Water-soluble phosphonium salts containing 1,12-dicarba-closo-dodecaborane(12)

Selective delivery of remarkably high levels of gadolinium to tumour cells using an arsonium salt

The use of a triphenylarsonium vector for tumour cell-targeting leads to a dramatic increase in Gd³⁺ uptake in human glioblastoma multiforme cells by up to an order of magnitude over the isosteric triarylphosphonium analogue, with significant implications for 'theranostic' applications involving delivery of this important lanthanoid metal ion to tumour cells.

Towards carborane-functionalised structures for the treatment of brain cancer

Boron neutron capture therapy (BNCT) is a promising targeted chemoradiotherapeutic technique for the management of invasive brain tumors, such as glioblastoma multiforme (GBM). A prerequisite for effective BNCT is the selective targeting of tumour cells with ¹⁰B-rich therapeutic moieties. To this end, polyhedral boranes, especially carboranes, have received considerable attention because they combine a high boron content with relative low toxicity and metabolic inertness. Here, we review progress in the molecular design of recently investigated carborane derivatives in light of the widely accepted performance requirements for effective BNCT.

Boron-containing delocalised lipophilic cations for the selective targeting of cancer cells

To limit the incidence of relapse, cancer treatments must not promote the emergence of drug resistance in tumour and cancer stem cells. Under the proviso that a therapeutic amount of boron is selectively delivered to cancer cells, Boron Neutron Capture Therapy (BNCT) may represent one approach that meets this requirement. To this end, we report the synthesis and pharmacology of several chemical entities, based on boron-rich carborane moieties that are functionalised with Delocalized Lipophilic Cations (DLCs), which selectively target the mitochondria of tumour cells. The treatment of tumour and cancer stem cells (CSCs) with such DLC-functionalized carboranes (DLC-carboranes) induces cell growth arrest that is both highly cancer-cell-selective and permanent. Experiments involving cultures of normal and cancer cells show that only normal cells exhibit recapitulation of their proliferation potential upon removal of the DLC-carborane treatment. At the molecular level, the pharmacological effect of DLC-carboranes is exerted through activation of the p53/p21 axis.

Remarkable cage deboronation and rearrangement of a closo-1,12-dicarbadodecaborane to form a neutral nido-7,9-dicarbaundecaborane

Deboronation and cage rearrangement of the closo-1,12-carborane salt [1,12-(PPh2Me)2-1,12-C2B10H10]I2 occurs in refluxing methanol to give the zwitterionic nido-7,9-carborane 7,9-(PPh2Me)2-7,9-C2B9H9. Notably, deboronation and cage substitution of the isomeric closo-1,7-carborane salt [1,7-(PPh2Me)2-1,7-C2B10H10]I2 takes place in methanol to afford the salt [10-OMe-7,9-(PPh2Me)2-7,9-C2B9H9]I.