Curcuminoids are a safe natural food coloring additive with anti-inflammatory, antioxidant, and anticarcinogenic activities. Although demethoxycurcumin is one of the major bioactive constituents of curcuminoids, knowledge about its metabolic fate is scant. In the present study, four new metabolites, 5-dehydroxy-hexahydro-demethoxycurcumin-A (M-1), 5-dehydroxy-hexahydro-demethoxycurcumin-B (M-2)...

Molecules bearing β-keto-enol functionality are potential candidates for coordination chemistry. Reported herein is the first synthesis and use of a novel designed ligand based on β-keto-enol group embedded with pyridine and thiophene moieties. The product was prepared in a one-step procedure by mixed Claisen condensation and was characterized by EA, m/z, FT-IR, (¹H, (13)C) NMR and single-cryst...

A series of new bis azo dyes were synthesized starting from aromatic diamine with S/SO2 bridges and cyclic-1,3-dicarbonyl groups; contain active methylene group, namely; 3,3-dimethyl-1,5-cyclohexadione (dimedone), 1,3-cyclohexadione 2,2-dimethyl-1,3-dioxane-4,6-dione to give 1-6. Whether the reaction is complete purity compounds checked TLC. The structure newly synthezed was investigated by usi...

In his book The Double Helix, James Watson describes an early proposal for DNA structure in which equal bases pair with each other. He writes: ‘‘My scheme was torn to shreds the following noon. Against me was the awkward chemical fact that I had chosen the wrong tautomeric forms for guanine and thymine.’’ This fact was pointed out to him by the American crystallographer Jerry Donahue who ‘‘ . ....

We investigate the acid-base proton exchange reaction in a microsolvated bifunctional chromophore by means of quantum chemical calculations. The UV/vis spectroscopy shows that equilibrium of the keto- and enol-forms in the electronic ground state is shifted to the keto conformation in the excited state. A previously unknown mechanism involving a hydroxide ion transport along a short water wire ...

The properties of xanthurenic acid (XAN) in ground and photoexcited states have been studied using steady-state and time-resolved optical methods as well as quantum chemistry calculations. In neutral aqueous solution and in alcohols, XAN is present in a single tautomeric form (keto form), whereas in aprotic solvents and probably in basic aqueous solutions, more than one tautomeric form is prese...

Fapy-adenine, Fapy-guanine, Tautomerism, Solvent Effect The results of theoretical geometry prediction of formamidopyrimidine(fapy)-adenine and fapy-guanine tautomers are presented. Among 54 potential tautomeric structures of fapyadenine the most stable structure corresponds to the diamino-keto isomer. The solvent effect has insignificant influence on the fapy-adenine tautomers succession. The ...