Interaction of quinolines and artemisinin based antimalarials drugs with ferriprotoporphyrin IX

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3.2 Preparations of solutions

3.2.1 Test of solubility of drugs and hemin in some usual solvents

Solubility of hemin and antimalarial drugs in some usual solvents are summarized in table 3-2. ART (artemisinin), AST (artesunate), DHA (dihydroartemisinin), EG (ethyleneglycol), PREG (propyleneglycol), ETOH (ethanol); +, a (in alkaline solution); +, b (in bicarbonate solution); +, c (soluble at pH >8).

Table 3-2. Solubility of hemin and antimalaraial drugs in studied medium

3.2.2 Buffer solutions

Tris-HCl buffer solutions were prepared by mixing different amounts of 0.2 M Tris and O.2 M HCl to give required pH.

For 100mL of Tris-HCl buffer, we mixed:

25 mL of Tris with 20.7mL of HCl and diluting it with 45.7 mL of distillated water (in case of pH 7.4).

25 mL of Tris with 2.5 mL of HCl and diluting it with distillated water to 100 mL (in case of pH 9).

Phospahte buffer solutions were prepared by mixing amounts of 0.2 M disodium phosphate and O.2 M of sodium phosphate to give required pH.

For 100 mL of phosphate buffer (pH 7.4), we mixed:

81 mL of disodium phosphate with 19 mL sodium phosphate.

3.2.3 Water- DMSO mixture

40% aqueous DMSO solutions (v/v) were prepared by mixing 40 mL of DMSO and 60 mL of corresponding buffer so that the final pH of the mixture was 7.4 or 9.

In addition, 25% aqueous DMSO were prepared by mixing 25 mL of DMSO and 75 mL of corresponding buffer in the same conditions.

2 M of hydrochloric acid and sodium hydroxide served to adjust the pH of all solutions.

3.2.4 Water-propylene glycol mixture

Both 50% ethylene glycol and propylene glycol water mixture were prepared by mixing 50mL of each of them with equivalent volume of buffer, adjusted to the pH of work solutions..

3.2.5 Hemin solutions

In the propylene glycol medium, hemin stock solution, 306 in concentration, was prepared by first dissolving 10 mg of in 25 mL of alkaline distilled water, followed by addition of equivalent volume of propylene glycol.

(25 or 40%) aqueous DMSO stock solutions of hemin (306 ) were prepared by first dissolving 10 mg of it in 12.5 or 20 mL of DMSO, followed by addition 37.5 or 30 mL of buffer.

DMSO stock solutions of hemin (1.0 mM) were prepared by dissolving 6.52 mg of it in 10mL of DMSO (for HPLC-MS analysis).

Aqueous ethanol 85% stock solutions of hemin (306 ) were prepared by dissolving 5 mg of it in 21.25 mL of ethanol and 3.75 mL of distillated water.

Aqueous stock solutions of hemin (306 ) were prepared by dissolving 5 mg of it in 25 mL of alkaline distillated water.

All stock solutions of hemin were refrigerated under 4^oC and, stored in the dark and were stable for at least two weeks.