-
Sommer Jepsen posted an update 6 months, 2 weeks ago
The most common variant of fullerene core functionalization is the cycloaddition process. Of these, reactions leading to methanofullerenes are the most promising. They are synthesized in two main reactions nucleophilic cyclopropanation according to the Bingel method and thermal addition of diazo compounds. This present review summarizes the material on the synthesis of monofunctionalized methanofullerenes – analogues of PCBM – based on various diazo compounds. The main cyclopropanating agents for the synthesis of monosubstituted methanofullerenes, the optimal conditions and the mechanism of the cycloaddition, as well as the practical application of the target products are analyzed.Chemical modifications have been extensively used for therapeutic oligonucleotides because they strongly enhance the stability against nucleases, binding affinity to the targets, and efficacy. We previously reported that oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA) bearing the thymine (T) nucleobase show excellent biophysical properties for applications in antisense technology. In this paper, we describe the synthesis of GuNA phosphoramidites bearing other typical nucleobases including adenine (A), guanine (G), and 5-methylcytosine (mC). The phosphoramidites were successfully incorporated into oligonucleotides following the method previously developed for the GuNA-T-modified oligonucleotides. The binding affinity of the oligonucleotides modified with GuNA-A, -G, or -mC toward the complementary single-stranded DNAs or RNAs was systematically evaluated. All of the GuNA-modified oligonucleotides were found to have a strong affinity for RNAs. These data indicate that GuNA could be a useful modification for therapeutic antisense oligonucleotides.Metal-catalysed depolymerisation of plastics to reusable building blocks, including monomers, oligomers or added-value chemicals, is an attractive tool for the recycling and valorisation of these materials. The present manuscript shortly reviews the most significant contributions that appeared in the field within the period January 2010-January 2020 describing selective depolymerisation methods of plastics. read more Achievements are broken down according to the plastic material, namely polyolefins, polyesters, polycarbonates and polyamides. The focus is on recent advancements targeting sustainable and environmentally friendly processes. Biocatalytic or unselective processes, acid-base treatments as well as the production of fuels are not discussed, nor are the methods for the further upgrade of the depolymerisation products.A method for the synthesis of 9,11-secosteroids starting from the natural corticosteroid cortisol is described. There are two key steps in this approach, combining chemistry and synthetic biology. Stereo- and regioselective hydroxylation at C9 (steroid numbering) is carried out using whole-cell biocatalysis, followed by the chemical cleavage of the C-C bond of the vicinal diol. The two-step method features mild reaction conditions and completely excludes the use of toxic oxidants.This Statement presents a proposal for harmonising the establishment of Health-Based Guidance Values (HBGVs) for regulated products that are also nutrients. This is a recurrent issue for food additives and pesticides, and may occasionally occur for other regulated products. The Statement describes the specific considerations that should be followed for establishing the HBGVs during the assessment of a regulated product that is also a nutrient. It also addresses the elements to be considered in the intake assessment; and proposes a decision tree for ensuring a harmonised process for the risk characterisation of regulated products that are also nutrients. The Scientific Committee recommends the involvement of the relevant EFSA Panels and units, in order to ensure an integrated and harmonised approach for the hazard and risk characterisation of regulated products that are also nutrients, considering the intake from all relevant sources.In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant Exponent International Ltd. (on behalf of the U.S. Highbush Blueberry Council (USHBC)) submitted a request to the competent national authority in France to set an import tolerance for the active substance potassium phosphonates in blueberries. The data submitted in support of the request were found to be sufficient to derive a maximum residue level (MRL) proposal for blueberries. Adequate analytical methods for enforcement are available to control the residues of phosphonic acid on the commodity under consideration at the validated limit of quantification (LOQ) of 0.1 mg/kg. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the use of potassium phosphonates according to the reported agricultural practice is unlikely to present a risk to consumer health. The consumer risk assessment shall be regarded as indicative and a refined intake assessment will be performed in the framework of the joint review of MRLs for fosetyl and phosphonates.The European Commission requested EFSA Panel on Plant Health to evaluate a dossier from Israel in which the application of the systems approach to mitigate the risk of entry of Thaumatotibia leucotreta to the EU when trading citrus fruits is described. After collecting additional evidence from the Plant Protection and Inspection Services (PPIS) of Israel, and reviewing the published literature, the Panel performed an assessment on the likelihood of pest freedom for T. leucotreta on citrus fruits at the point of entry in the EU considering the Israelian systems approach. An expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures on T. leucotreta, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,863 and 10,000 citrus fruits per 10,000 will be free from this pest. The Panel also evaluated each risk mitigation measure in the systems approach and identified any weaknesses associated with them. Specific actions are identified that could increase the efficacy of the systems approach.