RESUMO

The adaptation of amphibians to diverse environments is closely related to the characteristics of their skin. The complex glandular system of frog skin plays a pivotal role in enabling these animals to thrive in both aquatic and terrestrial habitats and consists of crucial functions such as respiration and water balance as well as serving as a defensive barrier due to the secretion of bioactive compounds. We herein report the first investigation on the skin secretion of Odontophrynus americanus, as a potential source of bioactive peptides and also as an indicator of its evolutionary adaptations to changing environments. Americanin-1 was isolated and identified as a neutral peptide exhibiting moderate antibacterial activity against E. coli. Its amphipathic sequence including 19 amino acids and showing a propensity for α-helix structure is discussed. Comparisons of the histomorphology of the skin of O. americanus with other previously documented species within the same genus revealed distinctive features in the Patagonian specimen, differing from conspecifics from other Argentine provinces. The presence of the Eberth-Katschenko layer, a prevalence of iridophores, and the existence of glycoconjugates in its serous glands suggest that the integument is adapted to retain skin moisture. This adaptation is consistent with the prevailing aridity of its native habitat.

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One approach to enhance the bioavailability and half-life of peptides in vivo is through N-methylation of one or more of the amino acids within the peptide sequence. However, commercially available Fmoc-N-Me-AA-OHs are limited and often expensive. In this study, a solid-phase synthesis method for Fmoc-N-Me-AA-OH was developed using a 2-chlorotrityl chloride (2-CTC) resin as a temporary protective group for the carboxylic acid strategy. Two strategies for the alkylation step were compared, employing either dimethyl sulfate or methyl iodide in the Biron-Kessler method. In this work we tested the protocol with two amino acids: Fmoc-Thr(tBu)-OH and Fmoc-ßAla-OH. The first one is an alpha amino acid, very hindered and with the amine group directly influenced by the electronic effects of the carboxy group, whereas in Fmoc-ßAla-OH, the presence of a methylene group weakens this influence due to the intervening carbon atoms. The desired amino acids, Fmoc-N-Me-Thr(tBu)-OH and Fmoc-N-Me-ßAla-OH, were synthesized by both strategies with high yield and purity.

RESUMO

Used in solid-phase peptide synthesis (SPPS) for peptides with an acid termination, the 2-chlorotrityl chloride (2-CTC) resin is highly susceptible to moisture, leading to reduced resin loading and lower synthetic yields. It is therefore recommended that the resin be activated with thionyl chloride (SOCl2) before peptide assembly. Here we present an optimized procedure for resin activation that minimizes the use of SOCl2 as the activation reagent and reduces the activation time. Additionally, we demonstrate the feasibility of reusing the 2-CTC resin when following the activation protocol, achieving comparable results to the first usage of the resin. Moreover, we achieved different degrees of resin activation by varying the amount of SOCl2. For instance, the use of 2% SOCl2 in anhydrous dichloromethane (DCM) allowed up to 44% activation of the resin, thereby making it suitable for the synthesis of longer peptides. Alternatively, employing 25% SOCl2 in anhydrous DCM resulted in up to 80% activation with a reaction time of only 5 min in both cases.

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The year 2022 witnessed the control of the COVID-19 pandemic in most countries through social and hygiene measures and also vaccination campaigns. It also saw a decrease in total approvals by the U.S. Food and Drug Administration (FDA). Nevertheless, there was no fall in the Biologics class, which was boosted through the authorization of 15 novel molecules, thus maintaining the figures achieved in previous years. Indeed, the decrease in approvals was only for the category of small molecules. Monoclonal antibodies (mAbs) continued to be the drug class with the most approvals, and cancer remained the most targeted disease, followed by autoimmune conditions, as in previous years. Interestingly, the FDA gave the green light to a remarkable number of bispecific Biologics (four), the highest number in recent years. Indeed, 2022 was another year without the approval of an antimicrobial Biologic, although important advancements were made in targeting new diseases, which are discussed herein. In this work, we only analyze the Biologics authorized in 2022. Furthermore, we also consider the orphan drugs authorized. We not only apply a quantitative analysis to this year's harvest, but also compare the efficacy of the Biologics with those authorized in previous years. On the basis of their chemical structure, the Biologics addressed fall into the following classes: monoclonal antibodies; antibody-drug conjugates; and proteins/enzymes.

