Table 5.

Binding energy and interacting residues of isoliquiritigenin and reference ligands at the active sites of human dopamine and vasopressin receptors (hD₁R, hD₃R, and hV_1AR).

Ligand	Binding energy (kcal/mol)	Binding interacting residues
		H-bond	Electrostatic	Hydrophobic
hD1R
Isoliquiritigenin	− 6.12	Ile154, Asp103, Asn292	–	Ile104 (Pi-Sigma), Phe288 (Pi-Pi T-shaped), Ser198 (Amide-Pi Stacked)
Dopaminea	− 6.68	Asp103 (Salt bridge, OH bond), Ser202, Ser199, Ser198	Phe288 (Pi-Cation)	Phe289 (Pi-Pi T-shaped), Ile104 (Pi-Alkyl)
SCH23390a (Antagonist)	− 7.16	Asp103 (Salt bridge), Ala195, Ser199	–	Le104 (Pi-sigma), Leu190 (Pi-Sigma, Alkyl), Phe288 (Pi-Pi T-shaped), Ala195 (Alkyl, Pi-Alkyl), Leu295 (Alkyl)
hD3R
Isoliquiritigenin	− 7.24	Val189, Cys181, Asp110	His349 (Pi-Cation)	Val189 (Pi-Alkyl), Val107 (Pi-Alkyl), Ile183 (Pi-Alkyl)
Dopaminea	− 5.47	Asp110 (Salt bridge, O–H bond), Tyr373, Ser192	–	Val111 (Pi-Alkyl), Cys114 (Pi-Alkyl)
hV1AR
Isoliquiritigenin	− 7.03	Gln108, Cys124, Cys203, Gln131, Glu54	Asp112	Val127 (Pi-Sigma), Lys128 (Pi-Alkyl)
AVPa	− 5.98	Gln311, Ser314, Asp112, Glu54	Lys128	Phe117 (Pi-Alkyl), Trp204 (Pi-Alkyl), Lys128 (Pi-Alkyl)

^aReference ligands for hD₁R, hD₃R, and hV_1AR.