Characterization of a novel LTA/LPS-binding antimicrobial and anti-inflammatory temporin peptide from the skin of Fejervary limnocharis (Anura: Ranidae).

Septic shock caused by Gram-positive bacteria continues to be a major cause of morbidity and mortality in intensive care units globally. Most Temporins are excellent growth inhibitors of gram-positive bacteria and candidates for developing antimicrobial treatments due to their biological action and small molecular weight. In this study, a novel Temporin peptide from the skin of Fejervarya limnocharis frog, named as Temporin-FL, was characterized. Temporin-FL was found to adopt typical α-helical conformation in SDS solution and to exhibit selective antibacterial activity against Gram-positive bacteria through a membrane destruction mechanism. Accordingly, Temporin-FL showed protective effects against Staphylococcus aureus-induced sepsis in mice. Finally, Temporin-FL was demonstrated to exert anti-inflammatory effects by neutralizing the action of LPS/LTA and by inhibiting MAPK pathway activation. Therefore, Temporin-FL represents a novel candidate for moleculartherapy of Gram-positive bacterial sepsis.

Multiple Mechanistic Action of Brevinin-1FL Peptide against Oxidative Stress Effects in an Acute Inflammatory Model of Carrageenan-Induced Damage.

Amphibian skin is acknowledged to contain an antioxidant system composed of various gene-encoded antioxidant peptides, which exert significant effects on host defense. Nevertheless, recognition of such peptides is in its infancy so far. Here, we reported the antioxidant properties and underlying mechanism of a new antioxidant peptide, brevinin-1FL, identified from Fejervarya limnocharis frog skin. The cDNA sequence encoding brevinin-1FL was successfully cloned from the total cDNA of F. limnocharis and showed to contain 222 bp. The deduced mature peptide sequence of brevinin-1FL was FWERCSRWLLN. Functional analysis revealed that brevinin-1FL could concentration-dependently scavenge ABTS+, DPPH, NO, and hydroxyl radicals and alleviate iron oxidation. Besides, brevinin-1FL was found to show neuroprotective activity by reducing contents of MDA and ROS plus mitochondrial membrane potential, increasing endogenous antioxidant enzyme activity, and suppressing H2O2-induced death, apoptosis, and cycle arrest in PC12 cells which were associated with its regulation of AKT/MAPK/NF-κB signal pathways. Moreover, brevinin-1FL relieved paw edema, decreased the levels of TNF-α, IL-1ß, IL-6, MPO, and malondialdehyde (MDA), and restored catalase (CAT) and superoxide dismutase (SOD) activity plus glutathione (GSH) contents in the mouse injected by carrageenan. Together, these findings indicate that brevinin-1FL as an antioxidant has potent therapeutic potential for the diseases induced by oxidative damage. Meanwhile, this study will help us further comprehend the biological functions of amphibian skin and the mechanism by which antioxidants protect cells from oxidative stress.

Discovery of Antioxidant Peptides from Amphibians: A Review.

In recent years, bioactive peptide drugs have attracted growing attention due to the increasing difficulty in developing new drugs with novel chemical structures. In addition, many diseases are linked to excessive oxidation in the human body. Therefore, the role of peptides with antioxidant activity in counteracting diseases related to oxidative stress is worth exploring. Amphibians are a major repository for bioactive peptides that protect the skin from biotic and abiotic stresses, such as microbial infection and radiation injury. We characterized the first amphibian- derived gene-encoded antioxidant peptides in 2008. Since then, a variety of antioxidant peptides have been detected in different amphibian species. In this work, the physicochemical properties of antioxidant peptides identified from amphibians are reviewed for the first time, particularly acquisition methods, amino acid characteristics, antioxidant mechanisms, and application prospects. This review should provide a reference for advancing the identification, structural analysis, and potential therapeutic value of natural antioxidant peptides.

In Silico Discovery of Antimicrobial Peptides as an Alternative to Control SARS-CoV-2.

