Bismuth(III) complexes of 2-mercaptoethanol: Preparation, structural and spectroscopic characterization, antibactericidal activity toward Helicobacter pylori, and inhibitory effect toward H-pylory-produced urease

In order to examine the potential ability of bismuth(III) thiolate complexes as new Bi-based chemotherapeutic agents, three bismuth(III) complexes of 2-mercaptoethanol (H(2)meret)-[Bi(Hmeret)(2)](NO3). H2O (1), [Bi(Hmeret)(meret)] (2), and [Bi(Hmeret)(3)] (3)- have been synthesized. X-ray structure determination of 1 and 2 showed that both complexes have one-dimensional polymeric structures where thiolato-S atoms bridge Bi atoms in 1 and alkoxo-O atoms bridge them in 2. On the other hand, their NMR study revealed that both complexes completely dissociate and behave as mononuclear species in solution. For the three and several Bi-containing compounds as references, antibacterial activities toward Helicobacter pylori, a pathogenic factor of clonic gastritis and peptic ulcer, were tested in vitro. All the complexes including the reference samples showed nearly the same and moderately strong activities. The inhibitory effect toward H. pylory-produced urease was also tested for the three and the reference samples, and further for free 2-mercaptoethanol, which is a well-known urease inhibitor. It was found that the activity of 2-mercaptoethanol was significantly enhanced on forming complex(es) with Bi(III).