Sequence analysis of suramin and diarylene ureas by negative ion fast atom bombardment and MS/MS

Abstract

Suramin and analogous diarylene ureas, which are potential compounds for the treatment of onchoceriasis (river blindness), have been investigated by negative ion fast atom bombardment mass spectrometry. Excellent abundances of the parent ions due to the sulfonate linkages were obtained, which enabled the determination of the sequences by tandem mass spectrometry experiments comparing model systems of unequivocal structures. In analogy to the fragmentation of peptides the preferential cleavages of NHCO bonds are observed, which are followed by consecutive degradations of the molecules. The formation of structure-specific fragment ions is influenced by the adjacent substituents within the phenylene moieties. The stabilities of the parent ions are documented by intense doubly charged species.