Synthesis, Characterization and Biological Activities of Creatinine Amides and Creatinine Schiff Bases.

BACKGROUND: In spite of substantial progress in scientific cognizance and medical technology, still infectious diseases are among the leading cause of morbidity and mortality. Creatinine and Schiff bases are well known for their diverse range of biological activities and thought to be emerging and useful therapeutic target for the treatment of several diseases. METHODS: The present work was aimed to illustrate the influence of substitution of amides and Schiff bases on creatinine and their antimicrobial, antioxidant and anti-urease effectiveness was determined. Creatinine substituted amides (1-2) and creatinine Schiff bases (3-7) were synthesized and characterized by NMR and IR spectral data in combination with elemental analysis. All the compounds (1-7) were investigated on Jack bean urease for their urease inhibitory potential. Investigation of antimicrobial activity of the compounds was made by the agar dilution method. Moreover, 1,1-diphenyl-2- picrylhydrazyl (DPPH) method was used to determine their antioxidant potential. Molecular docking studies were also carried out to elucidate their relationship with the binding pockets of the enzyme. RESULTS: The compounds were found to be potent inhibitors of urease. The synthesized derivatives exhibited significant inhibition against Gram-positive and Gram-negative bacterial strains, as compared to standard, ciprofloxacin. Creatinine based derivatives exhibited potential antifungal activity when tested on infectious and pathogenic fungal strains. Similarly, most of the compounds exhibited good antioxidant activity. CONCLUSION: These derivatives may serve as a source of potential antioxidants and also help to retard microbial growth in food industry. Similarly, the studies provide a basis for further research to develop more potent urease inhibitory compounds of medicinal /agricultural interest.

Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea.

Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations.

Synthesis of 1-(4-aminobutyl)-2-iminoimidazolidin-4-one aimed at preparation of a creatinine-specific antibody.

For the purpose of obtaining a creatinine-specific antibody, a creatinine derivative with 4-aminobutyl, which was served as a linker for preparing the creatinine-bovine serum albumin (BSA) conjugate, was synthesized from 4-benzylaminobutan-1-ol in 8 steps. Production of anti-creatinine antibodies was observed in two rabbits using the creatinine-BSA conjugate, although their titer was rather low.

Estandarización de los procedimientos de medida de creatinina: estado actual / Standardization of creatinine measurement methods: current status

La implementación de las ecuaciones de estimación del filtrado glomerular (FG) en los informes del laboratorio clínico ha colocado en el punto de mira las limitaciones de la medida de creatinina y promovido la puesta en marcha de un programa internacional para su estandarización. Hemos analizado el estado actual de implementación de dicho programa respecto a la trazabilidad, la conmutabilidad, la imprecisión, el error sistemático, así como la información acerca del tipo de ecuación a utilizar y sobre los valores de referencia, de los reactivos de creatinina más utilizados en los laboratorios españoles. La mayoría de los procedimientos de medida presentan trazabilidad al método de referencia y satisfacen los requerimientos de imprecisión; sin embargo, la información disponible sobre la inexactitud, el error total de medida, la verificación de la conmutabilidad de los materiales de calibración utilizados, la ecuación de FG a utilizar y los valores de referencia en población pediátrica es insuficiente o inexistente en la mayoría de las firmas comerciales evaluadas (AU)

The implementation of equations for estimating glomerular filtration rate (GFR) in clinical laboratory reports has placed the spotlight on the limitations of creatinine measurements and has promoted the establishment of an international program for standardisation. We have analysed the current state of implementation of this program with regard to traceability, commutability, imprecision, systematic error, as well as information on the type of equation to use and reference values, as well as the creatinine reagents commonly used in Spanish laboratories. Most of the measurement procedures have traceability to the reference method, and meet the requirements of imprecision. The available information available on the inaccuracy, the total error of measurement, verification of the commutability of calibration materials used, the glomerular filtration equation to use, and reference values in the paediatric population is unsatisfactory or non-existent in most commercial firms evaluated (AU)

Non-enzymatic cyclization of creatine ethyl ester to creatinine.

