Spectroscopic Properties of Curcumin: Orientation of Transition Moments

Abstract

Curcumin, a naturally occurring yellow-orange pigment with potent antioxidant and antitumor properties, has been attracting researchers from a wide range of fields including chemistry, spectroscopy, biology, and medicine. Ultrafast excited-state processes such as solvation and excited-state intramolecular hydrogen atom transfer (ESIHT) make curcumin an attractive agent for photodynamic therapy. In this report we present studies of linear dichroism and fluorescence anisotropy in oriented and isotropic media. The results show transition moments (long wavelength absorption and emission) oriented along the long molecular axis. Comparison of linear dichroism and excitation anisotropy in oriented and isotropic media suggests that excited-state intramolecular hydrogen atom transfer is probably associated with intramolecular conformational changes that can be constrained in highly stretched poly(vinyl alcohol) (PVA) film.

Auto-fluorescence lifetime and light reflectance spectroscopy for breast cancer diagnosis: potential tools for intraoperative margin detection

“…The measured integral-intensity-weighted mean lifetimes calculated using a two component exponent model were 4.04 ± 0.01 ns and 1.85 ± 0.02 ns for Fluorescein and Rhodamine B, respectively. These results were then confirmed by measuring a part of the same solution with another commercial TCSPC system (FluoTime 200, PicoQuant GmbH, Germany), using 1 mm thick cuvette and front-face geometry as described in [32]. The system is equipped with a micro-channel plate (MCP) detector [33] and excitation wavelength is selected from tunable laser system (Fianium SC400-4) with opto-acoustic filter system.…”

Binding of Curcumin to Senile Plaques and Cerebral Amyloid Angiopathy in the Aged Brain of Various Animals and to Neurofibrillary Tangles in Alzheimer's Brain

“…All sections were examined using a confocal laser scanning microscope (LSM510, Carl Zeiss, Oberkochen, Germany) (green: excitation wavelength 488 nm/emission filter 505 to 550 nm, red: excitation wavelength 488 nm/ emission filter over 650 nm) or a fluorescence microscope (DMI3000B, Leica microsystems, Wetzlar, Germany) (green: excitation filter 470 ± 40 nm/emission filter 525 ± 50 nm, red: excitation filter 546 ± 12 nm/emission filter 605 ± 75 nm). Emission wavelength of curcumin in water is about 550 nm when excited with wavelength 430 nm [15]. In the present study, we used merged pictures of red and green fluorescences to obtain higher-contrasted pictures (Fig.…”

Temperature Dependence of the Fluorescence Properties of Curcumin

“…8 Polarity, fluorescence anisotropy, π-bonding nature, and hydrogen bond donating and accepting properties of the solvent influence the excited state photophysics of curcumin in a complex manner. 14 The time-resolved optical spectrum of curcumin was recently studied using a variety of ultrafast spectroscopy techniques by several groups. Palit and co-workers 15,16 studied the relatively fast decay of the first electronically excited-state (S 1 ) of curcumin.…”