Abstract
The effects of ribavirin, an inhibitor of inosine-5′-monophosphate (IMP) dehydrogenase, on [8-
14C]inosine metabolism in tea leaves, coffee leaves and coffee fruits were investigated. Incorporation of radioactivity from [8-
14C]inosine into purine alkaloids, such as theobromine and caffeine, guanine residues of RNA, and CO
2 was reduced by ribavirin, while incorporation into nucleotides, including IMP and adenine residues of RNA, was increased. The results indicate that inhibition of IMP dehydrogenase by ribavirin inhibits both caffeine and guanine nucleotide biosynthesis in caffeine-forming plants. The use of IMP dehydrogenase-deficient plants as a potential source of good quality caffeine-deficient tea and coffee plants is discussed.