NEP (1-30 μM; 6 hours) has no or little cytotoxicity in HepG2 and PC12 cells.
NEP (10 μM; 4 hours) causes the fluorescence intensity to decrease gradually in PC12 cells pretreated with 6-OHDA (0, 50, 100, and 200 μM; for 30 min).
NEP contains a dithiarsolane moiety (five-membered As-S ring) as the receptor of VDPs. In the presence of VDPs, NEP displays a strong green fluorescence signal produced by the cyclic dithiarsolane cleavage and subsequent intramolecular cyclization to liberate the fluorophore. NEP maintains a reliable fluorescence response within the range of pH 7-10.