A very new and highly specialized category of radiotracers that is still growing is radiolabeled peptides. Radiolabeled peptides, or radiopeptides, are powerful elements for diagnostic imaging and radionuclide therapy. These laboratory-manufactured peptides have gained attention due to their unique properties. The tiny structure of these peptides compared to proteins and antibodies makes them favorable regarding their availability through simple synthesis from amino acids, easy uptake by receptors on cancer cells, and high specificity and affinity for high-quality and accurate radio imaging. This study highlighted the potential of technetium-99m-labeled peptides in advancing diagnostic capabilities in directed research in Latin America.

In recent years, research efforts have increased to develop new therapeutics aimed at combating antibiotic-resistant bacterial infections. These efforts focus on inhibiting the virulence factors bacteria secrete to proliferate. This review aims to highlight the advances in these antivirulence therapies, with a particular emphasis on those utilizing peptides to inhibit toxin activity. Specifically, we will review the mechanism of action of a group of toxins known as Repeat in ToXins (RTX) and the progress made regarding the use of peptides to inhibit their action. Notably, we will discuss the use of peptides mimicking either cholesterol recognition/interaction amino acid consensus (CRAC) or CARC motifs, which are similar to CRAC motifs but have the opposite orientation, to reduce their interaction with cholesterol in target cells. We will present results corresponding to the inhibition of three characteristic toxins of this group: HlyA from Escherichia coli, LtxA from Aggregatibacter actinomycetemcomitans, and CyaA from Bordetella pertussis. While these advances are very recent, they are promising for the development of new therapies. The advantage of this type of therapy is that it reduces the selective pressure for the growth of resistant bacteria.

The excessive use of antibiotics to treat bacterial infectious diseases in all living beings has caused a global epidemic of bacterial resistance to antibiotics, leading to the emergence of multidrug-resistant and pandrug-resistant strains. In 2019, the World Health Organization (WHO) reported that antimicrobial resistance causes at least 700,000 deaths per year worldwide. Therefore, in this global war against microorganisms, a therapeutic alternative is necessary to help us win this battle. A key in this race against the clock could be lactoferrin (Lf), a cationic glycoprotein of the mammalian innate immune system that is highly conserved among mammals. Lf is a multifunctional glycoprotein with immunomodulatory, anticarcinogenic, wound-healing, antioxidant, antimicrobial, and bone regeneration properties, in addition to improving the gut microbiota. Lf limits the growth of microorganisms through the sequestration of iron but can also interact directly with some components of the outer membrane of Gram-negative bacteria or bind to teichoic acids in Gram-positive bacteria, destabilizing the membrane and resulting in lysis. Moreover, cleavage of the Lf molecule could promote the production of lactoferricins (Lfcins) and lactoferrampin (Lfampin) from the N-terminal end, which are known to often have stronger antimicrobial effects than the native molecule, as well as analogous peptides, such as HLopt2, which have also shown enhanced antimicrobial activity. Bovine Lf (bLf) has been approved by the US Food and Drug Administration (FDA), and the European Food Safety Authority for its use as a dietary supplement in food products. Because of its effectiveness, accessibility, low cost, and nontoxicity, Lf could be a promising alternative for preventing or treating infections in animals and humans.

According to the International Union of Pure and Applied Chemistry (IUPAC), peptides are small proteins with a size between 2 and 50 amino acids residues. They are ubiquitous across the evolutionary scale, fulfilling a wide variety of functions, from immune system effectors in simple organisms to signaling or neuromodulating agents in high vertebrates. Following nature’s example, peptides have emerged as alternatives in various fields. One particularly relevant area is in drug discovery, offering alternatives to face the emergence of antibiotic-resistant microorganisms. Peptides are also prevalent in other sectors, such as the food industry, where they serve as food additives to enhance nutritional characteristics or aid in food preservation. Moreover, peptides are increasingly being utilized in cosmetics. Additionally, peptides serve as valuable tools in both basic and applied research, facilitating the exploration of specific activity mechanisms and the verification of particular activities, among various other applications. Despite certain limitations and disadvantages compared to other bioactive molecules, peptides remain a focal point of interest in research, as well as in applied and developmental fields, due to their versatility. In this report, we provide an overview of the extensive application landscape of synthetic peptides, presenting examples developed in-house across different areas which include a summary of the methodologies and results obtained.

Envenomation caused by snakes, scorpions, and spiders represents a serious public health problem in Latin America. The antivenoms used for its treatment are produced by immunizing horses repeatedly with sublethal doses of animal venoms along with the adjuvant. However, venom availability is a bottleneck. Furthermore, toxin-neutralizing antibodies are only a few of the total produced with this classical method. Therefore, high doses of antivenom are required to achieve the neutralization power, which usually causes adverse reactions in the patient. With the aim of obtaining a higher proportion of toxin-neutralizing antibodies while reducing the dependency on venom availability, alternative immunization protocols have been explored using synthetic peptides with epitopes from clinically relevant toxins. The process to design an immunogenic peptide entitles: (a) choice of the medical relevant toxins in the venom; (b) identification of the epitopes in the selected toxins; (c) improvement of peptide immunogenicity; (d) immunogen synthesis; and e) in vitro and in vivo evaluation. The present article aims to review the advances in the design of immunogenic synthetic peptides for their application in antivenom production in Latin America during the 21st century. Epitopes have been identified from many clinically important toxins in Latin American snakes (snake venom metalloproteinases, snake venom serine proteases, crotamine, phospholipases A2, and three-finger toxins), scorpions (beta-mammal/insect toxin Ts1, alpha-mammal toxin Ts2, alpha-mammal toxin Ts3, toxin Ts4, and beta-mammal Tt1g neurotoxin), and spiders (dermonecrotic toxin and delta-ctenitoxin-Pn2a). Nevertheless, their application is still experimental, even though they are ideal for large-scale and low-cost antivenom production, factors that are necessary to meet national and regional demands.