Biological and Medicinal Applications of Boronic Acids

Copyright 2005 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-30991-8 

In addition to being developed as enzyme inhibitors and boronolectins, boron-based compounds (not limited to boronic acid compounds although that is the focus of this chapter) are also being studied for their utility as boron neutron capture therapy (BNCT) agents [27, 28]. Such applications are based on the unique property of boron-10, which emit a particles upon irradiation with neutron. Since a particles travel only a few mm they are ideal for localized radiation therapy. Therefore, targeted delivery of high concentrations of boron agents can be used for BNCT of certain tumors. 

Because of the importance of boronic acids as potential pharmaceutical agents, we must ask whether they posses intrinsic and unusual toxicity and stability problems. The recent approval of bortezomib (Velcade), which is a boronic acid-based protea- 

This chapter discusses tile application of boronic adds as potential enzyme inhibitors, artificial lectins (boronolectins), feed-back controlled drug delivery materials, boron neutron capture therapy agents, and other biologically active agents. The discussion focuses on the underlying chemical principles important for the various applications using selected examples. It does not strive to be comprehensive in terms of covering all the literature reports in this area, for which one can consult various reviews already [9, 38-40]. Boronic acids have also been used for the transport of various compounds such as ribonudeosides [41], amino acids [42], catecholamine [43], and saccharides across membranes [44-47]. However, such applications are more aimed for purification and separation and, therefore, will not be addressed in detail in this chapter. 

Various boronic acid compounds have been widely studied for their inhibition of different enzymes. The following discussion is divided based on the target enzymes and/or kind of approach used for the design of boronic acid-based enzyme inhibitors. At the end of the section, many examples are summarized in a table format for ref- 

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