SPECTRAL AND PHOTOCHEMICAL PROPERTIES OF CURCUMIN
- 1 March 1994
- journal article
- Published by Wiley in Photochemistry and Photobiology
- Vol. 59 (3), 295-302
- https://doi.org/10.1111/j.1751-1097.1994.tb05037.x
Abstract
Curcumin, bis(4-hydroxy-3-methoxyphenyl)-l,6-heptadiene-3,5-dione, is a natural yellow-orange dye derived from the rhizome of Curcuma longa, an East Indian plant. In order to understand the photobiology of curcumin better we have studied the spectral and photochemical properties of both curcumin and 4-(4-hydroxy-3-methoxy-phenyl)-3-buten-2-one (hC, half curcumin) in different solvents. In toluene, the absorption spectrum of curcumin contains some structure, which disappears in more polar solvents, e.g. ethanol, acetonitrile. Curcumin fluorescence is a broad band in acetonitrile (λmax= 524 nm), ethanol (λmax= 549 nm) or micellar solution (λmax= 557 nm) but has some structure in toluene (λmax= 460, 488 nm). The fluorescence quantum yield of curcumin is low in sodium dodecyl sulfate (SDS) solution (φ= 0.011) but higher in acetonitrile (φ= 0.104). Curcumin produced singlet oxygen upon irradiation (φ > 400 nm) in toluene or acetonitrile (Φ= 0.11 for 50 μM curcumin); in acetonitrile curcumin also quenched 1O2 (kq, = 7 × 106 M−1 s−1). Singlet oxygen production was about 10 times lower in alcohols and was hardly detectable when curcumin was solubilized in a D2O micellar solution of Triton X-100. In SDS micelles containing curcumin no singlet oxygen phosphorescence could be observed. Curcumin photogenerates superoxide in toluene and ethanol, which was detected using the electron paramagnetic resonance/spin-trapping technique with 5,5-dimethyl-pyrroline-.N-oxide as a trapping agent. Unidentified carbon-centered radicals were also detected. These findings indicate that the spectral and photochemical properties of curcumin are strongly influenced by solvent. In biological systems, singlet oxygen, superoxide and products of photodegradation may all participate in curcumin phototoxicity depending on the environment of the dye.Keywords
This publication has 25 references indexed in Scilit:
- The composition, structure and hydrogen bonding of the β-diketonesPublished by Springer Science and Business Media LLC ,2007
- PHOTOCYTOTOXICITY OF CURCUMINPhotochemistry and Photobiology, 1994
- Photosensitized Generation of Superoxide Radical in Aprotic Solvents: an EPR and Spin Trapping StudyFree Radical Research Communications, 1993
- Keto-enol tautomerization of 2-(2-hydroxyphenyl)benzoxazole and 2-(2-hydroxy-4-methylphenyl)benzoxazole in the triplet state: hydrogen tunneling and isotope effects. 2. Dual phosphorescence kineticsThe Journal of Physical Chemistry, 1991
- THE PHOTO‐OXIDATION OF N, N‐DIETHYLHYDROXYLAMINE BY ROSE BENGAL IN ACETONITRILE AND WATERPhotochemistry and Photobiology, 1991
- Spin-Trapping of the Superoxide Radical in Aprotic SolventsFree Radical Research Communications, 1991
- Redox Properties Of Phenols, Their Relationships To Singlet Oxygen Quenching And To Their Inhibitory Effects On Benzo(A)Pyrene-Induced NeoplasiaFree Radical Research Communications, 1990
- Studies on curcumin and curcuminoids VIII. Photochemical stability of curcuminZeitschrift für Lebensmittel-Untersuchung und Forschung, 1986
- Selective photobleaching of the long-lived phosphorescence of 1-indanonesThe Journal of Physical Chemistry, 1986
- Studies on curcumin and curcuminoidsZeitschrift für Lebensmittel-Untersuchung und Forschung, 1985