Temporin-Like Peptides Show Antimicrobial and Anti-Biofilm Activities against Streptococcus mutans with Reduced Hemolysis.

In our previous study, temporin-GHaR (GHaR) showed potent antimicrobial activity with strong hemolytic toxicity. To overcome its weakness, we designed GHaR6R, GHaR7R, GHaR8R, GHaR9R, and GHaR9W by changing the number of positive charges and the hydrophobic surface of GHaR. With the exception of GHaR7R, the hemolytic toxicity of the derived peptides had been reduced, and the antimicrobial activities remained close to the parent peptide (except for GHaR9R). GHaR6R, GHaR7R, GHaR8R, and GHaR9W exhibited a great bactericidal effect on Streptococcus mutans (S. mutans), which is one of the main pathogens causing dental caries. According to the membrane permeation and scanning electron microscope (SEM) analysis, these derived peptides targeted to the cell membranes of planktonic bacteria, contributing to the disruption of the membrane integrity and leakage of the intracellular contents. Moreover, they inhibited the formation of biofilms and eradicated the mature biofilms of S. mutans. Compared with GHaR7R, the derived peptides showed less cytotoxicity to human oral epithelial cells (HOECs). The derived peptides are expected to be the molecular templates for designing antibacterial agents to prevent dental caries.

In Vitro and In Vivo Immunomodulatory Activity of Okra (Abelmoschus esculentus L.) Polysaccharides.

Crude okra (Abelmoschus esculentus L.) polysaccharide (RPS) was obtained by water extraction and alcohol precipitation. Three purified fractions of RPS, designated RPS-1, RPS-2, and RPS-3, were fractioned by diethylaminoethyl (DEAE)-cellulose chromatography. Their molecular weights, monosaccharide compositions, infrared (Fourier transform infrared [FT-IR]) spectra, and nuclear magnetic resonance (NMR) spectra were analyzed. Their immunomodulatory activity was evaluated with an in vitro cell model (RAW264.7 cells). In vivo immunomodulatory activity of RPS-2 was evaluated in normal and cyclophosphamide-induced immunosuppressed mice. The results showed that the molecular weights of RPS-1, RPS-2, and RPS-3 were 600, 990, and 1300 kDa, respectively. RPS-1 and RPS-2 were mainly composed of galactose, rhamnose, galacturonic acid, and glucuronic acid, while RPS-3 was mainly composed of galactose, rhamnose, galacturonic acid, glucuronic acid, and glucose. FT-IR and NMR spectrum data indicated a rhamnogalacturonan I characteristic of polysaccharide. Both RPS and its purified fractions RPS-1, RPS-2, and RPS-3 significantly increased RAW264.7 cell proliferation, nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression, and tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-10 secretion (P < .05). The purified fraction RPS-2 also increased the spleen index, splenocyte proliferation, and cytokine secretion in vivo. These results indicate that okra polysaccharides may potentially serve as novel immunomodulators.

Purification and characterization of a trypsin inhibitor from the seeds of Artocarpus heterophyllus Lam.

A proteinaceous inhibitor against trypsin was isolated from the seeds of Artocarpus heterophyllus Lam. by successive ammonium sulfate precipitation, ion-exchange, and gel-filtration chromatography. The trypsin inhibitor, named as AHLTI (A. heterophyllus Lam. trypsin inhibitor), consisted of a single polypeptide chain with a molecular weight of 28.5 kDa, which was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel-filtration chromatography. The N-terminal sequence of AHLTI was DEPPSELDAS, which showed no similarity to other known trypsin inhibitor sequence. AHLTI completely inhibited bovine trypsin at a molar ratio of 1:2 (AHLTI:trypsin) analyzed by native polyacrylamide gel electrophoresis, inhibition activity assay, and gel-filtration chromatography. Moreover, kinetic enzymatic studies were carried out to understand the inhibition mechanism of AHLTI against trypsin. Results showed that AHLTI was a competitive inhibitor with an equilibrium dissociation constant (Ki) of 3.7 × 10(-8) M. However, AHLTI showed weak inhibitory activity toward chymotrypsin and elastase. AHLTI was stable over a broad range of pH 4-8 and temperature 20-80°C. The reduction agent, dithiothreitol, had no obvious effect on AHLTI. The trypsin inhibition assays of AHLTI toward digestive enzymes from insect pest guts in vitro demonstrated that AHLTI was effective against enzymes from Locusta migratoria manilensis (Meyen). These results suggested that AHLTI might be a novel trypsin inhibitor from A. heterophyllus Lam. belonging to Kunitz family, and play an important role in protecting from insect pest.

