Table 2.
Antioxidant activity of 2–(3-oxo-2-phenoxypyrido[3,2-b]pyrazin-4(3H) -yl)acetic acid derivatives.
 | |||||
|---|---|---|---|---|---|
| Compd. | Substituent |
DPPH/sca% |
|||
| R1 | R2 | 100 μM | 50 μM | 10 μM | |
| 4a | H | H | 6.9 ± 1.2 | – | – |
| 4b | H | 4-OCH3 | 18.9 ± 0.8 | – | – |
| 4c | H | 3,4-(OCH3)2 | 21.2 ± 1.5 | – | – |
| 4d | H | 3,5-(OCH3)2 | 25.9 ± 1.3 | – | – |
| 4e | H | 3,4,5-(OCH3)3 | 17.8 ± 0.9 | – | – |
| 4f | H | 4-OH | 37.7 ± 1.0 | – | – |
| 4g | H | 3-OH, 4-OCH3 | 54.8 ± 1.6 | 21.5 ± 1.2 | – |
| 4h | H | 3,4-(OH)2 | 74.6 ± 1.4 | 44.1 ± 2.3 | – |
| 4i | H | 3-OH, 5-OCH3 | 78.4 ± 0.7 | 45.2 ± 1.8 | – |
| 4j | H | 3,5-(OH)2 | 95.0 ± 0.9 | 77.2 ± 1.5 | 45.3 ± 1.9 |
| 4k | Cl | 3,5-(OH)2 | 94.8 ± 1.1 | 76.4 ± 0.9 | 49.1 ± 2.4 |
| 4l | Br | 3,5-(OH)2 | 95.3 ± 1.2 | 80.6 ± 2.0 | 46.8 ± 1.5 |
| 4m | H | 3-OH, 4,5-(OCH3)2 | 56.9 ± 1.8 | 35.9 ± 1.1 | – |
| 4n | H | 3,5-(OH)2, 4-OCH3 | 65.7 ± 0.9 | 40.8 ± 1.6 | – |
| 4o | H | 3,4,5-(OH)3 | 88.5 ± 1.4 | 65.2 ± 1.9 | 23.4 ± 2.0 |
| Trolox | – | 96.7 ± 0.8 | 89.8 ± 1.0 | 85.9 ± 0.6 | |