Structure Characterization of Strictosidine‐Derived Indole Alkaloids and Their Tissue‐Specific Accumulation in <i>Neolamarckia cadamba</i> Using UHPLC–MS/MS and Principal Component Analysis

ABSTRACT Strictosidine‐derived indole alkaloids are the primary bioactive component of Neolamarckia cadamba and have been shown to inhibit DNA topoisomerase IB in Leishmania donovani . They also play a crucial role in a number of biological activities, including antileishmanial, antiplasmodial, and anthelmintic effects. However, there is still limited information on indole alkaloids in N. cadamba owing to the paucity of authentic standards and pertinent literature. For targeted metabolic profiling, a rapid UHPLC–PDA–ESI–MS/MS method was established for the screening of strictosidine‐derived indole alkaloids (IAs) from N. cadamba and the effect of seasonal variation on their tissue‐specific accumulation. Simultaneously, a principal component analysis (PCA) model was utilized to assess the seasonal and tissue‐specific distribution patterns of IAs. As a result, 17 metabolites were identified and structurally characterized using LC–MS/MS, including 10 IAs and other miscellaneous compounds. Four out of 10 IAs, namely, 5‐carboxystrictosidine, desoxycordifoline, strictosidinic acid, and strictosidine, were not previously reported from N. cadamba . Furthermore, 10 IAs—spirocadambine, 5‐carboxystrictosidine, desoxycordifoline, strictosidinic acid, dihydrocadambine, cadambine acid, strictosidine, strictosamide, vincosamide, and vallesiachotamine—were quantified in pre‐monsoon, monsoon, and post‐monsoon in stem, leaves, and stem bark tissues of N. cadamba . Strictosamide (977.5 ± 1.9 µg/g) and vincosamide (64.7 ± 2.8 µg/g) were shown to have the highest accumulation in stem bark during the post‐monsoon season. This study, through integrative application of LC–MS/MS and PCA, provides valuable insight to identify strictosidine‐derived IAs, as well as the significant effect of seasonal variations on IA accumulation.