Identification of a Previously Unknown Compound as 2'-Deoxycytidine Found in the Plasma of Breast Cancer Patients under Combined Chemotherapy

抄録

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, methotrexate 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 reacted with bromoacetoaldehyde and its concentration appeared proportional to the chemotherapeutic courses of treatment. The compound in its native state without fluorescent derivatization was efficiently purified by using columns of DEAE-and CM-Sephadex. Its UV spectrum revealed maxima at 271, 280 and 272 nm in solutions of pH 7, pH 3 and pH 12, respectively. The electrophoretograms showed that it was neutral, positively and negatively charged at pH 7, pH 3 and pH 12, respectively. Thin-layer chromatograms showed that it had the same Rf as 2'-deoxycytidine (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 exchange chromatograms. From the calculation of the recovery obtained by the purification process, the cancer patients undertaking more than 12 courses 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.