The peptide secreted at the water to land transition in a model amphibian has antioxidant effects

In addition to the morphophysiological changes experienced by amphibians during metamorphosis, they must also deal with a different set of environmental constraints when they shift from the water to the land. We found that Pithecopus azureus secretes a single peptide ([M + H]+ = 658.38 Da) at the developmental stage that precedes the onset of terrestrial behaviour. De novo peptide and cDNA sequencing revealed that the peptide, named PaT-2, is expressed in tandem and is a member of the tryptophyllins family. In silico studies allowed us to identify the position of reactive sites and infer possible antioxidant mechanisms of the compounds. Cell-based assays confirmed the predicted antioxidant activity in mammalian microglia and neuroblast cells. The potential neuroprotective effect of PaT-2 was further corroborated in FRET-based live cell imaging assays, where the peptide prevented lipopolysaccharide-induced ROS production and glutamate release in human microglia. In summary, PaT-2 is the first peptide expressed during the ontogeny of P. azureus, right before the metamorphosing froglet leaves the aquatic environment to occupy terrestrial habitats. The antioxidant activity of PaT-2, predicted by in silico analyses and confirmed by cell-based assays, might be relevant for the protection of the skin of P. azureus adults against increased O₂ levels and UV exposure on land compared with aquatic environments.

Promising self-emulsifying drug delivery system loaded with lycopene from red guava (Psidium guajava L.): in vivo toxicity, biodistribution and cytotoxicity on DU-145 prostate cancer cells

Background

Self-emulsifying drug delivery systems (SEDDSs) have attracted attention because of their effects on solubility and bioavailability of lipophilic compounds. Herein, a SEDDS loaded with lycopene purified from red guava (nanoLPG) was produced. The nanoemulsion was characterized using dynamic light scattering (DLS), zeta potential measurement, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), lycopene content quantification, radical scavenging activity and colloidal stability in cell culture medium. Then, in vivo toxicity and tissue distribution in orally treated mice and cytotoxicity on human prostate carcinoma cells (DU-145) and human peripheral blood mononuclear cells (PBMC) were evaluated.

Results

NanoLPG exhibited physicochemical properties with a size around 200 nm, negative zeta-potential, and spherical morphology. The size, polydispersity index, and zeta potential parameters suffered insignificant alterations during the 12 month storage at 5 °C, which were associated with lycopene stability at 5 °C for 10 months. The nanoemulsion showed partial aggregation in cell culture medium at 37 °C after 24 h. NanoLPG at 0.10 mg/mL exhibited radical scavenging activity equivalent to 0.043 ± 0.002 mg Trolox/mL. The in vivo studies did not reveal any significant changes in clinical, behavioral, hematological, biochemical, and histopathological parameters in mice orally treated with nanoLPG at 10 mg/kg for 28 days. In addition, nanoLPG successfully delivered lycopene to the liver, kidney and prostate in mice, improved its cytotoxicity against DU-145 prostate cancer cells—probably by pathway independent on classical necrosis and apoptosis—and did not affect PBMC viability.

Conclusions

Thus, nanoLPG stands as a promising and biosafe lycopene delivery system for further development of nanotechnology-based health products.

Graphical Abstract

Mechanistic Insights into the Leishmanicidal and Bactericidal Activities of Batroxicidin, a Cathelicidin-Related Peptide from a South American Viper (Bothrops atrox)

Snake venoms are important sources of bioactive molecules, including those with antiparasitic activity. Cathelicidins form a class of such molecules, which are produced by a variety of organisms. Batroxicidin (BatxC) is a cathelicidin found in the venom of the common lancehead (Bothrops atrox). In the present work, BatxC and two synthetic analogues, BatxC(C-2.15Phe) and BatxC(C-2.14Phe)des-Phe1, were assessed for their microbicidal activity. All three peptides showed a broad-spectrum activity on Gram-positive and -negative bacteria, as well as promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. Circular dichroism (CD) and nuclear magnetic resonance (NMR) data indicated that the three peptides changed their structure upon interaction with membranes. Biomimetic membrane model studies demonstrated that the peptides exert a permeabilization effect in prokaryotic membranes, leading to cell morphology distortion, which was confirmed by atomic force microscopy (AFM). The molecules considered in this work exhibited bactericidal and leishmanicidal activity at low concentrations, with the AFM data suggesting membrane pore formation as their mechanism of action. These peptides stand as valuable prototype drugs to be further investigated and eventually used to treat bacterial and protozoal infections.

Cell and platelet composition assays by flow cytometry: basis for new platelet-rich fibrin methodologies

Platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) are selective blood fractions obtained by cen¬trifugation. They act locally on inflammation and immunity as adjuvant homeostatic modulators during tissue regeneration. In recent years, many methods for achieving these blood concentrates have emerged, whose parameters of time and force of centrifugation presented themselves as critical, conflicting, and poorly understood points. Thus, the present study aimed to evaluate the effect of different centrifugal experimental parameters on the concentration of cells and platelets in samples of anticoagulated blood. Blood samples were centrifuged by forces of 200, 400 and 800 x g for 5, 10 and 15 minutes of centrifugation times to obtain three fractions: a) platelet-poor plasma (PPP), b) leukocyte-rich plasma (L- PRP) and c) red blood cell sed¬iment (RBC). The leukocyte and platelet content of each centrifuged fraction was measured by automated flow cytometry associated with the peroxidase reaction for differential leukocyte count. The application of 200 x g generated a more significant dispersive content of leukocytes and platelets in the supernatant fraction of PPP when compared to the other two strength ranges. However, it presented the highest concentration of platelets in the sediment (P <0.05 ANOVA), representing a loss of total mass during processing. The 400 and 800 x g forces showed leukocytes and platelets condensed in the L-PRP fraction and lower levels in the sedi¬ment, demonstrating the greater effectiveness of buoyancy in the resuspension of these sedimented elements. Our experimental data showed that the concentration and organization of leukocytes and platelets in the centrifuged blood matrices are very sensitive to variations in g force and centrifugation time, thus generating products with different biological composition and characteristics, and with specific potential therapeutic effects. The present study did not focus on comparing authoring methods, but on presenting the impact of methodological variations on the biological nature of centrifuged blood matrices. Further in vivo studies are needed to assess the specific clinical effect of each methodological change.

