HPLC-DAD, GC–MS, UHPLC-Q-TOF/MS2, ICP-MS and FT-NIR combined with the chemometrics explain seasonal variation in Cassia senna L. leaves from the coast of Red Sea in Sudan

Crops reveal considerable capability to regulate their phytochemicals and trace element contents to seasonal changes in temperature and rainfalls. In this study, we have measured the secondary metabolites, volatiles, and trace elements of Cassia senna L leaves collected from the Red Sea State, Sudan during winter 2018, summer 2019, and autumn 2020. Chemical profiles were evaluated by High-performance liquid chromatography with diode-array detection (HPLC-DAD), Ultra-high performance liquid chromatography (UHPLC); Inductively coupled plasma mass spectrometry(ICP-MS), Gas chromatography-mass spectrometry (GC–MS), Fourier-transform near-infrared spectroscopy (FT-NIR). 46 metabolites, 33 volatile compounds, and 13 elements were reported. The findings suggested significant seasonal variations in sennoside (A-B) compounds, which were reported to have positive health effects. In this study, aloesin was identified for the first time in senna leaves. Analysis of seasonal variations was obtained by principal component analysis and orthogonal partial least squares discriminant model. Additionally, chemical markers for each harvest season were reported. Overall, the number of metabolites and volatiles identified as a function of the season was autumn > summer> winter. Our results have enhanced the knowledge of the selection of harvesting time, with the best characteristics for the intended therapeutic application. [Display omitted] •The chemical composition of C. senna l leaves was monitored over three growing seasons.•Volatile compounds, secondary metabolites and elemental in leaves of C. senna were reported.•C. senna l leaf samples are a new potential source of aloesin.•The contents of sennosides (A-B) and aloesin were higher in autumn and summer.•PCA and OPLS-DA were used to classify and identify chemical markers for each season.