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Figure 12<br />

Predicted binding mode of 2' -deoxy-2'-(3-methoxybenzamido)adenosine to T.brucei<br />

GAPDH. (From Ref. 13. Copyright 1994 <strong>by</strong> the American Chemical Society.)<br />

enzyme. In conclusion, the strategy of burying hydrophobic residues with lipophilic substituents paid<br />

off.<br />

Page 386<br />

Despite the rather poor IC 50 values of our optimized inhibitors, an evaluation of their effect on live<br />

trypanosomes appeared to be useful. Enzyme inhibitors that are not taken up <strong>by</strong> the parasites would be<br />

of no use as a drug. Therefore, the effect of 2-methyl-adenosine, 8-(thien-2-yl)-adenosine and 2'- deoxy-<br />

2'-(3-methoxybenzamido)adenosine on the growth of T. brucei in cultures, as described <strong>by</strong> Baltz et al.<br />

[90], was monitored. At 0.1 mM all compounds inhibited the growth completely, unlike adenosine<br />

derivatives that were without inhibitory effect against T. brucei GAPDH [91]. Experiments are<br />

underway to confirm that the growth inhibition is due to blockage of the glycolytic pathway. Also, te<br />

mechanism of uptake of te inhibitors will be examined because it is now well established that<br />

trypanosomes possess a unique P 2 purine transporter that they use for uptake of purines from the host<br />

[15]. The experimental antitrypanosomal drug 5'-{[(Z)-4-amino-2-butenyl}methylamino}-5'deoxyadenosine(MDL<br />

73811) Figure 13), which is an irreversible S- adenosyl-L-methionine<br />

decarboxylase inhibitor, is actively taken up through the P2 transporter. Moreover, MDL 73811 is not<br />

actively transported in the human host, which presumably contributes to the drug's selectivity [19]. It is<br />

not unthinkable that our inhibitors might use the same transporter because of the nature of their scaffold,<br />

adenosine.<br />

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