Effect of beryllium chloride on porphyrin metabolism in pregnant mice administered by subcutaneous injection

Molecular docking studies of disubstituted diaryl diselenides as mammalian δ-aminolevulinic acid dehydratase enzyme inhibitors

δ-Aminolevulinic acid dehydratase (δ-ALAD) is a metalloprotein that catalyzes porphobilinogen formation. This enzyme is sensitive to pro-oxidants and classically used as a biomarker of lead (Pb) intoxication. Diphenyl diselenide [(PhSe)₂] and analogs bis(4-chlorophenyl) diselenide [(pCl₃PhSe)₂], bis(4-methoxyphenyl)diselenide [(pCH₃OPhSe)₂], and bis[3-(trifluoromethy)phenyl] diselenide [(mCF₃PhSe)₂] inhibit mammalian δ-ALAD by oxidizing enzyme cysteinyl residues, which are involved in diselenide-induced toxicity. 2-Cysteinyl residues from δ-ALAD are believed to sequentially interact with (PhSe)₂. Thus this study utilized protein-ligand docking analyses to determine which cysteinyl residues might be involved in the inhibitory effect of (PhSe)₂ and analogs toward δ-ALAD. All diselenides that interact in a similar manner with the active site of δ-ALAD were examined. Docking simulations indicated an important role for π-π interactions involving Phe208 and cation-π interactions involving Lys199 and Arg209 residues with the aromatic ring of (PhSe)₂ and analogs. Based upon these interactions an approximation between Se atoms and -SH of Cys124, with distances ranging between 3.3 Å and 3.5 Å, was obtained. These data support our previous postulations regarding the mechanism underlying δ-ALAD oxidation mediated by (PhSe)₂ and analogs. Based on protein-ligand docking analyses, data indicated that -SH of Cys124 attacks one of the Se atoms of -SH of (PhSe)₂ releasing one PhSeH (selenophenol). Subsequently, the -SH of Cys132 attacks the sulfur atom of Cys124 (from the bond of E-S-Se-Ph indermediate), generating the second PhSe⁻, and the oxidized and inhibited δ-ALAD. In conclusion, AutoDock Vina 1.1.1 was a useful tool to search for diselenides inhibitors of δ-ALAD, and, most importantly, it provided insight into molecular mechanisms involved in enzyme inhibition.

Attenuation of beryllium induced hepatorenal dysfunction and oxidative stress in rodents by combined effect of gallic acid and piperine

We determined a minimum effective dose of gallic acid (3,4,5-trihydroxy benzoic acid; 50 mg/ kg, i.p.) and piperine (10 mg/kg, p.o.) through their therapeutic potential and further evaluated them individually and in combination against beryllium-induced biochemical alterations and oxidative stress consequences in female albino rats. The administration of beryllium altered blood biochemical variables by significantly depleting hemoglobin, albumin and urea, whereas it enhanced bilirubin and creatinine. The release of serum transaminase, lactate dehydrogenase and gamma-glutamyl transpeptidase was significantly greater, and was concomitant with a decrease in serum alkaline phosphatase. A significant increase in lipid peroxidation and a decrease in glutathione, superoxide dismutase and catalase in the liver and kidney was an indication of oxidative stress due to beryllium exposure. Individual administration of gallic acid and piperine moderately reversed the altered biochemical variables, whereas the combination of these was found to completely reverse the beryllium-induced biochemical alterations and oxidative stress consequences. We concluded that gallic acid exerts a synergistic effect when administered with piperine and provides a more pronounced therapeutic potential in reducing beryllium-induced hepatorenal dysfunction and oxidative stress consequences.

Influence ofα-tocopherol, propolis and piperine on therapeutic potential of tiferron against beryllium induced toxic manifestations

The therapeutic potential of the chelator tiferron (sodium-4,5-dihydroxy-1,3-benzene disulphonate; 300 mg kg(-1), i.p.) and adjuvants, i.e. alpha-tocopherol (25 mg kg(-1), p.o.), propolis (a honey-bee hive product; 200 mg kg(-1), p.o.) and piperine (10 mg kg(-1), p.o.) were evaluated individually and in combination against beryllium induced biochemical alterations and oxidative stress consequences. Female albino rats were exposed to beryllium nitrate (1 mg kg(-1), i.p.) daily for 28 days followed by treatment with the above mentioned therapeutic agents for 5 consecutive days. Administration of beryllium altered blood biochemical variables with significant depletion in hemoglobin, blood sugar, total serum protein, albumin and significant enhancement in the release of serum transaminases. A significantly increased lipid peroxidation and a decreased level of glutathione after beryllium exposure indicated oxidative stress in the liver and kidney. Beryllium exposure decreased total protein and glycogen contents, whereas triglycerides and cholesterol increased significantly in liver and kidney. Individual administration of all the four compounds showed significant therapeutic potential in reverse of some of the biochemical parameters mentioned above. Furthermore, the combination of tiferron with alpha-tocopherol, propolis or piperine, respectively, could reverse all the variables significantly more towards the control. None of the test compounds showed any significant change in choleretic activity (bile flow and bile solids), indicating that these compounds had no adverse effects at these dose levels. It was concluded that all the combinations of tiferron and adjuvants played a beneficial role in reducing beryllium induced systemic toxicity at relatively lower doses and the combination of tiferron and propolis showed a more pronounced therapeutic potential.

Rapid and Simultaneous Determination of Coproporphyrin and Protoporphyrin in Feces by Derivative Matrix Isopotential Synchronous Fluorescence Spectrometry

Background: Measurement of fecal porphyrins is important in the diagnosis of porphyria, but conventional methods to measure them have drawbacks. We explored the use of derivative matrix isopotential synchronous fluorescence (MISF) spectrometry for the measurement of coproporphyrin and protoporphyrin.

Methods: The MISF scanning route was selected based on information from the three-dimensional fluorescence spectrum, which was a combination of the contour line of protoporphyrin via a detection point of coproporphyrin and that of coproporphyrin via a detection point of protoporphyrin. Derivative technique eliminated the constant interfering signals. MISF was used to measure porphyrins in stools from 2 pregnant women and 20 healthy volunteers.

Results: The coproporphyrin and protoporphyrin spectra were resolved with almost no mutual interference. The amplitudes of the derivative peaks were linearly related to the concentrations of coproporphyrin up to 310 nmol/L and protoporphyrin up to 590 nmol/L. The detection limits for coproporphyrin and protoporphyrin were 1.2 and 1.7 nmol/L, respectively. The within-run imprecision (CV; n = 6) was 2.2% at 175 nmol/L for coproporphyrin and 2.3% at 500 nmol/L for protoporphyrin. Bland–Altman analysis indicated no significant differences between the proposed MISF method and conventional spectrophotometry or fluorimetry. Mean (SD) recoveries of porphyrins added to fecal samples were of 98 (7)% for coproporphyrin and 102 (4)% for protoporphyrin.

Conclusions: This technique provides spectral resolution of coproporphyrin and protoporphyrin, obviating the need for chromatographic separation, and measurements can be made in a single scanning. The method also appears suitable for routine testing of large numbers of samples.