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Despite belonging to a relatively new class of pharmaceuticals, biological drugs have been used since the 1980s, when they brought about a breakthrough in the treatment of chronic diseases, especially cancer. They conquered a large space in the pipeline of the pharmaceutical industry and boosted the innovation portfolio and arsenal of therapeutic compounds available. Here, we report on biological drug approvals by the US Food and Drug Administration (FDA) from 2015 to 2021. The number of drugs included in this class grew over this period, totaling 90 approvals, with an average of 13 authorizations per year. This figure contrasts with previous periods, which registered between 2 and 8 approvals per year. We highlight the great potential and advantages of biological drugs. In this context, these therapeutics show high efficacy and high selectivity, and they have brought about a significant increase in patient survival and a reduction of adverse reactions. The development and production of biopharmaceuticals pose a major challenge because these processes require cutting-edge technology, thereby making the drugs very expensive. However, we believe that, in the near future, biological medicines will be more accessible and new drugs belonging to this class will become available as new technologies emerge. Such advances will enhance the production of these biopharmaceuticals, thereby making the process increasingly profitable and less expensive, thereby bringing about greater availability of these drugs.

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The skin glands of amphibian species hold a major component of their innate immunity, namely a unique set of antimicrobial peptides (AMPs). Although most of them have common characteristics, differences in AMP sequences allow a huge repertoire of biological activity with varying degrees of efficacy. We present the first study of the AMPs from Pleurodema somuncurence (Anura: Leptodactylidae: Leiuperinae). Among the 11 identified mature peptides, three presented antimicrobial activity. Somuncurin-1 (FIIWPLRYRK), somuncurin-2 (FILKRSYPQYY), and thaulin-3 (NLVGSLLGGILKK) inhibited Escherichia coli growth. Somuncurin-1 also showed antimicrobial activity against Staphylococcus aureus. Biophysical membrane model studies revealed that this peptide had a greater permeation effect in prokaryotic-like membranes and capacity to restructure liposomes, suggesting fusogenic activity, which could lead to cell aggregation and disruption of cell morphology. This study contributes to the characterization of peptides with new sequences to enrich the databases for the design of therapeutic agents. Furthermore, it highlights the importance of investing in nature conservation and the power of genetic description as a strategy to identify new compounds.

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Synthetic peptides mimicking protective B- and T-cell epitopes are good candidates for safer, more effective FMD vaccines. Nevertheless, previous studies of immunization with linear peptides showed that they failed to induce solid protection in cattle. Dendrimeric peptides displaying two or four copies of a peptide corresponding to the B-cell epitope VP1 [136-154] of type O FMDV (O/UKG/11/2001) linked through thioether bonds to a single copy of the T-cell epitope 3A [21-35] (termed B2T and B4T, resp.) afforded protection in vaccinated pigs. In this work, we show that dendrimeric peptides B2T and B4T can elicit specific humoral responses in cattle and confer partial protection against the challenge with a heterologous type O virus (O1/Campos/Bra/58). This protective response correlated with the induction of specific T-cells as well as with an anamnestic antibody response upon virus challenge, as shown by the detection of virus-specific antibody-secreting cells (ASC) in lymphoid tissues distal from the inoculation point.

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Foot-and-mouth disease virus (FMDV) causes a highly contagious disease in cloven-hoofed animals. A synthetic vaccine candidate consisting of dendrimeric peptides harbouring two copies of a B-epitope [VP1(136-154)] linked to a T-cell epitope [3A(21-35)] of FMDV confers protection to type O FMDV challenge in pigs. Herein we show in cattle that novel dendrimeric peptides bearing a T-cell epitope [VP1(21-40] and two or four copies of a B-cell epitope [VP1(135-160)] from type O1 Campos FMDV (termed B2T and B4T, respectively) elicited FMDV specific immune responses to similar levels to a commercial vaccine. Animals were challenged with FMDV and 100% of vaccinated cattle with B2T or B4T were protected to podal generalization. Moreover, bovines immunized with B4T were completely protected (with no clinical signs) against FMDV challenge after three vaccine doses, which was associated with titers of viral neutralizing antibodies in serum higher than those of B2T group (p< 0.05) and levels of opsonic antibodies similar to those of animals immunized with one dose of FMDV commercial vaccine. Bovines vaccinated with both dendrimeric peptides presented high levels of IgG1 anti FMDV in sera and in mucosa. When IgA in nasal secretions was measured, 20% or 40% of the animals in B2T or B4T groups respectively, showed anti-FMDV IgA titers. In addition, B2T and B4T peptides evoked similar consistent T cell responses, being recognized in vitro by lymphocytes from most of the immunized cattle in the proliferation assay, and from all animals in the IFN-γ production assay. Taken together, these results support the potential of dendrimers B2T or B4T in cattle as a highly valuable, cost-effective FMDV candidate vaccine with DIVA potential.

