Accumulation of plastic waste is a major environmental problem. Enzymes, particularly esterases, play an important role in the biodegradation of polyesters. These enzymes are usually only active on aliphatic polyesters, but a few have showed catalytic activity for semi-aromatic polyesters. Due to the importance of these processes, an atomic level characterization of how common polyesters are degraded by esterases is necessary. Hereby, we present a Molecular dynamics (MD) and Quantum Mechanics/Molecular Mechanics (QM/MM) MD study of the hydrolysis of a model of polycaprolactone (PCL), one of the most widely used biomaterials, by the thermophilic esterase from the archaeon Archaeoglobus fulgidus (AfEST). This enzyme is particularly interesting because it can withstand temperatures well above the glass transition of many polyesters. Our insights about the reaction mechanism are important for the design of customized enzymes able to degrade different synthetic polyesters.

Biodegradable polymers, obtained via chemical synthesis, are currently employed in a wide range of biomedical applications. However, enzymatic polymerization is an attractive alternative because it is more sustainable and safer. Many lipases can be employed in ring-opening polymerization (ROP) of biodegradable polymers. Nevertheless, the harsh conditions required in industrial context are not always compatible with their enzymatic activity. In this work, we have studied a thermophilic carboxylesterase and the commonly used Lipase B from Candida antarctica (CaLB) for tailored synthesis of amphiphilic polyesters for biomedical applications. We have conducted Molecular Dynamics (MD) and Quantum Mechanics/Molecular Mechanics (QM/MM) MD simulations of the synthesis of Polycaprolactone—Polyethylene Glycol (PCL—PEG) model co-polymers. Our insights about the reaction mechanisms are important for the design of customized enzymes capable to synthesize different polyesters for biomedical applications.

ABSTRACT. The association between TP53 gene polymorphisms and breast cancer (BC) in Brazilian women is a controversial topic. In this cross-sectional study, we evaluated the association between clinical pathological variables and three polymorphisms (TP53*11, TP53*72, and TP53*248) in BC patients and controls. Genomic DNA was extracted from the blood cells of 393 participants; the cancer-free control subjects were 26-72 years old (41 ± 11.03) and the BC patients were 28-80 years old (51 ± 10.70). We used standard polymerase chain reaction-restriction fragment length polymorphism and confirmed the results by genetic sequencing. In TP53*11, there was 100% homozygous Glu distribution in both groups. TP53*72 showed genotypic distribution: in the control group, there was 16.10% homozygous Pro, and 42.44% heterozygous and 41.46% homozygous Arg; in the BC group, there was 15.43% homozygous Pro, and 42.55% heterozygous and 42.02% homozygous Arg. The relative frequency of each allele was 0.37% for Pro and 0.63% for Arg in the control group, and 0.37% for Pro and 0.63% for Arg in the BC group. The nuclear grade (P = 0.0084) and adapted histological grade (P = 0.0265) were associated with TP53*72. The distribution of the codon 72 genotypes did not deviate from Hardy-Weinberg equilibrium in either group. In TP53*248, there was 100% homozygous Arg distribution in both groups. In codon 72, the Arg allele is the most prevalent in Brazilian women. TP53*72 may be associated with susceptibility to BC, although more studies are required to evaluate the profile of Brazilian women with BC.

Our reliance on synthetic polymers (plastics) is causing immeasurable damage to the environment. Better alternatives are actively being sought-after, such as biodegradable polyesters obtained by enzymatic synthesis. Here we compare in detail the catalytic mechanisms for poly(caprolactone) synthesis by the enzymes Archaeoglobus fulgidus carboxylesterase (AfEST) and Candida antarctica lipase B (CalB) using Quantum Mechanics/ Molecular Mechanics Molecular Dynamics simulations. In the ring-opening step (rate-limiting) the significantly higher free energy barrier found for AfEST is a consequence of the larger distance between the histidine-aspartate pair and the oxygen of the lactone, and a shorter distance to the serine nucleophile, favouring the reverse reaction towards the initial reactants. Our results give important insights towards the design of enzymatic variants which combine high activity and high thermostability in the synthesis of poly(caprolactone), which due to its bioresorbability is of great importance for biomedical applications.

Coronavirus disease-19 (COVID-19) emerged in December 2019 and quickly spread, giving rise to a pandemic crisis. Therefore, it triggered tireless efforts to identify the mechanisms of the disease, how to prevent and treat it, and to limit and hamper its global dissemination. Considering the above, the search for prophylactic approaches has led to a revolution in the reglementary pharmaceutical pipeline, with the approval of vaccines against COVID-19 in an unprecedented way. Moreover, a drug repurposing scheme using regulatory-approved antiretroviral agents is also being pursued. However, their physicochemical characteristics or reported adverse events have sometimes limited their use. Hence, nanotechnology has been employed to potentially overcome some of these challenges, particularly cyclodextrins. Cyclodextrins are cyclic oligosaccharides that present hydrophobic cavities suitable for complexing several drugs. This review, besides presenting studies on the inclusion of antiviral drugs in cyclodextrins, aims to summarize some currently available prophylactic and therapeutic schemes against COVID-19, highlighting those that already make use of cyclodextrins for their complexation. In addition, some new therapeutic approaches are underscored, and the potential application of cyclodextrins to increase their promising application against COVID-19 will be addressed. This review describes the instances in which the use of cyclodextrins promotes increased bioavailability, antiviral action, and the solubility of the drugs under analysis. The potential use of cyclodextrins as an active ingredient is also covered. Finally, toxicity and regulatory issues as well as future perspectives regarding the use of cyclodextrins in COVID-19 therapy will be provided.