Assessment of polyaniline nanoparticles toxicity and teratogenicity in aquatic environment using Rhinella arenarum model.

With the rapid growth of nanotechnology and the applications of nanoparticles, environmental exposure to these particles is increasing. However, their impact in human and environmental health is not well studied. Anurans, with life stage comprising embryos, tadpoles and adults, have an extremely permeable skin which makes them excellent indicators of environmental health. This study evaluated the acute toxicity effects of polyaniline nanoparticles (PANI-Np) in different dispersant on embryos and larvae of Rhinella arenarum. The results showed that LC50 of PANI-Np dispersed in polyvinylpyrrolidone (PVP) were 1,500 mg/L, while LC50 by PANI-Np dispersed in PVP+PNIPAM (polyN-isopropylacrilamide) showed a highest toxicity (1,170 mg/L). The embryo teratogenicity increased with increasing exposure concentration in both kinds of PANI-Np although in PANI-Np1, there is an increased teratogenic effect associated with the polymer stabilizer PVP.

Polyaniline nanofibers: acute toxicity and teratogenic effect on Rhinella arenarum embryos.

The fate and effect of nanomaterials in the environment is of paramount importance towards the technological application of the materials. This work shows the ecotoxicological potential of polyaniline (PANI) nanofibers in the larvae Rhinella arenarum by means of AMPHITOX test. Acute toxicity of PANI nanofibers towards embryos of the common South American toad R. arenarum (Anura: bufonidae) was evaluated in the premetamorphosis (stage 25) larvae. The exposure of R. arenarum larvae to at dose of 150, 250 and 400 mg L(-1) resulted in 100% viability within 96 h exposure. The embryos at 2-4 blastomers stage (early life stage teratogenic test) revealed that embryos were not killed and no teratogenic effects were observed when embryos were incubated with PANI nanofibers (150 and 250 mg L(-1)), while only a growth retardation of embryos was induced at levels of 250 mg PANI nanofibers L(-1). On the other hand, at 400 mg L(-1) concentration, a reduction in the body length of larvae and tail malformation was observed. This results suggest that a concentration-dependent toxicity is operative, typified by phenotypes that had abnormal body axes. The presence of PANI nanofibers in gut contents and its excretion by larval stages of R. arenarum was confirmed by UV-visible spectroscopy.

Immobilization stress responses in adult rats exposed in utero to immobilization.

The present study investigated the influence of immobilization prenatal stress on adult male rats, with the same postnatal stress, on the immune parameters and its relation with plasma corticosterone (COR) and glucose levels. To study the immunity parameters, profiles of the leucocytes, size of spleen and number of the mononuclear cells of this organ were determined. Basal levels of COR and glucose were higher in prenatally stressed animals. When the adult animals were exposed to immobilization stress, COR increased but the increase was less than that for the control group, and glucose was equal in both groups. Although postnatal acute stress decreased the number of leucocytes and lymphocytes and increased the number of neutrophils, the effect was lower in prenatally stressed animals; for that reason, the ratio neutrophil/lymphocyte increased less. The number of mononuclear cells were higher in the spleen of prenatally stressed animals. This effect was probably due to retention of blood lymphocytes in the spleen. There seemed to be an alteration in the redistribution of leucocytes, both in basal conditions and under postnatal stress. The alteration of the immunological function may be partly due to an alteration in the functionality of the hypothalamic­pituitary­adrenal axis, which was hyperactive in basal conditions but appeared to suffer habituation to the same stress.

Comparative photodynamic therapy study using two phthalocyanine derivatives.

