Severe myoclonic epilepsy of infancy (SMEI, Dravet syndrome), which is mainly caused by the SCN1A mutation, is a severe epileptic encephalopathy that manifests in infancy and leads to intractable seizures and developmental impairment. To discover new therapeutic chemotypes, we established a Nav1.1 (scn1lab) KO zebrafish model for chemical screening and identified novel 1,3,4-oxadiazol-2(3H)-one derivatives. Among them, compound 20e showed the most potent antiseizure efficacy in zebrafish behavioral assays and significantly reduced locomotion-related seizure parameters compared with repositioned drugs. In SCN1A^+/- mice, 20e reduced seizure severity, delayed onset, and suppressed hyperactivity. Notably, 20e normalized pathological spike and burst activity in SMEI patient-derived iPSC neurons. Mechanistically, 20e appears to elevate 5-HT levels via TPH2 upregulation. It demonstrated reasonable BBB penetration, favorable oral PK, and good safety without notable hERG inhibition, cytotoxicity, mutagenicity, or acute toxicity. Taken together, compound 20e shows promise as a therapeutic agent for SMEI.

Background: Aryl hydrocarbon receptor (AhR) is a transcription factor that is involved in the regulation of immunity. AhR inhibits T cell activation in tumors, which induces immune suppression in the blood and solid tumors. We identified effective small-molecule AhR antagonists for cancer immunotherapy. Methods: A new series of pyrazolopyrimidine derivatives was synthesized and evaluated for AhR antagonistic activity. Results: Compound 7k exhibited significant antagonistic activity against AhR in a transgenic zebrafish model. In addition, 7k exhibited good AhR antagonist activity, with a half-maximal inhibitory concentration (IC₅₀) of 13.72 nM. Compound 7k showed a good pharmacokinetic profile with an oral bioavailability of 71.0% and a reasonable half-life of 3.77 h. Compound 7k selectively exerted anti-proliferative effects on colorectal cancer cells without affecting normal cells, concurrently suppressing the expression of AhR-related genes and the PD-1/PD-L1 signaling pathway. Compound 7k exhibited potent antitumor activity in syngeneic colorectal cancer models. Importantly, the combination of anti-PD1 and compound 7k enhanced antitumor immunity by augmenting cytotoxic T lymphocyte (CTL)-mediated activity. Conclusions: Collectively, a new pyrazolopyrimidine derivative, 7k, shows promise as a potential therapeutic agent for treating colorectal cancer.