Phthalate and non-phthalate plasticizers are used in polymer materials, such as plastic and rubber. It has recently been found that diisobutyl adipate (DIBA), which is considered an environmentally safe non-phthalate plasticizer, potentially acts as a thyroid disruptor in fish. Here, we investigated the sexual hormone effects of DIBA based on the expression levels of genes that respond to endocrine disruption and sexual hormone activity in the livers and gonads, and on gonadal sexual differentiation in Japanese medaka. Compared with the control group, the mRNA expression of chgH, vtg1, vtg2, and esr1 was significantly suppressed in the livers of DIBA exposed XX individuals. Furthermore, the mRNA expression of gsdf was significantly upregulated and downregulated in the gonads of XX and XY individuals, respectively. The mRNA expressions of esr1 and esr2b were significantly suppressed by DIBA exposure in the gonads of both XX and XY individuals. These observations suggest that DIBA has potential androgenic activity in Japanese medaka. However, normal testes and ovaries were observed in respective XY and XX medaka after DIBA exposure; therefore, these results suggest that DIBA may have weak androgenic activity.
Crystals of 1,6-hexanedioic acid (I) undergo a temperature-dependent reversible phase transition from monoclinic P21/c at a temperature higher than the critical temperature (Tc) 130 K to another monoclinic P21/c at temperature lower than Tc. The phase transition is of first order, involving a discontinuity and a tripling of the b-axis at Tc whereas the other unit cell parameters vary continuously. The transition is described by the phenomenological Landau theory. The crystal structure analyses for data collected at 297(2) K and 120.0(1) K show that there is half of a molecule of (I) in the asymmetric unit at 297(2) K whereas there are one and a half molecules of (I) in the asymmetric unit at 120.0(1) K. At both temperatures, 297(2) and 120.0(1) K, intermolecular O-H···O hydrogen bonds link the molecules of I into infinite 1D chains along [101] direction. However there are significantly more O-H···O hydrogen bonds presented in the 120.0(1) K polymorph, thereby indicating this phase transition is negotiated via hydrogen bonds. The relationship of the conformational changes and hydrogen bonding for these two polymorphs are explained in detail.
In this study, an artificial neural network (ANN) trained by backpropagation algorithm, Levenberg-Marquadart, was applied to predict the yield of enzymatic synthesis of dioctyl adipate. Immobilized Candida antarctica lipase B was used as a biocatalyst for the reaction. Temperature, time, amount of enzyme, and substrate molar ratio were the four input variables. After evaluating various ANN configurations, the best network was composed of seven hidden nodes using a hyperbolic tangent sigmoid transfer function. The correlation coefficient (R2) and mean absolute error (MAE) values between the actual and predicted responses were determined as 0.9998 and 0.0966 for training set and 0.9241 and 1.9439 for validating dataset. A simulation test with a testing dataset showed that the MAE was low and R2 was close to 1. These results imply the good generalization of the developed model and its capability to predict the reaction yield. Comparison of the performance of radial basis network with the developed models showed that radial basis function was more accurate but its performance was poor when tested with unseen data. In further part of the study, the feedforward backpropagation model was used for prediction of the ester yield within the given range of the main parameters.
Plasticizer pollution of the water environment is one of the world's most serious environmental issues. Phthalate plasticizers can disrupt endocrine function in vertebrates. Therefore, this study analyzed thyroid-related, reproduction-related, and estrogen-responsive genes in Japanese medaka (Oryzias latipes) to determine whether non-phthalate diisobutyl adipate (DIBA) plasticizer could affect endocrine hormone activity or not. Developmental toxicity during fish embryogenesis was also evaluated. At a concentration of 11.57 mg/l, embryonic exposure to DIBA increased the mortality rate. Although abnormal development, including body curvature, edema, and lack of swim bladder inflation, was observed at 3.54 and 11.57 mg/l DIBA, growth inhibition and reduced swimming performance were also observed. In addition, DIBA exposure increased the levels of thyroid-stimulating hormone beta-subunit (tshβ) and deiodinase 1 (dio1) but decreased the levels of thyroid hormone receptor alpha (trα) and beta (trβ). These results suggest that DIBA has thyroid hormone-disrupting activities in fish. However, kisspeptin (kiss1 and kiss2), gonadotropin-releasing hormone (gnrh1), follicle-stimulating hormone beta (fshβ), luteinizing hormone beta (lhβ), choriogenin H (chgH), and vitellogenin (vtg1) expression did not change dose-dependently in response to DIBA exposure, whereas gnrh2 and vtg2 expression was elevated. These results indicate that DIBA has low estrogenic activity and does not disrupt the endocrine reproduction system in fish. Overall, this is the first report indicating that non-phthalate DIBA plasticizer is embryotoxic and disrupt thyroid hormone activity in fish.