A serious pandemic has been caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The interaction between spike surface viral protein (Sgp) and the angiotensin-converting enzyme 2 (ACE2) cellular receptor is essential to understand the SARS-CoV-2 infectivity and pathogenicity. Currently, no drugs are available to treat the infection caused by this coronavirus and the use of antimicrobial peptides (AMPs) may be a promising alternative therapeutic strategy to control SARS-CoV-2. In this study, we investigated the in silico interaction of AMPs with viral structural proteins and host cell receptors. We screened the antimicrobial peptide database (APD3) and selected 15 peptides based on their physicochemical and antiviral properties. The interactions of AMPs with Sgp and ACE2 were performed by docking analysis. The results revealed that two amphibian AMPs, caerin 1.6 and caerin 1.10, had the highest affinity for Sgp proteins while interaction with the ACE2 receptor was reduced. The effective AMPs interacted particularly with Arg995 located in the S2 subunits of Sgp, which is key subunit that plays an essential role in viral fusion and entry into the host cell through ACE2. Given these computational findings, new potentially effective AMPs with antiviral properties for SARS-CoV-2 were identified, but they need experimental validation for their therapeutic effectiveness.

Inhibitory effect of the antimicrobial peptide BLP-7 against Propionibacterium acnes and its anti-inflammatory effect on acne vulgaris.

Propionibacterium acnes (P. acnes) is a Gram-positive commensal bacterium, which is involved in the pathogenesis and inflammation of acne vulgaris. An antimicrobial peptide named bombinin-like peptide 7 (BLP-7), which was determined from Bombina orientalis, has been shown to possess certain antibacterial activity. This study was carried out with synthesized BLP-7 on the basis of the antimicrobial and anti-inflammatory activities against P. acnes in vitro and in vivo. The minimal inhibitory concentration (MIC) of BLP-7 against P. acnes is 5 µM. And BLP-7 exhibits strong resistance to heat, pH and salt concentration, but no significant cytotoxicity to normal human epidermal keratinocytes (NHEKs). Using the co-culture of P. acnes and NHEKs, this study demonstrated that BLP-7 significantly reduced the production of interleukin (IL)-8 and granulocyte-macrophage colony stimulating factor (GM-CSF), as well as the expression of these two pro-inflammatory cytokines at the transcriptional level. In a separate study, using the rat ear edema model, BLP-7 significantly suppressed P. acnes-induced skin inflammation, reducing the ear thickness by 54.21% of the negative control group. These results suggest that due to its anti-P. acnes and anti-inflammatory activities, BLP-7 could be used as a potential anti-acne agent.

Identification of new dermaseptins with self-assembly tendency: membrane disruption, biofilm eradication, and infected wound healing efficacy.

Severe infections associated with antibiotic-resistant bacteria and biofilms have attracted increasing interest as these diseases are difficult to treat with current antibiotics. Typical cationic antimicrobial peptides dermaseptins are considered to be the most promising next-generation antibiotics because of their broad-spectrum antimicrobial activities and minor side effects. Two new dermaseptin peptides, DMS-PS1 and DMS-PS2, have been identified by "shotgun" molecular cloning of encoding cDNAs in the crude skin secretions of the waxy monkey tree frog, Phyllomedusa sauvagei. The mature peptide sequences predicted from the cloned cDNAs were separated from crude skin secretions and confirmed by mass spectrometry. Chemically synthetic replicates were assessed for various biological activities. Both dermaseptins were potently effective against a broad spectrum of microorganisms including antibiotic-resistant bacteria and displayed significant potency against gram-positive and gram-negative bacterial biofilms with low toxicity towards mammalian red blood cells. Remarkably, DMS-PS2 was effective against infections in murine skin caused by methicillin-resistant Staphylococcus aureus as a result of an induced wound. The actions of DMS-PS2 were with a membrane permeabilization mode. Overall, the data provided convincing evidence for the development of anti-infectious agents and/or biomaterials as a new therapeutic approach against bacterial infections. STATEMENT OF SIGNIFICANCE: Bacterial adhesion to biomaterials remains a major problem. Antimicrobial peptides (AMPs) are well-known components of the innate immune system that can be applied to overcome biofilm-associated infections. Cationic dermaseptin peptides showed significant broad-spectrum antimicrobial activities and activities against bacterial biofilms of persistent infections in association with weak toxicity for mammalian red blood cells. The membrane permeabilizing ability of DMS-PS2 was confirmed, and importantly, it demonstrated potent efficiency of the treatment of MRSA infected murine skin model. Furthermore, beyond our expectation, DMS-PS2 showed a self-aggregating parameter, indicating a promising potential for the use of immobilized AMPs in clinical applications., which makes it also a promising suggestion for infection-proof biomaterial development.

