Conformation, optical properties, and absolute configuration of 2′,3′-isopropylideneadenosines: Theoretical vs. experimental study

On the Biosynthetic Pathway of Papaverine via (S)-Reticuline – Theoretical vs. Experimental Study

The electronic structures, optical properties and molecular structures of a series of isoquinoline alkaloids resulting in the formation of papaverine, through a proposed biosynthetic pathway via S(+)-reticuline were elucidated. The mechanism of papaverine synthesis was studied by electronic absorption, diffuse reflectance, fluorescence and CD spectroscopy, as well as ESI and MALDI Orbitrap imaging mass spectrometry. Quantum chemical DFT calculations in the gas phase and solution were performed with a view to study the electronic transitions of the interacting species, corresponding proposed intermediates, and the expected mass spectrometric fragments. The complete study and understanding of the mechanism of the biosynthetic pathway in the poppy plants appears important for the functional oriented drug-design and synthesis of corresponding structurally related alkaloids.

Physical Properties and Molecular Conformations of Indole Alkaloids and Model Protein Interactions – Theoretical vs. Experimental Study

The physical properties and molecular structure of five natural indole alkaloids (IAs) and their interaction with protein targets have been studied, experimentally and theoretically. Electronic absorption (EAs) and CD spectroscopy, electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), as well as imaging mass spectrometric techniques (IMS) were used, analyzing the isolated alkaloids and corresponding IAs/protein molecular complexes. Theoretical quantum chemical DFT calculations were also applied. The mechanism of their biological activity and structure-activity relationship as potential neurologically active compounds were studied, using the model interactions with 5HT2A receptors. The gas-phase stable molecular fragments of the IAs are discussed comparing the experimental mass spectrometric data and theoretical quantum chemical DFT calculations of the different molecular fragments of the IAs.