Table 1. ABS P. falciparum (Dd2 strain) growth inhibition potencies of 1 and racemic benzo-ring substitution variants^a.

Compound	X	Dd2 strain P. falciparum growth inhibition EC50 (nM)
1	H	250 ± 70 nMb
(±)-16a	5-Me	>10 000 nM
(±)-16b	6-Me	>10 000 nM
(±)-16c	7-Me	>10 000 nM
(±)-16d	8-Me	>10 000 nM
(±)-17a	5-CF3	>10 000 nM
(±)-17c	7-CF3	1250–2500 nM
(±)-18b	6-Br	>10 000 nM
(±)-19a	5-Cl	>10 000 nM

^aGrowth inhibition (EC₅₀ values) of ABS was determined using SYBR Green I assay at 72 h endpoint. P. falciparum Dd2 strain is multi-drug resistant.

^bPreviously reported.⁸