Loperamide hydrochloride

Synthesized T-X was donated by Prof. Sung Hoon Kim (Kunkuk University, South Korea). 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline 6-sulfonic acid ammonium salt) (ABTS), potassium persulfate, sodium phosphate buffer, potassium ferricyanide, trichloroacetic acid (TCA), ferric chloride, carmine, and loperamide hydrochloride were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO). All reagents used were of analytical grade.

Constipation was induced in the animals by oral administration of 3 mg/kg loperamide hydrochloride (Sigma, MO, USA) in a volume of 5 mL/kg (dissolved in saline), once per day for 6 continuous days 1 h before administration of the test agent, as described previously [36 (link), 37 (link)]; the control rats were administered normal saline only.

For work involving parasites, chlorpheniramine maleate salt, chlorpromazine hydrochloride, desipramine hydrochloride, promethazine hydrochloride, verapamil hydrochloride and CQ diphosphate (all from Sigma-Aldrich) were dissolved in PBS to a working concentration of 1 mM. LynxTag-CQ_GREEN (BioLynx Technologies, Singapore; hereafter abbreviated to ‘CQ_GREEN’) was dissolved in DMSO to the same concentration. All compounds were stored at −20°C and protected from light. For microsome uptake assays, methiothepin mesylate salt, metergoline, loperamide hydrochloride, octoclothepin maleate salt, mibefradil dihydrochloride hydrate, L703,606 oxalate salt hydrate, and chlorprothixene hydrochloride (all from Sigma-Aldrich) were dissolved in DMSO to 10 mM and stored at 4°C. verapamil hydrochloride, adenosine triphosphate (ATP), and CQ diphosphate (all from Sigma-Aldrich) were dissolved in water to 7.5 mM, 50 mM and 0.1 M respectively and stored at −20°C. Tritiated CQ (³H-CQ; from Moravek Biochemicals and Radiochemicals) was diluted in water to 5.32 µM and stored at −20°C; specific activity was 4.7 Ci/mmol.

The analytical-grade chemicals used in this study obtained from Sigma Company (St. Louis, MO, USA) include carbachol, loperamide hydrochloride, acetylcholine perchlorate (ACh), isoprenaline, verapamil, and papaverine. The physiological buffer (Tyrode) composition includes different salts obtained from Merck, Germany, and also includes calcium chloride, glucose, magnesium sulfate, potassium chloride, potassium di-hydrogen phosphate, sodium bicarbonate, and sodium chloride. For diarrhea induction, castor oil procured from local pharmacy was used.