Comparison Of The Inedible Parts Of White And Green Asparagus Based On Metabolomics

Background: Asparagus is a perennial herb eaten in the form of its very young thickened shoots and has been widely used as food and medicine in China.Asparagus is rich in various chemical compounds,including saponins,flavonoids,polysaccharides,amino acids,vitamins,essential minerals,and so on.Previous studies have shown that Asparagus extract exhibited anti-tumor,anti-oxidant and immunomodulatory effects.In addition to being used as vegetable,Asparagus is mainly used for processing canned food and quickfrozen products.In the processing of asparagus,many by-products are discarded and accounted for about 30% of asparagus materials,mainly including asparagus skins and old stems.At present,most of the studies on inedible parts of asparagus are the extraction process of total saponins and total flavonoids.Thus,comprehensive chemical characterization and systematic comparison between the inedible parts of white and green should be conducted.Purpose: This study aimed to compare the chemical difference and anti-breast cancer effect between the inedible parts of white and green asparagus and provides a theoretical basis for the resource utilization of inedible parts of asparagus.Methods:a)UPLC-Q-TOF MS/MS was used to collect the mass spectrum data,and the SCIEX TCM databases,self-built databases,MS-DIAL lipid databases and GNPS molecular network were used to identify the chemical compounds in the inedible parts of asparagus.b)The untargeted metabolomics analysis was applied to comprehensively compare the chemical difference between the edible and inedible parts of asparagus,as well as the inedible parts of white and green asparagus.In addition,this study explores the differences in steroidal saponins and flavonoids between the inedible parts of white and green Asparagus based on biosynthetic pathways.c)The anticancer activities of inedible parts of white and green asparagus in vitro were investigated by using murine breast cancer cell 4T-1 model.Then the differential compounds were subjected to network pharmacology analysis to explain the correlation of chemical difference and the biological difference.The key components and targets were finally verified by molecular docking.Result:a)A total of 327 metabolites are tentatively identified using a variety of databases,which are divided into 11 categories according to the types of substances,mainly including53 saponins,32 flavonoids,133 lipids,33 phenolic acids,31 amino acids,peptides and derivatives,10 carbohydrates,7 nucleosides,9 organic acids,4 alkaloids,3 lignans and norlignans and 12 other compounds.And 24 steroid saponins,31 oxylipins and 36 Lyso GPLs are identified for the first time in the inedible parts of asparagus.b)Chemical comparison by metabolomics shows that the inedible part of white asparagus is rich in steroidal saponins,oxylipins and alkaloids,while the inedible part of green asparagus contained flavonoids,phenolic acids,Lyso GPLs and amino acids.This work provides a theoretical basis for the resource utilization of inedible parts of asparagus.c)The inedible part of white asparagus shows significantly higher inhibitory effects on the breast cancer 4T-1 cells than the green asparagus,which may be related to the rich steroidal saponins and oxylipins in the inedible part of white asparagus using network pharmacology analysis and molecular docking analysis.The differential compounds mainly acted on the 27 key targets,including MTOR,PIK3 CA,VEGF,CDK4,MDM2,AKT1,etc.And they were associated with anti-breast cancer effects through the PI3K-Akt signaling pathway and mTOR signaling pathway.Conclusions: In this study,UPLC-Q-TOF-MS/MS was used to identify the chemical compounds in the asparagus,then the untargeted metabolomics analysis was applied to comprehensively compare the inedible parts of white and green asparagus.The inedible part of white asparagus is rich in steroidal saponins,oxylipins and alkaloids,while the inedible part of green asparagus contained flavonoids,phenolic acids,Lyso GPLs and amino acids.The inedible part of white asparagus showed significantly higher inhibitory effects,which may be related to the rich steroidal saponins and oxylipins.The results presented in this study are useful for the wasted resource utilization of inedible parts of asparagus.