Creatine ethyl ester was incubated at 37 degrees C in both water and phosphate-buffered saline and the diagnostic methylene resonances in the (1)H NMR spectrum were used to identify the resultant products. It was found that mild aqueous conditions result in the cyclization of creatine ethyl ester to provide inactive creatinine as the exclusive product, and this transformation becomes nearly instantaneous as the pH approaches 7.4. This study demonstrates that mild non-enzymatic conditions are sufficient for the cyclization of creatine ethyl ester into creatinine, and together with previous results obtained under enzymatic conditions suggests that there are no physiological conditions that would result in the production of creatine. It is concluded that creatine ethyl ester is a pronutrient for creatinine rather than creatine under all physiological conditions encountered during transit through the various tissues, thus no ergogenic effect is to be expected from supplementation.

Qualitative in vitro NMR analysis of creatine ethyl ester pronutrient in human plasma.

There are a number of forms of creatine available that attempt to improve the solubility and permeability, with the anticipation this will result in an improved pharmacokinetic profile and ultimately an enhanced ergogenic response. Previous research has shown that the different salt forms can improve solubility resulting in slightly altered pharmacokinetic profiles, however specific data exploring the conversion of esterified derivatives to creatine is lacking. The purpose of this study was to examine the assertion that creatine ethyl ester undergoes enzymatic conversion to creatine in human tissues. The IN VITRO response of creatine ethyl ester to incubation in human plasma was examined by H-NMR analysis. Lyophilized human plasma was reconstituted in D2O and phosphate-buffered saline and 1.5 mg of the analyte was added. Following incubation at 37 degrees C for 4 h and subsequent protein precipitation, the supernatant was analyzed by NMR, utilizing the diagnostic chemical shift of the methylene signal to determine the species present in solution, I.E. creatine ethyl ester, creatine, or creatinine. Both creatine and creatinine were run in parallel as control experiments and each assay was run in triplicate. As expected both creatine and creatinine remained unchanged. However, conversion of creatine ethyl ester to creatine by the esterases in human plasma was not observed to any detectable extent and the only species detected after the incubation period was creatinine. While not a definitive characterization of the IN VIVO behavior, these results strongly warrant a complete IN VIVO pharmacokinetic analysis of creatine ethyl ester since it appears these "pronutrients" may actually provide large exogenous sources of pharmacologically inactive creatinine rather than ergogenic creatine.

Isoleucine 69 and valine 325 form a specificity pocket in human muscle creatine kinase.

Creatine kinase (CK) catalyzes the reversible phosphorylation of creatine by ATP. From a structural perspective, the enzyme utilizes two flexible loop regions to sequester and position the substrates for catalysis. There has been debate over the specific roles of the flexible loops in substrate specificity and catalysis in CK and other related phosphagen kinases. In CK, two hydrophobic loop residues, I69 and V325, make contacts with the N-methyl group of creatine. In this study, we report the alteration of the substrate specificity of CK through the mutagenesis of V325. The V325 to glutamate mutation results in a more than 100-fold preference for glycocyamine, while mutation of V325 to alanine results in a slight preference of the enzyme for cyclocreatine (1-carboxymethyl-2-iminoimidazolidine). This study enhances our understanding of how the active sites of phosphagen kinases have evolved to recognize their respective substrates and catalyze their reactions.

Creatinine, lactam and cyclic peptide formation by the action of C2N2 on creatine, omega-amino acids and peptides.

Cyanogen, C2N2, affords a means to drive intramolecular conversion of ammonium salts to amides. Unlike other carboxyl activating agents, such as carbodiimides, used in peptide syntheses expressly to drive intermolecular condensations to form amide (peptide) bonds, C2N2 appears restricted to driving only intramolecular condensations. Rates decreased as a function of solvent composition as follows: organic much greater than 70%-80% aqueous organic much greater than 50% aqueous organic greater than H2O. Temperature dependence was also a function of solvent composition. Rates did not strongly reflect steric constraints with beta-lactams and epsilon-lactams forming at comparable rates to rates for gamma- and delta-lactam formation; likewise L-Leu-L-Leu cyclized at about the same rate as L-Leu-D-Leu. Pro-Pro is well documented as having a salt-bridged structure in a variety of solvents where it cyclized extremely rapidly. The reaction is proposed to be dependent on reaction of C2N2 with salt-bridges on the basis of 1) its preponderant if not exclusively intramolecular nature, 2) its solvent dependence, 3) its temperature dependence and 4) the conversion of known salt-bridged structures to amides. This reaction is a model for the observed rapid reaction of salt bridges in proteins.