Table 3. EC50 values from five antioxidant activity assays and contents of total phenolics and total flavonoids from five isolates of Rhodiola rhizomes.
| EC50 value (mg extract per mL) | Total phenols (mg g-1) | Total flavonoids (mg g-1) | |||||
|---|---|---|---|---|---|---|---|
| DPPH radicals | Hydroxyl radicals | Superoxide radicals | Nitrite radicals | Ferrous ions | |||
| Rct45 | 1.54 ± 0.007f | 1.41 ± 0.007g | 0.24 ± 0.007g | 14.85 ± 0.022a | 35.95 ± 0.050a | 24.64 ± 0.001b | 23.90 ± 0.001a |
| Rct63 | 3.54±0.013d | 35.75±0.016b | 5.36±0.011b | 12.14±0.016c | 18.22±0.069c | 12.31±0.001d | 23.67±0.002b |
| Rct64 | 4.66±0.038c | 3.17±0.020f | 3.03±0.007c | 14.46±0.013b | 3.03±0.067f | 24.75±0.002a | 12.15±0.000d |
| Rac76 | 7.33±0.011a | 13.99±0.173c | 0.92±0.007e | 9.14±0.011e | 28.89±0.060b | 11.96±0.001e | 23.39±0.001c |
| Rsc57 | 6.58±0.029b | 36.59±0.091a | 6.70±0.027a | 9.82±0.033d | 12.06±0.020d | 23.09±0.002c | 11.92±0.001e |
| Vc | 1.28±0.018g | 13.35±0.044d | 0.47±0.011f | 6.82±0.047g | — | — | — |
| BHT | 3.13 ± 0.009e | 7.09 ± 0.033e | 0.98 ± 0.011d | 8.42 ± 0.107f | — | — | — |
| EDTA-2Na | — | — | — | — | 9.68 ± 0.144e | — | — |
Rct: the isolates from Rc in Tibet; Rac and Rsc: the isolates from Ra and Rs in Changbai Mountain; Vc: Vitamin C; BHT: Butylated hydroxytoluene; EC50 value, effective concentration at which antioxidant activity was 50% obtained by interpolation from linear regression analysis; absorbance was 0.5 for 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radicals (OH), superoxide radicals (O2 −), and nitrite (NO2 −) scavenged by 50%. Ferrous ions were chelated by 50%. Each value was mean ± SD (n = 3). Means with different letters within a column were significantly different (p < 0.05).