Table 1.

AhR activity of 6-substituted indolo[3,2-b]carbazoles and quinone (13).

Compound	R	AhR EC50 (nM)
FICZ (1)	CHO	10 ± 10
CICZ (9)	CO2H	400 ± 100
10	CO2Et	160 ± 40
11	CH2OH	160 ± 90
ICZ (12)	H	30 ± 10
13		70 ± 15

Compounds were compared in a cyp1a1 reporter gene assay. The EC₅₀ for activation of AhR was determined, n = 4 ± S.D.