Characterization and Discrimination of Ophiopogonis Radix with Different Levels of Sulfur Fumigation Based on UPLC-QTOF-MS Combined Molecular Networking with Multivariate Statistical Analysis

Ophiopogonis Radix, also known as "Maidong" (MD) in China, is frequently sulfur-fumigated (SF) in the pretreatment process of MD to improve the appearance and facilitate preservation. However, the process leads to changes in chemical composition, so it is essential to develop an approach to identify the chemical characteristics between nonfumigated and sulfur-fumigated products. This paper provided a practical method based on UPLC-QTOF-MS combined Global Natural Products Social Molecular Networking (GNPS) with multivariate statistical analysis for the characterization and discrimination of MD with different levels of sulfur fumigation, high concentration sulfur fumigation (HS), low concentration sulfur fumigation (LS) and without sulfur fumigation (WS). First, a number of 98 compounds were identified in those MD samples. Additionally, the results of Principal component analysis (PCA) and Orthogonal partial least-squares-discriminant analysis (OPLS-DA) demonstrated that there were significant chemical differences in the chemical composition of MD with different degrees of SF. Finally, fourteen and sixteen chemical markers were identified upon the comparison between HS and WS, LS and WS, respectively. Overall, these results can be able to discriminate MD with different levels of SF as well as establish a solid foundation for further quality control and pharmacological research.