In the case of type 2 diabetes, inhibitors of glycogen phosphorylase (GP) may prevent unwanted glycogenolysis under high glucose conditions and thus aim at the reduction of excessive glucose production by the liver. Anomeric spironucleosides, such as hydantocidin, present a rich synthetic chemistry and important biological function (e.g., inhibition of GP). For this study, the Suárez radical methodology was successfully applied to synthesize the first example of a 1,6-dioxa-4-azaspiro[4.5]decane system, not previously constructed via a radical pathway, starting from 6-hydroxymethyl-β-d-glucopyranosyluracil. It was shown that, in the rigid pyranosyl conformation, the required [1,5]-radical translocation was a minor process. The stereochemistry of the spirocycles obtained was unequivocally determined based on the chemical shifts of key sugar protons in the 1H-NMR spectra. The two spirocycles were found to be modest inhibitors of RMGPb.
A fluorescence study of N1-(β-D-glucopyranosyl)-N4-[2-acridin-9(10H)-onyl]-cytosine (GLAC), the first fluorescent potent inhibitor of Glycogen Phosphorylase (GP), in neutral aqueous solution, is presented herein. Quantum chemistry (TD-DFT) calculations show the existence of several conformers both in the ground and first excited state. They result from rotation of the acridone and cytosine moieties around an NH bridge which may lead to the formation of non-emitting charge transfer states. The fingerprint of various conformers have been detected by time-resolved fluorescence spectroscopy (fluorescence upconversion and time-correlated single photon counting) and identified using as criteria their energy, polarization and relative population resulting from computations. Such an analysis should contribute to the design of new GP inhibitors with better fluorescence properties, suitable for imaging applications.
The reaction between 1-aminosugars and trimethylisocyanate (TMSNCO) was optimised as a one-step synthetic strategy for the synthesis of sugar biurets. This protocol was successfully applied to a number of 1-aminosugars, which exclusively provided the corresponding biurets in 67–99% yields. The new method- ology was applied in the de novo synthesis of N1-(2-deoxy-α/β-D-erythro-pentofuranosyl)biuret (dfBU) and N1-(2-deoxy-α/β-D-erythro-pentopyranosyl)biuret (dpBU), two known DNA lesions arising from the hydroxyl radical induced decomposition of 2’-deoxycytidine (dCyd).
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