title: Photo-ionization and photo-excitation of curcumin investigated by laser flash photolysis.
abstract: Curcumin (Cur) has putative antitumor properties. In the current study, we examined photophysical and photochemical properties of Cur using laser flash photolysis. The results demonstrated that Cur could be photo-ionized at 355 nm laser pulse to produce radical cation (Cur(+)) and solvated electron e(sol)(-) in 7:3 ethanol-water mixtures. The quantum yield of Cur photo-ionization and the ratio of photo-ionization to photo-excitation were also determined. Cur(+) could be transferred into neutral radical of Cur (Cur) via deprotonation with the pKa 4.13. The excited singlet of Cur ((1)Cur* could be transferred into excited triplet ((3)Cur*, which could be quenched by oxygen to produce singlet oxygen (1)O2*. Reaction of (3)Cur* with tryptophan was confirmed. The results encourage developing curcumin as a photosensitive antitumor agent.
authors.affiliation: School of Life Sciences and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, PR China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Qian
authors.forename: Li
authors.initials: L
authors.lastname: Kun
authors.forename: Bo
authors.initials: B
authors.lastname: Gao
authors.forename: Rongrong
authors.initials: R
authors.lastname: Zhu
authors.forename: Xianzheng
authors.initials: X
authors.lastname: Wu
authors.forename: Shilong
authors.initials: S
authors.lastname: Wang
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D003474:Curcumin / Q000737:chemistry*; D007834:Lasers; D010100:Oxygen / Q000737:chemistry; D010782:Photolysis; D026082:Singlet Oxygen / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D026082:Singlet Oxygen; D003474:Curcumin; D010100:Oxygen
keywords: Curcumin; Laser flash photolysis; Oxidative damage by curcumin; Photo-excitation; Photo-ionization; Quantum yield