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Girish et al.: Antibacterial Activity of Curcumin-cobalt(II) Complex To improve the bioavailability of curcumin numerous approaches were attempted, which included complexation with metal ions. In the present study, a metal ion complex of cobalt(II) with curcumin was synthesized and screened for in vitro antibacterial activity in comparison with curcumin on seven bacterial strains, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Shigella flexneri, Proteus vulgaris and Staphylococcus aureus. The cobalt-curcumin complex was effective against all strains tested and the activity was greater than that exhibited by curcumin. Comparison of the inhibitory activity with the macrolide antibiotic azithromycin revealed that cobalt-curcumin complex was as active as the antibiotic. The cobalt-curcumin complex could be a suitable candidate for further in vivo investigations. This is the first report of antibacterial activity of cobalt-curcumin complex against all the bacterial strains tested except Escherichia coli.

The interaction of 10-(3'-N-morpholinopropyl)phenoxazine [MPP], 10-(4'-N-morpholinobutyl)phenoxazine [MBP], 10-(3'-N-morpholinopropyl)-2-chlorophenoxazine [MPCP], 10-(3'-N-piperidinopropyl)-2-chlorophenoxazine [PPCP] or 10-(3'-N-morpholinopropyl)-2-trifluoromethylphenoxazine [MPTP] with bovine serum albumin (BSA) has been studied by gel filtration and equilibrium dialysis methods. The binding of these modulators, based on dialysis experiments, has been characterized using the following parameters: percentage of bound drug (b), the association constant (K 1), the apparent binding constant (k) and the free energy change (∆F°). The binding of phenoxazine derivatives to serum transporter protein, BSA, is correlated with their octanol-water partition coefficient, log 10 P. In addition, effect of the displacing activities of hydroxyzine and acetylsalicylic acid on the binding of phenoxazine derivatives to albumin has been studied. Results of the displacement experiments show that phenoxazine benzene rings and tertiary amines attached to the side chain of the phenoxazine moiety are bound to a hydrophobic area on the albumin molecule.

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Abstract. 10-[4 H -(N-diethylamino)butyl]-2-chlorophenoxazine (DBCP) undergoes a reversible one-electron oxidation with cerium (IV) to form a pink coloured radical cation [DBCP Á ] in the presence of stoichiometric amounts [DBCP: Ce(IV) 1:1] of the reactants. The radical cation underwent a second oneelectron oxidation to form a brownish yellow coloured dication [DBCP 2 ] in the presence of more than one equivalent of cerium(IV), which was characterized by UV-vis, IR and mass spectrometry. The cyclic voltammogram of DBCP exhibited two anodic waves at 721 mV and 1158 mV and two cathodic waves at 653 mV and 1076 mV at a scan rate of 24 mV/s. The peak at 721 mV corresponds to the oxidation of DBCP to the radical cation [DBCP Á ] and the second anodic peak at 1158 mV stands for the oxidation of the radical cation to the dication [DBCP 2 ]. Bromine oxidizes DBCP to three products as evidenced by HPLC and the tentatively predicted structures based on the massspectral data support the formation of brominated oxidized products. In order to explore the analytical applications, the optimum conditions for the successful use of DBCP as a redox indicator in the macro and micro estimation of ascorbic acid, methionine, isoniazid, phenylhydrazine hydrochloride and biotin using chloramine-B as oxidant, have been developed. The indicator gives sharp and stoichiometric end-points.