curcumin and acetonitrile

Topics: Acetonitriles; Benzylamines; Curcumin; Dimethyl Sulfoxide; Ethanol; Fluorescence; Fluorescent Dyes; Methanol; Molecular Structure; Palladium; Solvents; Water

[Reaction: see text] Despite the wide application of time-resolved spectra technology in investigating various chemical and biological processes, it is still a great challenge to give an unambiguous spectra assignment for observed transient species, e.g., the curcumin-derived radicals. Here we report that time-dependent density functional theory with the B3LYP functional and an appropriate basis set can give reliable absorption spectra for carbon- and oxygen-centered radicals derived from curcumin, which indicates the potential of theoretical methods in helping assign transient spectra.

Topics: Acetonitriles; Computer Simulation; Curcumin; Models, Molecular; Molecular Structure; Quantum Theory; Spectrum Analysis; Time Factors

Reactions of superoxide-crown ether complex with curcumin have been studied in acetonitrile. Optical absorption spectra showed that curcumin on reaction with superoxide forms a blue color intermediate absorbing at 560 nm, which subsequently decayed in a few hours with the development of the absorption band corresponding to the parent curcumin. The regeneration was 100% at low superoxide concentrations (1:1, or 1:2 or 1:3 of curcumin:superoxide) but reduced to 60% at high superoxide concentration (>1:5). The regeneration of curcumin is confirmed by HPLC analysis. Stopped-flow studies in acetonitrile following either the decay of parent curcumin at 420 nm or formation of 560 nm absorption have been used to determine the rate constant for the reaction of superoxide with curcumin. EPR studies confirmed the disappearance of characteristic superoxide signal in presence of curcumin with the formation of new featureless signal with g = 2.0067. Based on these studies it is concluded that at low superoxide concentrations curcumin effectively causes superoxide dismutation without itself undergoing any chemical change. At higher concentrations of superoxide, curcumin inhibits superoxide activity by reacting with it.

Topics: Acetonitriles; Antioxidants; Chromatography, High Pressure Liquid; Curcumin; Electron Spin Resonance Spectroscopy; Free Radicals; Ions; Models, Chemical; Spectrophotometry; Superoxides; Temperature

The supramolecular interaction of curcumin and beta-cyclodextrin (beta-CD) has been studied by spectrophotometry. The mechanism of the inclusion was studied and discussed based on the variations of pK(a), absorption intensity, and infrared spectrograms. The results show that beta-CD reacts with curcumin to form a 2:1 host-guest complex with an apparent formation constant of 5.53 x 10(5) mol(-2) x L2. Based on the enhancement of the absorbance of curcumin produced through complex formation, a spectrophotometric method for the determination of curcumin in bulk aqueous solution in the presence of beta-CD was developed. The linear relationship between the absorbance and curcumin concentration was obtained in the range of 0-15 microg/mL, with a correlation coefficient (r) of 0.9991. The detection limit was 0.076 microg/mL. The proposed method was used to determine the curcumin in curry and mustard with satisfactory results.

Topics: Acetonitriles; beta-Cyclodextrins; Curcumin; Cyclodextrins; Drug Interactions; Hydrogen-Ion Concentration; Solutions; Solvents; Spectrophotometry; Spectrophotometry, Infrared; Thermodynamics

The quenching of superoxide ions, O2.-, by curcumin has been studied by electrogenerating this anion radical from oxygen dissolved in acetonitrile solvent (that is, at best, a mimic of the lipofilic layer of biological membranes), containing known amounts of curcumin. Voltammetric tests, combined with coulometric and spectrophotometric measurements, pointed out that each mol of curcumin is able to react with six mols of such anion radical, through a process initiated by an acid-base step, which provides the perhydroxyl radical, HO2.; that disproportionates rapidly to the anionic form of hydrogen peroxide, HO2-, and oxygen, which is thus partially regenerated. At the same time, curcumin is converted to the corresponding three-charged anion. The strict resemblance existing between the mechanism of the rapid superoxide radical decay caused by curcumin and that involved in the presence of the superoxodismutase enzyme (SOD) is also underlined.

Topics: Acetonitriles; Antineoplastic Agents; Curcumin; Electrochemistry; Spectrophotometry, Ultraviolet; Superoxide Dismutase; Superoxides

Commercially available curcumin, a bright orange-yellow color pigment of turmeric, consists of a mixture of three curcuminoids, namely, curcumin, demethoxycurcumin, and bisdemethoxycurcumin. These were isolated by column chromatography and identified by spectroscopic studies. The purity of the curcuminoids was analyzed by an improved HPLC method. HPLC separation was performed on a C(18) column using three solvents, methanol, 2% AcOH, and acetonitrile, with detection at 425 nm. Four different commercially available varieties of turmeric, namely, Salem, Erode, Balasore, and local market samples, were analyzed to detect the percentage of these three curcuminoids. The percentages of curcumin, demethoxycurcumin, and bisdemethoxycurcumin as estimated using their calibration curves were found to be 1.06 +/- 0.061 to 5.65 +/- 0.040, 0.83 +/- 0.047 to 3.36 +/- 0.040, and 0.42 +/- 0.036 to 2.16 +/- 0.06, respectively, in four different samples. The total percentages of curcuminoids are 2.34 +/- 0.171 to 9.18 +/- 0.232%.

Topics: Acetonitriles; Chromatography, High Pressure Liquid; Coumaric Acids; Curcuma; Curcumin; Diarylheptanoids; Magnetic Resonance Spectroscopy; Methanol; Solvents