Table 1.

SAR of initial analogs.

#	Structure	R c	AMP IC50 µM	Ca2+ IC50 µM	ERK IC50 µM
11a		H	Inact	35a	<50%b
12a		H	Inact	Inact	<50%b
12c		Me	Inact	27 ± 13a	<50%b
12b		H	63 ± 0a	4.03 ± 0.07	<50%b
12d		Me	18 ± 3	1.0 ± 0.16	0.0091, 0.030c
13a		H	39 ± 0a	2.5 ± 0.4	<50%b
7		Me	1.7 ± 0.1	0.051 ± 0.008	0.030 ± 0.006
15a		H	Inact	7.3± 2.3	<50%b
15b		Me	Inact	2.8 ± 0.0	<50%b
18a		H	Inact	Inact	<50%b
18b		Me	Inact	Inact	<50%b
19a		H	Inact	Inact	<50%b
19b		Me	Inact	Inact	<50%b

The cAMP and Ca²⁺ assay activity is the mean IC₅₀ with SD from two separate experiments, each ran in duplicate. The ERK assay activity is the mean IC₅₀ with SD from one experiment run in duplicate.

^aThese compounds showed partial efficacy in their antagonistic behavior.

^bThese compounds showed <50% inhibition at the highest concentration (50 µM) tested.

^cBoth IC₅₀ values are reported here as we feel that the standard deviation between the replicates is significant. (Inact=Inactive)