Chemistry Reference
In-Depth Information
Synthesis of Carborane-Containing
Porphyrin Derivatives for the Boron Neutron
Capture Therapy of Tumors
N.V.S. Dinesh K. Bhupathiraju and M. Gra¸a H. Vicente
Abstract
The treatment of malignant brain tumors using conventional therapies
and surgery often leads to tumor recurrence and/or unwanted side effects. Boron
neutron capture therapy (BNCT) is a binary and localized form of treatment for brain
tumors and other difficult-to-treat cancers that uses nontoxic boron-containing
agents. Boronated porphyrins and derivatives constitute a class of highly promising
third-generation boron delivery agents for BNCT. These stable, tumor-specific, and
fluorescent macrocycles can be synthesized with high boron content, can deliver
therapeutic amounts of boron to target sites, and allow tumor detection and treatment
planning by optical imaging. In addition, boronated porphyrins have shown low
toxicity and enhanced tumor selectivity and retention times compared with clinically
approved BNCT agents, BSH and BPA. In this article the synthesis of carboranyl-
containing porphyrins and derivatives for application in BNCT is reviewed, with
special emphasis on macrocycles reported in the last decade. Current strategies for
enhancing the biological efficacy of BNCT agents involve their association with
tumor-targeting molecules, such as polyamines and peptides, for improved tumor
selectivity and accumulation.
Keywords
BNCT
Carborane
Chlorin
Phthalocyanine
Porphyrin
Contents
1 Introduction ................................................................................... 32
2 Synthetic Strategies and Early Reported Macrocycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......... 33
3 Recent Synthesis of Carboranyl-Containing Porphyrin Derivatives ........................ 35
3.1 Symmetric Carboranyl-Porphyrins and Chlorins ...................................... 35
3.2 Unsymmetric Carboranyl-Porphyrins and Chlorins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3 Carboranyl-Containing Corroles and Phthalocyanines ................................ 45
4 Conclusions and Outlook ..................................................................... 47
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
