Table 1.

In vitro activity of pyrazolone dimers against intracellular amastigotes of T. cruzi (Tulahuen strain) and on MRC‐5 cell growth by phenyldihydropyrazolone dimers with modifications on the phenyl ring.

Compd	R1			pIC50 [a]
	4‐	3‐	2‐	T. cruzi	MRC‐5
3	Br	H	H	5.4	<4.2
7 a	H	Br	H	<4.2	<4.2
7 b	H	H	Br	<4.2	<4.2
7 c	H	H	H	<4.2	<4.2
7 d	Cl	H	H	5.3	5.1
7 e	H	Cl	H	<4.2	<4.2
7 f	H	H	Cl	<4.2	<4.2
7 g	F	H	H	<4.2	<4.2
7 h	H	F	H	5.2	4.4
7 i	H	H	F	4.3	<4.2
7 j	OMe	H	H	5.0	<4.2
7 k	H	OMe	H	5.1	4.4
7 l	H	H	OMe	<4.2	<4.2
7 m	NMe2	H	H	<4.2	<4.2
7 n	H	NMe2	H	<4.2	<4.2
7 o	CN	H	H	<4.2	<4.2
7 p	H	CN	H	<4.2	<4.2
7 q	OMe	F	H	5.2	<4.2
7 r	OMe	Cl	H	5.9	<4.2
7 s	OMe	Br	H	6.4	<4.2
7 t	Cl	OMe	H	<4.2	<4.2
7 u	Br	OMe	H	<4.2	<4.2
7 v	OMe	OMe	H	4.3	<4.2
7 w	F	F	H	5.1	<4.2

[a] All reported values are within a standard deviation of ±0.2.