Cd(II) determination in the presence of aqueous micellar solutions

The equilibrium constants and molar absorptivities for the fast formation of a 1:3 complex between cadmium(II) (Cd(II)) and dithizonate anion, in the presence of cationic and non-ionic surfactants, allowed a simple and fast spectrophotometric determination of total cadmium. Indeed, the molar absorptivities of the Cd(II)-dithizone (Dz) complex formed in the presence of the neutral Triton X-100 and cationic cetyltrimethylammonium bromide (CTAB) surfactants are almost twice the value observed in the standard method and the maxima of absorption are shifted by about 40 nm when compared with the standard method. Clearly, the use of neutral and cationic surfactants promotes a higher value of the molar absorptivities of the complex, resulting in an increase in the sensitivity of the method. Application of the method to the desorption of Cd(II) ions from clays is illustrated.     

Synthesis and characterization of copper(II) and nickel(II) complexes of the Schiff base derived from 2-(2-aminophenyl)benzimidazole and salicylaldehyde

Summary Copper(II) and nickel(II) complexes with the Schiff base derived from 2-(2-aminophenyl)benzimidazole and salicylaldehyde, L, have been prepared. They are of the general types ML₂X₂ (M = Ni or Cu and X = Cl, Br, NO₃ or ClO₄) and NiL(NCS)₂.The compounds have been characterized by elemental analyses, magnetic measurements, e.s.r., electronic and i.r. spectra studies. The i.r. spectra suggest that the molecule, and not the anion, of the Schiff base is coordinated as a bidentate ligand with the metal ion. Possible structures for the complexes have been proposed.     

Antiedematogenic activity of two thiazolidine derivatives: N-tryptophyl-5-(3,5-di-tert-butyl-4-hydroxybenzylidene) rhodanine (GS26) and N-tryptophyl-5-(3,5-di-tert-butyl-4-hydroxybenzylidene)-2,4-thiazolidinedione (GS28)

The search for new anti-inflammatory drugs has been constant in several research centers. The use of the Bioisostery concept allows the elaboration of new bioactive compounds with different properties through the introduction of substitute groups in one or more positions of a main molecule with known biological activity. Preliminary works accomplished at our laboratory with 2,4-thiazolidinedione isosters demonstrated inhibitory activity on edema formation for N-tryptophyl-5-(3,5-di-tert-butyl-4-hydroxybenzylidene)-2,4-thiazolidinedione (GS28) and N-tryptophyl-5-(3,5-di-tert-butyl-4-hydroxybenzylidene) rhodanine (GS26). We verified the antiedematogenic and ulcerogenic activity of these two compounds in Wistar rats. The carrageenan induced paw edema suffered significant (p<0.05) inhibition (28.36% on average) for GS28 (100 mg/kg; v.o.) during the entire time of the experiment. GS26 (50 and 100 mg/kg; v.o.) significantly inhibited (p<0.05) the paw edema dextran induced (22.1 and 27.8%, for the respective doses) after 180 min. The compounds GS26 and GS28 did not show ulcerogenic activity on gastric mucous. The results suggest antiedematogenic action for both compounds without the appearance of gastric lesions.     

NMR characterization of new 10-membered-ring macrolactones and dihydrobenzophenazine-5-one, oxidized derivatives of benzo[a]phenazines

Peroxidation of the phenazine of beta-lapachone using m-ClC6H4CO3H-CH2Cl2 furnished a macrolactone with a rigid 10-membered ring, and the corresponding N-oxide, along with a dihydrobenzophenazine-5-one. All of the new compounds were fully characterized by spectroscopic methods, with the unambiguous assignment of the hydrogens and carbon NMR signals for the N-oxide, with the aid of 2-D NMR, mainly COSY, HMQC, HSQC and HMBC. For the other two compounds some signals could not be assigned owing to their own intrinsic features.     

Simultaneous purification and reversible immobilization of d-amino acid oxidase from Trigonopsis variabilis on a hydrophobic support

Purification and reversible immobilization of d-amino acid oxidase from Trigonopsis variabilis could be simultaneously accomplished by hydrophobic interaction on Phenyl Sepharose CL-4B in the presence of 50 mM pyrophosphate buffer (pH 8.5). The presence of a high salt concentration of 2M, which is generally required for the hydrophobic interactions, was not essential for the hydrophobic immobilization. The enzyme in free as well as immobilized form was optimally active between pH 7.0 and 9.0. The immobilized preparation could be reused in a batch process for the conversion of d-amino acids to α-keto acids. When the activity of the preparation dropped below practical limits, the gel could be regenerated by water wash and recharged with fresh crude extract from yeast.