Assessment of the potential of temporin peptides from the frog Rana temporaria (Ranidae) as anti-diabetic agents

Design, synthesis and activity evaluation of reduction-responsive anticancer peptide temporin-1CEa drug conjugates

Membranes that destroy anticancer peptides can bind to negatively charged cancer cell membranes through electrostatic interactions, destroying their functions and leading to cancer cell necrosis. Temporin-1CEa, obtained from the skin secretions of the Chinese frog Rana chensinensis, is an anticancer peptide with 17 amino acid residues that exhibits concentration-dependent cytotoxicity against a variety of cancer cell lines, although it has no obvious cytotoxicity to normal HUVECs. In this work, we designed and synthesized 12 derivative peptides through double-cysteine scanning of temporin-1CEa-truncated peptides. Most of these peptides had greater anticancer activity than the lead peptide temporin-1CEa. Among these derivative peptides, Nu-7 had the strongest anticancer activity. Nu-7 has a greater α-helicity than does temporin-1CEa. We connected Nu-7 to podophyllotoxin through a reduction-responsive linker to obtain Nu-7-1, which showed better anticancer activity than free podophyllotoxin. Nu-7-1 was less toxic to HUVECs and had low hemolytic activity at therapeutic concentrations (although Nu-7-1 showed hemolytic activity at 100 μM). Nu-7-1 functions through two mechanisms: damage to cell membranes and promotion of cell apoptosis. Nu-7-1 is less toxic to normal HUVECs than is podophyllotoxin and shows better safety. In summary, we carried out a series of modifications on temporin-1CEa, among which the anticancer activity of Nu-7-1 was significantly improved compared with that of the lead peptide temporin-1CEa, providing a useful reference for the structural modification of anticancer peptides.

Multifunctional host-defense peptides isolated from skin secretions of the banana tree dwelling frog Boana platanera (Hylidae; Hylinae)

Five host-defense peptides (figainin 2PL, hylin PL, raniseptin PL, plasticin PL, and peptide YL) were isolated from norepinephrine-stimulated skin secretions of the banana tree dwelling frog Boana platanera (Hylidae; Hylinae) collected in Trinidad. Raniseptin PL (GVFDTVKKIGKAVGKFALGVAKNYLNS.NH2) and figainin 2PL (FLGTVLKLGKAIAKTVVPMLTNAMQPKQ. NH2) showed potent and rapid bactericidal activity against a range of clinically relevant Gram-positive and Gram-negative ESKAPE + pathogens and Clostridioides difficile. The peptides also showed potent cytotoxic activity (LC50 values < 30 μM) against A549, MDA-MB-231 and HT29 human tumor-derived cell lines but appreciably lower hemolytic activity against mouse erythrocytes (LC50 = 262 ± 14 μM for raniseptin PL and 157 ± 16 μM for figainin 2PL). Hylin PL (FLGLIPALAGAIGNLIK.NH2) showed relatively weak activity against microorganisms but was more hemolytic. The glycine-leucine-rich peptide with structural similarity to the plasticins (GLLSTVGGLVGGLLNNLGL.NH2) and the non-cytotoxic peptide YL (YVPGVIESLL.NH2) lacked antimicrobial and cytotoxic activities. Hylin PL, raniseptinPL and peptide YL stimulated the rate of release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥100 nM. Peptide YL was the most effective (2.3-fold increase compared with basal rate at 1 μM concentration) and may represent a template for the design of a new class of incretin-based anti-diabetic drugs.

Amphibian host-defense peptides with potential for Type 2 diabetes therapy - an updated review

Investigations conducted since 2018 have identified several host-defense peptides present in frog skin secretions whose properties suggest the possibility of their development into a new class of agent for Type 2 diabetes (T2D) therapy. Studies in vitro have described peptides that (a) stimulate insulin release from BRIN-BD11 clonal β-cells and isolated mouse islets, (b) display β-cell proliferative activity and protect against cytokine-mediated apoptosis and (c) stimulate production of the anti-inflammatory cytokine IL-10 and inhibit production of the pro-inflammatory cytokines TNF-α and IL-1β. Rhinophrynin-27, phylloseptin-3.2TR and temporin F are peptides with therapeutic potential. Studies in vivo carried out in db/db and high fat-fed mice have shown that twice-daily administration of [S4K]CPF-AM1 and [A14K]PGLa-AM1, analogs of peptides first isolated from the octoploid frog Xenopus amieti, over 28 days lowers circulating glucose and HbA1c concentrations, increases insulin sensitivity and improves glucose tolerance and lipid profile. Peptide treatment produced potentially beneficial changes in the expression of skeletal muscle genes involved in insulin signaling and islet genes involved in insulin secretion in these murine models of T2D. Lead compounds uncovered by the study of frog HDPs may provide a basis for the design of new types of agents that can be used, alone or in combination with existing therapies, for the treatment of T2D.

