Table 3.

Anti-HIV activity of purine derivatives of 4′-C-cyano-2′-deoxy (4′CNd) and 4′-C-ethynyl-2′-deoxynucleosides

Structure	Base	EC50 (µM)a)	CC50 (µM)	S.I.
	A	0.051	12	235
	I	0.051	23	451
	2AAb)	0.00079	0.034	43
	G	0.000188	0.034	181
	A	0.098	16	1630
	I	0.15	216	1440
	2AA	0.0003	0.82	2733
	G	0.0014	1.5	975
AZT		0.0032	29.4	9190

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

b) 2-aminoadenine.