Synthesis and antiangiogenic activity of 6-amido-2,4,5-trimethylpyridin-3-ols.

We recently reported that 6-aminoalkyl-2,4,5-trimethylpyridin-3-ols, novel series of 6-aminopyridin-3-ol-based antioxidants, have high antiangiogenic activities. In pursuit of wider variety in the analogues, we here report the synthesis and antiangiogenic activities of 6-amidoalkyl-2,4,5-trimethylpyridin-3-ols, which would not be considered excellent antioxidants because of the poorer electron-donating effect of the C(6)-amido group than the corresponding C(6)-amino group. The selected 6-amido compounds showed up to several fold-higher antiangiogenic activities and up to an order of magnitude better antitumor activities in the chick embryo chorioallantoic membrane (CAM) assay than SU4312, a positive control. We also found that paracetamol, as a direct phenolic analogue of our simplest 6-amidopyridin-3-ol, showed a moderate level of antiangiogenic activity. We propose this study will offer a basis for a scaffold of novel angiogenesis inhibitors that can perturb angiogenesis-related pathologies.