Metabolic phosphorylation and excretion of some nucleoside analogues in insects

After oral administration to the hemipteran insect Pyrrhocoris apterus L. (Fireburg), the L-enantiomers and certain open-chain analogues of the nucleosides are rapidly converted into the corresponding monophosphates, which are then excreted. This metabolic phosphorylation is almost quantitative; it occurs at the primary as well as at the secondary hydroxylic groups. The process is abolished when the respective nucleoside analogues contain a free carboxylic group. By contrast, the phosphorylating capacity is unaffected by structural variations at the heterocyclic base. This phosphorylation and excretion may represent a part of detoxication mechanism for the above nucleoside analogues.