Antidepressant and antipsychotic drugs differentially affect PON1 enzyme activity

Figures & data

Figure 1. Molecular structure of antidepressant and antipsychotic drugs: [A] Fluoxoetine hydrochloride, [B] Haloperidol, [C] Acepromazine and [D] Diazepam.

Figure 2. SDS-PAGE of PON1 purified by ammonium sulfate precipitation and hydrophobic interaction chromatography gel serum hPON1 was purified with ammonium sulfate precipitation (60–80%) and hydrophobic interaction chromatography. Lane 1, a pooled sample obtained from a column showing paraoxonase enzyme activity. Lane 2 contains β-galactosidase (116 kDa), bovine serum albumin (66.0 kDa), ovalbumin (45 kDa), Carbonic Anhydrase (33.0 kDa), β-lactogloulin (25.0 kDa), lysozyme (19.5 kDa) protein marker. The molecular weight of PON1 was estimated to be approximately 43 kDa.

Figure 3. Inhibition of paraoxonase hydrolysis by Acepromazine (A), Diazepam (B), Fluoxetine hydrochloride (C), and Haloperidol (D). A purified paraoxonase from human serum was assayed for paraoxonase activity at pH 8 in the presence of various concentrations of Haloperidol, Fluoxetine hydrochloride, Diazepam and Acepromazine. IC₅₀ values of these were determined from C and D. The slope of Lineweaver-Burk plots indicates uncompetitive for Fluoxetine hydrochloride (E) and Haloperidol (F).

Table 1. Summary of the purification of human serum Paraoxonase.

Step	Volume (mL)	Activity (U/mL)	Total activity (U)	Protein content (mg/mL)	Total protein (mg)	Specific activity (U/mg)	% Yield	Purification Fold
Serum	57	57.72	3290.04	1271.34	72 466.38	0.0454	100	–
Ammonium sulphate precipitation	20	85.96	1719.2	1084.8	21 696	0.0791	52.25	1.74
Hydrophobic interaction chromatography	3	109.29	327.87	10.98	32.94	9.95	9.96	125.6

Units: 1 nmol: 4-nitrophenol formed per minute. Purification (fold): specific activity, n purification step/specific activity in serum. Yield: activity of fractions combined for the next purification step/total activity in serum × 100. Yields figures do not include all of the activity actually recovered. Usually, three tubes were pooled for hydrophobic interaction chromatography.

Table 2. The effects of Fluoxetine hydrochloride and Haloperidol on the purified human serum PON1 and the inhibition type of drugs.

Drugs	IC50 (mM)	Inhibition type
Fluoxetine hydrochloride	3.08	Uncompetetive
Haloperidol	0.187	Uncompetetive