Synthesis and biological activities of 2,3-dihydro-1,3,4-oxadiazole compounds and its derivatives as potential activator of ryanodine receptors.

A series of novel 2,3-dihydro-1,3,4-oxadiazoles containing N-pyridylpyrazole carboxamides moieties were obtained by applying a new synthetic route. Their insecticidal tests against oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella) indicated that most of the compounds showed moderate to excellent activities at the testing concentrations. In particular, compound 6a showed 40% larvicidal activities against oriental armyworm at 1mg/L, while 7a against diamondback was 100% at 0.01mg/L. Calcium imaging results demonstrated that 6a, 6d and 7a stimulated a transient elevation in [Ca(2+)]i in the absence of external calcium after the central neurons dye loading with fluo-3 AM, implying that these novel compounds were potential activators of the ligand-gated calcium channel on the endoplasmic reticulum.