Devine, Robert (2013) Design, synthesis and biological evaluation of antidiabetic agents. PhD thesis, National University of Ireland Maynooth.

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Abstract

Diabetes Mellitus is a metabolic disease characterised by hyperglycaemia, resulting from an inability to secrete insulin, a resistance to insulin or both. The number of individuals suffering from Type-2 diabetes (T2D) is currently 336 million and this number is expected to surpass 552 million by the year 2030. Consequently, there exists a need for novel antidiabetic agents for the treatment of T2D. The retinol transporter, RBP4, is a possible target for the treatment of T2D as elevated levels of this protein are found in T2D sufferers. Compounds that reduce the levels of RBP4 in vivo have been found to improve the diabetic condition. Disruption of the RBP4-TTR complex is a known method for decreasing the levels of RBP4. Therefore, reducing the levels of RBP4 provides a mechanism to treat/manage T2D and allows for the identification and synthesis of novel antidiabetic agents. Computational studies were used to identify compounds (1, 2 and 3) that bind within RBP4 and have the potential to prevent the formation of the RBP4-TTR complex. Biological assays (SPR, fluorometric binding assay) were performed on these compounds to verify their ability to bind within the protein cavity of RBP4 and inhibit the formation of the RBP4-TTR complex. A SAR study of compound 1 uncovered compound 4 which was more active than its parent compound in the SPR assay. A subsequent SAR study performed on the new lead compound 4 to identify the functional groups necessary for its biological activity. The derivatives required for this study were synthesised using a variety of chemical processes and were tested in an assay to assess their ability to stimulate muscle cells to take up glucose. This study uncovered a number of compounds with increased activity (64, 79 and 82). While the glucose uptake assay allowed for the identification of a number of active compound 4 derivatives, it also indicated that a secondary protein target was involved as the glucose uptake assay was RBP4 independent. A method for identifying this unknown target was therefore needed. The method chosen involved immobilising active compounds on an affinity column, which is composed of sepharose beads. A solution of cellular proteins is then passed through the column and the subsequent bound proteins are lysed and analysed by mass spectrometry. Immobilisation of compounds onto this column first required the attachment of a PEG linker to each molecule. Compounds 4 and 79 were successfully immobilised on the affinity column; at the time of writing, the results from their biological evulation remain outstanding. A SAR study was also performed on compounds 2 and 3. This uncovered compound 115, which proved to be highly active in the glucose uptake assay. A number of derivatives of compound 2 and 3 have been designed, synthesised and characterised and are currently awaiting biological evaluation. Animal studies were carried out on compounds 1, 4 and 2. Compounds 1 and 4 proved to be more effective than compound 2 at improving the insulin and glucose tolerance of diabetic mice, while also causing a reduced weight gain. Compound 4 was administered to animals after 17 weeks, once insulin resistance had been established. Compound 4 was found to restore both glucose and insulin sensitivity to normal levels. A number of additional animal studies were considered involving compound 4; however these required aqueous solutions of the compound. As compound 4 had proven to be insoluble in aqueous solutions, a method for preparing these solutions was needed. Cyclodextrins (CD) were chosen and the use of 20 eq of hydroxylpropyl-β-CD (HPBCD) gave a 0.02 M 5% DMSO/H2O solution of compound 4. The dissolution of compound 4 may have occurred due to the formation of an inclusion complex. A phase solubility diagram, SEM, DSC and NMR were used in the characterisation of the inclusion complex.

Item Type:	Thesis (PhD)
Keywords:	Design; synthesis; biological evaluation; antidiabetic agents;
Academic Unit:	Faculty of Science and Engineering > Chemistry
Item ID:	7700
Depositing User:	IR eTheses
Date Deposited:	10 Jan 2017 11:47
URI:
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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