Histological and immunohistochemical evaluation of the effect of tartrazine on the cerebellum, submandibular glands, and kidneys of adult male albino rats

Tartrazine is one of the most widely used food additives. The present investigation was carried out on 40 adult male albino rats. They were divided into four groups of ten animals for each. Group I was considered as a control group. Group II was treated with tartrazine daily in a dose 7.5 mg/kg body weight by oral gavage for 30 days. Group III was received 15 mg/kg body weight of tartrazine for the same period. Group IV was administered tartrazine in a dose 100 mg/kg body weight for the whole duration of the experiment. At the end of experiment, samples from the cerebellum, submandibular salivary glands, and kidneys were fixed in neutral buffered formalin 10% and prepared routinely for paraffin sectioning and staining for histopathological and immunohistochemical investigations of proliferating cell nuclear antigen "PCNA" and glial fibrillar acidic protein "GFAP". Tartrazine-treated groups revealed histopathological degenerative changes in the obtained organs. In group II, the cerebellum showed subcortical edema, congestion of the blood vessels, cytoplasmic vacuolations, and pyknosis of the nuclei in the gray matter neurons. Concerning the submandibular glands, they expressed cytoplasmic vacuolations and pyknosis of the nuclei of the acinar cells, congestion of the interacinar blood capillaries, and degenerative changes in the striated duct. The kidneys appeared with interstitial hemorrhage and dilatation of the glomerular capillaries. The PCT and DCT showed ill-defined cell boundaries. The collecting tubules in the renal medulla appeared with flattened epithelial cells. The severity of these changes increases by increasing the dose of tartrazine in group III and reach to the highest level in group IV. The immunoexpression of the GFAP in the cerebellum of the experimental groups was intense compared to the control group. The immunoreactivity of PCNA in the nuclei of the acinar and ductal cells of the submandibular gland and the cells of the renal cortex and medulla was strong in the tartrazine-treated groups compared to the control group. The current study concluded that the tartrazine had serious effect on the cerebellum, submandibular glands, and kidneys that adversely affect the functions of these organs.

In silico and crystallographic studies identify key structural features of biliverdin IXβ reductase inhibitors having nanomolar potency

Heme cytotoxicity is minimized by a two-step catabolic reaction that generates biliverdin (BV) and bilirubin (BR) tetrapyrroles. The second step is regulated by two non-redundant biliverdin reductases (IXα (BLVRA) and IXβ (BLVRB)), which retain isomeric specificity and NAD(P)H-dependent redox coupling linked to BR's antioxidant function. Defective BLVRB enzymatic activity with antioxidant mishandling has been implicated in metabolic consequences of hematopoietic lineage fate and enhanced platelet counts in humans. We now outline an integrated platform of in silico and crystallographic studies for the identification of an initial class of compounds inhibiting BLVRB with potencies in the nanomolar range. We found that the most potent BLVRB inhibitors contain a tricyclic hydrocarbon core structure similar to the isoalloxazine ring of flavin mononucleotide and that both xanthene- and acridine-based compounds inhibit BLVRB's flavin and dichlorophenolindophenol (DCPIP) reductase functions. Crystallographic studies of ternary complexes with BLVRB-NADP⁺-xanthene-based compounds confirmed inhibitor binding adjacent to the cofactor nicotinamide and interactions with the Ser-111 side chain. This residue previously has been identified as critical for maintaining the enzymatic active site and cellular reductase functions in hematopoietic cells. Both acridine- and xanthene-based compounds caused selective and concentration-dependent loss of redox coupling in BLVRB-overexpressing promyelocytic HL-60 cells. These results provide promising chemical scaffolds for the development of enhanced BLVRB inhibitors and identify chemical probes to better dissect the role of biliverdins, alternative substrates, and BLVRB function in physiologically relevant cellular contexts.

Photodynamic Efficiency of Xanthene Dyes and Their Phototoxicity against a Carcinoma Cell Line: A Computational and Experimental Study

The aim of this study is to assess the insights of molecular properties of the xanthene dyes [fluorescein (FL), Rose Bengal (RB), erythrosin B (EB), and eosin Y (EY)] to correlate systematically their photodynamic efficiency as well as their phototoxicity against a carcinoma cell line. The phototoxicity was evaluated by comparing the values of the medium inhibitory concentration (IC50) upon HEp-2 cells with the xanthene corresponding photodynamic activity using the uric acid as a chemical dosimeter and their octanol-water partition coefficient (log⁡P). RB was the more cytotoxic dye against HEp-2 cell line and the most efficient photosensitizer in causing photoxidation of uric acid; nevertheless it was the only one characterized as being hydrophobic among the xanthenes studied here. On the other hand, it was observed that the halogen substituents increased the hydrophilicity and photodynamic activity, consistent with the cytotoxic experiments. Furthermore, the reactivity index parameters, electric dipole moment, molecular volume, and the frontier orbitals were also obtained by the Density Functional Theory (DFT). The lowest dipole moment and highest molecular volume of RB corroborate with its highest hydrophobicity due to heavy atom substituents like halogens, while the halogen substituents did not affect expressively the electronic features at all.

