Article Figures & Data
Figures
- Fig. 1.
Inhibition of proliferation and induction of apoptosis of cells treated with curcumin and dimethoxycurcumin. A, HCT116 cells were treated for 48 h with various concentrations of curcumin (○) and dimethoxycurcumin (▪), and growth rates were estimated as percentage of growth of the untreated control cells. In another experiment, identical cell cultures were left untreated (B and E) or treated with 5 μmol/L of curcumin (C and F) or dimethoxycurcumin (D and G) for 48 h, and then, attached and detached cells were pooled and subjected to flow cytometry analysis of the cell cycle (B-D). E to G, in addition, the attached cells were photographed under a microscope. G1, G0 + G1 cells; G2, G2 + M cells; Ap, apoptotic cell fraction. Cell fraction calculations are shown as percentage of the total cell population. Results represent the mean of three independent experiments (coefficient of variation, <15%).
- Fig. 2.
Analyses of dimethoxycurcumin by MS methodologies. A, chromatogram of LC-MS analysis under gradient conditions. B, tautomeric forms of dimethoxycurcumin. I, enol; II, keto. C, full-scan spectrum of dimethoxycurcumin, [M+H]+ shown at m/z 397. D, product ion spectra of ion m/z 397. E, MS/MS/MS fragmentation of first precursor ion, m/z 397, and second precursor ion, m/z 313.
- Fig. 3.
Dimethoxycurcumin metabolites in microsomal preparations. A, dimethoxycurcumin in the absence of microsomes (control). B, dimethoxycurcumin in the presence of microsomes. C, spectrum of O-demethylated dimethoxycurcumin. D, spectrum of O-demethylated dihydrodimethoxycurcumin.
- Fig. 4.
Proposed scheme of dimethoxycurcumin (DMC) metabolic pathway.
- Fig. 5.
Curcumin (Cur) and dimethoxycurcumin stability detected by LC-MS/MS. A, stability in cultured cells. Curcumin and dimethoxycurcumin were added to cultures of HCT116 cells, and their presence in cells was relatively quantified at 2, 24, and 48 h. The concentration at 2 h was taken as 100% of peak height. B, stability in mouse. Curcumin and dimethoxycurcumin were injected i.p. in mice (n = 6, n = 4 for each time point for curcumin and dimethoxycurcumin, respectively) at 5 mg/kg of body weight, and compound concentrations (μmol/L) were detected in plasma samples collected at 15, 30, 60, and 120 min.
Tables
- Table 1.
Dimethoxycurcumin metabolites
Dimethoxycurcumin metabolite (m/z) Proposed transformation Q1* MRM†/EPI Prec‡/EPI 397 Parent compound + + + 369 −28/2×(O-demethylation) + + 371§ −26/2×(O-demethylation)+H2 + + 383 −14/(O-demethylation) + + + 385 −12/(O-demethylation)+H2 + + 399 +2/+H2 + + + 401 +4/+2H2 + + 559 +162/(O-demethylation)+Glu + + 561 +164/(O-demethylation)+H2+Glu +
Volume 13, Issue 4
