Table 1.
α-TQH2 effectively inhibits LDL lipid peroxidation induced by different oxidants
| Oxidant* | Onset of consumption,† min
|
Accumulation of LOOH,‡ μM
|
||
|---|---|---|---|---|
| CoQ10H2 | α-TOH | CE-O(O)H | PC-OOH | |
| AAPH | ||||
| − | 0 | 30 ± 10 | 20.4 ± 3.9 | 7.8 ± 3.1 |
| + | 20 ± 10 | 150 ± 25 | 0 | 0 |
| AMVN | ||||
| − | 0 | 30 ± 15 | 36.6 ± 11.5 | 10.5 ± 2.5 |
| + | 120 ± 2 | 270 ± 28 | 0 | 0 |
| SLO | ||||
| − | 0 | 33 ± 13 | 24.8 ± 8 | 9.3 ± 2.2 |
| + | 140 ± 20 | >450 | 0.6 ± 0.35 | 0 |
| Cu2+ (1)§ | ||||
| − | 0 | 0 | 27 ± 3.6 | ND |
| + | <5¶ | 35 ± 5 | 4 ± 1.2 | ND |
| Cu2+ (2) | ||||
| − | 0 | 30 ± 15 | 16.2 ± 3.3 | 4.3 ± 0.3 |
| + | 90 ± 11 | >360 | 0 | 0 |
| F-10 | ||||
| − | 0 | 145 ± 45 | 9.5 ± 4 | 1.8 ± 0.3 |
| + | >720 | >720 | 0 | 0 |
| MDM | ||||
| − | 0 | 95 ± 40 | 16.8 ± 11 | 3.3 ± 1.2 |
| + | 300 | >720 | 0 | 0 |
The results shown represent means ± SD from three separate experiments from two to three different donors. ND, not determined.
LDL (0.8–1.2 μM apoB) was supplemented with 10 μM α-TQH2 (+) or the appropriate volume of ethanol (−) immediately before oxidation. AAPH was used at 2 mM, AMVN at 1 mM, and SLO at 4 μg/ml. Cu2+ was used at either 16.7 (1) or 1.5 (2) molecules of Cu2+ per LDL particle. For cell-enhanced oxidation, LDL was diluted 5 times with sterile Ham’s F-10 medium and incubated in the absence (F-10) or presence (MDM) of ≈106 MDM per well.
Onset of oxidation refers to the first signs of significant decrease of CoQ10H2 or α-TOH.
The extent of lipid hydroperoxide accumulation was determined at a time where 20% of the initial α-TOH was depleted in the control, α-TQH2-free LDL samples. The times required for this varied for the different oxidants and were approximately: AAPH, 140 min; AMVN, 315 min; SLO, 315 min; Cu2+ (2), 180 min; F-10, 300 min; and MDM, 210 min.
For Cu2+ under condition (1), 25 μM of α-TQH2 was added and the level of CE-O(O)H accumulation was compared after complete α-TOH consumption and at a time of maximum peroxidation in the control LDL (≈120 min), as under these very strong oxidizing conditions only little lipid hydroperoxides accumulate as long as the vitamin is present (for example, see ref. 10).
Five minutes represents the earliest time point measured, where there was already detectable CoQ10H2 consumption.