Tokyo Pearl Co. Ltd.

The mol. and crystal structure of curcumin was investigated by X-ray anal. at 23°C.Anhydrous crystal was obtained from methanol.The crystal is monoclinic, and the space group is P2/n with Z = 4.The cell dimensions are α = 12.688(3) Å, b = 7.2061(5) ÅA, c = 19.897(5) ÅA, β = 95.28°(1).In this structure, the mols. are aggregated intermolecularly into infinite chains linked between the Ph OH and the carbonyl O (or -OH).The hydrogen bond between O1-O4 was weaker than that found in previous work due to a longer intermol. distance.It could be suggested that the enol ring was found to be more asym. than in the previous work.Such a network formation is attributed to intermol. hydrogen bonds between terminal phenol moieties of curcumin assembling in a fibrous structure.Furthermore, it was found that the hydrogen bonding played an important role in the mol. packing of crystal curcumin.Crystal curcumin interacted with solids and showed potential for use as an environmental probe for the estimation of solid surfaces on the basis of its fluorescent properties and interactions with polar materials.

Curcumin, is a kind of natural dye having fluorescence.Sodium salts of curcumin are susceptible of color fading with time.The color lasting of curcumin was achieved by the complexation of curcumin with basic amino acids (L-arginine, L-lysine) and alkylamines for the purpose of the stabilization in aqueous solutionsFurthermore, alkylamine salts showed surface-tension-lowering actions and formed micelles in aqueous solutionsOn the other hand, n-hexylamine salt of curcumin was effective for getting finger print spectra in fluorophotometry, reflecting the microenvironment of the membrane surfaces (keratin, collagen, and fibroin) as an environmental probe.The corresponding emission spectra were different from each other depending on the protein membranes.Furthermore, emission peaks of protein membranes shifted towards shorter wavelengths than that of cellulose (502nm).Methylthiomethyl derivative was prepared from curcumin for the improvement of the antioxidative activity and its effectiveness was confirmed.

Surfactin 2-pyrenyl-2-oxoethyl ester (I) was prepared from surfactin and 1-bromoacetylpyrene as a fluorescent probe with potential multifunctionalities, such as amphipathic characteristics, β-sheet formation, and ion sequestration.I was found to be useful as an indicator for the recognition of hydrophobic microenvironments in surfactant micelles.As a fluorescent probe, I was also used for the evaluation of the microenvironment in micelles and on the surface of biomembranes.