Differences in Bioactive Composition of Sea Buckthorn Berry Pulp during the Ripening Process as Analyzed by Metabolomics Based on Ultra-high Performance Liquid Chromatography Coupled to Mass Spectrometry

In order to reveal the differences in the biosynthesis and metabolism of the major bioactive composition in sea buckthorn berry pulp during ripening, non-targeted metabolomics based on ultra-high performance liquid chromatography coupled to mass spectrometry (UPLC-MS) was used to analyze the metabolites of sea buckthorn berry pulp from two strains at different developmental stages (green and orange pulp). The results showed that the four sample groups had significant metabolic differences. A total of 124 significantly differential metabolites were detected among the four groups based on variable importance in the projection (VIP) > 1 and t-test P < 0.05, including organic acids, carbohydrates, lipids, flavonoids and secondary metabolites. According to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, 15, 7 and 4 significantly differential metabolites associated with lipid, flavonoid and serotonin metabolism were identified, respectively, and eight significantly differential metabolites involved in anticancer function were selected. The significant up-regulation of phosphatidylcholine (PC) (16:0/16:0) and glycerophosphocholine could be the reason for the high accumulation of lipids in sea buckthorn berry pulp. The significant upregulation of isorhamnetin was key for the high flavonoid content in sea buckthorn berry pulp. Relatively high contents of N-acetylserotonin, capecitabine, γ-aminobutyric acid (GABA) and other bioactive composition involved in anticancer function were shown in sea buckthorn berry pulp during its development. These results provide a scientific basis for revealing the metabolic mechanism of bioactive composition of sea buckthorn berries and developing related functional products.