Investigating the theragnostic potential of 131I-caerin peptide in thyroid cancer.

OBJECTIVE: Caerin is a new peptide with tumour toxicity and its uptake by tumour cells is independent of the sodium iodide symporter (NIS). Thyroid cancer is the most common cancers of endocrine malignancy. Radioiodine (131I)-refractory thyroid cancer is the most lethal subtype of the thyroid cancers and remains a clinical challenge. In the current study, we investigated the 131I radiolabeling efficiency of Caerin and the effects of Caerin, 131I-Caerin and free 131I on differentiated and undifferentiated human thyroid cancer cell lines (B-CPAP and CAL-62) in vitro. MATERIALS AND METHODS: Cell Counting Kit-8 was used to assess the cytotoxic effect of Caerin, 131I-Caerin and free 131I on B-CPAP and CAL-62 cells. Laser scanning confocal microscope was exploited to evaluate the uptake and internalization of Caerin by thyroid cancer cells. The Chloramine-T method was used to label the peptide with 131I. And the stability and water partition coefficient (Log P) of 131I-Caerin were studied. RESULTS: Our results demonstrated that Caerin and 131I-Caerin could be accumulated by B-CPAP and CAL-62 cells, resulting in killing of the thyroid cancer cells in vitro. The efficacy of 131I-Caerin is much higher than 131I, especially to undifferentiated CAL-62 cells. The results prove the feasibility of radioiodination of the 131I-Caerin via the Chloramine-T method. Moreover, the result indicate the hydrophobic 131I-Caerin was stable in 72 hours. CONCLUSION: Iodine-131-Caerin can inhibit the cell viability of thyroid cancer and hold certain promise as a theragnostic tool for human thyroid cancers.

Synthesized natural peptides from amphibian skin secretions increase the efficacy of a therapeutic vaccine by recruiting more T cells to the tumour site.

BACKGROUND: Therapeutic vaccines against cervical cancer remain ineffective. Previously, we demonstrated that blocking the signalling of a cytokine, interleukin 10, at the time of immunisation elicited significantly higher numbers of antigen specific T cells and inhibited tumour growth in mice. RESULTS: In the current paper, we demonstrate, in a HPV16 E6/E7 transformed TC-1 tumour mouse model, that despite increased antigen specific T cell numbers, blocking IL-10 signalling at the time of immunisation does not increase the survival time of the TC-1 tumour bearing mice compared to mice receiving the same immunisation with no IL-10 signalling blockade. Moreover, the function of tumour infiltrating T cells isolated 3 weeks post TC-1 transplantation is more suppressed than those isolated 2 weeks after tumour inoculation. We demonstrate that synthesized caerin peptides, derived from amphibian skin secretions, 1) were able to inhibit TC-1 tumour growth both in vitro and in vivo; 2) are environmentally stable; and 3) promote the secretion of pro-inflammatory interlukine-6 by TC-1 cells. Notably caerin peptides were able to increase the survival time of TC-1 tumour bearing mice after therapeutic vaccination with a HPV16E7 peptide-based vaccine containing IL-10 inhibitor, via recruiting increased levels of T cells to the tumour site. CONCLUSION: Caerin peptides increase the efficacy of a therapeutic vaccine by recruiting more T cells to the tumour site.

Poly(lactide- co-glycolide) Nanoparticles for Prolonged Therapeutic Efficacy of Esculentin-1a-Derived Antimicrobial Peptides against Pseudomonas aeruginosa Lung Infection: in Vitro and in Vivo Studies.

