Table 1.
Linear and non-linear relationships obtained for different antioxidant concentrations (μM) applied against ABTS radical cations in 50% acetone or methanol (radical solution diluted with ethanol) and buffers of pH 3.6 and 7.4 (radical solution diluted with buffers) after standard and modified reaction times. In case of linear relations, slope (a), correlation coefficient (r) and lower linearity limits if occurring (MIN–as % of Acontr) were shown; in case of a non-linear relationship, equation type and correlation coefficient were shown.
| Antioxidant | 50% Acn + EtOH 6 min |
50% Acn + EtOH 30 min |
MeOH + EtOH 6 min |
pH 3.6 6 min |
pH 3.6 30 min |
pH 7.4 6 min |
pH 7.4 30 min |
|---|---|---|---|---|---|---|---|
| gallic acid | a = −98 r = −0.998 |
a = −109 r = −0.998 |
a = −97 r = −0.995 |
a = −69 r = −0.997 |
a = −85 r = −0.999 |
a = −112 −0.997 |
a = −125 −0.997 |
| ferulic acid | power r = −0.996 |
power r = −0.997 |
power r = −0.998 |
N.A. 1 | N.A. | N.A. | N.A. |
| catechin | power r = −0.995 |
a = −72 r = −0.991 |
power r = 0.997 |
N.A. | N.A. | N.A. | N.A. |
| quercetin | a = −78 r = −0.995 MIN = 30% |
a = −92 r = −0.993 |
a = −78 r = −0.997 MIN = 35% |
N.A. | N.A. | N.A. | N.A. |
| propyl gallate | a = −86 r = −0.999 |
a = −106 r = −0.999 |
a = −85 r = −0.999 |
a = −54 r = −0.996 |
a = −70 r = −0.998 |
a = −55 r = −0.998 |
a = −62 r = −0.997 |
| glutathione | power r = −0.989 |
a = −57 r = −0.996 MIN = 35% |
N.A. | power r = 0.999 |
power r = 0.993 |
a = −27 r = −0.995 |
a = −41 r = −0.996 MIN = 40% |
| carnosine | TR. 2 | TR. | N.A. | N.D. 3 | N.D. | N.D. | TR. |
| cysteine | a = −12 r = −0.995 MIN = 50% |
a = −22 r = −0.986 MIN = 35% |
N.A. | a = −12 r = −0.998 |
quadr. r = −0.996 |
a = −16 r = −0.993 |
power r = −0.977 |
| histidine | N.D. | N.D. | N.A. | N.D. | N.D. | N.D. | N.D. |
| ascorbic acid | a = −30 r = −0.999 |
a = −28 r = −0.999 |
a = −30 r = −0.999 |
a = −26 r = −0.999 |
a = −26 r = −0.999 |
a = −28 r = −0.999 |
a = −27 r = −0.999 |
| ascorbyl palmitate | N.A. | N.A. | a = −30 r = −0.999 |
N.A. | N.A. | N.A. | N.A. |
| α-tocopherol | N.A. | N.A. | a = −30 r = −0.999 |
N.A. | N.A. | N.A. | N.A. |
| tocopheryl acetate | N.A. | N.A. | N.D. | N.A. | N.A. | N.A. | N.A. |
| Trolox | a = −31 r = −0.999 |
a = −32 r = −0.999 |
a = −31 r = −0.999 |
a = −29 r = −0.999 |
a = −29 r = −0.999 |
a = −29 r = −0.999 |
a = −28 r = −0.999 |
| phenolic mixture | a = −60 r = −0.988 MIN = 40% |
a = −92 r = −0.995 MIN = 35% |
a = −77 r = −0.997 MIN = 40% |
N.A. | N.A. | N.A. | N.A. |
| peptide/AA mixture | a = −17 r = −0.994 MIN = 30% |
a = −26 r = −0.999 |
N.A. | expon. r = −0.996 |
power r = −0.998 |
a = −10 r = −0.999 |
a = −15 r = −0.999 |
| polar mixture | a = −43 r = −0.986 MIN = 40% |
a = −50 r = −0.996 |
N.A. | a = −20 r = −0.999 |
a = −22 r = −0.993 |
a = −27 r = −0.999 |
a = −29 r = −0.999 |
| applicable compounds mixture | N.A. | N.A. | a = −60 r = −0.997 MIN = 40% |
N.A. | N.A. | N.A. | N.A. |
1 N.A.—not applicable. 2 TR.—traces of activity. 3 N.D.—activity not detected.