Bioreversible derivatives of phenol. 2. Reactivity of carbonate esters with fatty acid-like structures towards hydrolysis in aqueous solutions

Engineered Geobacillus lipolytic enzymes - Attractive polyesterases that degrade polycaprolactones and simultaneously produce esters

Plastic pollution is one of the biggest environmental problems plaguing the modern world. Polyester-based plastics contribute significantly to this ecological safety concern. In this study, lipolytic biocatalysts GD-95RM and GDEst-lip developed based on lipase/esterase produced by Geobacillus sp. 95 strain were applied for the degradation of polycaprolactone films (Mn 45.000 (PCL45000) and Mn 80.000 (PCL80000)). The degradation efficiency was significantly enhanced by the addition of short chain alcohols. Lipase GD-95RM (1 mg) can depolymerize 264.0 mg and 280.7 mg of PCL45000 and PCL80000, films respectively, in a 24 h period at 30 °C, while the fused enzyme GDEst-lip (1 mg) is capable of degrading 145.5 mg PCL45000 and 134.0 mg of PCL80000 films in 24 h. The addition of ethanol (25 %) improves the degradation efficiency ~2.5 fold in the case of GD-95RM. In the case of GDEst-lip, 50 % methanol was found to be the optimal alcohol solution and the degradation efficiency was increased by ~3.25 times. The addition of alcohols not only increased degradation speeds but also allowed for simultaneous synthesis of industrially valuable 6-hydroxyhexonic acid esters. The suggested system is an attractive approach for removing of plastic waste and supports the principles of bioeconomics.

Influence of Sex on Urinary Organic Acids: A Cross-Sectional Study in Children

The characterization of urinary metabolome, which provides a fingerprint for each individual, is an important step to reach personalized medicine. It is influenced by exogenous and endogenous factors; among them, we investigated sex influences on 72 organic acids measured through GC-MS analysis in the urine of 291 children (152 males; 139 females) aging 1–36 months and stratified in four groups of age. Among the 72 urinary metabolites, in all age groups, 4-hydroxy-butirate and homogentisate are found only in males, whereas 3-hydroxy-dodecanoate, methylcitrate, and phenylacetate are found only in females. Sex differences are still present after age stratification being more numerous during the first 6 months of life. The most relevant sex differences involve the mitochondria homeostasis. In females, citrate cycle, glyoxylate and dicarboxylate metabolism, alanine, aspartate, glutamate, and butanoate metabolism had the highest impact. In males, urinary organic acids were involved in phenylalanine metabolism, citrate cycle, alanine, aspartate and glutamate metabolism, butanoate metabolism, and glyoxylate and dicarboxylate metabolism. In addition, age specifically affected metabolic pathways, the phenylalanine metabolism pathway being affected by age only in males. Relevantly, the age-influenced ranking of metabolic pathways varied in the two sexes. In conclusion, sex deeply influences both quantitatively and qualitatively urinary organic acids levels, the effect of sex being age dependent. Importantly, the sex effects depend on the single organic acid; thus, in some cases the urinary organic acid reference values should be stratified according the sex and age.

Cationic DOPC-Detergent Conjugates for Safe and Efficient in Vitro and in Vivo Nucleic Acid Delivery

The ability of a nonviral nucleic acid carrier to deliver its cargo to cells with low associated toxicity is a critical issue for clinical applications of gene therapy. We describe biodegradable cationic DOPC-C12 E4 conjugates in which transfection efficiency is based on a Trojan horse strategy. In situ production of the detergent compound C12 E4 through conjugate hydrolysis within the acidic endosome compartment was expected to promote endosome membrane destabilization and subsequent release of the lipoplexes into cytosol. The transfection efficiency of the conjugates has been assessed in vitro, and associated cytotoxicity was determined. Cellular uptake and intracellular distribution of the lipoplexes have been investigated. The results show that direct conjugation of DOPC with C12 E4 produces a versatile carrier that can deliver both DNA and siRNA to cells in vitro with high efficiency and low cytotoxicity. SAR studies suggest that this compound might represent a reasonable compromise between the membrane activity of the released detergent and susceptibility of the conjugate to degradation enzymes in vitro. Although biodegradability of the conjugates had low impact on carrier efficiency in vitro, it proved critical in vivo. Significant improvement of transgene expression was obtained in the mouse lung tuning biodegradability of the carrier. Importantly, this also allowed reduction of the inflammatory response that invariably characterizes cationic-lipid-mediated gene transfer in animals.

Use of the SPARC software program to calculate hydrolysis rate constants for the polymeric brominated flame retardants BC-58 and FR-1025

The SPARC software program was used to estimate the acid-catalyzed, neutral, and base-catalyzed hydrolysis rate constants for the polymeric brominated flame retardants BC-58 and FR-1025. Relatively rapid hydrolysis of BC-58, producing 2,4,6-tribromophenol-and ultimately tetrabromobisphenol A-as the hydrolytically stable end products from all potential hydrolysis reactions, is expected in both environmental and biological systems with starting material hydrolytic half-lives (t(1/2,hydr)) ranging from less than 1 h in marine systems, several hours in cellular environments, and up to several weeks in slightly acid fresh waters. Hydrolysis of FR-1025 to give 2,3,4,5,6-pentabromobenzyl alcohol is expected to be slower (t(1/2,hydr) less than 0.5 years in marine systems up to several years in fresh waters) than BC-58, but is also expected to occur at rates that will contribute significantly to environmental and in vivo loadings of this compound.