In the present study, a comparative photodynamic therapy (PDT) study was performed using the phthalocyanine derivatives, ZnPc(OCH(3))(4) and ZnPc(CF(3))(4), in a mouse tumor model, under identical experimental procedures. We studied the ablation of tumors induced by PDT. The end-point was to compare the photodynamic efficacy of ZnPc(OCH(3))(4) and ZnPc(CF(3))(4). ZnPc(OCH(3))(4) and ZnPc(CF(3))(4) were administered intraperitoneally at a dose of 0.2 mg/kg body weight. The injections of drugs were carried out in Balb/c mice bearing subcutaneously inoculated LM2 mouse mammary adenocarcinoma. Histological examination and serum biochemical parameters were used to evaluate hepatic and renal toxicity and function. Phototherapeutic studies were achieved employing a light intensity of 210 J/cm(2). After PDT, tumoral regression analyses were carried out, and the degree of tumor cell death was measured utilizing the vital stain Evan's blue. In this pilot study, we revealed that the cytotoxic effect of ZnPc(OCH(3))(4) after PDT led to a higher success rate compared to ZnPc(CF(3))(4)-PDT when both were intraperitoneally injectioned. Both phthalocynanine derivatives were able to induce ablation in the tumors. In summary, these results demonstrate the feasibility of ZnPc(OCH(3))(4)- or ZnPc(CF(3))(4)-PDT and its potential as a treatment for small tumors.

Biodistribution and phototherapeutic properties of Zinc (II) 2,9,16,23-tetrakis (methoxy) phthalocyanine in vivo.

Photodynamic therapy (PDT) was investigated using the phthalocyanine photosensitizer Zinc (II) 2,9,16,23-tetrakis (methoxy) phthalocyanine (ZnPc(OCH(3))(4)) on BALB/c mice. Animals bearing tumor were treated with 0.2mg/kg body weight (bw) ZnPc(OCH(3))(4) and 24h later were irradiated with 70, 140 and 210 J/cm(2) of visible light from a source delivering 39 mW/cm(2). In this study, we have tested the efficiency of ZnPc(OCH(3))(4) liposomal formulation on mice. Biodistribution studies were performed in tumor-free mice and tumor-bearing mice at various time points up to 24h after ZnPc(OCH(3))(4)-PDT treatment. The tumor sizes were evaluated over different period in parallel experiments. The maximal efficiency and selectivity of photosensitizer accumulation in tumor tissue take place at 24h after drug administration of 0.2mg/kg bw ZnPc(OCH(3))(4). In the tumor sections for biochemical studies, apoptosis was visualized by activation of caspase-3. ZnPc(OCH(3))(4)-PDT tumors showed a significant delay in growth as compared to untreated control mice. In all cases, ZnPc(OCH(3))(4)-PDT-treated tumors showed a significant regression. The results indicated a dramatic decrease of tumors size after 10 days post-irradiation with 210 J/cm(2) and no recurrence of the disease was detectable within at least 90 days. The phototherapeutic agent ZnPc(OCH(3))(4) demonstrated preferential accumulation in tumor in comparison with skin tissues, except in the case of kidney. The ratio of tumor/skin tissues ranged a value of 8. These results suggest that ZnPc(OCH(3))(4)-PDT may be of particular importance in the treatment of accessible malignancies.

Lethal and teratogenic effects of phenol on Bufo arenarum embryos.

Phenol and their derivatives are used in several industries and they have a high potential toxicity for animal and plant species. They were found in variable concentrations, as high as 1000 mg/L, in industrial wastewater and, they are often discharged into the environment. Amphibian embryos are useful indicators of environmental pollution. However, to our knowledge, there are not studies focussed on the toxic effects of phenol on Bufo arenarum, which is an anuran widely distributed in South America. Therefore, the effect of phenol on the survival and morphogenesis of these amphibian embryos was evaluated by means of AMPHITOX test. Embryos at 25 stage of development (acute test) and embryos at 2-4 blastomers stage (early life stage test), were exposed to phenol solutions in concentrations ranging from 25 to 250 mg/L, which were frequently found in the environment. Mortality and malformations were registered each 24h. LC(50), LC(99), NOEC, TC(50) and TI(50) values were 183.70, 250, 60, 113 mg/L and 1.62, respectively, at 96 h of treatment. Mortality and the percentage of malformations increased with increasing phenol concentrations. Teratogenic effects more frequently produced by phenol were: axial flexure, persistent yolk plug and different abnormalities which caused death of blastulae. Moreover, other malformations were registered, such as irregular form, acephalism, edema, axial shortening and underdevelopment of gills, among others. Larvae of B. arenarum, at early embryonic stages (blastulae), showed higher sensitivity to phenol than tadpoles at stage 25. Results confirm high susceptibility of amphibians to phenol and that environmental concentrations of this pollutant might be harmful to these populations.

