Table 2. Lengths of Induction Periods, τ, Stoichiometric Factors, n, Rate of Inhibited Peroxidation, Rinh, the Slow-Down Factors (Rox/Rinh, the Ratio of the Rate of the Non-Inhibited Process to the Rate of the Inhibited Process), the Inhibition Rate Constants, kinh, and Kinetic Chain Lengths, vinh = Rinh/Ri, Determined for Autoxidation of 2.74 mM MeLin Dispersed in 8 mM Triton X-100 Micelles in the Presence of 1 μM PMHC, RSV, 3,5-DHA, and 4-HBA or an Equimolar Mixture of PMHC/RSVa.
| pH | τ (min) | nb | Rinh (nM s–1) | Rox/Rinhc | 10–3kinh (M–1 s–1) | vinh |
|---|---|---|---|---|---|---|
| PMHC | ||||||
| 4.0 | 7.2 ± 0.1 | 2.0 | 35 ± 4 | 15.8 | 10.9 ± 2.2 | 7.6 |
| 6.0 | 7.2 ± 0.6 | 2.0 | 52 ± 7 | 9.1 | 6.7 ± 1.3 | 11.1 |
| 7.0 | 7.6 ± 0.7 | 2.0 | 37 ± 5 | 9.6 | 18.8 ± 3.8 | 8.4 |
| 8.0 | 7.5 ± 0.5 | 2.0 | 47 ± 5 | 7.5 | 17.0 ± 3.4 | 10.4 |
| 10.0 | 5.8 ± 0.7 | 2.0 | 37 ± 5 | 7.5 | 29.2 ± 5.8 | 6.5 |
| RSV | ||||||
| 4.0 | 15.6 ± 0.8 | 4.3 | 94 ± 6 | 5.9 | 1.5 ± 0.3 | 20.4 |
| 6.0 | 17.2 ± 0.7 | 4.9 | 103 ± 12 | 4.6 | 1.2 ± 0.2 | 21.9 |
| 7.0 | 16.2 ± 1.1 | 4.3 | 90 ± 6 | 4.0 | 1.5 ± 0.3 | 20.5 |
| 8.0 | 11.4 ± 0.2 | 3.1 | 81 ± 6 | 4.3 | 2.5 ± 0.5 | 18.0 |
| 10.0 | 4.6 ± 0.4 | 1.6 | 124 ± 13 | 2.2 | 3.7 ± 0.7 | 21.8 |
| 3,5-DHA | ||||||
| 4.0 | 231 ± 1d | 2.4d | e | 50.2 | ||
| 7.0 | 6.8 ± 0.3 | 1.8 | 109 ± 4 | 3.3 | 3.0 ± 0.6 | 24.8 |
| 4-HBA | ||||||
| 4.0 | 215 ± 3d | 2.6d | e | 46.7 | ||
| 7.0 | 6.4 ± 0.2 | 1.7 | 117 ± 5 | 3.1 | 2.8 ± 0.6 | 26.6 |
| PMHC/RSV | ||||||
| 4.0 | 21.5 ± 0.5 | 3.9f | 22 ± 5 | 25.2 | g | 4.8 |
| 6.0 | 25.7 ± 1.3 | 5.2 | 67 ± 6 | 7.0 | 14.3 | |
| 7.0 | 23.4 ± 1.7 | 4.2 | 66 ± 8 | 5.4 | 15.0 | |
| 8.0 | 18.5 ± 0.8 | 3.0 | 66 ± 14 | 5.3 | 14.7 | |
| 10.0 | 6.6 ± 0.7 | 0.3 | 21 ± 4 | 13.1 | 3.7 | |
The experiments were performed at 37 °C and pH 4.0, 6.0, 7.0, 8.0, and 10.0. Peroxidation was initiated by 10 mM ABAP. Values are expressed as the mean ± standard deviation (SD).
For α-TOH and PMHC, n = 2.0.
The Rox/Rinh ratio informs how many times the inhibited oxidation is slower than the spontaneous (non-inhibited) process (for Rox as well as Ri values, see Table S1).
There was no inhibition period for 3,5-DHA and 4-HBA at pH 4, 5, and 6. Rinh means rate of retardation; see Figure 1A.
For these systems, the inhibition time was not detected and kinh could not be calculated.
For PMHC/RSV, the parameter n corresponds to RSV and was calculated from the equation nRSV = Ri(τPMHC/RSV – τPMHC)/[RSV] adapted from ref (41).
kinh cannot be calculated for mixed antioxidants.