Table 2.
Linear and non-linear relationships obtained for different antioxidant concentrations (μM) applied against DPPH radicals in acetone or aqueous acetone after standard and modified reaction times (radical solution in methanol or acetone). In case of linear relations, slope (a), correlation coefficient (r) and lower/upper linearity limits if occurring (MIN/MAX–as % of Acontr) were shown; in case of a non-linear relationship, equation type and correlation coefficient were shown.
| Antioxidant | 50% Acn + MeOH 10 min |
50% Acn + MeOH 30 min |
50% Acn + MeOH 120 min |
70% Acn + MeOH 30 min |
Acn + MeOH 30 min |
Acn 30 min |
|---|---|---|---|---|---|---|
| gallic acid | a = −66 r = −0.994 MIN = 20% |
a = −71 r = −0.999 |
a = −77 r = −0.997 |
a = −59 r = −0.994 MIN = 20% |
expon. r = −0.996 |
expon. r = −0.996 |
| ferulic acid | a = −12 r = −0.993 MIN = 40% |
a = −14 r = −0.997 MIN = 30% |
a = −15 r = −0.996 MIN = 20% |
a = −11 r = −0.991 MIN = 30% |
power r = −0.976 |
power r = −0.996 |
| catechin | a = −20 r = −0.992 MIN = 15% |
expon. r = −0.997 |
power r = 0.999 |
a = −19 r = −0.999 MIN = 10% MAX = 90% |
a = −20 r = −0.999 MIN = 20% |
expon. r = −0.999 |
| quercetin | a = −35 r = −0.992 MIN = 30% |
a = −57 r = −0.999 |
a = −57 r = −0.998 |
a = −56 r = −0.999 MIN = 20% |
a = −34 r = −0.995 MIN = 40% |
N.R. 1 |
| propyl gallate | a = −46 r = −0.996 |
a = −54 r = −0.997 |
a = −60 r = −0.999 |
a = −53 r = −0.997 MIN = 15% |
a = −48 r = −0.994 MIN = 35% |
a = −39 r = −0.996 MIN = 25% |
| glutathione | power r = −0.993 |
power r = −0.989 |
power r = −0.996 |
expon. r = −0.992 |
N.A. 2 | N.A. |
| carnosine | N.D. 3 | TR. 4 | TR. | N.A. | N.A. | N.A. |
| cysteine | a = −2 r = −0.993 |
a = −9 r = −0.998 |
a = −9 r = −0.997 |
N.A. | N.A. | N.A. |
| histidine | N.D. | TR. | TR. | N.A. | N.A. | N.A. |
| ascorbic acid | a = −22 r = −0.998 MIN = 10% MAX = 90% |
a = −20 r = −0.995 MIN = 10% MAX = 90% |
a = −21 r = −0.993 MIN = 10% MAX = 90% |
a = −22 r = −0.998 |
N.A. | N.A. |
| ascorbyl palmitate | N.A. | N.A. | N.A. | a = −20 r = −0.997 MIN = 15% |
a = −28 r = −0.995 MIN = 20% MAX = 90% |
a = −29 r = −0.990 MIN = 25% MAX = 90% |
| α-tocopherol | N.A. | N.A. | N.A. | N.A. | a = −24 r = −0.999 MIN = 20% |
a = −24 r = −0.999 |
| tocopheryl acetate | N.A. | N.A. | N.A. | N.A. | TR. | TR. |
| Trolox | a = −24 r = −0.999 |
a = −26 r = −0.999 |
a = −24 r = −0.999 |
a = −25 r = −0.999 |
a = −24 r = −0.999 MIN = 20% |
a = −24 r = −0.998 |
| phenolic mixture | a = −32 r = −0.987 |
a = −36 r = −0.999 MIN = 20% |
a = −37 r = −0.997 MIN = 30% |
a = −40 r = −0.997 MIN = 30% |
N.T. 5 | N.T. |
| polar mixture | a = −20 r = −0.999 MIN = 20% |
a = −20 r = −0.999 MIN = 20% |
a = −22 r = −0.999 MIN = 30% |
a = −22 r = −0.993 MIN = 20% |
N.A. | N.A. |
1 N.R.—no relationship between concentration and activity. 2 N.A.—not applicable. 3 N.D.—activity not detected. 4 TR.—traces of activity. 5 N.T.—not tested.