Designing Anti-Tumor Drugs Using Natural and Synthetic Agents Herman L. Holt, Jr. University of North Carolina, Asheville Asheville, NC 28804

Medicinal Chemistry Folklore Medicinal chemistry is the science that deals with the discovery of therapeutic chemicals and their development into useful medicines Medicinal chemistry has been practiced for thousands of years The earliest written records of the African, Chinese, Indian, South American, and Mediterranean cultures and biblical languages describe the therapeutic effects of various plant concoctions Man has search for cures by chewing on bark, roots, leaves and berries Dr. Milton Brown, University of Virginia

...Milton Brown, a native of Baltimore, MD, received his bachelor’s degree from Oakwood College in 1987, a Ph.D. in organic chemistry from the University of Alabama, and a M.D. from the University of Virginia, where he currently serves as an associate professor of Chemistry and principal investigator for various NIH funded research projects. He has published in numerous prestigious academic journals as well as receiving awards in research and teaching.

A Father of Modern Medicinal Chemistry Edward E. Smissman, University of Kansas –Smissman Award of the ACS Division of Medicinal Chemistry named in his honor

Tsung Ying (T.Y.) Shen University of Virginia Professor Emeritus Famous for Synthesis and Discovery of the Mechanism of Action of: Indomethacin Sulindac Diflunisal Other anti-inflammatory-analgesic (NSAIDS) and immunoregulators More than 210 U.S. Patents and scientific publications

Medicinal Chemistry is defined as an interdisciplinary science situated at the interface of organic chemistry and life sciences (such as biochemistry, pharmacology, molecular biology, immunology, pharmacokinetics and toxicology) on one side and chemistry-based disciplines (such as physical chemistry, crystallography, spectroscopy and computer-based information technologies) on the other. Chemistry based disciplines Organic Chemistry Life Sciences Medicinal Chemistry

Terms more or less synonymous with medicinal chemistry –Pharmacochemistry –Molecular pharmacochemistry –Drug design –Selective toxicity

Definition and Objectives Medicinal chemistry relates to the design and production of compounds that can be used in medicine for the prevention, treatment or cure of human and animal diseases Medicinal chemistry covers three critical steps: A discovery step consisting of the identification and production of new active substances usually called lead compounds. Leads can originate from synthetic organic chemistry, from natural sources or from biotechnological processes. An optimization step that deals mainly with the synthetic modification of the lead structure in order to improve potency, selectivity and lessen toxicity. Its characteristics are the establishment and analysis of structure-activity relationships (SAR). A development step consisting of: –the optimization of the synthetic route for bulk production –modification of the pharmacokinetic and pharmaceutical properties of the active substance to render it suitable for clinical use. This may cover optimization of properties associated with: Chemical formulation Solubility Elimination of unpleasant taste or irritation Reduction of pain at site of injection

Challenges for Medicinal Chemistry Medicinal chemist must excel in organic synthesis and understanding modern approaches to structure-activity analysis. Medicinal chemist are involved in the design, synthesis, optimization and selection of new lead compounds A survey of a range of company hiring representatives suggested these desired qualities: –Ability to fit a multidisciplinary team –Ability to search for novel molecules –Increased knowledge of how to synthesize molecules for focused biological testing –Understanding of the reasons for making compounds –Understanding drug design –Insight in SAR with insufficient data –Knowledge in collateral fields (pathophysiology, cell biology, genetics) –Familiarity with new techniques

Designing Anti-Tumor Drugs Using Natural and Synthetic Agents Herman L. Holt, Jr. University of North Carolina, Asheville Asheville, NC 28804

TUBULIN Globular Protein Taxoid Site Vanca Alkaloid Domain Colchicine Site

MICROTUBULES Tubulin Polymers

MITOTIC SPINDLE Composed of Microtubules and associated proteins Needed for cellular division

MICROTUBULES Tubulin Polymers

What is the MTT assay? A dose response curve is plotted and the concentrationA dose response curve is plotted and the concentration at 50% cell growth is obtained at 50% cell growth is obtained Crystal is dissolved in a suitable solvent (e.g. DMSO,Crystal is dissolved in a suitable solvent (e.g. DMSO, acid-IPA) and the absorbance at 570 nm is obtained Living cells convert the yellow water soluble-tetrazoliumLiving cells convert the yellow water soluble-tetrazolium salt into an insoluble purple formazan crystal The amount of viable cells remaining can be determined spectrophotometricallyThe amount of viable cells remaining can be determined spectrophotometrically Cultured cancer cells are grown in the presence of potentialCultured cancer cells are grown in the presence of potential drug for a specific time period (e.g. 72, 96 h) drug for a specific time period (e.g. 72, 96 h)

MTT = 3-(4’,5’-dimethylthiazol-2’-yl)-2,5-diphenyltetrazolium bromide

CISPLATIN Anti-cancer agent Ovarian Testicular Lung Breast

CISPLATIN Cleaves DNA

TAXOL Anti-cancer agent Pacific Yew Tree Ovarian Testicular Lung Breast

TAXOL Stabilizes microtubules and prevents disassembly and re-polymerization

VANCOMYCIN Tubulin polymerization inhibitor

Meadow saffron or autumn Crocus COLCHICINE poisonous 1997 Alice B. Russell, James W. Hardin, Larry Grand

Tubulin binder COLCHICINE Inhibits tubulin polymerization

Derived from the African bush willow tree, Combretum caffrum COMBRETASTATIN

Tubulin binder Inhibits tubulin polymerization

Combretastatin A-4 is the most developed and furthest along in clinical studies among the vascular targeting agents.

HETEROCYCLE ANALOGS OF COMBRETASTATIN

Pati, Wicks, Holt, LeBlanc, Weisbruch, Forrest, Lee Heterocyclic Communications 2005, in press. Maintain structural rigidity Increase water solubility

COMBRETASTATIN AND TRIAZOLE SYNTHESIS

AZIRIDINE ANALOGS OF COMBRETASTATINS

AZIRIDINE TYPE ANALOGS OF COMBRETASTATINS

MITOMYCINS Anti-cancer agent Bladder

MITOMYCINS DNA Alkylating Agent

MITOMYCINS SYNTHESIS IS CURRENTLY IN PROGRESS RESEARCH PRESENTED AT: ► Southeast Regional Meeting of the American Chemical Society (joint meeting with Southwest region) ► North Carolina Undergraduate Research Symposium ► National Conference on Undergraduate Research (Held at UNCA in celebration of its 20 th Anniversary)

REFERENCES Chemical and Engineering News 2005, 83(5), several pages therein.

MUCH APPRECIATION Jessica Maddox David Mabe Regan LeBlanc John Dickson Dr. Moses Lee Dr. Toni Brown Dr. Karen Buchmueller Lee Group UNC-Asheville Furman University NSF-REU NSF-MRPG