urobilin and stercobilin

Fluorescence spectra of extracts of fecal material, in the presence of zinc ion, display the well-known green fluorescence used in the Schlesinger test for the urobilinoids, together with several other fluorescences. All of these can be demonstrated in a single spectrum by the synchronous fluorescence technique, which, with new extraction conditions, enables the urobilinoid fluorescence to be detected in quantities of human fecal material down to about 50 ng in mass. This represents a reduction on the order of a thousandfold in the detection limit of the original visual technique; selectivity too is greatly increased. The effects caused by a variety of reagents on the fluorescences have been examined. It is shown that in Edelman's version of the test the presence of mercuric ion largely quenches the fluorescence. The synchronous spectra vary considerably between different samples of human feces and between different mammals according to their diet. The specificity of the recommended technique is discussed with reference to the spectra given by other body materials.

Topics: Acetates; Acetic Acid; Animals; Bile Pigments; Dogs; Feces; Humans; Indicators and Reagents; Iodine; Mercury; Spectrometry, Fluorescence; Swine; Urobilin

Faecal pigments (FPs) are ubiquitous in the environment and are a primary contaminant in groundwater and surface water. This article presents a new analytical paradigm by a fluorescence coupled extraction-based method involving FP fluorescence enhancement and minimization of background fluorescence for high sensitivity detection. FPs show higher fluorescence intensity in aliphatic alcohols due to the breaking down of higher-order H-aggregates into lower-order H-aggregates (dimers). DFT studies using the B3LYP functional and LANL2DZ basis set show π-π stacking and hydrogen-bonding contributions towards forming H-aggregated dimers of FPs in the implicit and explicit solvent environments of 1-hexanol. This study is the first report on the extractability of FPs using 1-hexanol as an efficient extraction medium in comparison to higher-order aliphatic alcohols (1-butanol, 1-hexanol and 1-octanol). Furthermore, FP-Zn(II) complexes in 1-hexanol medium significantly enhance the fluorescence emission intensity (∼14-17 times), and the emission intensity remains stable over time. This further helps to increase the detection limit of FPs in the picomolar to sub-picomolar concentration range. This study proposes a protocol involving extraction of FPs by 1-hexanol followed by the complexation of FPs with Zn(II) in the alcohol media and subsequent fluorimetric detection of the FP-Zn(II) complex with a high level of sensitivity, enabled by reduced interference from the background fluorescence of humic acid. The complexation behaviour of FPs with various metal salts was also examined, which provided an understanding of the fluorescence behaviour of FPs with various other metal ions commonly present in natural environmental water. The proposed analytical method has been further validated using real water samples.

Topics: Bile Pigments; Ethanol; Fluorometry; Solvents; Urobilin

A detailed photophysical study of two faecal pigments (FPs), Urobilin (UB) and Stercobilin (SB), and their zinc complexes [FP-Zn(II)] was carried out. The enhancement of UB and SB fluorescence resulting from the formation of their Zn(II) complexes was attributed to the complexation-induced rigidity of the chromophoric units, and the corresponding decrease of nonradiative decay rate constants of the excited singlet states (k

Topics: Bile Pigments; Fluorescence; Urobilin; Zinc

Clean water is paramount to human health. In this article, we present a technique for detection of trace amounts of human or animal waste products in water using fluorescence emission cavity-enhanced spectroscopy. The detection of femtomolar concentrations of urobilin, a metabolic byproduct of heme metabolism that is excreted in both human and animal waste in water, was achieved through the use of an integrating cavity. This technique could allow for real-time assessment of water quality without the need for expensive laboratory equipment.

Topics: Animals; Bile Pigments; Bilirubin; Environmental Monitoring; Equipment Design; Feces; Heme; Humans; Optics and Photonics; Spectrometry, Fluorescence; Urine; Urobilin; Water Pollutants, Chemical; Water Pollution; Water Purification; Water Quality

Epidemiological studies report a negative association between circulating bilirubin concentrations and the risk for cancer and cardiovascular disease. Structurally related tetrapyrroles also possess in vitro anti-genotoxic activity and may prevent mutation prior to malignancy. Furthermore, few data suggest that tetrapyrroles exert anti-carcinogenic effects via induction of cell cycle arrest and apoptosis. To further investigate whether tetrapyrroles provoke DNA-damage in human cancer cells, they were tested in the single cell gel electrophoresis assay (SCGE). Eight tetrapyrroles (unconjugated bilirubin, bilirubin ditaurate, biliverdin, biliverdin-/bilirubin dimethyl ester, urobilin, stercobilin and protoporphyrin) were added to cultured Caco2 and HepG2 cells and their effects on comet formation (% tail DNA) were assessed. Flow cytometric assessment (apoptosis/necrosis, cell cycle, intracellular radical species generation) assisted in revealing underlying mechanisms of intracellular action. Cells were incubated with tetrapyrroles at concentrations of 0.5, 5 and 17μM for 24h. Addition of 300μM tertiary-butyl hydroperoxide to cells served as a positive control. Tetrapyrrole incubation mostly resulted in increased DNA-damage (comet formation) in Caco2 and HepG2 cells. Tetrapyrroles that are concentrated within the intestine, including protoporphyrin, urobilin and stercobilin, led to significant comet formation in both cell lines, implicating the compounds in inducing DNA-damage and apoptosis in cancer cells found within organs of the digestive system.

Topics: Antioxidants; Bile Pigments; Bilirubin; Caco-2 Cells; Comet Assay; DNA Damage; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Flow Cytometry; Hep G2 Cells; Humans; Intestinal Mucosa; Neoplasms; Osmolar Concentration; Protoporphyrins; Tetrapyrroles; Urobilin

Topics: Bile Pigments; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Feces; Fluorescence; Humans; Porphyrias; Porphyrins; Urobilin

i-Urobilin and 1-stercobilin were separated by high-performance liquid chromatography on a reversed-phase octadecylsilane-bonded column and detected fluorimetrically through formation of phosphor with zinc ions in the eluent. The separation and the intensity of the fluorescence response were affected by concentrations of zinc acetate and sodium borate buffer, pH and methanol content in the eluent. The optimal eluent used consisted of 0.1% zinc acetate in 75 mM boric acid buffer (pH 6.0)-methanol (25:75). The detection limit was 0.2 microgram/l for both i-urobilin and 1-stercobilin (signal-to-noise ratio 2), which makes the method 250-2500 times more sensitive than conventional methods.

Topics: Bile Pigments; Borates; Buffers; Chromatography, High Pressure Liquid; Humans; Hydrogen-Ion Concentration; Methanol; Spectrometry, Fluorescence; Urobilin; Zinc

Topics: Bile Pigments; Bilirubin; In Vitro Techniques; Urobilin

Topics: Animals; Bile Pigments; Biological Transport; Body Fluids; Chickens; Metabolism; Nitrogen; Poultry; Research; Ultraviolet Rays; Urobilin

Topics: Bile Pigments; Optical Rotation; Urobilin

Topics: Bile Pigments; Humans; Urobilin

Topics: Bile Pigments; Biliary Tract; Biliary Tract Diseases; Feces; Humans; Liver Diseases; Urine; Urobilin

Topics: Bile Pigments; Bilirubin; Feces; Humans; Urobilin

Topics: Anti-Bacterial Agents; Antibiotics, Antitubercular; Bile Pigments; Dermatologic Agents; Feces; Urobilin

Topics: Bile Pigments; Biliary Tract; Biliary Tract Diseases; Liver; Liver Function Tests; Urobilin

Topics: Bile Pigments; Urobilin

Topics: Bile Pigments; Urobilin