Su J, Zhen Y S, Qi C Q, Chen W J
Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Beijing.
Yao Xue Xue Bao. 1994;29(9):656-61.
Antibiotic C3368-B (CB), identified as 3,9-dihydroxy-1-methoxy-7-methylanthraquinone, is produced by a fungus strain, Chrysosporium verrucosum Tubaki, isolated from a soil sample collected from Antarctica. CB was found to be a highly-active nucleoside transport inhibitor. By radiolabelled nucleoside assay, CB was shown to markedly inhibit thymidine and uridine transport in Ehrlich carcinoma cells, with IC50 values of 7.5 and 9.6 mumol.L-1 respectively. CB showed fairly low cytotoxicity to tumor cells. The IC50 values for epidermoid cancer KB cells and hepatoma BEL-7402 cells in clonogenic assay was 77 and 69 mumol.L-1. At relatively noncytotoxic concentrations, CB markedly enhanced the cytotoxicity of methotrexate, 5-fluorouracil, mitomycin C against KB cells and BEL-7402 cells. CB was also found to partly reverse the multi-drug resistance to vincristine and actinomycin D in leukemia L1210/MDR cells. The IC50 values were reduced by 4.9-fold (1.75 to 0.36 mumol.L-1) for vincristine and 3.3-fold (0.39 to 0.12 mumol.L-1) for actinomycin D. These results suggest that CB, as a newly-found nucleoside transport inhibitor, may be potentially useful in cancer chemotherapy.
