| Assay Method Information | |
| | FRET-suppression assay |
| Description: | All compounds were evaluated by FRET-suppression assay in side-by-side experiments using 21b as a control inhibitor (Table 2). Protection of the aldehyde group in 21b as the 1,3-dioxane or dithiane acetal (24 and 25) resulted in weaker IRE-1 inhibitory activity. Alkylation of the phenol oxygen (compounds 26, 27, and 35) resulted in a complete loss of potency below 20 mM. The N-acyl derivative 29 exhibited an IC50 value of 312 nM while N-alkyl analogs 30-33 were found to be slightly more potent. N-benzyl analog 31 was almost 3-fold more active than the corresponding fluorinated derivative 32. Guanidinylation to give 34 resulted in a notable increase in potency (IC50=47 nM) relative to the parent compound, though solubility decreased. Ketone 36, vinyl sulfone 38, and Weinreb amide 42 showed no significant IRE-1 RNase inhibitory activity below 20 mM. However, electrophilic compounds 37, 40, and 41 displayed moderate potency (1-5 mM) in vitro. Also of note, 1,3-dioxane derivative 24 exhibited an in vitro IC50 of 3.1 mM, whereas the corresponding 1,3-dithiane analog 25 displayed more than 5-fold weaker activity. To confirm that the enhanced inhibitory activity of 24 is not simply a function of a labile aldehyde masking group, stability studies in assay buffer were carried out; no significant decomposition of the 1,3-dioxane moiety over 12 hours was observed. |
| Affinity data for this assay | |
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