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A fully validated bio-analytical method based on Matrix-Assisted-Laser-Desorption/Ionization-Time of Flight Mass Spectrometry was developed for quantitation in human plasma of the anti-tumor peptide CIGB-300. An analog of this peptide acetylated at the N-terminal, was used as internal standard for absolute quantitation. Acid treatment allowed efficient precipitation of plasma proteins as well as high recovery (approximately 80%) of the intact peptide. No other chromatographic step was required for sample processing before MALDI-MS analysis. Spectra were acquired in linear positive ion mode to ensure maximum sensitivity. The lower limit of quantitation was established at 0.5 µg/mL, which is equivalent to 160 fmol peptide. The calibration curve was linear from 0.5 to 7.5 µg/mL, with R(2)>0.98, and permitted quantitation of highly concentrated samples evaluated by dilution integrity testing. All parameters assessed for five validation batches met the FDA guidelines for industry. The method was successfully applied to analysis of clinical samples obtained in a phase I clinical trial following intravenous administration of CIGB-300 at a dose of 1.6 mg/kg body weight. With the exception of Cmax and AUC, pharmacokinetic parameters were similar for ELISA and MALDI-MS methods.

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La fosforilación de la glucosa en los mamíferos, es catalizada por una familia de isoenzimas (hexoquinasas I-IV; HQ) de diferente Km para el azúcar. En los hepatocitos y células b-pancreáticas se encuentra la glucoquinasa (GQ; HQ IV) de Km elevado (12-20 mM). Hemos observado que GQ está presente en el intestino delgado y podría contribuir a la producción de lactato durante la absorción del azúcar. En este trabajo se determinó el efecto de la dieta (ratarina R; 60% de glucosa G; sacarosa S; almidón A; caseína C), suministrada ad libitum, sobre las actividades de HQ y GQ en homogenatos de hígado y mucosa intestinal de rata. El suministro de glucosa (5%) en el agua de beber (SG) también fue evaluado en las dietas con R y G. Las actividades de HQ (Glucosa 1 mM) y la capacidad fosforilativa total (CFT: Glucosa = 100 mM) se determinaron enzimáticamente. GQ se estimó por diferencia. En el grupo control (R) y en S, A y C, la GQ hepática fue un 85% de la CFT, mientras que en G, GSG y RSG un 66%. La HQ intestinal alcanzó en los grupos R, GSG, A y C un 87% y en RSG un 30% de la CFT. La GQ en G, S, aumentó, pero una menor magnitud. La presencia de GQ en el intestino delgado y su expresión diferencial de acuerdo a la dieta, abren la posibilidad de que dicho órgano contribuya al metabolismo inicial de la glucosa procedente de la dieta y provea al hígado de un precursor (lactato) muy eficaz para sus procesos anabólicos.

Glucose phosphorylation in mammals, is catalyzed by a family of isoenzymes (hexokinases I- IV; HQ) of different Km for the sugar. In hepatocytes and pancreatic b- cells are glucokinase (GQ ; HQ IV) of high Km (12-20 mM). We observed that GQ is present in the small intestine and may contribute to the production of lactate during the absorption of sugar. In this work, the effect of diet (ratarina R, G 60% glucose, sucrose S; starch A; casein C) provided ad libitum , on the activities of HQ and GQ in liver homogenates of rat intestinal mucosa . The supply of glucose (5%) in the drinking water ( SG ) was also evaluated in the diets with R and G. HQ activities (Glucose 1 mM) and phosphorylating full capacity ( CFT : Glucose = 100 mM ) were determined enzymatically . GQ was estimated by difference. In the control group (R) and S, A and C, the GQ liver was about 85% of CFT, whereas G, GSG and RSG 66%. The intestinal HQ reached in the R groups, GSG, A and C by 87% and 30% RSG the CFT. The GQ in G, S , increased , but a lower magnitude. the presence of glucokinase in the small intestine and its differential expression according to diet, open the possibility that this structure contributes to initial metabolism of glucose and provide to the liver a precursor (lactate) very effective for their anabolic processes.

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