Table 2.
Reduction potentials and relative toxicity (LC50) of naphthoquinones used in this study.
| NQ | pKa NQ·−, QH2 |
Q/NQ·− | NQ·−/QH2 | Q/QH2 | LC50 (μM) 1 | Superoxide Formation 1 |
|---|---|---|---|---|---|---|
| 1,4-NQ (2) | 4.1, 9.4 | −140 a | +306 | +83 | 15 | ↑ |
| Juglone (2,3,5) | 6.6 | −93, −95 | +311 | +109, +82 | 6 | ↑ |
| Plumbagin (3) | −156 | +196 | +20 | 5 | ↑↑ | |
| Lawsone (2,5) | 4.7, 8.7 | −415 b | +135 | −140, −86 | >100 | →/↑ |
| Vit K1 (4)
(phylloquinone) |
−78 | |||||
| Vit K2
(menaquinone) |
−70 | |||||
| Vit K3 (menadione) (3,5) | 9.6 | −203, −335 | +193 | −5, +20 | 40 | ↑↑↑ |
| Benzoquinone (3) | +99 | +473 | +286 | |||
| 2-methoxy 1,4-NQ (3) | 9.4 | −39 | ||||
| Anthraquinone | −445 |
1 Ref. [11], 2 Ref. [36] and references therein, 3 Ref. [12] and references therein, 4 Ref. [39], 5 Ref. [40] and references therein as half-wave potentials relative to NHE, pKa from [36,40]. Up arrows indicate degree of increase, horizontal arrow indicates no change. a, [40]; b, addition of corresponding oxidized NQ.