Preliminary safety assessment of C-8 xylitol monoester and xylitol phosphate esters.

OBJECTIVES: Most of the cosmetic compounds with preservative properties available in the market pose some risks concerning safety, such as the possibility of causing sensitization. Due to the fact that there are few options, the proper development of new molecules with this purpose is needed. Xylitol is a natural sugar, and the antimicrobial properties of xylitol-derived compounds have already been described in the literature. C-8 xylitol monoester and xylitol phosphate esters may be useful for the development of skincare products. As an initial screen for safety of chemicals, the combination of in silico methods and in vitro testing can aid in prioritizing resources in toxicological investigations while reducing the ethical and monetary costs that are related to animal and human testing. This study was designed to evaluate the safety of C-8 xylitol monoester and xylitol phosphate esters regarding carcinogenicity, mutagenicity, skin and eye irritation/corrosion and sensitization through alternative methods. METHODS: For the initial safety assessment, quantitative structure-activity relationship methodology was used. The prediction of the parameters carcinogenicity/mutagenicity, skin and eye irritation/corrosion and sensitization was generated from the chemical structure. The analysis also comprised physical-chemical properties, Cramer rules, threshold of toxicological concern and Michael reaction. In silico results of candidate molecules were compared to 19 compounds with preservative properties that are available in the market. Additionally, in vitro tests (Ames test for mutagenicity, cytotoxicity and phototoxicity tests and hen's egg test--chorioallantoic membrane for irritation) were performed to complement the evaluation. RESULTS: In silico evaluation of both molecules presented no structural alerts related to eye and skin irritation, corrosion and sensitization, but some alerts for micronucleus and carcinogenicity were detected. However, by comparison, C-8 xylitol monoester, xylitol phosphate esters showed similar or better results than the compounds available in the market. Concerning experimental data, phototoxicity and mutagenicity results were negative. As expected for compounds with preservative activity, xylitol-derived substances presented positive result in cytotoxicity test. In hen's egg test, both molecules were irritants. CONCLUSION: Our results suggested that xylitol-derived compounds appear to be suitable candidates for preservative systems in cosmetics.

3,4-methylenedioxymethamphetamine (MDMA--Ecstasy) decreases neutrophil activity through the glucocorticoid pathway and impairs host resistance to Listeria monocytogenes infection in mice.

Ecstasy is the popular name of the abuse drug 3,4-methylenedioxymethamphetamine (MDMA) that decreases immunity in animals. The mechanisms that generate such alterations are still controversial. Seven independent pharmacological approaches were performed in mice to identify the possible mechanisms underlying the decrease of neutrophil activity induced by MDMA and the possible effects of MDMA on host resistance to Listeria monocytogenes. Our data showed that MDMA (10 mg kg(-1)) administration decreases NFκB expression in circulating neutrophils. Metyrapone or RU-486 administration prior to MDMA treatment abrogated MDMA effects on neutrophil activity and NFκB expression, while 6-OHDA or ICI-118,551 administration did not. As MDMA treatment increased the plasmatic levels of adrenaline and noradrenaline, propranolol pre-treatment effects were also evaluated. Propranolol suppressed both MDMA-induced increase in corticosterone serum levels and its effects on neutrophil activity. In a L. monocytogenes experimental infection context, we showed that MDMA: induced myelosuppression by decreasing granulocyte-macrophage hematopoietic progenitors (CFU-GM) in the bone marrow but increased CFU-GM in the spleen; decreased circulating leukocytes and bone marrow cellularity and increased spleen cellularity; decreased pro-inflammatory cytokine (IL-12p70, TNF, IFN-γ, IL-6) and chemokine (MCP-1) production 24 h after the infection; increased the production of pro-inflammatory cytokines and chemokines 72 h after infection and decreased IL-10 levels at all time points analyzed. It was proposed that MDMA immunosuppressive effects on neutrophil activity and host resistance to L monocytogenes rely on NFκB signaling, being mediated by HPA axis activity and corticosterone.

ß-1,3-Glucan given orally modulates immunomyelopoietic activity and enhances the resistance of tumour-bearing mice.