A Comprehensive Review of Patented Antimicrobial Peptides from Amphibian Anurans

Since the 1980s, studies of antimicrobial peptides (AMPs) derived from anuran skin secretions have unveiled remarkable structural diversity and a wide range of activities. This study explores the potential of these peptides for drug development by examining granted patents, amino acid modifications related to patented peptides, and recent amphibians' taxonomic updates influencing AMP names. A total of 188 granted patents related to different anuran peptides were found, with Asia and North America being the predominant regions, contributing 65.4% and 15.4%, respectively. Conversely, although the Neotropical region is the world's most diversified region for amphibians, it holds only 3.7% of the identified patents. The antimicrobial activities of the peptides are claimed in 118 of these 188 patents. Additionally, for 160 of these peptides, 66 patents were registered for the natural sequence, 69 for both natural and derivative sequences, and 20 exclusively for sequence derivatives. Notably, common modifications include alterations in the side chains of amino acids and modifications to the peptides' N- and C-termini. This review underscores the biomedical potential of anuran-derived AMPs, emphasizing the need to bridge the gap between AMP description and practical drug development while highlighting the urgency of biodiversity conservation to facilitate biomedical discoveries.

Tandem Mass Spectrometry de novo Sequencing of the Skin Defense Peptides of the Central Slovenian Agile Frog Rana dalmatina

Peptides released on frogs' skin in a stress situation represent their only weapon against micro-organisms and predators. Every species and even population of frog possesses its own peptidome being appropriate for their habitat. Skin peptides are considered potential pharmaceuticals, while the whole peptidome may be treated as a taxonomic characteristic of each particular population. Continuing the studies on frog peptides, here we report the peptidome composition of the Central Slovenian agile frog Rana dalmatina population. The detection and top-down de novo sequencing of the corresponding peptides was conducted exclusively by tandem mass spectrometry without using any chemical derivatization procedures. Collision-induced dissociation (CID), higher energy collision-induced dissociation (HCD), electron transfer dissociation (ETD) and combined MS3 method EThcD with stepwise increase of HCD energy were used for that purpose. MS/MS revealed the whole sequence of the detected peptides including differentiation between isomeric Leu/Ile, and the sequence portion hidden in the disulfide cycle. The array of the discovered peptide families (brevinins 1 and 2, melittin-related peptides (MRPs), temporins and bradykinin-related peptides (BRPs)) is quite similar to that of R. temporaria. Since the genome of this frog remains unknown, the obtained results were compared with the recently published transcriptome of R. dalmatina.

Venom Peptides, Polyphenols and Alkaloids: Are They the Next Antidiabetics That Will Preserve β-Cell Mass and Function in Type 2 Diabetes?

Improvement of insulin secretion by pancreatic β-cells and preservation of their mass are the current challenges that future antidiabetic drugs should meet for achieving efficient and long-term glycemic control in patients with type 2 diabetes (T2D). The successful development of glucagon-like peptide 1 (GLP-1) analogues, derived from the saliva of a lizard from the Helodermatidae family, has provided the proof of concept that antidiabetic drugs directly targeting pancreatic β-cells can emerge from venomous animals. The literature reporting on the antidiabetic effects of medicinal plants suggests that they contain some promising active substances such as polyphenols and alkaloids, which could be active as insulin secretagogues and β-cell protectors. In this review, we discuss the potential of several polyphenols, alkaloids and venom peptides from snake, frogs, scorpions and cone snails. These molecules could contribute to the development of new efficient antidiabetic medicines targeting β-cells, which would tackle the progression of the disease.

Temporins: Multifunctional Peptides from Frog Skin

Temporins are short peptides secreted by frogs from all over the world. They exert antimicrobial activity, mainly against Gram-positive bacteria, including resistant pathogens; recent studies highlight other possible applications of these peptides as anticancer or antiviral agents. This review is meant to describe the main features of temporins produced by different ranid genera. Due to the abundance of published papers, we focus on the most widely investigated peptides. We report studies on their mechanism of action and three-dimensional structure in model systems mimicking bacterial membranes or in the presence of cells. The design and the antimicrobial activity of peptide analogues is also described, with the aim of highlighting elements that are crucial to improve the bioactivity of peptides while reducing their toxicity. Finally, a short section is dedicated to the studies aimed at applying these peptides as drugs, to produce new antimicrobial materials or in other technological uses.

