Composition of peony petal fatty acids and flavonoids and their effect on Caenorhabditis elegans lifespan.

The colorful petals of tree peony (Paeonia suffruticosa Andrews) are widely used as a source of additives in food, fragrances, and cosmetics. However, the nutritional composition of peony petals is undetermined, thereby limiting utility and product development. In this work, fresh petals of 15 traditional Chinese tree peony cultivars were selected to analyze the composition of soluble sugars, starch, and soluble protein. Extracted fatty acids (FAs) and flavonoids from petals were characterized by GC-MS and UPLC-triple-TOF-MS, respectively. The oxidative stress resistance (generated by paraquat) effects of petal extracts of three cultivars were also investigated in the model organism Caenorhabditis elegans. Our results showed that the petals were highly enriched in soluble sugars. 11 FAs were found in tree peony petals, and their compositions were similar to that of tree peony seeds. A total of 56 flavonoids were detected in tree peony petals, 28 of which were reported for the first time in tree peony petals, indicating that UPLC-triple-TOF-MS can improve the identification efficiency of flavonoids. Further analysis of tree peony petal metabolites indicated that anthocyanidin and flavonol composition might be used as specific chemotaxonomic biomarkers for cultivar classification. Flavonoids, linoleic acid, and α-linolenic acid (ALA) in petals might provide antioxidant activity. 150 mg/L of petal extracts of all three tested cultivars increased the lifespan of C. elegans. It was suggested that the petal extracts possessed anti-aging effects and oxidative stress resistance. These results highlight that tree peony petals can serve as natural antioxidant food resources in the future.