. Author manuscript; available in PMC: 2015 Jun 25.

Published in final edited form as: J Am Chem Soc. 2003 May 14;125(19):5745–5753. doi: 10.1021/ja034162h

Table 2.

Antitumor Analysis Comparing Mithramycin (1), Mithramycin SK (2), and Demycarosylmithramycin SK (3)^a

	1	comparison with 2			comparison with 3
	1	2	Δ₁_–₂	activity improvement factor^e	3	Δ₁_–₃	activity improvement factor^e
(a) Average log(GI₅₀) Values^b
leukemia (5)^c	−6.65	−7.59	0.94	8.7	−5.55	−1.10	0.08
NSCLC (8)^c	−6.73	−7.37	0.64	4.4	−5.30	−1.43	0.04
colon (7)^c	−6.65	−7.32	0.67	4.7	−5.35	−1.30	0.05
CNS (5)^c	−6.78	−7.61	0.83	6.8	−5.30	−1.48	0.03
melanoma (8)^c	−6.72	−7.64	0.92	8.3	−5.37	−1.35	0.04
ovarian (6)^c	−6.60	−7.53	0.93	8.5	−5.23	−1.37	0.04
renal (8)^c	−6.73	−7.29	0.56	3.6	−5.14	−1.59	0.03
prostate (2)^c	−6.90	−7.48	0.58	3.8	−5.25	−1.65	0.02
breast (8)^c	−6.59	−5.89	−0.70	0.2	−5.15	−1.44	0.04
(b) Average log(IC₅₀) Values^d
squamous carcinoma	−5.04	−5.99	0.95	8.9
melanoma	−5.05	−6.25	1.20	15.8
lung carcinoma (A549)	−4.92	−6.88	1.96	91.2
breast carcinoma (MCF-7)	−4.95	−6.74	1.79	61.6

Data show that 2 exhibits an activity that is up to 90 times higher than that of 1, whereas 3 is ~25 times less active than 1.

Average log(GI₅₀) values resulting from the sulforhodamine B assay.^40,45,46

Number in parentheses is the number of cell lines tested in each family.

Average log(IC₅₀) values resulting from the neutral red assay.⁴²

The activity improvement factor is equal to 10^Δ₁_–_x, where x is the identifying value for compound 2 or 3. An activity improvement factor of 1.0 corresponds to no difference in activity.