Peptidomic analysis of the host-defense peptides in skin secretions of the Amazon River frog Lithobates palmipes (Ranidae)

Skin secretions of certain frog species represent a source of host-defense peptides (HDPs) with therapeutic potential and their primary structures provide insight into taxonomic and phylogenetic relationships. Peptidomic analysis was used to characterize the HDPs in norepinephrine-stimulated skin secretions from the Amazon River frog Lithobates palmipes (Ranidae) collected in Trinidad. A total of ten peptides were purified and identified on the basis of amino acid similarity as belonging to the ranatuerin-2 family (ranatuerin-2PMa, -2PMb, -2PMc, and-2PMd), the brevinin-1 family (brevinin-1PMa, -1PMb, -1PMc and des(8-14)brevinin-1PMa) and the temporin family (temporin-PMa in C-terminally amidated and non-amidated forms). Deletion of the sequence VAAKVLP from brevinin-1PMa (FLPLIAGVAAKVLPKIFCAISKKC) in des[(8-14)brevinin-1PMa resulted in a 10-fold decrease in potency against Staphylococcus aureus (MIC = 31 μM compared with 3 μM) and a > 50-fold decrease in hemolytic activity but potency against Echerichia coli was maintained (MIC = 62.5 μM compared with 50 μM). Temporin-PMa (FLPFLGKLLSGIF.NH₂) inhibited growth of S. aureus (MIC = 16 μM) but the non-amidated form of the peptide lacked antimicrobial activity. Cladistic analysis based upon the primary structures of ranaturerin-2 peptides supports the division of New World frogs of the family Ranidae into the genera Lithobates and Rana. A sister-group relationship between L. palmipes and Warszewitsch's frog Lithobates warszewitschii is indicated within a clade that includes the Tarahumara frog Lithobates tarahumarae. The study has provided further evidence that peptidomic analysis of HDPs in frog skin secretions is a valuable approach to elucidation of the evolutionary history of species within a particular genus.

DIC/Oxyma-based accelerated synthesis and oxidative folding studies of centipede toxin RhTx

Coupling reagents play crucial roles in the iterative construction of amide bonds for the synthesis of peptides and peptide-based derivatives. The novel DIC/Oxyma condensation system featured with the low risk of explosion displayed remarkable abilities to inhibit racemization, along with efficient coupling efficiency in both manual and automated syntheses. Nevertheless, an ideal reaction molar ratio in DIC/Oxyma condensation system and the moderate reaction temperature by manual synthesis remain to be further investigated. Herein, the synthetic efficiencies of different reaction ratios between DIC and Oxyma under moderate reaction temperature were systematically evaluated. The robustness and efficiency of DIC/Oxyma condensation system are validated by the rapid synthesis of linear centipede toxin RhTx. Different folding strategies were applied for the construction of disulfide bridges in RhTx, which was further confirmed in assays of circular dichroism and patch-clamp electrophysiology evaluation. This work establishes the DIC/Oxyma-based accelerated synthesis of peptides under moderate condensation conditions, which is especially useful for the manual synthesis of peptides. Besides, the strategy presented here provides robust technical supports for the large-scale synthesis and oxidative folding of RhTx.

Mesoporous polydopamine nanoparticles carrying peptide RL-QN15 show potential for skin wound therapy

BACKGROUND

Skin wound healing remains a considerable clinical challenge, thus stressing the urgent need for the development of new interventions to promote repair. Recent researches indicate that both peptides and nanoparticles may be potential therapies for the treatment of skin wounds.

METHODS

In the current study, the mesoporous polydopamine (MPDA) nanoparticles were prepared and the peptide RL-QN15 that was previously identified from amphibian skin secretions and exhibited significant potential as a novel prohealing agent was successfully loaded onto the MPDA nanoparticles, which was confirmed by results of analysis of scanning electron microscopy and fourier transform infrared spectroscopy. The encapsulation efficiency and sustained release rate of RL-QN15 from the nanocomposites were determined. The prohealing potency of nanocomposites were evaluated by full-thickness injured wounds in both mice and swine and burn wounds in mice.