The full mol-ecule of the binuclear title compound, [Cd2Cl2(C6H8O4)(C6H8N2)2(H2O)2], is generated by the application of a centre of inversion located at the middle of the central CH2-CH2 bond of the adipate dianion; the latter chelates a CdII atom at each end. Along with two carboxyl-ate-O atoms, the CdII ion is coordinated by the two N atoms of the chelating benzene-1,2-di-amine ligand, a Cl- anion and an aqua ligand to define a distorted octa-hedral CdClN2O3 coordination geometry with the monodentate ligands being mutually cis. The disparity in the Cd-N bond lengths is related to the relative trans effect exerted by the Cd-O bonds formed by the carboxyl-ate-O and aqua-O atoms. The packing features water-O-H⋯O(carboxyl-ate) and benzene-1,2-di-amine-N-H⋯Cl hydrogen bonds, leading to layers that stack along the a-axis direction. The lack of directional inter-actions between the layers is confirmed by a Hirshfeld surface analysis.
Dimethyl adipate (DMA) was synthesized by immobilized Candida antarctica lipase B-catalyzed esterification of adipic acid and methanol. To optimize the reaction conditions of ester production, response surface methodology was applied, and the effects of four factors namely, time, temperature, enzyme concentration, and molar ratio of substrates on product synthesis were determined. A statistical model predicted that the maximum conversion yield would be 97.6%, at the optimal conditions of 58.5 degrees C, 54.0 mg enzyme, 358.0 min, and 12:1 molar ratio of methanol to adipic acid. The R(2) (0.9769) shows a high correlation between predicted and experimental values. The kinetics of the reaction was also investigated in this study. The reaction was found to obey the ping-pong bi-bi mechanism with methanol inhibition. The kinetic parameters were determined and used to simulate the experimental results. A good quality of fit was observed between the simulated and experimental initial rates.
Organostannum(IV) complexes derived from dicarboxylic acids have been successfully synthesised from triphenylstannum(IV) hydroxide (Ph3SnOH). The complexes were obtained by refluxing Ph3SnOH and the respective dicarboxylic acids (malonic, succinic, glutaric and adipic acids) using a Dean and Stark apparatus in the appropriate solvent. The free ligands and complexes were characterised by C, Hand Sn elemental analysis and spectroscopic methods such as infrared and nuclear magnetic resonance (1H, 13C NMR). Structure determination of triphenylstannum(IV) succinate, 2, showed that each dicarboxylate anion was bonded monodentatically to two triphenylstannum(IV) moieties. The geometry surrounding each stannum atom is close to a tetrahedron. Spectroscopic data obtained for all complexes were found to be similar and thus it may be concluded that all complexes have the same structure as 2.
Immobilized Candida antarctica lipase-catalyzed esterification of adipic acid and oleyl alcohol was investigated in a solvent-free system (SFS). Optimum conditions for adipate ester synthesis in a stirred-tank reactor were determined by the response surface methodology (RSM) approach with respect to important reaction parameters including time, temperature, agitation speed, and amount of enzyme. A high conversion yield was achieved using low enzyme amounts of 2.5% w/w at 60 degrees C, reaction time of 438 min, and agitation speed of 500 rpm. The good correlation between predicted value (96.0%) and actual value (95.5%) implies that the model derived from RSM allows better understanding of the effect of important reaction parameters on the lipase-catalyzed synthesis of adipate ester in an organic solvent-free system. Higher volumetric productivity compared to a solvent-based system was also offered by SFS. The results demonstrate that the solvent-free system is efficient for enzymatic synthesis of adipate ester.
Hydroxyapatite (HAP) is a significant bone mineral that establishes bone strength. HAP composites in combination with biodegradable and bioactive polymer poly xylitol sebacic adipate (PXSA) would result in a constant release at target sites. Numerous studies have shown that vitamin K (VK) might possess a vital function in bone metabolism. The purpose of the present study was to inspect the synthesized composite HAP/PXSA/VK in developing polymeric biomaterials composite for the application of bone tissue regeneration. FTIR, X-ray diffraction, SEM and TEM techniques were applied to characterize the prepared composites. The release of VK from the HAP/PXSA/VK composite was evidenced through UV-Vis spectroscopy. In vitro studies proved that the HAP/PXSA/VK composite is appropriate for mesenchymal stem cell culture. Compared to pure HAP prepared following the same method, HAP/PXSA/VK composite provided favourable microstructures and good biodegradation distinctiveness for the application of tissue engineering, as well as tissue in-growth characteristics and improved scaffold cell penetration. This work reveals that the HAP/PXSA/VK composites have the potential for applications in bone tissue engineering.
Purified lipopolysaccharide (LPS) of Pasteurella multocida type 6:B, while toxic at higher doses, was protective at lower dose levels against experimentally-induced pasteurellosis in mice. However, the observed protection was abrogated if such LPS was digested with proteinase K prior to use in immunisation. The O-antigen polysaccharide side-chain (OS) of LPS did not appear to contribute to the observed protection as judged by the fact that immunisation of mice with purified OS or OS-protein conjugates, all of which were nontoxic, failed to confer protection against challenge with homologous virulent organisms. This was despite generation of significant levels of OS-specific antibodies, predominantly either of the IgM or IgG isotypes, in immunised mice.