Figure 1.
In situ analysis of intracellular ROS.
A) All samples were first incubated (30 min) with different concentration of curcumin (a, 0.0; b, 0.1; c, 0.25; d, 0.5; e, 1.0; f, 2.0; g, 4.0 µM), then the DCF fluorescence intensity changes were monitored by the addition of the ROS stimulating agent cumene hydroperoxide (CHP). In the absence of CHP, no change in DCF fluorescence intensity was seen with time; however, it started increasing in presence of CHP. B) The principle of the intracellular ROS protection activity of curcumin. Curcumin diffuses easily into the cells prevents ROS production, thereby preventing oxidation of DCFH2 and the formation of the fluorescent DCF product.
Table 1.
Effect of curcumin on viability of L-6 myoblasts exposed to cumene hydroperoxide (CHP).
Table 2.
Comparative physical properties of curcumin, trolox and α-tocopherol.
Figure 2.
Evaluation of Gox• scavenging rate by curcumin based on ESR results.
The ESR spectra were followed after addition of different concentrations of curcumin (10 µM •; 20 µM ▪; 40 µM ▴). Inset: ESR spectra of 10 µM galvinoxyl radicals in different conditions. a) before addition of curcumin, b) 10 min after addition of 10 µM curcumin, c) 10 min after addition of 40 µM curcumin.
Figure 3.
Chemical structures of galvinoxyl radical.
Figure 4.
Ability of curcumin to reduce ferric iron in comparison with a known hydrophilic antioxidant, trolox.
Measurements were made at pH 7.4 in phosphate buffered saline (PBS) using a UV-Vis spectrophotometer to monitor the reduction of ferric ion to ferrous ion at OD700 nm. This assay used a 1∶1 mixture of potassium ferricyanide (1%) and PBS containing different concentrations of curcumin (▴) and trolox (♦).
Figure 5.
Chemical structures of curcumin, α-tocopherol, and trolox.
Figure 6.
The mechanism of probable three different sites of curcumin reactions with free radicals.
Reactions I and II produce a phenoxyl radicals and reaction III produces the carbon-centered radical at the methylene CH2 group.