Isolation of a guanine-malondialdehyde adduct from rat and human urine.

A 1:1 adduct of guanine with malondialdehyde (MDA) was isolated from rat and human urine. This compound was shown to be identical to a synthetic adduct prepared according to the procedure of Seto et al. (Bull. Chem. Soc. Jpn. 58, 3431-3435, 1985). The UV, NMR and other characteristics of the compound were consistent with the tricyclic pyrimidinopurine structure proposed by these investigators. Its endogenous origin is indicated by its presence in the urine of rats fed an MDA-free diet, and by the observation that its excretion increased following iron or carbon tetrachloride administration. It may serve as a marker for nucleic acid modification caused by lipid peroxidation in vivo.