Targeting Biological Systems by Organic Synthesis Methods - Cancer Cells and Proteins

Abstract: This thesis describes the design and synthesis of molecules with potential roles in biomedicine, with an emphasis on molecular recognition in complex biological environments. The first chapter describes the synthesis and evaluation of compounds for use in nuclide therapy. Carboranes are frequently used in the development of drugs for Boron Neutron Capture Therapy. New routes for monohydroxylation at the B and C atoms of p-carborane have been developed. The Suzuki-Miyaura reaction has been applied to the cross-coupling of bis(neopentyl glycolato)diboron or bis(pinacolato)diboron and 2-I-p-carborane. The synthesized derivatives are important intermediates in the synthesis of a number of potentially biologically active carborane-containing molecules.The DNA intercalator doxorubicin has been functionalized to enable 125I labelling. The aim of combining the DNA intercalator with 125I was to achieve high delivery of cytotoxic radiation to the nucleus. The DNA-binding ability and cellular uptake of the synthesized compounds have been evaluated. One of the compounds bound strongly to DNA and had similar cellular uptake as daunorubicin, which makes the compound very interesting for further biological evaluation.The second chapter describes the use of polypeptide conjugates to broaden our knowledge of molecular recognition. The polypeptides consist of 42 amino acids each and are designed to fold into helix-loop-helix motifs that dimerize due to their amphiphilic character. The polypeptides are combined with a variety of small organic molecules. The incorporation of small aromatic molecules to influence the structure and dynamics of a polypeptide has been investigated. By attaching a dansyl group to the side chain of a lysine residue, the dynamics of the protein’s hydrophobic core where affected to such a degree that a native-like fold was formed. The polypeptide conjugates have also been used to study the binding and recognition of native proteins. High-affinity binders for chitinases and acetylcholine esterase have been developed and evaluated.