Table 4.
Antioxidant activities of P. tricornutum exudates cultured under different copper concentrations and collected after 18 days.
| Antioxidant assay (units) | Control | Cu(II) 0.31 µM | Cu(II) 0.79 µM | Cu(II) 1.57 µM |
|---|---|---|---|---|
|
DPPH (fmol DPPH cell-1) |
1.00 ± 0.02 | 1.12 ± 0.02 | 4.04 ± 0.00 | 5.43 ± 0.00 |
|
FRAP (fmol Fe(II) cell-1) |
1.64 ± 0.05 | 1.53 ± 0.09 | 4.24 ± 0.03 | 5.34 ± 0.13 |
|
CUPRAC (fmol TR cell-1) |
1.35 ± 0.01 | 1.12 ± 0.01 | 3.78 ± 0.03 | 3.28 ± 0.08 |
| CCA (fmol Cu cell-1) | 0.234 ± 0.006 | 1.646 ± 0.004 | 3.228 ± 0.004 | 7.53 ± 0.02 |
The results are expressed as fmol cell−1 (means ± standard deviations of three measurements).
Significantly positive correlations (p < 0.05) were observed between the CCA values and the total polyphenol content (R = 0.9820) and total carbohydrate content (R = 0.9806).