Preparation of mixed trialkyl alkylcarbonate derivatives of etidronic acid via an unusual route

A method to prepare four (3a–d) trialkyl alkylcarbonate esters of etidronate from P,P'-dimethyl etidronate and alkyl chloroformate was developed by utilizing unexpected demethylation and decarboxylation reactions. The reaction with the sterically more hindered isobutyl chloroformate at a lower temperature (90 °C) produced the P,P'-diester (2) as a stable intermediate product. A possible reaction mechanism is discussed to explain these methyl substitutions. These unusual reactions also clarify why it is difficult to prepare alkylcarbonate prodrugs from bisphosphonates. The compounds prepared were analysed by spectroscopic techniques.

Relationships between base-catalyzed hydrolysis rates or glutathione reactivity for acrylates and methacrylates and their NMR spectra or heat of formation

The NMR chemical shift, i.e., the π-electron density of the double bond, of acrylates and methacrylates is related to the reactivity of their monomers. We investigated quantitative structure-property relationships (QSPRs) between the base-catalyzed hydrolysis rate constants (k1) or the rate constant with glutathione (GSH) (log k(GSH)) for acrylates and methacrylates and the (13)C NMR chemical shifts of their α,β-unsaturated carbonyl groups (δC(α) and δC(β)) or heat of formation (Hf) calculated by the semi-empirical MO method. Reported data for the independent variables were employed. A significant linear relationship between k1 and δC(β), but not δC(α), was obtained for methacrylates (r(2) = 0.93), but not for acrylates. Also, a significant relationship between k1 and Hf was obtained for both acrylates and methacrylates (r(2) = 0.89). By contrast, log k(GSH) for acrylates and methacrylates was linearly related to their δC(β) (r(2) = 0.99), but not to Hf. These findings indicate that the (13)C NMR chemical shifts and calculated Hf values for acrylates and methacrylates could be valuable for estimating the hydrolysis rate constants and GSH reactivity of these compounds. Also, these data for monomers may be an important tool for examining mechanisms of reactivity.

Investigation of self-immolative linkers in the design of hydrogen peroxide activated metalloprotein inhibitors

A series of self-immolative boronic ester protected methyl salicylates and metal-binding groups with various linking strategies have been investigated for their use in the design of matrix metalloproteinase proinhibitors.

Can mutagenicity information be useful in an Integrated Testing Strategy (ITS) for skin sensitization?

Our previous work has investigated the utility of mutagenicity data in the development and application of Integrated Testing Strategies (ITS) for skin sensitization by focusing on the chemical mechanisms at play and substantiating these with experimental data where available. The hybrid expert system TIMES (Tissue Metabolism Simulator) was applied in the identification of the chemical mechanisms since it encodes a comprehensive set of established structure-activity relationships for both skin sensitization and mutagenicity. Based on the evaluation, the experimental determination of mutagenicity was thought to be potentially helpful in the evaluation of skin sensitization potential. This study has evaluated the dataset reported by Wolfreys and Basketter (Cutan. Ocul. Toxicol. 23 (2004), pp. 197-205). Upon an update of the experimental data, the original reported concordance of 68% was found to increase to 88%. There were several compounds that were 'outliers' in the two experimental evaluations which are discussed from a mechanistic basis. The discrepancies were found to be mainly associated with the differences between skin and liver metabolism. Mutagenicity information can play a significant role in evaluating sensitization potential as part of an ITS though careful attention needs to be made to ensure that any information is interpreted in the appropriate context.

Bioreversible derivatives of phenol. 1. The role of human serum albumin as related to the stability and binding properties of carbonate esters with fatty acid-like structures in aqueous solution and biological media

With the overall objective of assessing the potential of utilizing plasma protein binding interactions in combination with the prodrug approach for improving the pharmacokinetics of drug substances, a series of model carbonate ester prodrugs of phenol, encompassing derivatives with fatty acid-like structures, were characterized in vitro. Stability of the derivatives was studied in aqueous solution, human serum albumin solution, human plasma, and rat liver homogenate at 37 degrees C. Stability of the derivatives in aqueous solution varied widely, with half-lives ranging from 31 to 1.7 x 10(4) min at pH 7.4 and 37 degrees C. The carbonate esters were subject to catalysis by plasma esterases except for the t-butyl and acetic acid derivatives, which were stabilized in both human plasma and human serum albumin solutions relative to buffer. In most cases, however, hydrolysis was accelerated in the presence of human serum albumin indicating that the derivatives interacted with the protein, a finding which was confirmed using the p-nitrophenyl acetate kinetic assay. Different human serum albumin binding properties of the phenol model prodrugs with fatty acid-like structure and neutral carbonate esters were observed. In the context of utilizing plasma protein binding in combination with the prodrug approach for optimizing drug pharmacokinetics, the esterase-like properties of human serum albumin towards the carbonate esters potentially allowing the protein to act as a catalyst of parent compound regenerations is interesting.