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Abstract: An effective and rapid method for the microwave-assisted preparation of the key intermediate for the total synthesis of tetrahydroprotoberberines (THPBs) including l-stepholidine (l-SPD) was developed. Thirty-one THPB derivatives with diverse substituents on A and D ring were synthesized, and their binding affinity to dopamine D1, D2 and serotonin 5-HT1A and 5-HT2A receptors were determined. Compounds 18k and 18m were identified as partial agonists at the D1 receptor with K i values of 50 and 6.3nM, while both compounds act as D2 receptor antagonists (K i =305 and 145nM, respectively) and 5-HT1A receptor full agonists (K i =149 and 908nM, respectively). These two THPBs compounds exerted antipsychotic actions in animal models. Further electrophysiological studies employing single-unit recording in intact animals demonstrated that 18k-excited dopaminergic (DA) neurons are associated with its 5-HT1A receptor agonistic activity. These results suggest that these two compounds targeted to multiple neurotransmitter receptors may present novel lead drugs with new pharmacological profiles for the treatment of schizophrenia. [Copyright &y& Elsevier]

Abstract: A series of new tetrahydroprotoberberine (THPB) derivatives were designed, synthesized, and tested for their binding affinity towards dopamine (D1 and D2) and serotonin (5-HT1A and 5-HT2A) receptors. Many of the THPB compounds exhibited high binding affinity and activity at the dopamine D1 receptor, as well as high selectivity for the D1 receptor over the D2, 5-HT1A, and 5-HT2A receptors. Among these, compound 19c exhibited a promising D1 receptor binding affinity (K i =2.53nM) and remarkable selectivity versus D2R (inhibition=81.87%), 5-HT1AR (inhibition=61.70%), and 5-HT2AR (inhibition=24.96%). Compared with l-(S)-stepholidine (l-SPD) (D1 K i =6.23nM, D2 K i =56.17nM), compound 19c showed better binding affinity for the D1 receptor (2.5-fold higher) and excellent D2/D1 selectivity. Functional assays found compounds 18j, 18k, and 19c are pure D1 receptor antagonists. These results indicate that removing the C10 hydroxy group and introducing a methoxy group at C11 of the pharmacophore of l-SPD can reverse the function of THPB compounds at the D1 receptor. These results are in accord with molecular docking studies. [Copyright &y& Elsevier]