Systematic Characterization of Isoquinoline Alkaloids Constituents in Corydalis impatiens (Pall.) Fisch Based on UPLC-QTOF-MS/MS Combined With Feature-Based Molecular Networking.

The isoquinoline alkaloids from Corydalis impatiens (Pall.) Fisch, a traditional Tibetan medicine used for treating liver diseases, are considered to be a major bioactive constituent potentially contributing to its hepatoprotective activity. This study aimed to systematically characterize the isoquinoline alkaloids in C. impatiens and expand their chemical inventory, thereby providing a basis for understanding their potential bioactivity and further application. UPLC-QTOF-MS/MS combined with a feature-based molecular networking (FBMN) approach was employed to comprehensively profile the isoquinoline alkaloids. In this way, the cleavage patterns and diagnostic ions of different isoquinoline alkaloid types were systematically summarized, and a total of 74 isoquinoline alkaloids were identified, including 20 tetrahydroprotoberberines, 13 phthalide isoquinolines, 19 protoberberines, 4 protopines, 17 benzylisoquinolines, and 1 benzophenanthridine. Among these, eight compounds were tentatively identified as putatively new alkaloids belonging to the phthalide isoquinoline-type and benzylisoquinoline-type alkaloids. In addition, distributional differences among C. impatiens samples were investigated. This study expanded the current understanding of isoquinoline alkaloids in C. impatiens. Moreover, the FBMN approach proved to be a rapid and effective strategy for characterizing complex chemical compositions and discovering new compounds in crude drugs.