Comparative Metabolomic Analysis of Shoot Apices and Leaves of Idesia polycarpa and Quantitative Determination of Leaf Flavonoids

Idesia polycarpa is a multipurpose tree species valued for both fruit production and timber and is often referred to as a “beautiful oil reservoir on trees”. However, research has largely focused on fruits, whereas the metabolic composition and potential value of other tissues, such as leaves and shoot tips, remain insufficiently characterized. Here, we employed UPLC–MS/MS-based untargeted metabolomics to compare metabolite profiles and functional components between the leaves and shoot tips of I. polycarpa. In total, 378 differential metabolites were identified, with 105 significantly upregulated in leaves and 273 significantly upregulated in shoot tips. Among these, 32 metabolites were detected exclusively in shoot tips, and 22 were unique to leaves. Leaves were enriched in secondary metabolites, particularly flavonoids and phenolic acids, with scutellarin and catechol as representative compounds. In contrast, shoot tips exhibited higher levels of primary metabolites, including nucleotides and their derivatives as well as amino acids, with catechin and epicatechin being representative compounds. In addition, targeted metabolomics was performed to quantify 53 flavonoids in leaves; scutellarin (2088.1350 μg/g) and apigenin-7-O-glucuronide (1020.9085 μg/g) showed the highest concentrations. Collectively, these results reveal tissue-specific metabolic characteristics in I. polycarpa and provide a data basis for future functional studies and the comprehensive utilization of leaves and shoot tips.