Transesterification of PHA to Oligomers Covalently Bonded with (Bio)Active Compounds Containing Either Carboxyl or Hydroxyl Functionalities

© 2015 The Authors. Published by Public Library of Science. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0120149This manuscript presents the synthesis and structural characterisation of novel biodegradable polymeric controlled-release systems of pesticides with potentially higher resistance to weather conditions in comparison to conventional forms of pesticides. Two methods for the preparation of pesticide-oligomer conjugates using the transesterification reaction were developed. The first method of obtaining conjugates, which consist of bioactive compounds with the carboxyl group and polyhydroxyalkanoates (PHAs) oligomers, is "one-pot" transesterification. In the second method, conjugates of bioactive compounds with hydroxyl group and polyhydroxyalkanoates oligomers were obtained in two-step method, through cyclic poly(3-hydroxybutyrate) oligomers. The obtained pesticide-PHA conjugates were comprehensively characterised using GPC, 1H NMR and mass spectrometry techniques. The structural characterisation of the obtained products at the molecular level with the aid of mass spectrometry confirmed that both of the synthetic strategies employed led to the formation of conjugates in which selected pesticides were covalently bonded to PHA oligomers via a hydrolysable ester bond

O-Acetyl location on Cepacian, the principal exopolysaccharide of Burkholderia cepacia complex bacteria

Cepacian is an exopolysaccharide produced by the majority of the isolates belonging to the Burkholderia cepacia complex bacteria, a group of 17 species, some of which infect cystic fibrosis patients, sometime with fatal outcome. The repeating unit of cepacian consists of a backbone having a trisaccharidic repeating unit with three side chains, as reported in the formula below. The exopolysaccharide is also acetylated, carrying from one to three acetyl esters per repeating unit, depending on the strain examined. The consequences of O-acetyl substitution in a polysaccharide are important both for its biological functions and for industrial applications, including the preparation of conjugated vaccines, since O-acetyl groups are important immunogenic determinants. The location of acetyl groups was achieved by NMR spectroscopy and ESI mass spectrometry and revealed that these substituents are scattered in non-stoichiometric ratio on many sugar residues in different positions, a feature which adds to the already unique carbohydrate structure of the polysaccharide

Characterization of biodegradable poly(3-hydroxybutyrate-co-butyleneadipate) copolymers obtained from their homopolymers by microwave-assisted transesterification

Copolymers containing(R)-3-hydroxybutyricacid (HB), 1,4-butanediol (B), andadipicacid (A) were synthesized by microwave-assisted transesterification o fbiodegradable poly(R-3-hydroxybutyrate) (PHB) and poly(1,4-butyleneadipate) (PBA) in solution at different reaction times, composition of the starting mixture, and amount of 4-toluene sulfonic acid, used as a catalyst. The copolyesters were characterized with regard to their molecular weights, thermal properties, molar composition, and average blockl ength of repeating units by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXS), 1H-NMR, and 13C-NMR, respectively. Random and microblock copolymers could be obtained depending on experimental conditions, with weight average molecular weight of up to 17,000. The glass transition temperature (Tg) of all samples lay in the range between the Tgs of PBA and PHB, while their structure varied from partially crystalline to totally amorphous. Matrix-assisted laser desorption ionization time-of-flight (MALDI- TOF) mass spectra of copolymers allowed us to ascertain that they were hydroxyl and carboxyl chain-end terminated

SEQUENCE DISTRIBUTION OF BETA-HYDROXYALKANOATE UNITS WITH HIGHER ALKYL-GROUPS IN BACTERIAL COPOLYESTERS

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Inositol-specific phosphorilipase D activity in health and disease.

1. We report the first demonstration of the pathophysiological importance and clinical applications of the relatively recently discovered circulating enzyme, phosphoinositol-specific phospholipase D. This enzyme is known to cleave the large variety of important cell-surface molecules linked to the cell membrane by glycan-phosphatidylinositol linkages (glycan- phosphatidylinositol anchors). 2. When measured in the sera of healthy individuals, phosphoinositol-specific phospholipase D activity was found to show a strong negative correlation with age, the degree of depreciation being greater than that measured for most other analytes. 3. Serum phosphoinositol- specific phospholipase D activity was considerably depressed in patients presenting with conditions leading to reduced liver synthetic reserve, such as hepatocellular carcinoma or liver cirrhosis caused by chronic viral hepatitis, and correlated with reduced albumin levels in these conditions, indicating that the liver is the site of phosphoinositol-specific phospholipase D synthesis and that phosphoinositol-specific phospholipase D may be used as an additional marker of liver synthetic reserve. 4. When measured in patients with acute liver disease, such as acute viral hepatitis, or in patients with bronchopneumonia, phosphoinositol-specific phospholipase D activity was found to be significantly raised, demonstrating features characteristic of an acute-phase reactant. 5. These findings indicate that, besides its pathophysiological importance, phosphoinositol-specific phospholipase D and the measurement of its activity in serum may have a useful place in the investigation of a range of clinical conditions, including tissue injury and inflammation

Exopolysaccharides produced by clinical strains belonging to the Burkholderia cepacia complex

Background: In the frame of a research line dedicated to better clarify the role of exopolysaccharides (EPS) in bacterial virulence, EPS produced by species of the Burkholderia cepacia complex (Bcc), namely Burkholderia multivorans, Burkholderia cenocepacia, and a Bcc member of undetermined genomovar, all isolated at the Cystic Fibrosis Regional Centre of Florence (Italy), were investigated for they structural properties. Methods: Three strains of B. multivorans, three of B. cenocepacia and one of a Bcc member of undetermined genomovar were isolated from CF patients. The reference strains C1576 and J2315, for genomovar II and III, respectively, were included in the study. The bacteria were grown on solid media, the exopolysaccharides produced were purified, and their structures were determined. In addition, sugar analysis of sputum samples was accomplished to search for EPS produced in vivo. Results: Six strains out of seven produced the exopolysaccharide cepacian, while one strain of B. multivorans produced a completely different polymer, previously known in the literature as PS1. Two strains synthesised very small amounts of EPS. No definitive evidence for the presence of cepacian in sputum samples was found. Conclusions: Most strains examined produced abundant amounts of polysaccharides. Cepacian was the most common EPS isolated and its production was not associated to a particular genomovar