Neuroprotective Effects of N-Acetyldopamine Dimers from Cicadidae Periostracum

The chemical investigation of the 90% EtOH extract from Cicadidae Periostracum led to the isolation and identification of seven known N-acetyldopamine dimers (1-7). These compounds were identified by comparing mass spectrometry data and NMR spectroscopic data with those previously reported. In this study, complete interpretation of 1D and 2D NMR data of 1 and 2 were reported for the first time. In addition, compounds 3 and 4 were isolated from this material for the first time. All isolates were obtained as racemic mixtures, as confirmed by chiral HPLC. Furthermore, we evaluated the neuroprotective activities of compounds 1-7 and found that compounds 1, 5, and 6 significantly attenuated rotenone-induced death of SH-SY5Y neuroblastoma cells at a concentration of 100 μM. Parallel to this result, compounds 3 and 6 displayed antioxidant effects in the cytoplasm, as determined by CM-H2DCFDA fluorescence intensity, while compounds 1 and 5 showed antioxidant effects in the mitochondria, as assessed by MitoSox fluorescence intensity. Overall, these results suggest that some of these compounds protect neuroblastoma cells by ameliorating the release of reactive oxygen species. Further studies are warranted to elucidate the underlying mechanisms by which these compounds exhibit antioxidant and neuroprotective actions.