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A convenient chemical-microbial method for developing fluorinated pharmaceuticals

2013, Bright, Tara V., Dalton, Fay, Elder, Victoria L., Murphy, Cormac D., O'Connor, Neil K., Sandford, Graham

A significant proportion of pharmaceuticals are fluorinated and selecting the site of fluorine incorporation can be an important beneficial part a drug development process. Here we describe initial experiments aimed at the development of a general method of selecting optimum sites on pro - drug molecules for fluorination, so that metabolic stability may be improved. Several model biphenyl derivatives were transformed by the fungus Cunninghamella elegans and the bacterium Streptomyces griseus, both of which contain cytochromes P450 that mimic oxidation processes in vivo, so that the site of oxidation could be determined. Subsequently, fluorinated biphenyl derivatives were synthesised using appropriate Suzuki - Miyaura coupling reactions, positioning the fluorine atom at the pre - determined site of microbial oxidation; the fluorinated biphenyl derivatives were incubated with the microorganisms and the degree of oxidation assessed. Biphenyl-4-carboxylic acid was transformed completely to 4' - hydroxybiphenyl - 4 - carboxylic acid by C. elegans but, in contrast, the 4' fluoro - analogue remained untransformed exemplifying the microbial oxidation – chemical fluorination concept. 2' - Fluoro-and 3' - fluoro - biphenyl - 4 - carboxylic acid were also transformed, but more slowly than the non - fluorinated biphenyl carboxylic acid derivative. Thus, it is possible to design compounds in an iterative fashion with a longer metabolic half - life by identifying the sites that are most easily oxidised by in vitro methods and subsequent fluorination without recourse to extensive animal studies.

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Targeted Fluorination of a Non-steroidal Anti-inflammatory Drug to Prolong Metabolic Half-life

2014-04, Shaughnessy, Maxwell J., Harsanyi, Antal, Li, Jingji, Bright, Tara V., Murphy, Cormac D., Sandford, Graham

In drug design, one way of improving metabolic stability is to introduce fluorine at a metabolically labile site. In the early stages of drug design, identification of such sites is challenging, and a rapid method of assessing the effect of fluorination on a putative drug’s metabolic stability would be of clear benefit. One approach to this is to employ micro-organisms that are established as models of drug metabolism in parallel with the synthesis of fluorinated drug analogues. In this study, we have used the filamentous fungus Cunninghamella elegans to identify the metabolically labile site of the nonsteroidal anti-inflammatory drug flurbiprofen, to aid in the design of fluorinated derivatives that were subsequently synthesised. The effect of the additional fluorine substitution on cytochrome P450-catalysed oxidation was then determined via incubation with the fungus, and demonstrated that fluorine substitution at the 4′-position rendered the drug inactive to oxidative transformation, whereas substitution of fluorine at either 2' or 3' resulted in slower oxidation compared to the original drug. This approach to modulating the metabolic stability of a drug-like compound is widely applicable and can be used to address metabolic issues of otherwise good lead compounds in drug development.