of 98.60% to 102.6% with the RSD (n=6) between 0.60% and 3.7%. This method was proved to be simple, accurate and repeatable. The quantitative results showed that there were significant differences in the contents of seven alkaloids and three flavonoids among the different samples. This result revealed that the quality of Sophorae Tonkinensis Radix et Rhizoma varied widely. This method could be used for the simultaneous determination of the multi-ingredients from Sophorae Tonkinensis Radix et Rhizoma, which might provide scientific evidences to evaluate/control the quality of Sophorae Tonkinensis Radix et Rhizoma, comprehensively.