Vol.
664
s
Relation of Structure to Activity of Purine 3'-deoxy nucleosides in KB Cell and Chick Embryo Fibroblast Cell Cultures'
A number of 3'-deoxyrihonucleosides were compared m-it113'-deosyatienosine for cytotositr activity and effects on iiridine-3H incorporation in K B cells a i d chick fibroblasts. Iri K B cells 6-methvlaminopllriIie 3'-deo. side exhibited delayed cytotoxicity greater than 3'-deoxyadenosine but was about as potent ari inhibitor of uridine incorporation as was 3'-deoxyadeiiosiiic. I n chick cells, it x a s neither as cytotoxic as 3'-deoxyadenosine, nor was it as potent an inhibitor of uridine incorporation. The 3-ethyl- and X-dimethylaminopurine derivatives were significantly less active than 3'-deoxyadeiiosiiie. T-ery striking differences in the response of K B cells and chick cells t o the 3'-deoxyribosides of guariiiie arid %,&dianiinopiirinewere observed. I n chick cells, these two compounds were nearly as cytotoxic and as effective as inhibittrrs of uridine incorporation as was 3'-deosyaderiosine. I n K B cells, holvever, the c~)nipouiidswere only slightly cytotoxic arid actnallg stimiilated urjdine incorporation.
3'-Deosyndenosine has been isolated from thc fernieritcd broth of Aspei~giliusnidulam, using cytotoxic activity against KB cells to help guide the fractionatioii of the broth.? Cordycepin, a nietabolic product previously isolated from CoTdyccps mdituris, has beeii shown to be identical4 with S'-deoxyadenoxine. Other 3'-dcoxyadeiiosinc nucleosides were synthesized in our lahoratoricsj arid were tested for cytotoxic activitie; against KB cells arid chick embryo fibroblast cells. Bccausc. 3'-deoxyadenosine was known to be an inhibitor of R S A synthesis,G each coinpourid was also comparcd with 3'-deoxyadeiiosine for its effect 011 thc incorporation of ~ r i d i n e - ~ H into the acid-insolublr fraction of KB cells and chick embryo fibroblast cell.. The rcsults of these studies are rcportcd hrre.
Materials and Methods Eagle's medium,' with Earle's brt1:mced salts solution, supplemented with calf serum was used throughout. Stock medium contained lo$;, calf serum; test medium contained 554 calf serum. All media contained, per milliliter, 100 units of penicillin and 3 1 'y of streptomycin. Primary cultures of chick embryo fibroblast cells were prepared from 11-day-old embryos by a method similar to that described b y Temin and Rubin.8 The suspension of cells obtained from tre:ttment of the enibryos with trypsiii was dilutedinstockmediuni to it concentration of 7 . 5 X IO5 cells/ml. The diluted suspension ( 2 0 ml.) w t s seeded into each of several milk dilution bottles. These were gassed with :t Con-air mixture ( 3 : 9 5 ) , closed n i t t i rubber stoppers, and incubated a t 37". The medium was renewed on the third and fifth day. On the sixth day, the cells were harvested u-ith the aid of trypsin, centrifuged, and suspexided in test mediuni for the preparation of secondary cultures of (,hick embryo fibroblast cells. (1) 'This investigation u-as supymted, in p a r t , under Xational Institutes of €Iealtli Contract S o . Sh-43-ph-3057, I)y tlie Cancer Chemotherapy Sational Service Center, Sational Cancer Institute, Department of IIealtli, I'ducation arid TVelfare, U. P. Public Health Service, Bethesda, hld. (2) 1:. -1. Iiacaka, E;. L. Dulaney, C . 0. Gitterman, H. B. \Voodruff. and I\. b'olkers, Biochem. B i o p h y e . Res. Commzrn., 14, 462 (1964). Spring, J . Chem. Sol.., (3) II. R. I%entleg,I
