Table 2.

Anti-HIV activity of 4′-C-substituted-2′-deoxynucleosides

Compound	EC50 (mM)a)	CC50 (mM)	S.I.
4′-C-cyanothymidine	0.002	1	500
4′-C-azidothymidine	0.01	8	300
4′-C-ethynylthymidine	0.83	>400	>482
4′-C-ethynylarabinofuranosylthymine	119	>400	>3.4
4′-C-azidomethylthymidine	2.1	333	159
4′-C-methylthymidine	7.2	104	14
4′-C-ethylthymidine	>400	400	ND
4′-C-methoxythymidine	8.49	200	24
4′-C-vinylthymidine	>400	>400	ND
4′-C-hydroxymethylthymidine	7.0	>400	>57
4′-C-propylthymidine	>100	>100	ND
4′-C-cyano-2′-deoxycytidine	0.0012	0.17	142
4′-C-azido-2′-deoxycytidine	0.004	0.21	52
4′-C-ethynyl-2′-deoxycytidine	0.0048	2.2	458
l-4′-C-ethynyl-2′-deoxycytidine	>400	>400	ND
4′-C-ethynyl-2′-deoxy-5-fluorocytidine	0.030	>100	>3333
4′-C-ethynylarabinofuranosylcytidine	0.043	2.0	46.5
4′-C-methyl-2′-deoxycytidine	0.015	1.0	66.7
4′-C-fluoromethyl-2′-deoxycytidine	0.0068	0.12	18
4′-C-methyl-2′-deoxyadenosine	2.6	2.6	1
4′-C-azido-2′-deoxyadenosine	0.13	50	385
4′-C-ethynyl-2′-deoxyadenosine	0.098	16	1630
2′,3′-dideoxy-3′-thia-l-cyrtidine (3TC)	0.10	>100	>1000
3′-azido-3′-deoxythymidine (AZT)	0.0032	29.4	9190

a) Anti-HIV activity was determined by MTT assay. MT-4 cells and HIV-1_LAI were employed.

ND: not determined.