Comparative protective effects of royal jelly and cod liver oil against neurotoxic impact of tartrazine on male rat pups brain

This study is aimed to evaluate the possible neurotoxic effect of tartrazine (T), an extensively used synthetic azo dye, as well as to determine the potential modulatory role of cod liver oil (CLO) or royal jelly (RJ) against such effects. For this purpose, thirty-six male rat pups were allocated into six groups. The 1st group received distilled water (control group), the 2nd group was given 300 mg RJ/kg bw (RJ group), the 3rd group was given 0.4 ml CLO/kg bw (CLO group), the 4th was given 500 mg T/kg bw (T group). The 5th group was given T concurrently with RJ (TRJ group) and the 6th group was given T concurrently with CLO (TCLO group), at the same doses as the former groups. All treatments were given orally for 30 consecutive days. The concentrations of different brain neurotransmitters, gamma amino butyric acid (GABA), dopamine (DA) and serotonin (5HT) as well as the antioxidant and oxidative stress biomarkers were measured in the brain homogenates. An immunohistochemical staining of the cerebral cortex was applied with the anti-ssDNA antibody (an apoptotic cell marker) to reveal the changes in brain structure. The T group revealed a significant decrease in the concentration of the brain neurotransmitters, a sharp shortage in the level of antioxidant biomarkers (super oxide dismutase, catalase and the reduced glutathione), a marked increase in malondialdehyde levels, and numerous apoptotic cells in the brain cortex compared with the other groups. Interestingly, all the previously mentioned parameters were almost retrieved in both the TRJ and TCLO groups compared to the T group. These results conclusively demonstrate that RJ and CLO administration provides sufficient protection against the ruinous effects of T on rat pups brain tissue function and structure.

Ecotoxicity of xanthene dyes and a non-chlorinated bisphenol in soil

Soil eco-toxicity testing was conducted in support of Canada's Chemical Management Plan (CMP) to fill data gaps for organic chemicals known to primarily partition to soil, and of which the persistence and inherent toxicity are uncertain. Two compounds representative of specific classes of chemicals: non-chlorinated bisphenols containing an -OH group (4,4'-methylenebis(2,6-di-tert-butylphenol (Binox)) and xanthene dyes (2',4',5',7'-tetrabromo-4,5,6,7-tetrachloro-3',6'-dihydroxy-, disodium salt (Phloxine B), 2',4',5',7'-tetrabromofluorescein (TBF), 4',5'-dibromofluorescein (DBF), and 4,5,6,7-tetrachlorofluorescein (TCF)) were evaluated. The effect of these substances on plant growth (Elymus lanceolatus and Trifolium pratense) and soil invertebrate survival and reproduction (Folsomia candida and Eisenia andrei) were assessed using a field-collected sandy soil. Binox was persistent throughout testing (up to 63 d) with an average recovery of 77±2.9% at test end. Binox was not toxic to plants (IC50s>1076 mg kg(-1)) or E. andrei (IC50s>2651 mg kg(-1)); however, a significant reduction in F. candida adult survival and reproduction (IC50=89 (44-149) mg kg(-1)) was evident. Phloxine B was also persistent throughout testing, with an average recovery of 82±3.0% at test end. Phloxine B was significantly more toxic than Binox, with significant reductions in plant root growth (IC50s ≥ 11 mg kg(-1)) and invertebrate reproduction (IC50s ≥ 22 mg kg(-1)). DBF toxicity was not significantly different from that of Phloxine B for plant root growth (IC50s ≥ 30 mg kg(-1)), but was significantly less toxic for shoot growth (IC50s ≥ 1758 mg kg(-1)), and invertebrate adult survival (IC50s ≥ 2291 mg kg(-1)) and reproduction (IC50s ≥ 451 mg kg(-1)). A comparison between all four xanthene dyes was completed using F. candida, with the degree of toxicity in the order of Phloxine B ≥ TBF∼DBF>TCF. The results from these studies will contribute to data gaps for poorly understood chemicals (and chemical groupings) under review for environmental risk assessments, and will aid in the validation of model predictions used to characterize the fate and effects of these substances in soil environments.

On-line HPLC analysis system for metabolism and inhibition studies in precision-cut liver slices

