Identification and evaluation of antioxidant components in the flowers of five Chimonanthus species

Abstract Chimonanthus Lindl. has seven family members with Ch. praecox blooming in winter and others in autumn. The plants are widely used in landscaping, fragrance industry, as well as production of medicinal material because of their flower fragrance. Both Chimonanthus flowers and leaves contain abundant secondary metabolites. But it is unclear whether the flowers from different species have distinct ingredients and antioxidant activity. To address the question, we evaluated the main compositions of the flowers from five Chimonanthus species and analyzed the antioxidant activity of the compositions. The results indicated that flavonoids and coumarins are the two major types of substances with antioxidant capacity in Chimonanthus flowers. Totally nine antioxidative compounds, including scopolin and scopoletin, were identified based on the high performance liquid chromatography-photo diode array detection-electrospray ionization tandem mass spectrometry (HPLC-DAD/ESI–MS). All the antioxidant compounds were confirmed by pre-column 2, 2-diphenyl-1- picryhydrazyl (DPPH) assay. Rutin (highest in content), isoquercitrin and quercetin appeared stronger scavenging DPPH radical ability than the other five compounds, mainly due to their ortho -dihydroxyl groups. Among the five Chimonanthus species, Ch . praecox flower is most abundant in secondary metabolites and shows most potent antioxidant activity. The other four flowers contain the same types of ingredients with Ch. praecox , but exhibit lower antioxidant activity. The results obtained from this comprehensive analysis provide a theoretical basis for the utilization of the plant resources of Chimonanthus genus.