Identification of metabolite changes and evaluation of biological activities in edible flowers of Magnolia kobus at different developmental stages

Abstract

Abstract Background Magnolia kobus belongs to the Magnoliaceae family and the genus Magnolia. The flowers are widely used in herbal tea and dietary supplements. It is effectively used in traditional medicines and its chemical constituents have various biological activities, such as anti-obesity, antioxidant, anticancer, anti-inflammatory, and anti-hyperlipidaemic activities. The flower developmental process of M. kobus involves a complex regulatory network and is intensively related to the quality and relative composition of primary and secondary metabolites of the flower. Hence, the identification of metabolic changes during different developmental stages of the flower was important for enhancing organoleptic and nutritional characteristics. To our knowledge, to date, none of the studies has investigated the relationship between metabolic changes (primary and secondary metabolites) during different developmental stages of the M. kobus flower. Results This study investigated metabolic changes in 47 hydrophilic and 13 lipophilic compounds and biological activities in Magnolia kobus flowers during four developmental stages. Metabolites were identified using HPLC, GC–qMS, and GC–TOFMS. Throughout flower development, metabolite accumulation showed significant differences based on metabolomics approaches. The dynamic changes of 21 differential metabolites occurred between the young and mature stages. Flower buds exhibited high levels of phenylpropanoids and phytosterols. The total phenolic and flavonoid contents were most abundant in the buds and decreased from the bud to the old stages. Flower bud extracts showed the most powerful effects in three antioxidant assays and antibacterial effects against 10 pathogenic bacterial strains. Conclusions These findings emphasise the value of M. kobus flower buds as an edible natural source and provide valuable insight into the metabolic changes that occur in M. kobus flowers during development. Graphical Abstract

Keywords

• Edible flower
• Magnolia kobus
• Metabolomics
• Phenylpropanoid
• Phytosterol
• Biological activity