Detection of N7-(2-hydroxyethyl)guanine adducts in DNA and 9L cells treated with 1-(2-chloroethyl)-1-nitrosourea.

A sensitive analytical method, HPLC-ED, was developed for the measurement of N7-(2-hydroxyethyl)guanine (N7-HOEtG). A detection limit of 3.2 N7-HOEtG/10(8) nucleotides was obtained with this method. Linear dose response curves for the formation of N7-HOEtG were obtained following treatment of either calf thymus DNA or 9L cells with 1-(2-chloroethyl)-1-nitrosourea (CNU). Using HPLC-ED a significant increase in the level of N7-HOEtG could be detected in 9L cells following treatment with 5 microM CNU. Our study suggests that with this analytical method the formation of N7-HOEtG in the white blood cells of patients treated with chloroethylnitrosoureas may be determined.