The Effects of Bioavailability-Enhanced Curcuminoids on Serum Paraoxonase-1 Activity in Patients with Metabolic Syndrome

Metabolic syndrome (MetS) is characterised by a clustering of metabolic cardiovascular disease (CVD) risk factors that include: central obesity, impaired glucose metabolism, dyslipidaemia (hypertriglyceridemia, increased low-density lipoprotein [LDL], decreased high-density lipoprotein [HDL]) and hypertension. Paraoxynase-1 (PON1) is a plasma HDL associated protein that inhibits the oxidation of other lipoproteins. There is some evidence of reduced enzyme activity in subjects with metabolic syndrome. Curcumin is a natural polyphenol, it has been reported that curcumin has beneficial effects on several metabolic syndrome associated parameters. The aim of this study was to evaluate the effect of phospholipid complex of curcumin as an antioxidant on the activity of this enzyme in subjects with metabolic syndrome. A double-blind randomised control study was undertaken in 80 patients with metabolic syndrome. Subjects in the intervention (n = 40) were given capsules of phospholipidated curcumin (1 g/day) for a period of 6 weeks. The control subjects (n = 40) received a placebo. Fasting blood samples of each person were obtained during the start and the end of the study. Paraoxonase activity was measured using a PON1 fluorescence Paraoxonase Assay Kit and Arylesterase activity was measured by photometeric method using a UV-Visible spectrophotometer. Serum paraoxonase enzyme activity did not change significantly between the curcumin treated group and the control group before the intervention (0.54 ± 0.18 U/µl versus 0.49 ± 0.14 U/µl; P > 0.05), nor did serum arylesteras activity change significantly between two study groups (152.67 [46.60 to 916.05] U/µl versus 129.77 [55.34 to 344.78] U/µl; P > 0.05). In addition, there was no significant difference in changes at baseline and after the intervention in serum PON1 activity between the curcumin treated group and the control group (-0.03±0.19 U/µl versus -0.04±0.18 U/µl; P > 0.05), nor was there a significant change in arylesteras activity (-12.36 [-88.83 to 110.24] U/µl versus -4.58 [-61.06 to 47.07] U/µl; P > 0.05). Phospholipid fortified curcumin has no significant effect on serum PON1 activity.