Due to their excellent in vitro activity against multidrug resistant bacteria, antimicrobial peptides (AMPs) hold promise for treatment of Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) sufferers. In this work, poly(lactide- co-glycolide) (PLGA) nanoparticles for lung delivery of AMPs deriving from the frog-skin esculentin-1a, namely, Esc(1-21) and Esc(1-21)-1c (Esc peptides), were successfully developed. Improved peptide transport through artificial CF mucus and simulated bacterial extracellular matrix was achieved in vitro. The formulations were effectively delivered through a liquid jet nebulizer already available to patients. Notably, Esc peptide-loaded nanoparticles displayed an improved efficacy in inhibiting P. aeruginosa growth in vitro and in vivo in the long term. A single intratracheal administration of Esc peptide-loaded nanoparticles in a mouse model of P. aeruginosa lung infection resulted in a 3-log reduction of pulmonary bacterial burden up to 36 h. Overall, results unravel the potential of PLGA nanoparticles as a reliable delivery system of AMPs to lungs.

Dermaseptins as potential antirabies compounds.

Over the last 20 years, natural peptides playing a key role in defense mechanisms and innate immunity have been isolated from unicellular organisms. Amphibian skin secretes dermaseptins, 24-34 amino acids in length that have a wide antimicrobial spectrum incorporating yeast, fungi, protozoa, bacteria and enveloped viruses. The anti-rabies virus (RABV) activity of dermaseptins S3 (30aa) and S4 (28aa) from Phyllomedusa sauvagei has been investigated, and further dissected its molecular basis by comparing punctual mutation or deletion of S4 analogues. The results showed that: (1) S4 is more active than S3 against RABV infection, 89% versus 38% inhibition at 7.5 µM; (2) the 5 NH2-aa of S4 are crucial for its inhibitory potential (S46-28 lost any inhibition) but the COOH terminus stabilizes the inhibitory potential (S41-16 showed only 23% inhibition at 7.5 µM); (3) there is a correlation between viral inhibition and dermaseptin cytotoxicity, which remains however moderated for BSR cells (≤12% at 10 µM). A single mutation in position 4 (S4M4K) slightly reduced cytotoxicity while keeping its antiviral activity, 97% at 7.5 µM. S4 and S4M4K showed an antiviral activity in vitro when provided 1 h after infection. In vivo experiments in mice by intramuscular injection of non-toxic doses of dermaseptin S4M4K 1 h post-infection by a lethal dose of RABV at the same site allowed more than 50% improvement in mice survival. This study highlights the potential interest of dermaseptins as non-expansive alternatives to rabies immunoglobulins for the treatment of rabies that continues to claim about 60,000 human lives per year worldwide, almost exclusively in developing countries.

Iodine-125 labeled Australian frog tree host-defense peptides caerin 1.1 and 1.9 better inhibit human breast cancer cells growth than the unlabeled peptides. 125I-caerin 1.9 may better be used for the treatment of breast cancer.

OBJECTIVE: We recently showed that host defense caerin peptides isolated from Australian frog tree were able to inhibit cervical cancer tumour cell growth in vitro. We wished to determine if radioactive isotope iodine-125 (125I) can be labeled to caerin 1.9 peptide and if this peptide is bioactive for breast cancer cells treatment. SUBJECTS AND METHODS: The biological function of caerin (1.1 and 1.9) peptides were investigated by in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay. The anti-cancer effect of 125I labeled caerin 1.9 was compared with unlabeled caerin 1.9 peptide. The tissue distribution of 125I labeled caerin 1.9 peptide was further studied in mice. RESULTS: In the current paper, we demonstrated that caerin peptides (1.1 and 1.9) were separately able to inhibit the viability of two breast cancer cell lines in vitro and this inhibition was more profound when these peptides were simultaneously applied. Moreover, 125I can be stably attached to caerin 1.9 peptide with high efficiency. Iodine-125 labeled caerin 1.9 inhibited breast cancer cells line MCF-7 viability more efficiently than free 125I and also than unlabeled caerin 1.9. Additionally, iodine-125 labeled caerin 1.9 in vivo imaging demonstrated that although slightly, it could be accumulated in tumor tissue. CONCLUSION: Our results from this totally original study indicated that radioactive isotope 125I labeled to caerin peptide 1.9 may be used to treat breast cancer while at the same time the response to treatment may be monitored by simultaneous imaging.

