Content change of main components in processed Ligustrum lucidum fruits of different processing time and their characteristic quality standard based on UPLC technology

To investigate the dynamic change law of the main components in Ligustri Lucidi Fructus during the wine-steaming process and attempt to establish the characteristic quality standard of wine-steamed Ligustri Lucidi Fructus by determining the content of salidroside and specnuezhenide using Ultra Performance Liquid Chromatography (UPLC) technology at different processing time points (12, 15, 18, 21, 24 h). The chromatographic separation was performed on Waters Acquity UPLC®BEH C₁₈ column (2.1 mm×50 mm, 1.7 μm) with acetonitrile and 0.2% formic acid aqueous solution as the mobile phase for gradient elution; and the detection wavelength was set at 280 nm; the flow rate was 0.5 mL·min⁻¹, and the column temperature was set at 40 °C. The results showed that the two components were well separated in the above conditions. The salidroside and specnuezhenide showed a good linear relationship within the range of 10.19-326 ng and 49.53-1 585 ng, respectively. Their average recovery was 103.4% and 101.7% with RSD of 0.81% and 0.79%, respectively. With the extension of processing time, the content of specnuezhenide was decreased, while salidroside was gradually increased. For the 27 batches of Ligustri Lucidi Fructus, the content of salidroside was between 0.042 5% and 0.192 4%, and that of specnuezhenide was between 0.829 7% and 5.218 0%. While for the 25 batches of wine-steamed Ligustri Lucidi Fructus, the content of the first one was between 0.229 2% and 1.045 8%, and the latter one was between 0.743 8% and 3.645 4%. As compared with Ligustri Lucidi Fructus, the ratio of specnuezhenide to salidroside was significantly decreased in the wine-steamed Ligustri Lucidi Fructus. According to the experimental results, the quality standard of Ligustri Lucidi Fructus is tentatively fixed as follows: the content of specnuezhenide shall not be less than 0.80%, and the ratio of specnuezhenide content/salidroside content (Sp/Sa) should not be smaller than 15. As for the wine-steamed ones, the content of salidroside should not be less than 0.20%, and specnuezhenide content should not be less than 0.70%; Sp/Sa should not be greater than 8. The method established in this study is simple and reliable, which could be used for the content detection of salidroside and specnuezhenide in Ligustri Lucidi Fructus samples. The characteristic quality standard established in this study could be used to distinguish the Ligustri Lucidi Fructus and wine-steamed Ligustri Lucidi Fructus.