Table 3. Antagonist potencies and selectivities of nuciferine (3a) and roemerine (3b) enantiomers for 5-HT_2A and α_1A receptors determined from Schild analysis.

	pKb a		5-HT2A/α1A selectivity b
Compound	5-HT2A	α1A
(R)-Nuciferine	7.26 ± 0.12	7.31 ± 0.11	1
(S)-Nuciferine	6.85 ± 0.14	6.91 ± 0.07	1
(R)-Roemerine	7.88 ± 0.13	6.38 ± 0.11	32
(S)-Roemerine	7.06 ± 0.11	6.62 ± 0.11	3

^aValues are expressed as mean ± SD.

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