ß-Glucans have been reported to be potent adjuvants in stimulating innate and adaptive immune responses. The aim of the present study was to determine the immunohematopoietic effects of Imunoglucan (HEBRON) following its oral administration to normal and Ehrlich ascites tumour (EAT)-bearing mice. Mice were treated with 250, 500 and 1000 mg/kg per day, p.o., Imunoglucan (ß-1,3-glucan extracted from Saccharomyces cerevisae) for 18 consecutive days. Treatment started 10 days prior to and ended 8 days after tumour inoculation. At 500 and 1000 mg/kg per day, Imunoglucan enhanced the life span of EAT-bearing mice and prevented myelosuppression and splenomegaly caused by the tumour by increasing the number of granulocyte-macrophage progenitors in the bone marrow and increasing colony-stimulating activity in the serum. At 500 mg/kg, Imunoglucan restored the reduced ability of stromal cells to display myeloid progenitors in long-term bone marrow cultures of EAT-bearing mice and upregulated the production of interleukin (IL)-6 and IL-1α by these cells, consistent with a higher number of non-adherent cells. Moreover, 500 mg/kg Imunoglucan restored natural killer cell activity in tumour-bearing mice, consistent with the increased production of interferon (IFN)-γ observed. The results of the present study suggest that Imunoglucan given orally indirectly modulates immune activity and probably disengages tumour-induced suppression by producing a higher reserve of myeloid progenitors in the bone marrow in consequence of biologically active cytokine release (colony-stimulating factors, IL-1α, IL-6 and IFN-γ).

Bcl-2 expression and apoptosis induction in human HL60 leukaemic cells treated with a novel organotellurium(IV) compound RT-04.

Organotellurium(IV) compounds have been reported to have multiple biological activities including cysteine protease-inhibitory activity, mainly cathepsin B. As cathepsin B is a highly predictive indicator for prognosis and diagnosis of cancer, a possible antitumor potential for these new compounds is expected. In this work, it was investigated the effectiveness of organotellurium(IV) RT-04 to produce lethal effects in the human promyelocytic leukaemia cell line HL60. Using the MTT tetrazolium reduction test, and trypan blue exclusion assay, the IC50 for the compound after 24 h incubation was 6.8 and 0.35 microM, respectively. Moreover, the compound was found to trigger apoptosis in HL60 cells, inducing DNA fragmentation and caspase-3, -6, and -9 activations. The apoptsosis-induced by RT-04 is probably related to the diminished Bcl-2 expression, observed by RT-PCR, in HL60-treated cells. In vivo studies demonstrated that the RT-04 treatment (2.76 mg/kg given for three consecutive days) produces no significant toxic effects for bone marrow and spleen CFU-GM. However, higher doses (5.0 and 10 mg/kg) produced a dose-dependent reduction in the number of CFU-GM of RT-04-treated mice. These results suggest that RT-04 is able to induce apoptosis in HL60 cells by Bcl-2 expression down-modulation. Further studies are necessary to better clarify the effects of this compound on bone marrow normal cells.

Early proliferation of umbilical cord blood cells from premature neonates.

BACKGROUND AND OBJECTIVE: Human umbilical cord blood (UCB) is an important source of haematopoietic stem cells; however, the behaviour of progenitor cells obtained from premature and full-term neonates is still a controversy subject. Thus, the aim of this study was to evaluate cell cycle parameters and the proliferative capacity of UCB progenitor cells from premature and full-term neonates. MATERIAL AND METHODS: Clonogenic assays were performed with methylcellulose, medium supplemented with recombinant stimulating growth factors and the colonies were scored on the seventh day and the 14th day of culture. A cell cycle study was carried out by DNA analysis using flow cytometry and 30 000 events were acquired; p107 and p130 expressions were analysed by Western blotting. RESULTS: Cultures obtained from UCB of premature neonates showed an early growth of colony-forming unit (CFU)-burst forming unit erythroid/CFU-granulocyte, erythrocyte, macrophage and megakaryocyte (BFU-E/GEMM), and CFU-granulocyte, macrophage (GM) by the seventh day of culture (P < 0.001). Therefore, the number and morphological characteristics of these colonies were comparable with those obtained from full-term neonates, on the 14th day of culture. At the 14th day, a large amount of CFU-GM was detected in the premature group (P < 0.0032). The premature culture on the 14th day showed fibroblasts and was comparable to those of full-term neonates on the 21st day in terms of number and morphology of the colonies. DNA analysis showed that the number of cells in S-phase was also higher in premature samples when compared to full-term neonates, P < 0.0021 (0 h = 12.8 vs. 2.5%; 16 h = 10.5 vs. 5.9%; 20 h = 13.5 vs. 10.3%; 24 h = 13.8 vs. 9.1%; 48 h = 14.0 vs. 5.4%; 72 h = 20.5 vs. 8.9%; 96 h = 13.8 vs. 7.7%). The Western blotting results demonstrated that p107 and p130 cell cycle protein expressions were higher in premature cells than in full-term cells. CONCLUSION: These results suggest that the higher capacity of proliferation and early differentiation of premature UCB might not be related only to the amount of stem/progenitor cells but also to a different timing of cell cycle entry.

