Siddig Ibrahim Abdelwahab¹ , Heyam Mohamed Ali Sidahmed², Manal Mohamed Elhassan Taha¹ , Hassan Alfaifi³, Dina Abdulrahman Ismail Albadawi⁴, Amal Hamdan Alzahrani⁵

Abstract

Purpose: To investigate the cholinergic, muscarinic and antagonistic effects of Khat (Catha edulis) on native nicotinic acetylcholine receptors (nAChR) and understand its associated mechanism. Methods: Fresh leaves of Catha edulis (50 g) were pulverized and subjected to extraction using 200 mL of methanol and filtered. The filtrate was reconstituted with 0.02 N sulfuric acid, and then chloroform extraction. Properties of the crude alkaloid extract of khat (CAEK) were assessed in skeletal muscles isolated from frog rectus abdominis. In silico analysis of the effects of cathine (CAT) and cathinone (CATO) on muscle-type nicotinic acetylcholine receptors (nAChRs) and molecular docking to predict their potential binding sites on nAChR subunits were carried out. Results: Pre-treatment of isolated muscles with CAEK inhibited carbachol-induced contractility in a dose-dependent manner. At 10, 20, 40 and 80 mg/mL concentrations of CAEK, inhibition percentages were 74.4, 85.2, 95.4 and 99.5 %, respectively. Molecular docking studies show that CAT and CATO modulate the function of nAChRs through competitive antagonism. Conclusion: These results reveal that khat consumption could contribute to the development of skeletal muscle-associated ailments; hence, detailed studies emphasizing cardiac complications and muscular toxicity mechanisms should be conducted.