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360ChemInform Abstract The structure of the title compound, the major component of the calichemicin complex (isolated from Micromonospora echinospora ssp. calichensis and known as LL-E33288 antibiotics) is investigated in part by chemical (derivatization, degradations etc.) and physical methods. It can be shown that the title compound consists of four glycosidic units, a hexasubstituted benzene moiety and an undefined C18H16NO4S3 unit. The exact configuration of the ethylamino sugar is unknown. In the following paper the structure of the undefined aglycone is reported.

361ChemInform Abstract Further chemical and physical investigations on the structure of the title compound, in addition to the results of the preceding paper, establish its complete structure as (I).

Section. His research Interests are focused on natural products chemistry, drug/DNA Interactions, and mechanisms of antibiotic activity. Donald B. Borders Is the Department Head for the Microbial Chemistry Department In the Medical Research Division of American Cyanamid. He was bom In 1932 In Logansport, IN. He received a B.S. (1954) and M.A. (1958) In chemistry from Indiana University and a Ph.D. (1963) In Organic Chemistry from the University of Illinois (with K. L. Rinehart). From 1962 to 1964 he was a research chemist for Rohm and Haas Company and then Joined Lederle Laboratories, a Division of American Cyanamid. His research Interests have been In the Isolation, structure determination, and biosynthesis of natural products.

A range of genomics technologies are increasingly becoming integrated with existing scientific disciplines to broaden and strengthen existing capabilities and open new avenues of research in drug discovery and development. Examples of these new research fields are proteomics, pharmacogenomics, metabolomics and toxicogenomics. Here we review the application of toxicogenomics to improve the evaluation of drug safety, mechanism of action and toxicity in the drug discovery and development process.

We have used a supervised classification approach to systematically mine a large microarray database derived from livers of compound-treated rats. Thirty-four distinct signatures (classifiers) for pharmacological and toxicological end points can be identified. Just 200 genes are sufficient to classify these end points. Signatures were enriched in xenobiotic and immune response genes and contain un-annotated genes, indicating that not all key genes in the liver xenobiotic responses have been characterized. Many signatures with equal classification capabilities but with no gene in common can be derived for the same phenotypic end point. The analysis of the union of all genes present in these signatures can reveal the underlying biology of that end point as illustrated here using liver fibrosis signatures. Our approach using the whole genome and a diverse set of compounds allows a comprehensive view of most pharmacological and toxicological questions and is applicable to other situations such as disease and development.

Hydrogenation of the C(4') exocyclic olefin of the pacidamycins has been shown to produce a series of semisynthetic compounds, the dihydropacidamycins, with antimicrobial activity similar to that of the natural products. Elucidation of stereochemistry in the pacidamycins has been completed through a campaign of natural product degradation experiments in combination with the total synthesis of the lowest-molecular weight dihydropacidamycin, dihydropacidamycin D. The stereochemical identities of the tryptophan and two alanine residues contained in pacidamycin D have been shown to be of the natural (S) configuration, and the unique 3-methylamino-2-aminobutyric acid contained in this series of antibiotics has been shown to be of the (2S,3S) configuration. Finally, the stereochemistry obtained by hydrogenation of the C(4')-C(5') exocyclic olefin has been shown to be (R) at the C(4') nucleoside site.

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