RESULTS

Our results indicated that, compared with RL-QN15 alone, the prohealing potency of nanocomposites of MPDA and RL-QN15 in the full-thickness injured wounds and burn wounds in mice was increased by up to 50 times through the slow release of RL-QN15. Moreover, the load on the MPDA obviously increased the prohealing activities of RL-QN15 in full-thickness injured wounds in swine. In addition, the obvious increase in the prohealing potency of nanocomposites of MPDA and RL-QN15 was also proved by the results from histological analysis.

CONCLUSIONS

Based on our knowledge, this is the first research to report that the load of MPDA nanoparticles could significantly increase the prohealing potency of peptide and hence highlighted the promising potential of MPDA nanoparticles-carrying peptide RL-QN15 for skin wound therapy.

Differentiation of Central Slovenian and Moscow populations of Rana temporaria frogs using peptide biomarkers of temporins family

Skin secretion represents the only means of defense for the majority of frog species. That phenomenon is based on the fact that the main components of the secretion are peptides demonstrating greatly varying types of bioactivity. They fulfill regulatory functions, fight microorganisms and may be even helpful against predators. These peptides are considered to be rather promising pharmaceuticals of future generation as according to the present knowledge microorganisms are unlikely to develop resistance to them. Mass spectrometry sequencing of these peptides is the most efficient first step of their study providing reliably their primary structures, i.e., amino acids sequence and S-S bond motif. Besides discovering new bioactive peptides, mass spectrometry appears to be an efficient tool of taxonomy studies, allowing for distinguishing not only between closely related species, but also between populations of the same species. Application of several tandem mass spectrometry tools (CID, HCD, ETD, EThcD) available with Orbitrap mass analyzer allowed us to obtain full sequence of about 60 peptides in the secretion of Slovenian population of brown ranid frog Rana temporaria. The problem of sequence inside C-terminal cycle formed by two Cys and differentiation of isomeric Leu and Ile residues was done in top-down mode without any derivatization steps. Besides general biomarkers of Rana temporaria species, Central Slovenian population of Rana temporaria demonstrates six novel temporins and one brevinin 1, which may be treated as biomarkers of that population.

Naturally-Occurring Alkaloids of Plant Origin as Potential Antimicrobials against Antibiotic-Resistant Infections

Antibiotic resistance is now considered a worldwide problem that puts public health at risk. The onset of bacterial strains resistant to conventional antibiotics and the scarcity of new drugs have prompted scientific research to re-evaluate natural products as molecules with high biological and chemical potential. A class of natural compounds of significant importance is represented by alkaloids derived from higher plants. In this review, we have collected data obtained from various research groups on the antimicrobial activities of these alkaloids against conventional antibiotic-resistant strains. In addition, the structure–function relationship was described and commented on, highlighting the high potential of alkaloids as antimicrobials.

Frog Skin-Derived Peptides Against Corynebacterium jeikeium: Correlation between Antibacterial and Cytotoxic Activities

Corynebacterium jeikeium is a commensal bacterium that colonizes human skin, and it is part of the normal bacterial flora. In non-risk subjects, it can be the cause of bad body smell due to the generation of volatile odorous metabolites, especially in the wet parts of the body that this bacterium often colonizes (i.e., groin and axillary regions). Importantly, in the last few decades, there have been increasing cases of serious infections provoked by this bacterium, especially in immunocompromised or hospitalized patients who have undergone installation of prostheses or catheters. The ease in developing resistance to commonly-used antibiotics (i.e., glycopeptides) has made the search for new antimicrobial compounds of clinical importance. Here, for the first time, we characterize the antimicrobial activity of some selected frog skin-derived antimicrobial peptides (AMPs) against C. jeikeium by determining their minimum inhibitory and bactericidal concentrations (MIC and MBC) by a microdilution method. The results highlight esculentin-1b(1-18) [Esc(1-18)] and esculentin-1a(1-21) [Esc(1-21)] as the most active AMPs with MIC and MBC of 4-8 and 0.125-0.25 µM, respectively, along with a non-toxic profile after a short- and long-term (40 min and 24 h) treatment of mammalian cells. Overall, these findings indicate the high potentiality of Esc(1-18) and Esc(1-21) as (i) alternative antimicrobials against C. jeikeium infections and/or as (ii) additives in cosmetic products (creams, deodorants) to reduce the production of bad body odor.

