Interaction of Nitroaromatic Radiosensitizers with Irradiated Polyadenylic Acid as Measured by an Indirect Immunochemical Assay with Specificity for the 8,5′-cycloadenosine Moiety

Summary

The relative reactivity of a series of nitroaromatic radiosensitizers toward the C(5′) radical intermediate leading to 8,5′-cycloadenosine formation in deoxygenated solutions of irradiated polyadenylic acid (poly A) was assessed using standard competition kinetic analysis. Formation of 8,5′-cycloadenosine was assayed by an indirect, competitive, enzyme-linked immunosorbent assay (ELISA) described in an earlier report. In the absence of oxygen, the nitroaromatics inhibit 8,5′-cyclonucleoside formation in a way which generally increases with radiosensitizer electron affinity. Although hydroxyl radical scavenging by the nitroaromatics may account for a relatively small decrease in 8,5′-cyclonucleoside formation, the data suggest that oxidation of the C(5′) radical intermediate is the more plausible explanation for the decreased yield of the 8,5′-cyclonucleoside with increasing nitroaromatic electron affinity.

• 8,5′-cyclonucleosides (tides)
• polyadenylic acid
• nitroaromatic radiosensitizers
• enzyme-linked immunosorbent assay (ELISA)
• hydroxyl radicals