Pharmacokinetic, toxicological and phototherapeutic studies of phthalocyanine ZnPcCF3.

Photodynamic therapy (PDT) is an alternative modality for cancer therapy. It induces neoplasic cells death through photoachievable sensitizers. The aim of this work was to evaluate the pharmacokinetic, toxic and phototherapeutic effects of the phthalocyanine ZnPcCF(3) in a Balb/c mice tumor model. Biodistribution studies were carried out by intraperitoneal injection of 0.2mg/kg ZnPcCF(3). Histological studies and serum biochemical parameters were used to evaluate hepatic and renal toxicity and functionality. After tumor irradiation (210J/cm(2)), an analysis of tumor necrosis degree was used to evaluate the phototherapeutic effects. It was measured at 1, 2, 3 and 4 days after PDT. Vital staining was performed by intraperitoneal injection of 0.35ml 1% Evans Blue solution. Six hours later, tumors were excised and examined. The unstained area was attributed to necrotic tissue, whereas the stained area showed tissue with preserved blood supply. ZnPcCF(3) was accumulated in spleen, liver and duodenum. It suggests that ZnPcCF(3) is eliminated from the body via bile-gut. The phthalocyanine was not found in brain, therefore, it would not cross the blood-brain barrier, thus toxicity risk in the central nervous system is not probable. Moreover, ZnPcCF(3) does not accumulate in skin, it would eliminate cutaneous photosensitizing risks. The dose of 0.2mg/kg ZnPcCF(3) resulted in a low acute toxicity with revertible damages, which indicates that this dose can be used for PDT. The tumor death was of 89% 4 days after PDT. It indicates that ZnPcCF(3) would be effective in PDT.

Pharmacokinetic and phototherapeutic studies of monocationic methoxyphenylporphyrin derivative.

BACKGROUND AND OBJETIVE: Photodynamic therapy, a novel treatment for cancer, works through photoactivation of a tumor-localized photosensitive drug, and localized through oxidative damage to kill cells and ablate tumors. Pharmacokinetic and phototherapeutic properties of a cationic porphyrin were assayed in a Balb/c mouse cancer model in order to evaluate its efficiency as photosensitizer. METHODS: Biodistribution studies were carried out by intraperitoneal injection of 5mg/kg CP incorporated into a liposome solution. CP was recovered from serum and organs at various times after treatment. The serum biochemical parameters and histological studies were used to test hepatic and renal functionality. For phototherapeutic studies, the light source used was a slide projector (360J/cm(2)). The efficiency of CP was evaluated by following tumor growth curves for 10 days after PDT doses. Immunohistochemical detection was carried out to evaluate caspase-3 activation in CP-PDT-treated tumors. RESULTS AND CONCLUSIONS: The photosensitizer distribution suggests that CP is mainly eliminated from the organism via the bile-gut pathway, and that neurotoxic and cutaneous photosensitivity effects are reduced or absent. The porphyrin distribution from bloodstream to tissue began at 24h of drug administration. CP did not affect the hepatic and renal functionality, as was demonstrated by the physiological parameters. PDT-treated tumors showed delay in growth rate as compared to untreated control mice. Biochemical studies showed that the efficient tumor regression is dependent on caspase-3 activity signaling response associated with apoptosis. The results obtained suggest that the porphyrin CP may be a promising candidate for further use in PDT treatments.

Pharmacokinetic and tumour-photosensitizing properties of methoxyphenyl porphyrin derivative.

The photokilling activity of 5-[4-N-(2',6'-dinitro-4'-trifluoromethylphenyl) aminophenyl]-10,15,20-tris(2,4,6-trimethoxy phenyl) porphyrin (CF3) was evaluated on a Hep-2 human larynx-carcinoma cell line. An apoptotic mechanism of cell death was found at low irradiation doses. Pharmacokinetic and tumour-photosensitizing properties were studied in mice. The results show that a different mechanism of cell death can be induced depending on the irradiation doses in the photodynamic treatments with CF3, which makes this agent an interesting sensitizer for potential tumour photosensitizer.