An Atlas of Anionic Antimicrobial Peptides from Amphibians.

Anionic antimicrobial peptides (AAMPs) with net charges ranging from -1 to -8 have been identified in frogs, toads, newts and salamanders across Africa, South America and China. Most of these peptides show antibacterial activity and a number of them are multifunctional, variously showing antifungal activity, anticancer action, neuropeptide function and the ability to potentiate conventional antibiotics. Antimicrobial mechanisms proposed for these AAMPs, include toroidal pore formation and the Shai-Huang-Matsazuki model of membrane interaction along with pH dependent amyloidogenesis and membranolysis via tilted peptide formation. The potential for therapeutic and biotechnical application of these AAMPs has been demonstrated, including the development of amyloid-based nanomaterials and antiviral agents. It is concluded that amphibian AAMPs represent an untapped potential source of biologically active agents and merit far greater research interest.

Peptides from frog skin with potential for development into agents for Type 2 diabetes therapy.

Several frog skin peptides, first identified as result of their antimicrobial or immunomodulatory activities, have subsequently been shown to stimulate insulin release both in vitro and in vivo and so show potential for development into incretin-based drugs for treatment of patients with Type 2 diabetes mellitus. However, their therapeutic potential as anti-diabetic agents is not confined to this activity as certain frog skin-derived peptides, such as magainin-AM2 and CPF-SE1 and analogs of hymenochirin-1B, tigerinin-1R, and esculentin-2CHa, have been shown to increase insulin sensitivity, promote ß-cell proliferation, suppress pancreatic and circulating glucagon concentrations, improve the lipid profile, and selectively alter expression of genes involved in insulin secretion and action in mice with diet-induced obesity, insulin resistance and impaired glucose tolerance. This review assesses the therapeutic possibilities of peptides from frogs belonging to the Pipidae, Dicroglossidae, and Ranidae families, focusing upon work that has been carried out since 2014.

Actions of PGLa-AM1 and its [A14K] and [A20K] analogues and their therapeutic potential as anti-diabetic agents.

PGLa-AM1 (GMASKAGSVL10GKVAKVALKA20AL.NH2) was first identified in skin secretions of the frog Xenopus amieti (Pipidae) on the basis of its antimicrobial properties. PGLa-AM1 and its [A14K] and [A20K] analogues produced a concentration-dependent stimulation of insulin release from BRIN-BD11 rat clonal ß-cells without cytotoxicity at concentrations up to 3 µM. In contrast, the [A3K] analogue was cytotoxic at concentrations ≥ 30 nM. The potency and maximum rate of insulin release produced by the [A14K] and [A20K] peptides were significantly greater than produced by PGLa-AM1. [A14K]PGLa-AM1 also stimulated insulin release from mouse islets at concentrations ≥ 1 nM and from the 1.1B4 human-derived pancreatic ß-cell line at concentrations > 30 pM. PGLa-AM1 (1 µM) produced membrane depolarization in BRIN-BD11 cells with a small, but significant (P < 0.05), increase in intracellular Ca2+ concentrations but the peptide had no direct effect on KATP channels. The [A14K] analogue (1 µM) produced a significant increase in cAMP concentration in BRIN-BD11 cells and down-regulation of the protein kinase A pathway by overnight incubation with forskolin completely abolished the insulin-releasing effects of the peptide. [A14K]PGLa-AM1 (1 µM) protected against cytokine-induced apoptosis (p < 0.001) in BRIN-BD11 cells and augmented (p < 0.001) proliferation of the cells to a similar extent as GLP-1. Intraperitoneal administration of the [A14K] and [A20K] analogues (75 nmol/kg body weight) to both lean mice and high fat-fed mice with insulin resistance improved glucose tolerance with a concomitant increase in insulin secretion. The data provide further support for the assertion that host defense peptides from frogs belonging to the Pipidae family show potential for development into agents for the treatment of patients with Type 2 diabetes.

