Chemical constituents of cyclic peptides from fibrous roots of Pseudostellaria heterophylla / 中国中药杂志

Four cyclic peptides were isolated from the 75% ethanol extract of the fibrous roots of Pseudostellaria heterophylla by silica gel, Sephadex LH-20 column chromatography, and semi-preparative HPLC. Through mass spectrometry, NMR and other methods, they were identified as pseudostellarin L(1), heterophyllin B(2), pseudostellarin B(3), and pseudostellarin C(4). Among them, compound 1 was a new cyclic peptide, and compounds 2-4 were isolated from the fibrous roots of P. heterophylla for the first time. None of these compounds displayed cytotoxic activities against MCF-7, A549, HCT-116, and SGC-7901 cells.

Advances in several important antimicrobial lipopeptids from Bacillus spp / 生物工程学报

Bacillus spp. are probiotics and can secrete a variety of natural antimicrobiol active substances, of which lipopeptides are an important class. Up to now, about 90 lipopeptides have been identified, and most of them are cyclic lipopeptides. surfactin, iturin, fengycin, bacillomycin and polymyxins are widely studied, and the first three have huge potential for application due to their properties of surfactants and anti-fungal, anti-bacterial, anti-viral, anti-tumor and anti-inflammatory functions. In this paper, the research progress in the structure, function, synthesis regulation, separation, purification and production of surfactin, iturin and fengycin was reviewed. Synthetic biology is a vital means to increase the yield of lipopeptides, and in the future, lipopeptides can be used in crop cultivation, animal farming, food, medicine and petroleum industries as well as environmental protection. Future research should be strengthened on the discovery of new lipopeptides, synthesis of high-activity lipopeptides, economical production of lipopeptides on a large scale and their safety evaluation.

Ultrastructural changes in methicillin-resistant Staphylococcus aureus (MRSA) induced by a novel cyclic peptide ASP-1 from Bacillus subtilis: A scanning electron microscopy (SEM) study / Cambios ultraestructurales en Staphylococcusaureus resistente a meticilina (SARM) inducidos por un nuevo péptido cíclico ASP-1 de Bacillussubtilis: un estudio con microscopio electrónico de barrido (MEB)

ABSTRACT Increasing antimicrobial resistance amongStaphylococcus aureusnecessitates a new antimicrobial with a different site of action. We have isolated a novel cyclic peptide-1 (ASP-1) fromBacillussubtiliswith potent activity against methicillin-resistantS. aureus(MRSA) at a minimum inhibitory concentration (MIC) of 8-64μg/ml. Scanning electron micrographs demonstrated drastic changes in the cellular architecture of ASP-1 treated cells ofS. aureusATCC 29213 and an MRSA clinical isolate at MICs, with damages to the cell wall, membrane lysis and probable leakage of cytoplasmic contents at minimum bactericidal concentrations. The ultrastructure alterations induced by ASP-1 have also been compared with those of oxacillin-treated MRSA cells at its MIC using scanning electron microscopy.

RESUMEN El incremento de la resistencia antimicrobiana entre los tipos deS. aureusexige un nuevo agente antimicrobiano con un sitio de acción diferente. Aislamos un nuevo péptido cíclico (ASP-1) deBacillussubtiliscon potente actividad frente aS. aureusresistente a meticilina (SARM) en una concentración inhibitoria mínima (CIM) de 8-64μg/ml. Las micrografías obtenidas con microscopio electrónico de barrido mostraron cambios drásticos en la arquitectura celular de las células deS. aureusATCC 29213 tratadas con ASP-1, y un aislamiento clínico de SARM a la CIM, con daños a la pared celular, lisis de la membrana y probable fuga de contenido citoplasmático a concentraciones bactericidas mínimas. Comparamos también, las alteraciones de la ultraestructura inducidas por ASP-1 con las de células de SARM tratadas con oxacilina a su CIM, utilizando microscopio electrónico de barrido.

Enhanced production of mosquitocidal cyclic lipopeptide from Bacillus subtilis subsp. subtilis.

Background & objectives: A cyclic lipopeptide, surfactin produced by a strain of Bacillus subtilis subsp. subtilis (VCRC B471) was found to exhibit activity against both the larval and pupal stages of mosquitoes. The present study was aimed at increasing the production of the mosquitocidal metabolite by modifying the conventional medium. Methods: Enhancement of mosquitocidal metabolite production was attempted by replacing the existing micronutrients of the conventional NYSM and supplementing the medium with additional amounts of glucose. The LC50 value of culture supernatant (CS) against the larval and pupal stages of Anopheles stephensi was determined. Crude mosquitocidal metabolite (CMM) was separated from the CS, identified by MALDI-TOF analysis and its LC50 dosage requirement for the pupal stage of the above mosquito species determined. Results: The medium containing a new composition of micronutrients and glucose up to 1 per cent resulted in increased metabolite production. The LC50 value of the CS obtained in the improved medium against larvae and pupae of An. stephensi was 5.57 and 0.71 μl/ml, respectively. The yield of CMM was doubled in the improved medium. MALDI-TOF analysis revealed that the CMM was surfactin. Interpretation & conclusions: The new improved medium enhanced the production of mosquitocidal metabolite as the dosage required for inciting 50 per cent mortality among the pupal stages of mosquitoes was only half of that required when the metabolite was produced in the conventional medium. The mosquitocidal metabolite was identified as surfactin, a cyclic lipopeptide and biosurfactant.