Natural killer cell activity, lymphocyte proliferation, and cytokine profile in tumor-bearing mice treated with MAPA, a magnesium aggregated polymer from Aspergillus oryzae.

The present study examined the effects of MAPA, an antitumor aggregated polymer of protein magnesium ammonium phospholinoleate-palmitoleate anhydride, isolated from Aspergillus oryzae, on concanavalin A (Con A)-induced spleen cell proliferation, cytokine production and on natural killer (NK) cell activity in Ehrlich ascites tumor-bearing mice. The Ehrlich ascites tumor (EAT) growth led to diminished mitogen-induced expansion of spleen cell populations and total NK activity. This was accompanied by striking spleen enlargement, with a marked increase in total cell counts. Moreover, a substantial enhancement in IL-10 levels, paralleled by a significant decrease in IL-2 was observed, while production of IL-4 and interferon-gamma (IFN-gamma) was not altered. Treatment of mice with 5 mg/kg MAPA for 7 days promoted spleen cell proliferation, IL-2 production and NK cell activity regardless of tumor outgrowth. In addition, MAPA treatment markedly enhanced IFN-gamma levels and reduced IL-10 production relative to EAT mice. A 35% reduction in splenomegaly with normal number of nucleated cells was also found. Altogether, our results suggest that MAPA directly and/or indirectly modulates immune cell activity, and probably disengages tumor-induced suppression of these responses. Clearly, MAPA has an impact and may delay tumor outgrowth through immunotherapeutic mechanisms.

Effects of deltamethrin on the growth and differentiation of bone marrow hematopoietic stem cells

1. The effects of deltamethrin on mouse bone marrow and spleen progenitor cell responsiveness to granulocyte and macrophage colony-stimulating factors (CSFs) were evaluated. 2. Deltamethrin (1-5 mg/kg) was administered four times subcutaneously on alternate days for one week to male BALB/c mice, 5-8 weeks old (N = 6 mice/group), raised under pathogen-free conditions and maintained in conventional animal rooms for four weeks before use. Soft agar colony formation (CFU-C), marrow and spleen cell counts as well as body, spleen and thymus weights were determined. 3. Although treatment with the lowest dose (1 mg kg-1 48 h-1) produced no significant effect on CFU-C, the administration of 3 and 5 mg kg-1 48 h-1 caused a more than two-fold increase in the formation of granulocyte and macrophage colonies in the marrow, but not in the spleen (control value = 100.5 +/- 12 for N = 6). Colony numbers returned to normal values within five days after the end of deltamethrin administration. 4. No changes were observed in the total (range: 1-3 x 10(8) per spleen) and differential marrow and spleen cell counts, nor was there any alteration in spleen weight. However, treatment with the three doses resulted in a dramatic reduction in thymus weight. 5. These effects were not due to the liberation of endotoxin, because if endotoxin had been present it would have been < 0.060 ng/ml, a concentration that would not have a biological effect. 6. In vitro addition of 0.10 to 10 microM deltamethrin to marrow cell cultures obtained from untreated mice did not induce any response. 7. These data indicate that the CSF-driven granulocyte and macrophage development provides a useful model for the study of the effects of toxicants on myelopoiesis