The Potential of Frog Skin Peptides for Anti-Infective Therapies: The Case of Esculentin-1a(1-21)NH2

Antimicrobial Peptides (AMPs) are the key effectors of the innate immunity and represent promising molecules for the development of new antibacterial drugs. However, to achieve this goal, some problems need to be overcome: (i) the cytotoxic effects at high concentrations; (ii) the poor biostability and (iii) the difficulty in reaching the target site. Frog skin is one of the richest natural storehouses of AMPs, and over the years, many peptides have been isolated from it, characterized and classified into several families encompassing temporins, brevinins, nigrocins and esculentins. In this review, we summarized how the isolation/characterization of peptides belonging to the esculentin-1 family drove us to the design of an analogue, i.e. esculentin-1a(1-21)NH2, with a powerful antimicrobial action and immunomodulatory properties. The peptide had a wide spectrum of activity, especially against the opportunistic Gram-negative bacterium Pseudomonas aeruginosa. We described the structural features and the in vitro/in vivo biological characterization of this peptide as well as the strategies used to improve its biological properties. Among them: (i) the design of a diastereomer carrying Damino acids in order to reduce the peptide's cytotoxicity and improve its half-life; (ii) the covalent conjugation of the peptide to gold nanoparticles or its encapsulation into poly(lactide- co-glycolide) nanoparticles; and (iii) the peptide immobilization to biomedical devices (such as silicon hydrogel contact lenses) to obtain an antibacterial surface able to reduce microbial growth and attachment. Summing up the best results obtained so far, this review traces all the steps that led these frog-skin AMPs to the direction of peptide-based drugs for clinical use.

Isolation and characterization of cytotoxic and insulin-releasing components from the venom of the black-necked spitting cobra Naja nigricollis (Elapidae)

Four peptides with cytotoxic activity against BRIN-BD11 rat clonal β-cells were purified from the venom of the black-necked spitting cobra Naja nigricollis using reversed-phase HPLC. The peptides were identified as members of the three-finger superfamily of snake toxins by ESI-MS/MS sequencing of tryptic peptides. The most potent peptide (cytotoxin-1N) showed strong cytotoxic activity against three human tumor-derived cell lines (LC₅₀ = 0.8 ± 0.2 μM for A549 non-small cell lung adenocarcinoma cells; LC₅₀ = 7 ± 1 μM for MDA-MB-231 breast adenocarcinoma cells; and LC₅₀ = 9 ± 1 μM for HT-29 colorectal adenocarcinoma cells). However, all the peptides were to varying degrees cytotoxic against HUVEC human umbilical vein endothelial cells (LC₅₀ in the range 2–22 μM) and cytotoxin-2N was moderately hemolytic (LC₅₀ = 45 ± 3 μM against mouse erythrocytes). The lack of differential activity against cells derived from non-neoplastic tissue limits their potential for development into anti-cancer agents. In addition, two proteins in the venom, identified as isoforms of phospholipase A₂, effectively stimulated insulin release from BRIN-BD11 cells (an approximately 6-fold increase in rate compared with 5.6 mM glucose alone) at a concentration (1 μM) that was not cytotoxic to the cells suggesting possible application in therapy for Type 2 diabetes.

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Four members of the three-finger superfamily of toxins were isolated from N. nigricollis venom.

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All peptides were cytotoxic to human tumor-derived cells.

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The peptides were also cytotoxic to non-neoplastic HUVEC cells.

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Two isoforms of phospholipase A₂ effectively stimulated insulin release from rat clonal β-cells.

Accelerated Wound Healing Induced by a Novel Amphibian Peptide (OA-FF10)

BACKGROUND

Despite the continued development of modern medicine, chronic wounds are still a critical issue in clinical treatment, placing a great physiological, psychological, and financial burden on patients. Researchers have investigated many methods to solve this problem, with bioactive peptides gaining increasing attention due to their considerable advantages and diverse functions, as well as low cost, simple storage, and easy transportation.

METHODS

In this research, a novel peptide (named OA-FF10) was identified from the skin secretions of the odorous frog species Odorrana andersonii. The sequence of mature OA-FF10 was "FFTTSCRSGC", which was produced by the post-translational processing of a 61-residue prepropeptide.

RESULTS

Similar to most frog peptides, OA-FF10 showed an intramolecular disulfide bridge at the C-terminus. OA-FF10 demonstrated no antibacterial, antioxidant, hemolytic, or acute toxic activity, but promoted wound healing and proliferation of human keratinocytes (HaCaT) both time- and dose-dependently. Furthermore, while OA-FF10 had no effect on wound healing of Human Skin Fibroblasts (HSF), it did accelerate healing in a full-thickness skin-wound mouse model.

