LC-MS-based identification and antioxidant evaluation of small molecules from the cinnamon oil extraction waste

[Display omitted] •Small molecules in the wasted cinnamon leaves were clarified for the first time.•101 small molecules were identified by MS/MS molecular networking-based analysis.•Lactones, lignans and flavanols were firstly reported from the cinnamon leaves.•Potential antioxidant constituents of wasted cinnamon leaves were investigated. Cinnamon oil is obtained by steam distillation from cinnamon leaves and is usually considered highly cost-effective compared to bark oil, however, which results in tons of waste cinnamon leaves (WCL) discarded annually. By using MS/MS molecular networking (MN) assisted profiling, six main chemical diversities including flavonols and flavones, phenolic acids, lactones, terpenoids, phenylpropanoids and flavanols were rapid revealed from WCL aqueous extract. 101 compounds were tentatively identified by assigning their MS/MS fragments within typical pathways under ESI-MS/MS dissociation. The featured phenolic acids, terpenoids and their glycosides in cinnamon species were recognized as the main constituents of WCL. The hydrophilic lactones, lignans and flavanols were reported for the first time in cinnamon leaves. Furthermore, ABTS and FRAP assays integrated with MN analysis were conducted to uncover an antioxidant fraction, from which 40 potential antioxidant compounds were rapidly annotated. This fundamental information will help expand the utilization of WCL from cinnamon oil industry.