Chem. Pharm. Bull.(オピニオン)

Polyphenols as antimicrobial agents

https://zenodo.org/record/1003263/files/Cushnie%20et%20al%20%282011%29%20post-peer%20reviewed%20version.pdf

Recent advances in understanding the antibacterial properties of flavonoids

This paper discusses the effects of curcumin on patients with Alzheimer's disease (AD). Curcumin (Turmeric), an ancient Indian herb used in curry powder, has been extensively studied in modern medicine and Indian systems of medicine for the treatment of various medical conditions, including cystic fibrosis, haemorrhoids, gastric ulcer, colon cancer, breast cancer, atherosclerosis, liver diseases and arthritis. It has been used in various types of treatments for dementia and traumatic brain injury. Curcumin also has a potential role in the prevention and treatment of AD. Curcumin as an antioxidant, anti-inflammatory and lipophilic action improves the cognitive functions in patients with AD. A growing body of evidence indicates that oxidative stress, free radicals, beta amyloid, cerebral deregulation caused by bio-metal toxicity and abnormal inflammatory reactions contribute to the key event in Alzheimer's disease pathology. Due to various effects of curcumin, such as decreased Beta-amyloid plaques, delayed degradation of neurons, metal-chelation, anti-inflammatory, antioxidant and decreased microglia formation, the overall memory in patients with AD has improved. This paper reviews the various mechanisms of actions of curcumin in AD and pathology.

The effect of curcumin (turmeric) on Alzheimer's disease: An overview

Curcumin, with its recent success as an anti-tumor agent, has been attracting researchers from wide ranging fields of physics, chemistry, biology and medicine. The chemical structure of curcumin has two o-methoxy phenols attached symmetrically through α,β-unsaturated β-diketone linker, which also induces keto–enol tautomerism. Due to this, curcumin exhibits many interesting photophysical and photochemical properties. The absorption maximum of curcumin is ∼408–430 nm in most of the organic solvents, while the emission maximum is very sensitive to the surrounding solvent medium (460–560 nm) and the Stokes’ shift varied from 2000 to 6000 cm−1. The fluorescence quantum yield in most of the solvents is low and reduced significantly in presence of water. The fluorescence lifetime is short (<1 ns) and displayed multi-exponential decay profile. The singlet excited states of curcumin decay by non-radiative processes contributed mainly by intra- and intermolecular proton transfer with very low intersystem crossing efficiency. Polarity, π-bonding nature, hydrogen bond donating and accepting properties of the solvent influence the excited state photophysics of curcumin in a complex manner. The triplet excited states of curcumin absorb at 720 nm and react with oxygen to produce singlet molecular oxygen. The photodegradation of curcumin produces smaller phenols and the photobiological activity of curcumin is due to the generation of reactive oxygen species.

Being lipophilic in nature, the water solubility of curcumin could be enhanced upon the addition of surfactants, polymers, cyclodextrins, lipids and proteins. Changes in the absorption and fluorescence properties of curcumin have been found useful to follow its interaction and site of binding in these systems. Curcumin fluorescence could be employed to follow the unfolding pattern and structural changes in proteins. The intracellular curcumin showed more fluorescence in tumor cells than in normal cells and fluorescence spectroscopy could be used to monitor its preferential localization in the membrane of tumor cells. This review, presents the current status of research on the photophysical, photochemical and photobiological processes of curcumin in homogeneous solutions, bio-mimetics and living cells. Based on these studies, the possibility of developing curcumin, as a bimolecular sensitive fluorescent probe is also discussed.

Photophysics, photochemistry and photobiology of curcumin : Studies from organic solutions, bio-mimetics and living cells

The potential energy surface of curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] was explored with the DFT correlation functional B3LYP method using 6-311G* basis. The single-point calculations were performed at levels up to B3LYP/6-311++G**//B3LYP/6-311G*. All isomers were located and relative energies determined. According to the calculation the planar enol form is more stable than the nonplanar diketo form. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. In addition, harmonic vibrational frequencies of the molecule were evaluated theoretically using B3LYP density functional methods. The computed vibrational frequencies were used to determine the types of molecular motions associated with each of the experimental bands observed. Our vibrational data show that in both the solid state and in all studied solutions curcumin exists in the enol form. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

Bistra A. Stamboliyska

Papers

DFT and experimental studies of the structure and vibrational spectra of curcumin

Examination of growth inhibitory properties of synthetic chalcones for which antibacterial activity was predicted.

The infrared spectra and structure of o-sulfobenzimide (saccharin) and of its nitranion: An ab initio force field treatment

The infrared spectra and structure of acetylsalicylic acid (aspirin) and its oxyanion: an ab initio force field treatment

IR spectra and structure of benzylidenemalononitrile and its cyanide, methoxide and heptylamine adducts: experimental and ab initio studies