Calixarenes as Therapeutic Agents

There is some evidence that particular calixarene derivatives have direct therapeutic properties. The antitubercular action of 4-octylcalix[8]arenes with pendent polyether chains was determined by Cornforth s group in the early 1950s where the compound, then of unknown composition and called Macrocyclon, was shown to be generally non-toxic to mammals and yet more potent than streptomycin in the treatment of tubercular bacilli [32], 

The compound s activity was later reinvestigated by Tascon and colleagues who confirmed the original findings [33], Both macrophages and live mice were infected with Mycobacterium tuberculosis to determine the effects at the level of the cell and organism levels, respectively. Macrocyclon, illustrated in Fig. 7.12, was found 

How do calixarenes enter cells To answer this question Matthews, Mueller and co-workers prepared a soluble calix[4]arene with quaternary ammonium groups on the upper rim and a fluorescent label on the lower rim [35], Following the progress of the compound by fluorescence confocal microscopy it was apparent that molecules were not transported across the membrane by normal endocytosis mechanisms, nor did they penetrate the cell nucleus but remained in the cytoplasm. This would seem to point to a membrane bound channel as the point of entry and paves the way for an array of therapeutic interventions. 

One potential application is to incorporate a calixarene into a prodrug designed to deliver a pharmaceutical to a destination within a bacterium. To make a prodrug the 

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