Abstract
Metformin (N,N-dimethylbiguanide) is the most widely used anti-diabetic drug to treat type II diabetes. It exhibits blood glucose lowering action by regulating glucose formation in the liver (gluconeogenesis), increases glucose utilisation in muscles and reduces glucose absorption in the intestine. Clinical studies have shown that metformin, and other biguanides (buformin and phenformin), have lowered the risk of different kinds of cancer, such as breast, lung, colon, pancreas, and liver cancers. The purpose of this project is to investigate the efficacy of metformin and other biguanides to treat glioblastoma multiforme (GBM). The first step was to produce these compounds in sufficient quantities and purity, to enable all the necessary in vitro experiments to be carried out. The work presented in this study, reports the synthesis and purification of metformin. Literature methods have been vague and/or purification methods have not been disclosed, partly for commercial reasons. Metformin hydrochloride has been prepared by refluxing a reaction mixture of dimethylamine hydrochloride and dicyandiamide using different molar ratios, different reaction solvents (water, water/methanol, ethanol, toluene, xylene, and butanol), various reaction times (2 to 48 h) and using different recrystallisation solvents. In some cases, solvent extraction was used for further purification. Solid products were analysed using a range of techniques, such as melting points, Fourier Transform Infra-red (FTIR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and high performance liquid chromatography (HPLC). Impurities associated with starting materials and other known side-products, e.g., melamine, were identified. The conditions for the synthesis of pure metformin in good yield were also identified. The project is now moving on to testing the synthesised metformin on various GBM cell lines. Other biguanides, including buformin and phenformin, will also be synthesised, purified and their anti-neoplastic properties towards GBM investigated.