Metabolomics‐based analysis of flavonoid metabolites in Chinese jujube and sour jujube fruits from different harvest periods

Chinese jujube (Ziziphus jujuba Mill.) and sour jujube (Ziziphus spinosa Hu.) fruits have health benefits because they contain bioactive compounds such as flavonoids. However, differences in the flavonoid metabolites of these two fruits remain unclear. We determined the flavonoids present in Z. jujuba cv. Hupingzao (HPZ) and Z. spinosa cv. Taigusuanzao (TGSZ) from two different harvest periods fruits: HPZ white period (HW) and HPZ red period (HR) as well as TGSZ white period (SW) and TGSZ red period (SR). We identified 123 flavonoid metabolites: 40 flavonols, 37 flavones, 12 anthocyanins, 9 dihydroflavones, 8 flavanols, 7 flavonoid carbonosides, 5 dihydroflavonols, 3 isoflavones, and 2 chalcones. The total flavonoid content of both HPZ and TGSZ decreased with fruit development and was significantly higher in TGSZ than in HPZ fruits. Moreover, we detected 63, 81, 56, and 63 differential flavonoid metabolites (DFMs) between HW and HR (two upregulated and 61 downregulated), SW and SR (four upregulated and 77 downregulated), HW and SW (54 upregulated and two downregulated), and HR and SR (62 upregulated and one downregulated), respectively. KEGG pathway annotation and enrichment analysis showed that 22 DFMs were annotated seven relevant metabolic pathways, among which flavonoid biosynthesis pathway and secondary metabolites biosynthesis pathway were the main pathways, and flavanols were the primary metabolites that influenced the difference in flavonoid accumulation between the fruits. To our knowledge, this is the first study to reveal the differences in flavonoid metabolism between Chinese jujube and sour jujube. Our findings may facilitate the comprehensive use of functional flavonoids. PRACTICAL APPLICATION: Chinese jujube (Ziziphus jujuba Mill.) and sour jujube (Ziziphus spinosa Hu.) fruits have health benefits because they contain bioactive compounds such as flavonoids. However, differences in the flavonoid metabolites of these two fruits remain unclear. We determined the flavonoids present in Z. jujuba cv. Hupingzao (HPZ) and Z. spinosa cv. Taigusuanzao (TGSZ) from two different harvest periods. Our findings may facilitate the comprehensive use and product research of functional flavonoids of jujube.