Quantification of lipid bodies in monocytes from patients with periodontitis

OBJECTIVES

For the first time in the history of periodontics, the production of lipid bodies by monocytes was assessed from blood of patients with periodontitis in comparison to systemically healthy individuals. The purpose of this study was to compare the lipid body frequency within monocytes between healthy patients and those with periodontal disease.

MATERIALS AND METHODS

A total of 30 participants (11 males and 19 females), were divided between orally healthy control subjects (C, n = 16) and periodontitis subjects (P, n = 14), in a cross-sectional study. Both groups were systemically healthy. The following clinical periodontal parameters were assessed: probing depth, clinical attachment level, visible plaque index and gingival bleeding on probing index. Blood samples were collected to obtain monocytes containing lipid bodies, which were analyzed by light microscopy.

RESULTS

The periodontitis group demonstrated a higher corpuscular index than the control group (nonopsonized p = .0296 or opsonized p = .0459; Mann-Whitney). The frequency of monocyte cells containing lipid bodies (basal p = .0147, opsonized p = .0084 or nonopsonized, p = .026; Mann-Whitney) was also higher compared to those observed in healthy individuals.

CONCLUSIONS

The data suggest that periodontitis may contribute to a higher production of lipid bodies. It was also hypothesized that a major production of lipid bodies by monocytes in severe periodontitis, compared to orally healthy subjects, could interfere with the innate immune response or represents a higher reservoir of cholesterol esters within macrophages and a major risk to systemic implications, such as atherosclerosis.

Structure⁻Activity Relationship of Piplartine and Synthetic Analogues against Schistosoma mansoni and Cytotoxicity to Mammalian Cells

Schistosomiasis, caused by helminth flatworms of the genus Schistosoma, is an infectious disease mainly associated with poverty that affects millions of people worldwide. Since treatment for this disease relies only on the use of praziquantel, there is an urgent need to identify new antischistosomal drugs. Piplartine is an amide alkaloid found in several Piper species (Piperaceae) that exhibits antischistosomal properties. The aim of this study was to evaluate the structure–function relationship between piplartine and its five synthetic analogues (19A, 1G, 1M, 14B and 6B) against Schistosoma mansoni adult worms, as well as its cytotoxicity to mammalian cells using murine fibroblast (NIH-3T3) and BALB/cN macrophage (J774A.1) cell lines. In addition, density functional theory calculations and in silico analysis were used to predict physicochemical and toxicity parameters. Bioassays revealed that piplartine is active against S. mansoni at low concentrations (5⁻10 µM), but its analogues did not. In contrast, based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, piplartine exhibited toxicity in mammalian cells at 785 µM, while its analogues 19A and 6B did not reduce cell viability at the same concentrations. This study demonstrated that piplartine analogues showed less activity against S. mansoni but presented lower toxicity than piplartine.

Anthelmintic activity in vivo of epiisopiloturine against juvenile and adult worms of Schistosoma mansoni

Schistosomiasis is a serious disease currently estimated to affect more that 207 million people worldwide. Due to the intensive use of praziquantel, there is increasing concern about the development of drug-resistant strains. Therefore, it is necessary to search for and investigate new potential schistosomicidal compounds. This work reports the in vivo effect of the alkaloid epiisopiloturine (EPI) against adults and juvenile worms of Schistosoma mansoni. EPI was first purified its thermal behavior and theoretical solubility parameters charaterised. In the experiment, mice were treated with EPI over the 21 days post-infection with the doses of 40 and 200 mg/kg, and 45 days post-infection with single doses of 40, 100 and 300 mg/kg. The treatment with EPI at 40 mg/kg was more effective in adult worms when compared with doses of 100 and 300 mg/kg. The treatment with 40 mg/kg in adult worms reduced parasite burden significantly, lead to reduction in hepatosplenomegaly, reduced the egg burden in faeces, and decreased granuloma diameter. Scanning electron microscopy revealed morphological changes to the parasite tegument after treatment, including the loss of important features. Additionally, the in vivo treatment against juvenile with 40 mg/kg showed a reduction of the total worm burden of 50.2%. Histopathological studies were performed on liver, spleen, lung, kidney and brain and EPI was shown to have a DL50 of 8000 mg/kg. Therefore EPI shows potential to be used in schistosomiasis treatment. This is the first time that schistosomicidal in vivo activity of EPI has been reported.

Novel dermaseptins from Phyllomedusa hypochondrialis (Amphibia)

Six new antimicrobial peptides structurally related to the dermaseptin family have been isolated from the skin secretion of the amphibian Phyllomedusa hypochondrialis. The primary structures of these molecules named as DShypo 01, 02, 03, 04, 06, and 07 were determined by de novo MS/MS experiments, Edman degradation, and cDNA sequencing. The fifth peptide was found to be precisely the same DS 01 from Phyllomedusa oreades previously described by our group. The majority of the peptides purified from the crude skin secretion could be directly localized and mapped onto a freshly dissected dorsal skin fragment using mass spectrometry-imaging techniques. Comparisons between peptides and commercial drugs on their antibacterial and anti-Leishmania amazonensis efficiencies, associated with peptide lytic effects on mammalian blood cells and surface plasmon resonance interaction studies on immobilized DMPC vesicles, were also performed.