State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, #639 Longmian Avenue, Jiangning District, Nanjing 211198, China.
State Key Laboratory of Natural Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, #639 Longmian Avenue, Jiangning District, Nanjing 211198, China; Department of Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China; Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
J Chromatogr A. 2020 Aug 16;1625:461296. doi: 10.1016/j.chroma.2020.461296. Epub 2020 Jun 3.
Saponins constitute an important class of secondary metabolites of the plant kingdom. Here, we present a mass spectrometry-based database for rapid and easy identification of saponins henceforth referred to as saponin mass spectrometry database (SMSD). With a total of 4196 saponins, 214 of which were obtained from commercial sources. Through liquid chromatography-tandem high-resolution/mass spectrometry (HR/MS) analysis under negative ion mode, the fragmentation behavior for all parent fragment ions almost conformed to successive losses of sugar moieties, α-dissociation and McLafferty rearrangement of aglycones in high-energy collision induced dissociation. The saccharide moieties produced sugar fragment ions from m/z (monosaccharide) to m/z (polysaccharides). The parent and sugar fragment ions of other saponins were predicted using the above mentioned fragmentation pattern. The SMSD is freely accessible at http://47.92.73.208:8082/ or http://cpu-smsd.com (preferrably using google). It provides three search modes ("CLASSIFY", "SEARCH" and "METABOLITE"). Under the "CLASSIFY" function, saponins are classified with high predictive accuracies from all metabolites by establishment of logistic regression model through their mass data from HR/MS input as a csv file, where the first column is ID and the second column is mass. For the "SEARCH" function, saponins are searched against parent ions with certain mass tolerance in "MS Ion Search". Then, daughter ions with certain mass tolerance are input into "MS/MS Ion Search". The optimal candidates were screened out according to the match count and match rate values in comparison with fragment data in database. Additionally, another logistic regression model completely differentiated between parent and sugar fragment ions. This function designed in front web is conducive to search and recheck. With the "METABOLITE" function, saponins are searched using their common names, where both full and partial name searches are supported. With these modes, saponins of diverse chemical composition can be explored, grouped and identified with a high degree of predictive accuracy. This specialized database would aid in the identification of saponins in complex matrices particular in the study of traditional Chinese medicines or plant metabolomics.
皂苷是植物界中一类重要的次生代谢产物。在这里，我们提供了一个基于质谱的数据库，用于快速、轻松地鉴定皂苷，我们将其称为皂苷质谱数据库（SMSD）。该数据库共包含 4196 种皂苷，其中 214 种来自商业来源。通过负离子模式下的液相色谱-串联高分辨率/质谱（HR/MS）分析，所有母体碎片离子的裂解行为几乎符合糖基连续丢失、苷元α裂解和高能碰撞诱导解离中的麦拉弗蒂重排。糖基部分产生从 m/z（单糖）到 m/z（多糖）的糖片段离子。其他皂苷的母体和糖片段离子则是根据上述裂解模式预测得到的。SMSD 可在 http://47.92.73.208:8082/ 或 http://cpu-smsd.com（推荐使用谷歌）上免费访问。它提供了三种搜索模式（“CLASSIFY”、“SEARCH”和“METABOLITE”）。在“CLASSIFY”功能下，通过将 HR/MS 输入的质量数据作为 csv 文件建立逻辑回归模型，可以根据所有代谢物的高预测精度对皂苷进行分类，其中第一列是 ID，第二列是质量。对于“SEARCH”功能，可以在“MS Ion Search”中对具有一定质量容限的母体离子进行搜索，然后在“MS/MS Ion Search”中输入具有一定质量容限的子离子。根据与数据库中片段数据的匹配计数和匹配率值，筛选出最佳候选物。此外，另一个逻辑回归模型可以完全区分母体和糖片段离子。这个在前端网页上设计的功能有利于搜索和复查。使用“METABOLITE”功能，可以使用皂苷的通用名称进行搜索，支持全名和部分名称搜索。使用这些模式，可以对具有不同化学组成的皂苷进行探索、分组和鉴定，具有很高的预测精度。这个专门的数据库将有助于在复杂基质中鉴定皂苷，特别是在中药或植物代谢组学研究中。
