IDENTIFICATION OF A PREVIOUSLY UNKNOWN COMPOUND AS 2'-DEOXYCYTIDINE FOUND IN THE PLASMA OF BREAST-CANCER PATIENTS UNDER COMBINED CHEMOTHERAPY

In an attempt to find an end-point for cancer chemotherapy, this study was designed to measure the adenine compounds in the plasma of breast cancer patients using HPLC with a selective reagent for adenine bases . The patients were treated by chemotherapy using cyclophosphamide, me thotrexate and 5-fluorouracil. Blood was collected in tubes containing EDTA, the plasma separated by centrifugation and analysed by HPLC. An early peak due to the fluorescent derivative of an unknown compound r eacted with bromoacetoaldehyde and its concentration appeared proporti onal to the chemotherapeutic courses of treatment. The compound in its native state without fluorescent derivatization was efficiently purif ied by using columns of DEAE- and CM-Sephadex. Its UV spectrum reveale d maxima at 271, 280 and 272nm in solutions of pH 7, pH 3 and pH 12, r espectively. The electrophoretograms showed that it was neutral, posit ively and negatively charged at pH 7, pH 3 and pH 12, respectively. Th in-layer chromatograms showed that it had the same Rf as 2'-deoxycytid ine (dCyd) which was confirmed by a positive reaction for deoxyribose. It was concluded that bromoacetoaldehyde formed a weakly fluorescent product with dCyd which gave rise to the early peak in the anion excha nge chromatograms. From the calculation of the recovery obtained by th e purification process, the cancer patients undertaking more than 12 c ourses had a dCyd level of approximately 20 mM while the corresponding figure in normal volunteers was less than 1 mM. These results may be useful in assessing the status of the cancer patients.