Z-L-pyroglutamic acid 4-nitrophenyl ester

During the last years, there has been a remarkable increase in the use of inorganic nanoparticles (NP) in different applications, including consumer and medical products. Despite these promising applications, the extremely small size of NP allows them to penetrate cells, in which they can interact with intracellular structures causing serious side effects. A number of studies showed that NP cause adverse effects predominantly via induction of an oxidative stress - an imbalance between damaging oxidants and protective antioxidants - resulting in inflammation, immune response, cell damages, genotoxicity, etc … Most of the in vitro methods used for measurement of oxidative stress biomarkers were designed and standardized for conventional organic, inorganic and biochemical compounds. More recently, these methods have been adapted to studies related to various nanomaterials. Thus, this review is an attempt to highlight some current methods employed in and to provide a critical analysis of the major challenges and issues faced in this emerging field.

Glucuronoyl esterases (GEs) are microbial enzymes with potential to cleave the ester bonds between lignin alcohols and xylan-bound 4-O-methyl-d-glucuronic acid in plant cell walls. This activity renders GEs attractive research targets for biotechnological applications. One of the factors impeding the progress in GE research is the lack of suitable substrates. In this work, we report a facile preparation of methyl esters of chromogenic 4-nitrophenyl and 5-bromo-4-chloro-3-indolyl β-D-glucuronides for qualitative and quantitative GE assay coupled with β-glucuronidase as the auxiliary enzyme. The indolyl derivative affording a blue indigo-type product is suitable for rapid and sensitive assay of GE in commercial preparations as well as for high throughput screening of microorganisms and genomic and metagenomic libraries.