Current and potential applications of bismuth-based drugs

Special issue: practical applications of metal complexes

In 1913 Alfred Werner received the Nobel Prize in Chemistry for his work that was of great importance for the development of coordination chemistry. In the years that followed numerous complexes consisting of metal ions and organic ligands were isolated, thus building a strong connection between inorganic and organic chemistry. Coordination compounds have many interesting properties which find diverse applications in numerous aspects of human life. Fourteeen contributions were received for this Special Issue covering very different aspects of metal complexes and their practical applications. The highest number of manuscripts deals with the biological activity of complexes which might potentially be used in the clinical practice. Authors have tested their cytotoxicity, antibacterial activity and enzyme inhibition. Their optical properties were studied in view of their potential use in photodynamic therapy. Moreover, optical properties could also be used for bioanalysis. It is also known that metal complexes are useful catalysts and a few such examples are also described herein. Many other interesting properties and facts about the isolated and described complexes are also reported (radioactivity, design of metal-organic frameworks, etc.).

Glutathione and multidrug resistance protein transporter mediate a self-propelled disposal of bismuth in human cells

Glutathione and multidrug resistance protein (MRP) play an important role on the metabolism of a variety of drugs. Bismuth drugs have been used to treat gastrointestinal disorder and Helicobacter pylori infection for decades without exerting acute toxicity. They were found to interact with a wide variety of biomolecules, but the major metabolic pathway remains unknown. For the first time (to our knowledge), we systematically and quantitatively studied the metabolism of bismuth in human cells. Our data demonstrated that over 90% of bismuth was passively absorbed, conjugated to glutathione, and transported into vesicles by MRP transporter. Mathematical modeling of the system reveals an interesting phenomenon. Passively absorbed bismuth consumes intracellular glutathione, which therefore activates de novo biosynthesis of glutathione. Reciprocally, sequestration by glutathione facilitates the passive uptake of bismuth and thus completes a self-sustaining positive feedback circle. This mechanism robustly removes bismuth from both intra- and extracellular space, protecting critical systems of human body from acute toxicity. It elucidates the selectivity of bismuth drugs between human and pathogens that lack of glutathione, such as Helicobacter pylori, opening new horizons for further drug development.