| The present work focuses on the isolation and structure characterization of a wide variety of biologically important compounds. In the first project, oscillacidins A and B are cyclic peptides isolated from blue-green algae collected from Homer Lake in central Illinois and were found to be very active in inhibiting the growth of leukemia cell lines. Tandem mass spectrometry and high-resolution mass spectrometry were employed in conjunction with 1D and 2D NMR techniques to elucidate the structures of these complex molecules. Marfey's procedure was used to determine the stereochemistry of the individual amino acids present in the molecule.; Microcystins are hepatotoxins produced by toxic strains of cyanobacteria, which are found worldwide in lakes, drinking water reservoirs and coastal waters. Microcystins can cause animal poisoning and pose risks to human health. The second part of the work has demonstrated that electrospray tandem mass spectrometry is a rapid and sensitive technique for the structure characterization of microcystins. The characteristic product ions in the electrospray tandem mass spectra can be used to elucidate the structures of microcystins. Using this method, the structures of several new microcystins collected worldwide were elucidated. LC/MS was also used to detect low levels of microcystins in food supplements. MALDI analysis was performed on water samples collected from Brazil. This analysis in conjunction with the analysis on liver samples of dead patients had confirmed for the first time that several microcystins were involved in human fatalities in Brazil.; The third part of this work focused on the isolation and structure characterization of bacterial autoinducers, N-acyl homoserine lactones produced by many gram-negative bacteria to regulate gene expression based on population density, a process known as autoinduction. HPLC was employed to fractionate and concentrate these signal molecules. Tandem MS and HRMS were used to characterize the structures of these molecules.; In the last part of this project, ESIMS and ESIMS/CID/MS were employed to profile eicosanoids in different cell cultures. Eicosanoids are fatty acid derivatives with a variety of extremely potent hormone-like actions on various tissues of vertebrate animals. Profiling eicosanoids by mass spectrometry has very significant pharmacological implications. |