Safety, pharmacokinetic and pharmacodynamic studies of batifiban injection following single- and multiple-dose administration to healthy Chinese subjects / 华中科技大学学报（医学）（英德文版）

Batifiban, a synthetic cyclic peptide, is a potent platelet glycoprotein GPIIb/IIIa antagonist which may be useful in the treatment and prevention of acute coronary syndromes. The pharmacokinetics and pharmacodymanic (inhibition of platelet aggregation) effects, and tolerability of batifiban were investigated in healthy subjects following single bolus injection with doses of 55, 110, or 220 microg/kg, or multiple doses of an bolus followed intravenous infusion for 24 h (180 microg/kg plus 2.0 microg/min.kg, and 220 microg/kg plus 2.5 microg/min.kg) in this phase I clinical trial. Plasma levels of batifiban and areas under the curve were found to be proportional to doses. Batifiban was rapidly eliminated with a half-life of approximately 2.5 h. Significant differences were noted for plasma levels of batifiban and areas under the curve between males and females. No significant differences in the terminal half-life were found between males and females. Batifiban reversibly inhibited ex vivo platelet aggregation in a dose- and concentration-dependent manner, consistent with its mechanism as a GPIIb/IIIa antagonist. Single and multiple intravenous doses of batifiban were found to be safe and well tolerated in healthy subjects. These results support a bolus injection plus intravenous infusion regimen of batifiban for the treatment and prevention of acute coronary syndromes.

Protective effect of endothelin antagonist (TAK-044) on neuronal cell viability in in vitro oxygen-glucose deprivation model of stroke.

The present study was carried to investigate the effect of endothelin antagonist (TAK-044) in an in vitro model of stroke using primary neuronal culture. Hypoxia in neuronal culture was induced for 3 h using oxygen glucose deprivation (OGD) model, thereafter cells were reperfused. In separate group cultures were incubated with graded concentrations of TAK-044 (0.01, 0.1 and 1 microg/microl) for different time duration i.e. 6, 12 and 24 hours after reperfusion. Percent cell viability was assessed 24 h after reperfusion using MTT assay. It was observed that percent cell viability was reduced to 13.7 +/- 0.4% in the cells under 3 h hypoxic condition as compared to the cells under normal condition (100%). TAK-044 at the concentrations of 0.1 and 1 microg/microl, but not at 0.01 microg/microl showed significant (P<0.01) improvement in the % cell viability as compared to the cells in hypoxic condition. Percent cell viability at the concentration of 0.1 and 1 microg/microl for 24 h time duration after reperfusion were 54.8 +/- 3.2% and 75.4 +/- 1.8% respectively as compared to the cells under hypoxic condition (13.7 +/- 0.4%). The results demonstrate the neuroprotective effect of TAK-044 against neuronal damage caused by hypoxia induced in neuronal culture.

Effect of alternaria pathotoxin(s) on expression of p53-like apoptotic protein in calli and leaves of Brassica campestris.

Possible involvement of apoptosis was investigated in pathotoxin-treated and nutritionally-depleted in vitro cultured calli by comparing levels of p53-like protein. Antibodies raised against human p53 were used to detect and quantify p53 in B. campestris. Expression of p53-like protein increased from proliferating to static growth stage and reached to constant level at decaying stage. Both ELISA and dot immuno-binding assay showed that p53-like protein was over expressed in toxin treated and nutritionally depleted calli. Almost similar changes were seen in senescent damage in Brassica species indicating involvement of p53 dependent pathways.

Biochemical characterization and inhibitory effects of dinophysistoxin-1, okadaic acid and microcystine 1-r on protein phosphatase 2a purified from the mussel Mytilus chilensis

Protein phosphatases are involved in many cellular processes. One of the most abundant and best studied members of this class is protein phosphatase type-2A (PP2A). In this study, PP2A was purified from the mussel Mytilus chilensis. Using both SDS-PAGE and size exclusion gel filtration under denaturant conditions, it was confirmed that the PP2A fraction was essentially pure. The isolated enzyme is a heterodimer and the molecular estimated masses of the subunits are 62 and 28 kDa. The isolated PP2A fraction has a notably high p-NPP phosphatase activity, which is inhibited by NaCl. The hydrolytic p-NPP phosphatase activity is independent of the MgCl2 concentration. The time courses of the inhibition of the PP2A activity of p-NPP hydrolysis by increasing concentrations of three phycotoxins that are specific inhibitors of PP2A are shown. Inhibitions caused by Okadaic acid, dinophysistoxin-1 (DTX1, 35-methylokadiac acid) and Microcystine L-R are dose-dependent with inhibition constants (Ki) of 1.68, 0.40 and 0.27 nM respectively. Microcystine L-R, the most potent phycotoxin inhibitor of PP2A isolated from Mytilus chilensis with an IC50 = 0.25 ng/ml, showed the highest specific inhibition effect an the p-NPP hydrolisis. The calculated IC50 for DTX1 and OA was 0.75 ng/ml and 1.8 ng/ml respectively.