Determination of the Major Bioactive Component of Silybum marianum in Nutricosmetics by a HPLC Method With Amperometric Detection and UAE Pretreatment

ABSTRACT Introduction Nutricosmetics derived from Silybum marianum , known for their anti‐inflammatory and hepatoprotective properties, necessitate accurate quantification of silybin, a key bioactive component. Objectives This study aims to develop a novel high‐performance liquid chromatography (HPLC) method with amperometric detection (HPLC‐ECD) for the precise determination of silybin. An ultrasound‐assisted extraction (UAE) procedure is also established for solid sample preparation prior to chromatographic analysis. Materials and Methods Chromatographic separation of silybin was performed on a C18 column and using methanol–0.035 M potassium phosphate (pH 4.0) at 1.0 mL min −1 flow rate as mobile phase in gradient mode. The electrochemical detection (ECD) of silybin was carried out on a glassy carbon electrode (GCE) at +1.10 V versus Ag/AgCl. The UAE procedure for silybin extraction from solid samples was performed by 15 min sonication in an ultrasonic bath (80 kHz and 100% power) at room temperature. Results Under the optimal chromatographic conditions, silybin diastereoisomers (silybin A and silybin B) can be separated from other S. marianum flavonolignans in less than 20 min, with a detection limit (LOD) of 0.060 mg L −1 and a reproducibility (RSD) of 5%. This method was successfully applied to analyze silymarin‐containing products with recoveries close to 100%. Conclusions This work presents the first HPLC method for silybin determination using an amperometric detector with a GCE. The LOD is competitive in comparison with previously published HPLC‐DAD methods. This HPLC‐ECD method allows silybin diastereoisomers identification without interferences of other flavonolignans present in silymarin extracts.