Six chalcones from Angelica keiskei KOIDZUMI (Ashitaba in Japanese) and two chalcones from Humulus lupulus L. (hop) were examined for their cytotoxicity in two human neuroblastoma cell lines (IMR-32 and NB-39) and normal cells (primary culture of rat cerebellar granule cells) by [3-(4,5)-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. All chalcones exhibited cytotoxicity against neuroblastoma cells, and two of them (isobavachalcone and xanthoangelol H) had no effect on normal cells even at high concentration (10 ؊4 M) exposure. Typical morphologic features of apoptosis, including cell shrinkage, chromatin condensation, nuclear fragmentation and formation of apoptotic bodies, were observed in isobavachalcone-treated cells by Hoechst 33342 staining. Western blot analysis showed that isobavachalcone significantly reduced pro-caspase-3 and pro-caspase-9, and subsequently increased the level of cleaved caspase-3 and cleaved caspase-9 in both neuroblastoma cell lines. Moreover, Bax was markedly induced by isobavachalcone application. These results suggest that isobavachalcone induces apoptotic cell death in neuroblastoma via the mitochondrial pathway and has no cytotoxicity against normal cells. Therefore, isobavachalcone may be applicable as an efficacious and safe drug for the treatment of neuroblastoma.

Norovirus, which belongs to the family Caliciviridae, is one of the major causes of nonbacterial acute gastroenteritis in the world. The main human noroviruses are of genogroup I (GI) and genogroup II (GII), which were subdivided further into at least 15 and 18 genotypes (GI/1 to GI/15 and GII/1 to GII/18), respectively. The development of immunological diagnosis for norovirus had been hindered by the antigen specificity of the polyclonal antibody. Therefore, several laboratories have produced broadly reactive monoclonal antibodies, which recognize the linear GI and GII cross-reactive epitopes or the conformational GI-specific epitope. In this study, we characterized the novel monoclonal antibody 14-1 (MAb14-1) for further development of the rapid immunochromatography test. Our results demonstrated that MAb14-1 could recognize 15 recombinant virus-like particles (GI/1, 4, 8, and 11 and GII/1 to 7 and 12 to 15) and showed weak affinity to the virus-like particle of GI/3. This recognition range is the broadest of the existing monoclonal antibodies. The epitope for MAb14-1 was identified by fragment, sequence, structural, and mutational analyses. Both terminal antigenic regions (amino acid positions 418 to 426 and 526 to 534) on the C-terminal P1 domain formed the conformational epitope and were in the proximity of the insertion region (positions 427 to 525). These regions contained six amino acids responsible for antigenicity that were conserved among genogroup(s), genus, and Caliciviridae. This epitope mapping explained the broad reactivity and different titers among GI and GII. To our knowledge, we are the first group to identify the GI and GII cross-reactive monoclonal antibody, which recognizes the novel conformational epitope. From these data, MAb14-1 could be used further to develop immunochromatography.

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