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NMR and Docking Studies of Novel Macrolide Conjugates

Macrolide antibiotics are effective and well- tolerated therapeutic agents for treating infectious diseases owing to their high efficacy and safety [1]. They have been in widespread clinical use for over 60 years and are effective against Gram-positive and certain Gram-negative microorganisms. Macrolides exert their biological activity by binding to the 50S bacterial ribosome subunit at early stage of the translation process. They bind to the ribosomal 23S rRNA in domain V at or near the peptidyl transferase region and block the exit tunnel through which the nascent peptides leave the ribosome. However, in spite of a number of existing antibiotics, the emerging multi-drug resistant microbial pathogens present serious and challenging problems in medical treatment which demand novel and more effective antimicrobial agents to be discovered. We have shown that NMR spectroscopy could reveal valuable data on free and bound state macrolide conformations [2-4] which can guide efforts directed to discovery of novel, more potent inhibitors. Here we present our recent NMR studies of new macrolide conjugates, the macrozones prepared by coupling of azithromycin and thiosemicarbazones. Macrozones have shown good activity against Gram positive strains, some Gram negative strains and also against efflux-mediated resistant Streptococcus pneumoniae. In order to characterize binding epitopes and asses bound conformations of macrozones we applied a combination of NMR experiments such as transferred nuclear Overhauser effect spectroscopy (trNOESY) and saturation transfer difference (STD) and molecular modeling

macrolide conjugates ; NMR ; docking

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