β 2-Adrenergic activity of 6-methoxykaempferol-3-O-glucoside on rat uterus: In vitro and in silico studies

6-Methoxykaempferol-3-O-glucoside (6-MKG) was isolated from a Sudanese herb (El-hazha). The pharmacological effects of 6-MKG were tested on isolated non-pregnant or late-pregnant rat uteri in vitro, whilst docking studies were carried out modelling of the binding of 6-MKG to the rat β 2- adrenoceptor in silico. In vitro studies revealed that 6-MKG was able to relax both the non-pregnant and the late-pregnant uterine contractility with 50% of the E max of terbutaline, whilst the EC 50 for 6-MKG was at least half than that of terbutaline. The β 2-adrenoceptors antagonist 3-(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol(ICI118,551) competitively antagonised the relaxing effect of 6-MKG. Radioligand binding and cAMP studies confirmed the β 2-adrenoceptors agonistic property of the compound. In in silico docking studies, 6-MKG bound to rat β 2-adrenoceptors with low ΔG bind value (- 11.53 ± 0.06 kcal/mol) and it interacted with four residues of the active site (Asp 113, Asn 312, Cys 191and Tyr 316). It is concluded that 6-MKG exerts weak β 2-adrenoceptor agonistic activity and can be considered a natural compound with potential therapeutic significance in the field of premature pregnant uterine contractions and asthmatic problems. © 2011 Elsevier B.V. All rights reserved.