STRUCTURE DETERMINATION OF A QUINOLINONE ALKALOID FROM THE FUNGUS ASPERGILLUS NIDULANS USING 1D AND 2D-NMR ANALYSIS

Abstract

Nuclear Magnetic Resonance (NMR) spectroscopy techniques have been used rigorously by analytical chemists to determine the molecular structure of natural products derived from plants, bacteria and fungi for purposes such as drug discovery and genome mining. In this work, Mass Spectroscopy (MS), Infrared Spectroscopy (IR) and 1D and 2D NMR techniques were employed to determine the full structure of a quinolinone alkaloid (compound 1) derived from the fungus Aspergillus Nidulans. The final structure obtained was a hydroxylated quinolinone alkaloid derivative with a 2,2,4-trimethyl-4-vinyl-3-oxabicyclo[3.1.0]hexane moiety attached. Since the lack of protonation on certain carbons prevented NOESY NMR from determining stereochemistry of all stereocenters, Residual Dipolar Couplings (RDCs) and Electronic Circular Dichroism (ECD) spectroscopy can be utilized in the future to ascertain the absolute stereochemistry of the quinolinone alkaloid.