Prokineticin system modulation as a new target to counteract the amyloid beta toxicity induced by glutamatergic alterations in an in vitro model of Alzheimer's disease.

The accumulation of ß-amyloid (Aß) is one of the hallmarks of Alzheimer disease (AD). Beyond the inflammatory reactions promoted by Aß, it has been demonstrated that the prokineticin (PK) system, composed of the chemokine prokineticin 2 (PK2) and its receptors, is involved in Aß toxicity. In this study we have analyzed how the Aß chronic treatment affects the glutamatergic transmission on neurons from primary cortical cultures, clearly demonstrating the PK system involvement on its action mechanism. In fact, we have observed a significant increase of the ionic current through the AMPA receptors in primary cortical neurons and an up-regulation of the PK system in cultures chronically treated with Aß. All effects were nullified by the prokineticin antagonist PC-1. Moreover, we have herein firstly demonstrated that the incubation of primary cortical culture with Bv8, the amphibian homologue of PK2, was able to increase in neurons the AMPA currents at specific doses and exposure times, measured both as evoked and as spontaneous currents. This effect was not due to a modification of the AMPA receptor subunit expression. In contrast, the up-modulation of AMPA currents were blocked by PC-1 and were mediated by the activation of the intracellular protein kinase C (PKC) transduction pathways because Gö6983, the PKC inhibitor added in the medium, nullified the effect. Finally, cellular death induced by kainate was also reduced following treatment with PC1. In conclusion, our results show that the prokineticin system may be a key mediator in the Aß-induced neuronal damage, suggesting PK antagonists as new therapeutic compounds to ameliorate the AD progression.

An overview of Brevinin superfamily: structure, function and clinical perspectives.

Antimicrobial peptides are the backbone of first-line defense against various microorganisms in the animal kingdom. Thus, not surprisingly, they are gaining attention in the science and medical fields as a rich repository of new pro-drugs. Below, we focus our attention on the Brevinin family of anuran peptides. While most of them show strong antibacterial activities, some, e.g. Brevinin-2R, appear to be promising anticancer molecules, exhibiting better a therapeutic window than widely-use anticancer drugs like doxorubicin. We briefly introduce the field, followed by highlighting the promising therapeutic properties of Brevinins. Next, we provide information about the cloning and phylogenetic aspects of Brevinin genes. In the final paragraphs of this chapter, we discuss possible large-scale production methods of Brevinins, giving examples of some systems that are already in use. Towards the end, we discuss various means of modification of biologic properties of Brevinins, either by chemical modifications or by amino acid substitution and sequence rearrangements. In this context, also other unique properties of Brevinins are briefly mentioned. Finally, we discuss the future of the Brevinin field, particularly highlighting yet to be answered biologic questions, like for example presumed anti-viral and antitumor activities of Brevinin family members.

Leczyme: a new candidate drug for cancer therapy.

Sialic acid-binding lectin (SBL), isolated from oocytes of Rana catesbeiana, is leczyme and has both lectin and ribonuclease (RNase) activities. A remarkable antitumor effect of SBL has also been reported. SBL agglutinates various kinds of tumor cells but not normal cells. SBL agglutination activity is not affected by mono- or oligosaccharides. However, SBL-induced agglutination and antitumor effects are inhibited by sialomucin but not asialomucin. In addition, SBL has very little effect on sialidase-treated cells. SBL causes cancer-selective induction of apoptosis by multiple signaling pathways, which target RNA. Synergistic antitumor effects with other molecules, such as tumor necrosis factor-related apoptosis ligand (TRAIL) and interferon- γ (IFN-γ), have been reported. Thus, SBL may be a novel candidate molecule for anticancer drug development. Sialoglycoconjugates on the tumor cell surface may be associated with lectin activity and antitumor effects of SBL. We review the properties of SBL, particularly its lectin, RNase, and antitumor activities, and comprehensively examine the potential application of SBL for clinical purposes.

Insulinotropic actions of the frog skin host-defense peptide alyteserin-2a: a structure-activity study.

