Roeb García-Arrazola

Environmental epigenomics: Current approaches to assess epigenetic effects of endocrine disrupting compounds (EDC’s) on human health

Environmental Epigenomics is a developing field to study the epigenetic effect on human health from exposure to environmental factors. Endocrine disrupting chemicals have been detected primarily in pharmaceutical drugs, personal care products, food additives, and food containers. Exposure to endocrine-disrupting chemicals (EDCs) has been associated with a high incidence and prevalence of many endocrine-related disorders in humans. Nevertheless, further evidence is needed to establish a correlation between exposure to EDC and human disorders. Conventional detection of EDCs is based on chemical structure and concentration sample analysis. However, substantial evidence has emerged, suggesting that cell exposure to EDCs leads to epigenetic changes, independently of its chemical structure with non-monotonic low-dose responses. Consequently, a paradigm shift in toxicology assessment of EDCs is proposed based on a comprehensive review of analytical techniques used to evaluate the epigenetic effects. Fundamental insights reported elsewhere are compared in order to establish DNA methylation analysis as a viable method for assessing endocrine disruptors beyond the conventional study approach of chemical structure and concentration analysis.

Growth of epithelial cells on films of enzymatically synthesized poly(gallic acid) crosslinked to carboxymethylcellulose

Poly(gallic acid), a novel polymer obtained by enzymatic polymerization of gallic acid, was successfully cross-linked to carboxymethylcellulose using citric acid as a cross-linker. Non-woven sheets were prepared with the resulting copolymer and their in vitro biocompatibility was assessed. The results on the characterizations of the produced films by mechanical tests, water vapour permeability, contact angle, and antioxidant activity by electronic paramagnetic resonance were adequate for skin tissue regeneration. Films were also decomposed under physiological conditions using universal buffers at pH 3, 7 and 10. In vitro experiments with fibroblast-like and epithelial-like cells showed good adhesion and proliferation onto the PGAL-co-CMC sheets. These non-woven sheets can consequently be considered as novel biocompatible and biodegradable films with high-responsiveness for biomedical or tissue engineering applications.

Cytoprotective effect of the enzyme-mediated polygallic acid on fibroblast cells under exposure of UV-irradiation

The poly(gallic acid), produced by laccase-mediated oxidation of gallic acid in aqueous media (pH5.5) to attain a novel material with well-defined molecular structure and high water solubility (500mg/mL at 25°C), has been investigated to understand its potential biological activities. In this regard, a biomedical approach based on cytoprotective effect on human fibroblast cells exposed to UV-irradiation in the presence of the polymer has been demonstrated. The results also shows that 200μg/mL of poly(gallic acid) inhibits the growth and migration of dermal fibroblasts and cancer cell lines without affecting cell viability. Poly(gallic acid) pretreatment with 10μg/mL protects dermal fibroblasts from UV induced cell death and additionally, the cytoprotective effect reduce ROS presence in the cells. This property can be correlated with the antioxidant power (IC50 of 23.5μg/mL) of this novel material, which was ascertained by electronic paramagnetic resonance spectroscopy and spectrophotometrically. Additionally, the antimicrobial activity of this material was corroborated with the inhibition of Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212) strains (MIC=400mg/mL) common bacteria found in hospitals.

Effect of the initial water activity on the yields and molecular wWeights of the lipase-catalysed synthesis of aliphatic polyesters in low pressure liquid R-134a

Abstract The enzymatic synthesis of the polyester poly(epsilon-caprolactone) (PCL) were evaluated on the basis of the initial water activity (awi) using liquid 1,1,1,2-tetrafluoroethane (R-134a) as solvent media at 2.5 MPa. Polymer yields and molecular weights were directly related to awi and reaction times. The highest molecular weight (Mn) was 83,600 gmol-1, Mw /Mn 1.4, with a 67% yield after 48 h of reaction with the lowest biocatalyst awi preparation (awi <0.16). It is suggested that the enhanced solubility of the growing polymer chains in liquid R-134a may be responsible for the attainment of such high molecular weight. A maximum polymer yield of 99% with Mn 7,246 gmol-1 and Mw/Mn 4.5 was attained when the biocatalyst was adjusted to awi =0.22.