Dimethyl Phthalate Induces Blood Immunotoxicity Through Oxidative Damage And Caspase-Dependent Apoptosis

Dimethyl phthalate (DMP), a low molecular weight phthalate ester, is present in ectoparasiticides, plastics, and insect repellants, has been linked to neurotoxic, reproductive, and endocrine disruptive responses. However, its blood immunotoxic effects and mechanism remain poorly understood. In this study, rats were exposed to graded concentrations of DMP through intragastric administration to assess the blood immunotoxic effects using a combination assay of biomarker, cytometry, and transcriptomics. DMP treatment altered the redox status of rats, causing that oxidative damage. Significantly decreased blood cell counts and disordered antibody and cytokine secretion were observed, suggesting the suppressed immune defense and destructed inflammatory regulation. Flow cytometry showed for lymphocytes, especially CD3+CD4+ T cells, apoptosis/necrosis occurred positively related to DMP exposure level. Transcriptomics revealed responses that were in line with oxidative damage effects. Overexpression of the Bcl-2 family genes and activation of the Fas/FasL pathway trigger downstream caspase cascade, causing reactive oxygen species signaling mediated apoptosis/necrosis. This is the first report on immunotoxic effects of low molecular weight phthalate esters.

Determination of Phthalate Esters in Beverages and Water Samples by Solid Phase Extraction with Resin Based COFs as Filler

Resin based covalent organic framework material was used as filler for solid phase extraction (SPE), and the solid phase extraction effect was compared with that of traditional COF material (TpBD COFs). The enrichment capacity of four phthalate esters (dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate) in beverage samples was investigated by SPE. Adsorption experiments showed that the kinetic adsorption behavior of COF materials for phthalate esters (PAEs) was more consistent with the quasi-second-order kinetic adsorption model, and the static adsorption behavior is more in line with the Freundlich isothermal adsorption model. Solid phase extraction experiments proved that the SPE column prepared with two COF materials as adsorbents had good adsorption effects, high recovery (water: 97.99–100.56% and beverage: 97.93–100.23%) and were reusable (50 cycles), which could meet the requirements for trace detection of phthalate ester. It was found that the solid phase extraction effect was better than the four types of commercial SPE columns. The new COF material reduced the cost of monomer use and provided the possibility for its industrial production. Meanwhile, it also provided a new feasible scheme for enriching trace phthalate esters in practical samples.

Bioassay and NMR-Guided Isolation of Natural Products from Pacific Marine Invertebrates

<p>In the present study, bioassay and NMR approaches were used in combination to guide isolation of two new and three known compounds. An extract library of New Zealand and Tongan marine invertebrates was screened for activity inhibiting the growth of Saccharomyces cerevisiae. From this, ‘hits’ were identified and validated and three New Zealand sponges and a Tongan ascidian were chosen for bulk extraction. These invertebrates were extracted in methanol and purified using normal and reversed-phase chromatography to isolate the compounds of interest. The isolation of compounds was guided by either inhibitory activity towards S. cerevisiae, 1H NMR spectroscopy or a combination of the two. The known trihydroxylated steroid (14) was isolated from the calcareous sponge Leucosolenia sp. A fatty acid and mixture of phthalate esters were isolated from an unidentified Tongan ascidian. The fatty acid was proposed to be cis-vaccenic acid (13) on the basis of 1H and 13C NMR data. The phthalate ester mixture was not purified further. Work on these two compounds was discontinued due to a lack of activity observed in the S. cerevisiae assay and the well-known nature of fatty acids and phthalate esters. Work was also done on an assay targeting the large mechanosensitive channel (MscL) of bacteria. Some parameters were optimised for this assay, however some work remains to be done. The screening of the extract library of New Zealand and Tongan marine invertebrates using this assay was unsuccessful. More studies to better understand the behaviour of this assay are required, some of which are proposed herein. The extraction of the New Zealand marine sponge Haliclona sp. yielded one known and two new 3-alkyl pyridinium alkaloid (3-APA) monomers. The structures of these 3-APA monomers—dehydrohaliclocyclin C (58), dehydrohaliclocyclin F (59) and the known haliclocyclin C (20)—were elucidated using a combination of NMR spectroscopy, mass spectrometry (MS) and chemical degradation. This is the first report of a 3-APA cyclic monomer with unsaturation in the alkyl chain being isolated. 3-APAs were identified as the source of inhibitory activity in the S. cerevisiae assay, however, no inhibitory activity was found for 58, 59 and 20 against the clinically relevant fungus C. albicans.</p>

Bioassay and NMR-Guided Isolation of Natural Products from Pacific Marine Invertebrates