Complete genome sequence of bovine papillomavirus genotype 13 from local yellow cattle in hainan province, china.

Here, we present the complete genome sequence of bovine papillomavirus genotype 13 isolated from local yellow cattle in Hainan, China. The genome is 7,961 bp and contains six early genes and two late genes. This analysis provides important information for the research of bovine papillomavirus (BPV) in China.

Characteristics of hemolytic activity induced by skin secretions of the frog Kaloula pulchra hainana

The hemolytic activity of skin secretions obtained by stimulating the frog Kaloula pulchra hainana with diethyl ether was tested using human, cattle, rabbit, and chicken erythrocytes. The skin secretions had a significant concentration-dependent hemolytic effect on erythrocytes. The hemolytic activity of the skin secretions was studied in the presence of osmotic protectants (polyethylene glycols and carbohydrates), cations (Mg2+, Ca2+, Ba2+, Cu2+, and K+), or antioxidants (ascorbic acid, reduced glutathione, and cysteine). Results Depending on their molecular mass, osmotic protectants effectively inhibited hemolysis. The inhibition of skin hemolysis was observed after treatment with polyethylene glycols (1000, 3400, and 6000 Da). Among divalent cations, only 1 mM Cu2+ markedly inhibited hemolytic activity. Antioxidant compounds slightly reduced the hemolytic activity. Conclusions The results suggested that skin secretions of K. pulchra hainana induce a pore-forming mechanism to form pores with a diameter of 1.36-2.0 nm rather than causing oxidative damage to the erythrocyte membrane.

Characteristics of hemolytic activity induced by skin secretions of the frog Kaloula pulchra hainana

Background: Previous works had shown that scorpion venom induced neurotransmitter elevation and an inflammatory response associated with various anatomo-pathological modifications. The most dangerous scorpions species in Algeria responsible for these effects are Androctonus australis hector (Aah) and Androctonus amoreuxi (Aam). Results: Comparison of the physiopathological effects induced by the two venoms showed differences in the kinetic of cytokine release and in lung injury. The lung edema was only observed in response to Aah venom and it was correlated with cell infiltration. In order to better understand the involved mechanism in inflammatory response, we used two antagonists, atropine (non-selective muscarinic antagonist) and propranolol (ß adrenergic antagonist), which lead to a decrease of cell infiltration but has no effect on edema forming. Conclusion: These results suggest another pathway in the development of lung injury following envenomation with Aam or Aah venom.(AU)

Characteristics of hemolytic activity induced by skin secretions of the frog Kaloula pulchra hainana.

BACKGROUND: The hemolytic activity of skin secretions obtained by stimulating the frog Kaloula pulchra hainana with diethyl ether was tested using human, cattle, rabbit, and chicken erythrocytes. The skin secretions had a significant concentration-dependent hemolytic effect on erythrocytes. The hemolytic activity of the skin secretions was studied in the presence of osmotic protectants (polyethylene glycols and carbohydrates), cations (Mg2+, Ca2+, Ba2+, Cu2+, and K+), or antioxidants (ascorbic acid, reduced glutathione, and cysteine). RESULTS: Depending on their molecular mass, osmotic protectants effectively inhibited hemolysis. The inhibition of skin hemolysis was observed after treatment with polyethylene glycols (1000, 3400, and 6000 Da). Among divalent cations, only 1 mM Cu2+ markedly inhibited hemolytic activity. Antioxidant compounds slightly reduced the hemolytic activity. CONCLUSIONS: The results suggested that skin secretions of K. pulchra hainana induce a pore-forming mechanism to form pores with a diameter of 1.36-2.0 nm rather than causing oxidative damage to the erythrocyte membrane.