Diversity of red, green and black cultivars of Chinese Toon [ Toona sinensis (A. Juss.) Roem]: anthocyanins, flavonols and antioxidant activity

Young buds of Toona sinensis (A. Juss.) Roem with abundant flavonoids have aroused considerable attention for their health benefits. In this study, the diversity of anthocyanins (two cyanidin glycosides) and flavonols (11 quercetin and kaempferol derivatives) of five dominant cultivars of T. sinensis were analysed using HPLC–DAD and HPLC–ESI–MS/MS, and their antioxidant activities were evaluated with DPPH, FRAP and ORAC assays. Results showed that these characteristics were significantly cultivar-dependent (P < 0.05). By hierarchical cluster analysis, cultivars ‘Red Toon’ and ‘Chaigouzi’ with red buds were classified together for their high levels of total anthocyanins (TAC, respective averages of 155.82 ± 9.72 and 73.12 ± 1.56 mg/100 g), total flavonols (TFC, 1,206.34 ± 61.27 and 1003.01 ± 33.49 mg/100 g), and antioxidant activity (average DPPH values of 539.74 ± 21.34 and 546.97 ± 27.28 mg/100 g; FRAP: 439.44 ± 34.98 and 411.12 ± 17.24 mg/100 g; ORAC: 900.77 ± 187.49 and 521.96 ± 64.36 μM/g); ‘Green Toon’ with green buds was clustered alone due to its relatively low levels of TAC (2.71 ± 0.05 mg/100 g), TFC (563.45 ± 24.49 mg/100 g) and antioxidant activity (DPPH: 506.39 ± 4.04 mg/100 g; FRAP: 250.38 ± 18.47 mg/100 g; ORAC: 384.60 ± 15.32 μM/g). All results suggest that buds of T. sinensis are valuable natural antioxidant sources, and intuitively, the red buds are more desirable. In addition, cyanidin 3-O-neohesperidose, cyanidin 3-O-rutinoside, kaempferol 3-O-rutinoside, quercetin 3-O-xyloside and kaempferol 3-O-galactoside were firstly detected in T. sinensis.