<p>In the present study, bioassay and NMR approaches were used in combination to guide isolation of two new and three known compounds. An extract library of New Zealand and Tongan marine invertebrates was screened for activity inhibiting the growth of Saccharomyces cerevisiae. From this, ‘hits’ were identified and validated and three New Zealand sponges and a Tongan ascidian were chosen for bulk extraction. These invertebrates were extracted in methanol and purified using normal and reversed-phase chromatography to isolate the compounds of interest. The isolation of compounds was guided by either inhibitory activity towards S. cerevisiae, 1H NMR spectroscopy or a combination of the two. The known trihydroxylated steroid (14) was isolated from the calcareous sponge Leucosolenia sp. A fatty acid and mixture of phthalate esters were isolated from an unidentified Tongan ascidian. The fatty acid was proposed to be cis-vaccenic acid (13) on the basis of 1H and 13C NMR data. The phthalate ester mixture was not purified further. Work on these two compounds was discontinued due to a lack of activity observed in the S. cerevisiae assay and the well-known nature of fatty acids and phthalate esters. Work was also done on an assay targeting the large mechanosensitive channel (MscL) of bacteria. Some parameters were optimised for this assay, however some work remains to be done. The screening of the extract library of New Zealand and Tongan marine invertebrates using this assay was unsuccessful. More studies to better understand the behaviour of this assay are required, some of which are proposed herein. The extraction of the New Zealand marine sponge Haliclona sp. yielded one known and two new 3-alkyl pyridinium alkaloid (3-APA) monomers. The structures of these 3-APA monomers—dehydrohaliclocyclin C (58), dehydrohaliclocyclin F (59) and the known haliclocyclin C (20)—were elucidated using a combination of NMR spectroscopy, mass spectrometry (MS) and chemical degradation. This is the first report of a 3-APA cyclic monomer with unsaturation in the alkyl chain being isolated. 3-APAs were identified as the source of inhibitory activity in the S. cerevisiae assay, however, no inhibitory activity was found for 58, 59 and 20 against the clinically relevant fungus C. albicans.</p>

The Peculiar Estrogenicity of Diethyl Phthalate: Modulation of Estrogen Receptor α Activities in the Proliferation of Breast Cancer Cells

Phthalates comprise a group of synthetic chemicals present in the environment because of their wide use as plasticizers and as additives in products for personal care. Among others, diethyl phthalate (DEP) is largely used in products for infants, children, and adults, in which its exposure has been correlated with an increased risk of breast cancer. The adverse health outcomes deriving from phthalate exposure have been associated with their activity as endocrine disruptors (EDCs) of the steroid and thyroid hormone signaling by affecting developmental and reproductive health, and even carcinogenicity. However, the estrogen disruptor activities of DEP are still controversial, and the mechanism at the root of the estrogenic-disrupting action of DEP remains to be clarified. Here, we evaluated the DEP mechanism of action on the activation status of estrogen receptor α (ERα) by analyzing the receptor’s phosphorylation as well as both nuclear and extra-nuclear pathways triggered by the receptor to modulate the proliferation of breast cancer cells. Although DEP does not bind to ERα, our results suggest that this phthalate ester exerts multiple parallel interactions with ERα signaling and emphasize the importance to determine an appropriate battery of in vitro methods that will include specific molecular mechanisms involved in the endocrine disruption.

Biodegradation of Di-(2-ethylhexyl) Phthalate by Novel Rhodococcus Aetherivorans PFS1 Strain Isolated From Paddy Field Soil

Di-(2-ethylhexyl)-phthalate (DEHP) is the phthalate ester frequently utilized as a plasticizer, commonly found in cosmetics, packaging materials, moreover, it has carcinogenic and mutagenic effect on humans. In the current study, we isolated the soil bacterium Rhodococcus aetherivorans PFS1 and to assess its DEHP degradation ability in various environmental conditions. The strain PFS1 was isolated from paddy field soil and identified by the 16S rRNA sequencing analyses. The strain PFS1 was examined for its biodegradation ability of DEHP at various pH, temperature, salt concentration, glucose concentration, and high and low concentration of DEHP. Moreover, the biodegradation of DEHP at a contaminated soil environment by strain PFS1 was assessed. Further, the metabolic pathway of DEHP degradation by PFS1 was analyzed by HPLC-MS analysis. The results showed that the strain PFS1 effectively degraded the DEHP at neutral pH and temperature 30 °C, moreover, expressed excellent DEHP degradation at the high salt concentration (up to 50 g/L). The strain PFS1 was efficiently degraded the different tested phthalate esters (PAEs) up to 90%. Significantly removed the DEHP contamination in soil along with native organisms which are present in soil up to 94.66%, nevertheless, the PFS1 alone degraded the DEHP up to 87.665% in sterilized soil. According to HPLC-MS analysis, DEHP was degraded into phthalate (PA) by PFS1 strain via mono (2-ethylehxyl) phthalate (MEHP), then PA was utilized for cell growth. These results suggest that R. aetherivorans PFS1 has excellent potential to degrade DEHP at various environmental conditions especially in contaminated paddy field soil.