A novel approach for on-line monitoring of drug metabolism in continuously perifused, precision-cut liver slices (PCLS) in a microfluidic system has been developed using high-performance liquid chromatography with UV detection (HPLC-UV). In this approach, PCLS are incubated in a microfluidic device made of poly(dimethylsiloxane) (PDMS) by continuous, single-pass perifusion with fresh medium. Two syringe pumps are incorporated into the system to infuse substrates or inhibitors at varying concentrations into the perfusion medium just before the chip entrance. The medium containing the metabolites produced by the PCLS is directed toward an injection loop. Once filled, the content of this injection loop is automatically injected onto an HPLC for analysis. The on-line analysis of metabolites was tested by using the substrate, 7-hydroxycoumarin (7-HC). Rapid switching between substrate and solvent control was possible, and a direct metabolic response of the liver slice to perifusion with substrate was detected. Very stable phase II metabolism over a period of 24 h was observed. The inhibitory effect of phloxine B on the formation of 7-hydroxycoumarin glucuronide (phase II product of 7-HC) was also investigated. Phloxine B was injected into the incubation medium in increasing concentrations varying from 0 to 200 μM. The results showed a concentration-dependent inhibition of 7-HC glucuronide formation and allowed the calculation of an IC50 value (concentration in which 50% of the enzyme is inhibited) of ∼85 μM using one single liver slice. On-line detection was also shown to be advantageous for the detection of unstable metabolites. This was demonstrated by determination of the metabolites of the drug diclofenac. The reactive metabolite, acyl glucuronide, was detected at relatively high concentrations which remained very constant over a period of 4 h. In contrast, only low and decreasing amounts of diclofenac acyl glucuronide could be measured in the conventional well-plate incubation system. The advantages of this novel on-line analysis system for PCLS include the capability to obtain direct information about tissue function, assess the concentration dependence of drug-drug interactions in one single slice, and detect unstable metabolites. The system also enables fast analysis without the need to store samples, thus eliminating the associated freeze-thaw problems, and allows the simultaneous analysis of multiple metabolites.

Toxicity of xanthene food dyes by inhibition of human drug-metabolizing enzymes in a noncompetitive manner

The synthetic food dyes studied were rose bengal (RB), phroxine (PL), amaranth, erythrosine B (ET), allura red, new coccine, acid red (AR), tartrazine, sunset yellow FCF, brilliant blue FCF, and indigo carmine. First, data confirmed that these dyes were not substrates for CYP2A6, UGT1A6, and UGT2B7. ET inhibited UGT1A6 (glucuronidation of p-nitrophenol) and UGT2B7 (glucuronidation of androsterone). We showed the inhibitory effect of xanthene dye on human UGT1A6 activity. Basic ET, PL, and RB in those food dyes strongly inhibited UGT1A6 activity, with IC₅₀ values = 0.05, 0.04, and 0.015 mM, respectively. Meanwhile, AR of an acidic xanthene food dye showed no inhibition. Next, we studied the inhibition of CYP3A4 of a major phase I drug-metabolizing enzyme and P-glycoprotein of a major transporter by synthetic food dyes. Human CYP3A4 and P-glycoprotein were also inhibited by basic xanthene food dyes. The IC₅₀ values of these dyes to inhibit CYP3A4 and P-glycoprotein were the same as the inhibition level of UGT1A6 by three halogenated xanthene food dyes (ET, PL, and RB) described above, except AR, like the results with UGT1A6 and UGT2B7. We also confirmed the noninhibition of CYP3A4 and P-gp by other synthetic food dyes. Part of this inhibition depended upon the reaction of ¹O₂ originating on xanthene dyes by light irradiation, because inhibition was prevented by ¹O₂ quenchers. We studied the influence of superoxide dismutase and catalase on this inhibition by dyes and we found prevention of inhibition by superoxide dismutase but not catalase. This result suggests that superoxide anions, originating on dyes by light irradiation, must attack drug-metabolizing enzymes. It is possible that red cosmetics containing phloxine, erythrosine, or rose bengal react with proteins on skin under lighting and may lead to rough skin.

Inhibition of human CYP3A4, UGT1A6, and P-glycoprotein with halogenated xanthene food dyes and prevention by superoxide dismutase

Synthetic food dyes are xenobiotics, and, after ingestion, portions of these dyes may be absorbed and metabolized by phase I and II drug-metabolizing enzymes, and excreted by transporters of phase III enzymes. In the previous report, it was shown that inhibition of UDP-glucuronosyltrasnferase 1A6 occurred following ingestion of phloxine, erythrosine, and rose bengal present in 12 permitted synthetic food dyes. In this report, the influence of dyes was examined on CYP3A4, a major phase I drug-metabolizing enzyme, and P-glycoprotein, a major transporter by synthetic food dyes. Human cytochrome P-450 (CYP) 3A4 and P-glycoprotein were inhibited by xanthene food dyes. The IC(50) values of these dyes to inhibit CYP3A4 and P-glycoprotein were the same as the level of inhibition of UGT1A6 produced by three haloganated xanthene food dyes in the previous report, except acid red, which inhibited only CYP3A4. Data suggest that inhibition by dyes is not enzyme specific but may be in a membrane-specific or protein-specific manner, such as conformational changes in protein. In the previous study, it was suggested that inhibition by dyes depended upon light irradiation due to generation of (1)O2 from these dyes. In this study, the influence of superoxide dismutase and catalase on inhibition by dyes was examined. Superoxide dismutase but not catalase was effective in preventing the inhibition of UGT1A6 by the dyes. Data suggest that superoxide anions, originating from dyes via light irradiation, may attack drug-metabolizing enzymes. It is possible that red cosmetics containing phloxine, erythrosine, or rose bengal react with proteins in skin and may lead to skin damage.