Novel Steroidal Saponins in Oat Identified by Molecular Networking Analysis and Their Levels in Commercial Oat Products

Through the use of the Global Natural Product Social (GNPS) feature-based networking system, a series of newly identified steroidal saponins were discovered in oat. The structures of the three new major steroidal saponins, sativacosides A-C (1-3), were characterized by analyzing their high-resolution MS, 1D and 2D NMR spectra, and an additional eight new steroidal saponins were also tentatively identified (4-11) based on their tandem mass spectra and typical fragments. Using ultrahigh-performance liquid chromatography with tandem mass spectrometry techniques, a complete profile of the new sativacoside series was established, and the contents of sativacosides A-C were quantified in 18 different commercial oat products. The total levels of sativacosides A-C varied from 62.2 to 192.9 mu g/g in these 18 products, in which oat bran (11 samples) and oatmeal (3 samples) had higher levels than cold oat cereal (4 samples).