Cytokinetic study on the effects of N 4 ‐behenoyl‐1‐β‐d‐arabinofuranosylcytosine on murine leukemic cells L 1210: A comparison with the effects of 1‐β‐d‐arabinofuranosylcytosine

The effects of N 4 ‐behenoyl‐1‐β‐d‐arabinofuranosylcytosine (BH‐AC) on the cell cycle of murine leukemic cells (L 1210 cells) were compared with those of 1‐β‐d‐arabinofuranosylcytosine (ara‐C), known to be effective for acute leukemia. In a cytokinetic study, a combination of Feulgen microcytofluorometry and tritiated thymidine autoradiography ( 3 H‐TdR ARG) was used to measure DNA content and to determine DNA synthesis simultaneously in a single cell. Administration of 200 mg/kg of BH‐AC significantly prolonged the survival time of mice bearing L 1210. In addition, the cells in the G 1 + S 1 phases increased with time, accounting for 94.4 per cent of all cells measured at 48 h after the administration, compared to 73.7 per cent before administration. On the other hand, following the administration of 86 mg/kg of ara‐C (equivalent to 200 mg/kg of BH‐AC), the percentage of cells in the S 1 + S 1 phases increased maximally to 75.9 per cent at 18 h. Cytokinetic studies further showed that BH‐AC administration blocks DNA synthesis of the cells in the S‐phase for a longer period than does ara‐C. These results suggest that the prolonged inhibition by BH‐AC on DNA synthesis allows cells to accumulate in the S‐phase to a greater degree.