Alyteserin-2a (ILGKLLSTAAGLLSNL.NH2 ) stimulated the rate of insulin release from BRIN-BD11 clonalß cells at a concentration of 30 nm (p < 0.05) with a response of 296 ± 26% of basal release at 3 µm (p < 0.001). The insulinotropic actions of analogs containing substitutions by l-lysine, d-lysine, or l-tryptophan at sites that maintain amphipathicity were evaluated. The [G11K], [S7k], [S7k,G11k], and [G11k,N15K] analogs were the most potent stimulating insulin release at 0.01 nm (p < 0.05). The [S7K], [G11K], [S14K], [N15K], [G11k], and [S7K,G11K] analogs were the most effective producing an approximately twofold greater (p < 0.001) release of insulin at 3 µm compared with alyteserin-2a. The [T8W] and [A9W] analogs were less active than alyteserin-2a. No peptide-stimulated release of lactate dehydrogenase at concentrations up to 3 µm, indicating that the integrity of the plasma membrane had been preserved. Membrane depolarization and an increase in intracellular Ca(2+) concentration are involved in the mechanism of action of the peptides. Administration of [G11k]alyteserin-2a (75 nmol/kg body weight) to high-fat-fed mice with obesity and insulin resistance significantly (p < 0.01) enhanced insulin release and improved glucose tolerance during the 60-min period following an intraperitoneal glucose load.

Pharmacological activity of a Bv8 analogue modified in position 24.

BACKGROUND AND PURPOSE: The amphibian peptide Bv8 induces potent nociceptive sensitization in rodents. Its mammalian homologue, prokineticin 2 (PROK2), is strongly up-regulated in inflamed tissues and is a major determinant in triggering inflammatory pain. Bv8 and PROK2 activate two closely related GPCRs, PK(1) and PK(2) , in a relatively non-selective fashion. To characterize better the roles of the two receptors in hyperalgesia and to obtain ligands whose binding affinity and efficacy differed for the two receptors, we modified the Bv8 molecule in regions essential for receptor recognition and activation. EXPERIMENTAL APPROACH: We modified the Bv8 molecule by substituting Trp in position 24 with Ala (A-24) and compared it with Bv8 for binding and activating PK(1) and PK(2) receptors in cell preparations and in affecting nociceptive thresholds in rodents. KEY RESULTS: A-24 preferentially bound to PK(2) receptors and activated them with a lower potency (5-fold) than Bv8. When systemically injected, A-24 induced Bv8-like hyperalgesia in rats and in mice, at doses 100 times higher than Bv8. Locally and systemically injected at inactive doses, A-24 antagonized Bv8-induced hyperalgesia. In rat and mouse models of inflammatory and post-surgical pain, A-24 showed potent and long-lasting anti-hyperalgesic activity. Unlike Bv8, A-24 increased ß-endorphin levels in mouse brain. CONCLUSIONS AND IMPLICATIONS: A-24 induced its anti-hyperalgesic effect in rodents by directly blocking nociceptor PK(1) receptors and by activating the central opioid system and the descending pain control pathway through brain PK(2) receptors.

In vitro activity of dermaseptin S1 derivatives against genital pathogens.

The aim of this study was to evaluate the biological activity of nine dermaseptin-S1 (DRS-S1) derivatives (synthesized by solid-phase methods and purified) against different pathogens causing genital infections (Trichomonas vaginalis, Herpes simplex virus, Papillomavirus). The in vitro activity on T. vaginalis was determined by counting the protozoon in a hemocytometer after vital staining with trypan blue; antiviral activity of the compounds was tested on monolayers of Vero cells for Herpes simplex virus-1 (GFP) and on 293TT cells for human papillomavirus (HPV-16) pseudovirions (GFP). The cytotoxicity of the derivatives was assessed by evaluating both the hemolytic activity and the effect on Vero and 293TT cells. The DRS-S1 longer peptides demonstrated a superior activity on T. vaginalis but also a certain cytopathic effect. The compounds with 29 amino acids exhibited activity against the two viruses tested at concentrations not toxic to cells. The results obtained show that some of the synthetic peptides assessed have inhibitory activity against the pathogens tested, indicating a potential for the development of new molecules for use as topical microbicides to prevent the sexual transmission of microorganisms.