Table 1.

In vitro activity, toxicity, and selectivity index found for the terpenoids derivatives on epimastigote and axenic-amastigote forms of Trypanosoma cruzi*

Compound	Activity IC50 (mM)†		Toxicity on Vero cell IC50 (mM)‡	SI§
	Epimastigote forms	Axenic amastigote forms		Epimastigote forms	Axenic amastigote forms
Benznidazole	15.89 ± 1.1	18.92 ± 1.1	13.60 ± 0.9	0.8	0.7
Compound 1	6.10 ± 0.2	6.03 ± 0.3	98.95 ± 6.2	16.2 (20)	16.4 (23)
Compound 2	7.98 ± 0.8	6.81 ± 0.1	154.66 ± 17.3	19.4 (24)	22.7 (32)
Compound 3	50.03 ± 6.6	30.44 ± 2.3	117.67 ± 21.8	2.4 (3)	3.9 (6)
Compound 4	69.01 ± 7.7	38.72 ± 3.6	163.14 ± 14.5	2.4 (3)	4.2 (6)

^*Results are averages of three separate determinations.

^†IC₅₀ = the concentration required to give 50% inhibition, calculated by linear regression analysis from the Kc values at concentrations used (1, 10, 25, 50, and 100 μM).

^‡On Vero cells after 72 h of culture. IC₅₀ = the concentration required to give 50% inhibition, calculated by linear regression analysis from the Kc values at concentrations used (1, 10, 25, 50 and 100 μM).

^§Selectivity index = IC₅₀ Vero cells/IC₅₀ epimastigote and axenic amastigote forms of the parasite. In brackets: number of times that compound SI exceeds the reference drug SI.