Flavonoid constituents and antioxidant capacity in flowers of different Zhongyuan tree penoy cultivars

Flavonoid components in flowers of 48 Zhongyuan tree penoy cultivars were identified by means of a hyphenated technique of HPLC coupled with a photodiode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESIMS). The total phenolic content (TPC) was determined by Folin–Ciocalteu method and the antioxidant activity with both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. About 14 flavonoids including five anthocyanins, three flavonol glycosides and six flavone glycosides were described. Apigenin-pento-hexoside and Apigenin-hexo-glucuronide were reported for the first time. TPC, expressed as gallic acid content, varied between 3.97 and 21.73 mg/g fresh weight. Antioxidant activity varied among the cultivars (7.66–31.36 and 4.80–17.87 mg ascorbic acid equivalents/g fresh weight for DPPH and FRAP assays, respectively) and highly corresponded with TPC.