Comparison of the in vivo total antioxidant capacity in healthy volunteers at the different curcuminoids doses by oxygen radical absorbance capacity assay

Abstract

The total antioxidant activity in healthy volunteers obtaining the different dosages of curcuminoids extract was determined using the oxygen radical absorbance capacity assay (ORAC). Twenty four male and female Thai healthy volunteers were divided into three groups. Group A and B were administrated with curcuminoids extract at the dose of 500 mg/day and 6g/day, respectively. Group C received vitamin E supplement at the dose of 200 IU/day. Every subject was treated for seven days. Blood samples were collected before experimentation and on the first and seventh days up to 12 hrs. after administration, were immediately centrifuged to separate plasma and kept at the -48°C for subsequent analysis. No any adverse reaction was observed in any subject during and after 7 days of curcuminoids extract and vitamin E supplementations. Before experimentation, the concentrations of α-tocopherol of all subjects were within the normal range of healthy people (7.58 – 19.52 µg/ml). The ORAC values comparing before and after curcuminoids extracts administration of subjects in group A were ranged from 5,797-15,689 and 8,269-20,186 µmol TE/L, respectively, and those of subjects in group B were ranged 9,022-24,834 and 3,530-20,595 µmol TE/L, respectively. No significant increase in the ORAC values were observed either in group A subjects or group B subjects (p=0.270 and 0.33, respectively). For the subjects in group C, the ORAC values before and after vitamin E supplementations were ranged from 8,422-13,922 and 9,216-23,574 µmol TE/L, respectively. From the analysis of plasma endogenous α-tocopherol, there was statistically significant increased in α- tocopherol concentration from 9.16 ± 1.21 to 14.38 ± 2.85 µg/ml (p =0.007). The increasing of α-tocopherol concentration was related to antioxidant activity of α-tocopherol. However, there were no statistically significant increased in the ORAC values (p =0.585). Therefore, it is suggested that the supplementation of any antioxidants may not be essential for any healthy people. In addition, there are possibly balance functions to regulate the maximum antioxidant activity in our body.