Host-defense peptides AC12, DK16 and RC11 with immunomodulatory activity isolated from Hypsiboas raniceps skin secretion

Anti-inflammatory peptide therapeutics and the role of sulphur containing amino acids (cysteine and methionine) in inflammation suppression: A review

BACKGROUND

Inflammation serves as our body's immune response to combat infections, pathogens, viruses, and external stimuli. Inflammation can be classified into two types: acute inflammation and chronic inflammation. Non-steroidal anti-inflammatory medications (NSAIDs) are used to treat both acute and chronic inflammatory disorders. However, these treatments have various side effects such as reduced healing efficiency, peptic ulcers, gastrointestinal toxicities, etc. METHOD: This review assesses the potential of anti-inflammatory peptides (AIPs) derived from various natural sources, such as algae, fungi, plants, animals, and marine organisms. Focusing on peptides rich in cysteines and methionine, sulphur-containing amino acids known for their role in suppression of inflammation.

RESULT

Due to their varied biological activity, ability to penetrate cells, and low cytotoxicity, bioactive peptides have garnered interest as possible therapeutic agents. The utilisation of AIPs has shown great potential in the treatment of disorders associated with inflammation. AIPs can be obtained from diverse natural sources such as algae, fungi, plants, and animals. Cysteine and methionine are sulphur-containing amino acids that aid in the elimination of free radicals, hence assisting in the treatment of inflammatory diseases.

CONCLUSION

This review specifically examines several sources of AIPs including peptides that contain numerous cysteines and methionine. In addition, the biological characteristics of these amino acids and advancements in peptide delivery are also discussed.

Structure and function of cationic hylin bioactive peptides from the tree frog Boana pulchella in interaction with lipid membranes

Amphibians have a great diversity of bioactive peptides in their skin. The cDNA prepro-peptide sequencing allowed the identification of five novel mature peptides expressed in the skin of Boana pulchella, four with similar sequences to hylin peptides having a cationic amphipathic-helical structure. Whole mature peptides and some of their fragments were chemically-synthesized and tested against Gram-positive and Gram-negative bacterial strains. The mature peptide hylin-Pul3 was the most active, with a MIC= 14 µM against Staphylococcus aureus. Circular dichroism assays indicated that peptides are mostly unstructured in buffer solutions. Still, adding large unilamellar vesicles composed of dimyristoyl phosphatidylcholine and dimyristoylphosphatidylglycerol increased the α-helix content of novel hylins. These results demonstrate the strong influence of the environment on peptide conformation and highlight its significance while addressing the pharmacology of peptides and their biological function in frogs.

An experimental protocol for molecular biology lab at an Amazonian University

Laboratory-based practical classes are an essential component in teaching molecular biology for undergraduate students. Universidad Regional Amazonica Ikiam is a higher education institution located in the Ecuadorian Amazon rainforest, a high biodiversity place, including amphibians. Based on this, we have established a practical molecular biology program with eight sessions that contextualize the biodiverse surroundings of the University. This program stimulates synchronization of information between theory and practice and improves research skills. During these sessions, students are motivated to identify and characterize antimicrobial peptides from Ecuadorian frog skin secretions, using molecular biology techniques and biochemistry and microbiology knowledge. This practical course was held twice with a total of 56 students from the fifth semester of the biotechnology engineering. The evaluation of the practical program was carried out through a questionnaire applied to students using the Likert scale. Overall, this form of teaching had high receptivity and presented benefits for student learning. Interestingly, 80% of respondents strongly agreed that this course provided tools and knowledge for the development of their undergraduate dissertation. Therefore, practical courses tailored to the student's context can stimulate student learning and interest. Additionally, this experimental methodology is interdisciplinary and can be applied to other research fields and subjects.

Host defense peptides as immunomodulators: The other side of the coin

Host defense peptides (HDPs) exhibit a broad range of antimicrobial and immunomodulatory activities. In this sense, both functions are like different sides of the same coin. The direct antimicrobial side was discovered first, and widely studied for the development of anti-infective therapies. In contrast, the immunomodulatory side was recognized later and in the last 20 years the interest in this field has been continuously growing. Different to their antimicrobial activities, the immunomodulatory activities of host defense peptides are more effective in vivo. They offer a great opportunity for new therapeutic applications in the fields of anti-infective therapy, chronic inflammatory diseases treatment, novel vaccine adjuvants development and anticancer immunotherapy. These immune related functions of HDPs includes chemoattraction of leukocytes, modulation of inflammation, enhancement of antigen presentation and polarization of adaptive immune responses. Our attempt with this review is to make a careful evaluation of different aspects of the less explored, but attractive immunomodulatory side of the HDP functional coin.

OR, Fontes W, Castro MS. Biological Properties of a Novel Multifunctional Host Defense Peptide from the Skin Secretion of the Chaco Tree Frog, Boana raniceps

In recent years, the number of new antimicrobial drugs launched on the market has decreased considerably even though there has been an increase in the number of resistant microbial strains. Thus, antimicrobial resistance has become a serious public health problem. Amphibian skin secretions are a rich source of host defense peptides, which generally are cationic and hydrophobic molecules, with a broad-spectrum of activity. In this study, one novel multifunctional defense peptide was isolated from the skin secretion of the Chaco tree frog, Boana raniceps. Figainin 2 (1FLGAILKIGHALAKTVLPMVTNAFKPKQ28) is cationic and hydrophobic, adopts an α-helical structure in 50% (v/v) trifluoroethanol (TFE), and is thermally stable. This peptide exhibited activity against Gram-negative and Gram-positive pathogenic bacteria arboviruses, T. cruzi epimastigotes; however, it did not show activity against yeasts. Figainin 2 also showed antiproliferative activity on cancer cells, is moderately active on human erythrocytes, and activates the oxidative burst in human neutrophils.

Anti-Inflammatory Activity of a Peptide from Skipjack (Katsuwonus pelamis)

In this paper, the effect of skipjack (Katsuwonus pelamis) enzymatic peptide (SEP), which was prepared and purified from a byproduct of skipjack, on inflammation, ulcerative colitis and the regulation of intestinal flora was studied in a mouse ulcerative colitis model and a transgenic zebrafish inflammation model. The aggregation of transgenic granulocyte neutrophils in zebrafish from a normal environment and from a sterile environment was calculated, and the anti-inflammatory activity of SEP was evaluated. To evaluate the anti-ulcerative colitis activity of SEP, DSS-induced colitis mice were given SEP, salicylazosulfapyridine (SASP), or SASP + SEP. Then, the concentrations of IL-6, IL-10 and TNF-α in the serum were detected, the HE-stained colon tissue was examined by microscopy the species composition and abundance distribution of the intestinal flora was analyzed. The results showed that 500 μg/mL SEP treatment significantly alleviated neutrophil granulocyte aggregation in the zebrafish inflammation model; Diarrhea, hematochezia and body weight loss were alleviated to a certain extent in mice gavaged with SEP and SASP, and the combination of SASP with SEP was the most effective in mice. The damage to villi in the intestine was completely repaired, and the levels of IL-6, IL-10 and TNF-α, which are associated with inflammation, were all reduced. In addition, the proportion of intestinal probiotics or harmless bacteria increased, while that of pathogenic bacteria decreased, and the effect of the combined treatment was the most pronounced. These results show that SEP could relieve inflammation, cure ulcerative colitis, regulate intestinal flora and enhance the therapeutic effect of the clinical drug SASP. This study provides a theoretical basis for the development of SEP as an anti-inflammatory adjuvant therapy and intestinal flora regulator.