Probing NMR chemical shifts in a pharmaceutical compound

Munich

Encuentro; 8th ORCA User Meeting; 2022

By using ORCA we compute the NMR chemical shifts and IR spectra for the pharmaceuticalcompound oxytetracycline (OTC) in solution. OTC, an antibiotic of the tetracycline family, is apolymorphic drug that evidences erratic absorption in oral administration.The results performed within Density Functional Theory were compared with the experimental resultsfor oxytetracycline hydrochloride (OTC.HCl) obtained using a Bruker Avance II Spectrometer.We built the molecule by geometry optimization with Avogadro code, then DFT energyminimizations in vacuum and D2O were performed using ORCA quantum chemistry program.After the geometry was optimized we calculated the chemical shifts of 1H, 13C and 15N and comparedour calculations with NMR experimental results in solution and solid state.The project aims to explore conformations and hydrogen bonds in solids, where this compound canexist in different polymorphic forms. The study of the solid forms is important for developing strategiesof repositioning and the use of known compounds in new therapeutic alternatives.