Table 1. Antagonist potencies and selectivities of nuciferine (3a) and roemerine (3b) enantiomers for 5-HT₂ receptor subtypes calculated from pIC₅₀ curves.

	pKb a			K b (nM)			Subtype selectivity b
Compound	5-HT2A	5-HT2B	5-HT2C	5-HT2A	5-HT2B	5-HT2C	5-HT2A/5-HT2B	5-HT2A/5-HT2C	5-HT2C/5-HT2B
(R)-Nuciferine	7.18 ± 0.03	7.51 ± 0.21	7.44 ± 0.01	65.3	31.0	36.4	0.5	0.6	1
(S)-Nuciferine	7.07 ± 0.17	7.38 ± 0.01	7.51 ± 0.22	84.3	41.7	41.7	0.5	0.4	1
(R)-Roemerine	7.97 ± 0.18	7.08 ± 0.43	7.82 ± 0.08	10.8	84.0	15.1	8	1	6
(S)-Roemerine	7.37 ± 0.10	7.03 ± 0.33	7.12 ± 0.13	42.9	92.7	76.9	2	2	1
Ketanserin c	8.69 ± 0.03	5.70 ± 0.04	6.95 ± 0.08	2.0	1980	112	1000	60	20

^aValues are expressed as mean ± SEM from at least 2 separate experiments.

^bSelectivities for receptor X/receptor Y were calculated as the ratio of K_{b receptor Y}/K_{b receptor X}.

^cPositive control.