ABSTRACT1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes nigrostriatal dopaminergic pathway damage similar to that observed in Parkinson disease (PD). To study the role of NO radical in MPTP-induced neurotoxicity, we injected MPTP into mice in which nitric oxide synthase (NOS) was inhibited by 7-nitroindazole (7-NI) in a time-and dose-dependent fashion. 7-NI dramatically protected MPTP-injected mice against indices of severe injury to the nigrostriatal dopaminergic pathway, including reduction in striatal dopamine contents, decreases in numbers of nigral tyrosine hydroxylase-positive neurons, and numerous silverstained degenerating nigral neurons. The resistance of 7-NIinjected mice to MPTP is not due to alterations in striatal pharmacokinetics or content of 1-methyl-4-phenylpyridinium ion (MPP+), the active metabolite of MPTP. To study specifically the role of neuronal NOS (nNOS), MPTP was administered to mutant mice lacking the nNOS gene. Mutant mice are significantly more resistant to MPTP-induced neurotoxicity compared with wild-type littermates. These results indicate that neuronally derived NO mediates, in part, MPTPinduced neurotoxicity. The similarity between the MPTP model and PD raises the possibility that NO may play a significant role in the etiology of PD.

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Complementary DNAs encoding D-amino acid oxidase (EC 1.4.3.3, DAO), one of the principal and characteristic enzymes of the peroxisomes of porcine kidney, have been isolated from the porcine kidney cDNA library by hybridization with synthetic oligonucleotide probes corresponding to the partial amino acid sequences. Analysis of the nucleotide sequences of two clones revealed a complete 3211-nucleotide sequence with a 5'-terminal untranslated region of 198 nucleotides, 1041 nucleotides of an open reading frame that encoded 347 amino acids, and a 3'-terminal untranslated region of 1972 nucleotides. The deduced amino acid sequence was completely identical with the reported sequence of the mature enzyme [Ronchi, S., Minchiotti, L., Galliano, M., Curti, B., Swenson, R. P., Williams, C. H. J., & Massey, V. (1982) J. Biol. Chem. 257, 8824-8834]. These results indicate that the primary translation product does not contain a signal peptide at its amino-terminal region for its translocation into peroxisomes. RNA blot hybridization analysis suggests that porcine kidney D-amino acid oxidase is encoded by three mRNAs that differ in size: 3.3, 2.7, and 1.5 kilobases. Comparison of the sequences of the two cDNA clones revealed that multiple polyadenylation signal sequences (ATTAAA and AACAAA) are present in the 3'-untranslated region, making the different mRNA species. The efficiency of 3' processing of the RNA was quite different between the two signal sequences ATTAAA and AACAAA. Southern blot analysis showed the presence of a unique gene for D-amino acid oxidase in the porcine genome.

A bioassay-directed investigation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia resulted in the isolation of two cytotoxic compounds designated dolastatin H (2) and isodolastatin H (3) from the wet animals at the yields of 9 × 10-7%. On the basis of spectroscopic analysis, these compounds were shown to be new peptides that were closely related to dolastatin 10 (1) isolated from Western Indian Ocean specimens of this animal. The notable structural feature of these new compounds, 2 and 3, is that 3-phenylpropane-1,2-diol is attached through the ester linkage to the C-terminus of a tetrapeptide containing unusual amino acids. The absolute stereostructures of 2 and 3 were unambiguously determined by enantioselective total synthesis. A cytotoxicity test for synthetic 2, 3, and their C-2 epimers revealed that the stereochemistry of the 3-phenylpropane-1,2-diol moiety on the C-terminus plays an important role in their cytotoxicity. In vivo antitumor activity against murine P388 leukemia was evaluated, and it was shown that isodolastatin H (3) exhibited antitumor activity a little weaker than that of dolastatin 10 (1).

FR-900482 is a new antitumor antibiotic produced by a new actinomyces named Streptomyces sandaensis No. 6897. It exhibits potent cytotoxic activity against various tumor cells in vitro. Furthermore, it has weak antimicrobial activity against some Gram-positive or