CONCLUSION

Our research revealed the strong wound-healing activity of OA-FF10 in vivo and in vitro, thus providing a new candidate for the development of novel wound-healing drugs.

Temporins: An Approach of Potential Pharmaceutic Candidates

Antimicrobial peptides (AMPs), also known as host defense peptides, are small and mostly polycationic molecules that form part of the innate immune response. There are currently more than 3000 experimentally reported AMPs. Particularly in frogs, the temporin family has been discovered as potential AMPs. The aim of this work is to review the latest publications about this class of peptides, discuss their properties, and present an update of the last studies and new discoveries in the field. More than 130 temporins have been identified in this family. The most studied temporins are temporin A (TA), temporin B (TB), and temporin L (TL). These peptides showed antimicrobial activity against gram-negative, gram-positive bacteria and fungi. Since the discovery of temporins in 1996, several groups of researchers isolated different peptides from various species of frogs that were included as members of this family. Although antimicrobial activity of many temporins has not been analyzed yet, most of them showed antimicrobial and antifungal activities. A combination of nanotechnology and AMPs for temporins in different antimicrobial treatments could be a promising alternative for resistant pathogens. These studies demonstrate that, even with the advancement in scientific research on the composition and antimicrobial activity of temporins, further studies are necessary to wholly understand their components and mechanisms of action.

Insulinotropic activity of the host-defense peptide frenatin 2D: Conformational, structure-function and mechanistic studies

Of four naturally occurring frenatin peptides tested, frenatin 2D (DLLGTLGNLPLPFI.NH₂) from Discoglossus sardus was the most potent and effective in producing concentration-dependent stimulation of insulin release from BRIN-BD11 rat clonal β-cells without displaying cytotoxicity. The peptide also stimulated insulin release from 1.1B4 human-derived clonal β-cells and isolated mouse islets and improved glucose tolerance concomitant with increased circulating insulin concentrations in mice following intraperitoneal administration. The insulinotropic activity of frenatin 2D was not associated with membrane depolarization or an increase in intracellular [Ca²⁺] but incubation of the peptide (1 μM) with BRIN-BD11 cells produced a modest, but significant (P < 0.05), increase in cAMP production. Stimulation of insulin release was abolished in protein kinase A-downregulated cells but maintained in protein kinase C-downregulated cells. Circular dichroism studies showed that, in the presence of dodecylphosphocholine micelles, frenatin 2D exhibited a helical content of 35% and a turn content of 28%. Substitution of the Thr⁵, Asn⁸, Pro¹⁰, and Ile¹⁴ residues in frenatin-2D by Trp and interchange of Pro¹² and Phe¹³ led to loss of insulinotropic activity but the [D1W] and [G7W] analogues were as potent and effective as the native peptide. Frenatin 2D (1 μM) also stimulated proliferation of BRIN-BD11 cells and provided significant protection of the cells against cytokine-induced apoptosis. It is concluded that the insulinotropic activity of frenatin 2D is mediated predominantly, if not exclusively, by the K_ATP channel-independent pathway.

Antibacterial, antifungal, anticancer activities and structural bioinformatics analysis of six naturally occurring temporins

Antimicrobial peptides are a special class of natural products with potential applications as novel therapeutics. This study focuses on six temporins (four with no activity data and two as positive controls). Using synthetic peptides, we report antibacterial, antifungal, and anticancer activities of temporins-CPa, CPb, 1Ga, 1Oc, 1Ola, and 1SPa. While temporin-1Ga and temporin-1OLa showed higher antifungal and anticancer activity, most of these peptides were active primarily against Gram-positive bacteria. Temporin-1OLa, with the highest cell selectivity index, could preferentially kill methicillin-resistant Staphylococcus aureus (MRSA), consistent with a reduced hemolysis in the presence of bacteria. Mechanistically, temporin-1OLa rapidly killed MRSA by damaging bacterial membranes. Using micelles as a membrane-mimetic model, we determined the three-dimensional structure of temporin-1OLa by NMR spectroscopy. The peptide adopted a two-domain structure where a hydrophobic patch is followed by a classic amphipathic helix covering residues P3-I12. Such a structure is responsible for anti-biofilm ability in vitro and in vivo protection of wax moths Galleria mellonella from staphylococcal infection. Finally, our bioinformatic analysis leads to a classification of temporins into six types and confers significance to this NMR structure since temporin-1OLa shares a sequence model with 62% of temporins. Collectively, our results indicate the potential of temporin-1OLa as a new anti-MRSA compound, which shows an even better anti-biofilm capability in combination with linezolid.