Degradation of N-Acyl Homoserine Lactone Quorum Sensing Signals by Bacillus thuringiensis AHL Lactonase

Bacterial cells rely on signaling molecules to communicate with others from the same species and induce certain genes in a process known as quorum sensing (QS). A common molecule is N-acyl homoserine lactone (AHL) which is responsible for the expression of virulence and other factors that allow the organisms to compete in a given environment. On the other hand, other bacteria produce certain enzymes such as AHL-lactonase that break down AHL molecules and prevent gene expression of these factors. The aim of this work was to examine the level of degradation of AHL molecules by AHL-lactonase in 62 Bacillus thuringiensis (Bt) strains isolated from Middle Tennessee, Mississippi, and Alabama. N-hexanoyl-homoserine lactone (C6-HSL) and N-3-oxo-hexanoyl homoserine lactone (3-oxo-C6-HSL), which cause Chromobacterium violaceum (CV026) to produce a purple pigment were tested at different concentrations to view the Bt lactonase activity. In addition, PCR was used to test for the presence of the lactonase gene. The results showed that among the 62 Bt strains, there were 58 that possessed the AHL-lactonase (aiiA) gene and 48 strains were able to degrade C6-HSL. At high concentrations of AHL, only 13 strains were able to completely degrade C6-HSL. In addition, degradation of 3-oxo-C6-HSL was weak compared to C6-HSL. The results also revealed that AHL lactonase was thermostable, and it was concluded that the level of degradation varies in Bt strains. Only 13 of the strains studied have potent inhibitory activity against C6-HSL, which may be good to be used in field applications to control agricultural pest.

A Preliminary Study of Cell Membrane Mediated Immobilization of a Recombinant Acyl-homoserine Lactonase AidH

The aim of this work was to inhibit biofilm formation by taking advantages of bacterial surface display technology in combination with cell membrane chromatography.A recombinant protein INPAidH was constructed by fusing a quorum signal hydrolase AidH to the C-terminus of the ice nucleation protein(INP).Expression of INP-AidH was achieved on E.coli cell surface at an expression level of 30%of total membrane proteins.Activity of INP-AidH on cell membranes was confirmed in degrading the quorum signal C6-HSL as well as inhibiting bacterial biofilm.Immobilization of INP-AidH anchored cell membranes on silica gel particles was facilitated by taking advantages of cell membrane chromatography.The functionalized silica gel particles also exhibit activities in degrading C6-HSL and inhibiting bacterial biofilm.This article presents a new approach to prevent biofilm formation of silica-based materials.

Histone Deacetylation Modifier Induced One New Resorcylic Acid Lactone 7′(Z)-zeaenol from the Zoanthid-Derived Fungus Cochliobolus lunatus

Chemical epigenetic manipulation was applied to the zoanthid-derived fungus Cochliobolus lunatus(TA26-46)with a histone deacetylation modifier(100μmol L^(−1) nicotinamide),resulting in the isolation of a new 14-membered resorcylic acid lactone named 7′(Z)-zeaenol(1),together with six known analogues(2−7)from the treated broth.The planar structure of 1 was determined by comprehensive NMR spectroscopy and HRESIMS data.The absolute configuration of 1 was elucidated by ECD spectrum,^(13)C NMR shift calculations,and on the basis of biogenetic considerations.Compound 5 exhibited cytotoxic activity against the human tumor cell lines A549,HCT-116,HT-29,Hela,MCF-7,and K562 with the IC_(50) values ranging from 2.54 to 7.44μmolL^(−1).

Enzymatic Synthesis and Characterization of Biodegradable Poly(w-pentadecalactone-co-ε-caprolactone)Copolymers

As an alternative biodegradable aliphatic polyester,poly(w-pentadecalactone-co-ε-caprolactone)copolymer was synthesized via enzymatic ring-opening polymerization.A new biocatalyst,Candida antarctica lipase B,immobilized onto rice husk ash was used for catalysis.Reactions were carried out at various temperatures and periods for varied copolymer compositions in order to obtain the highest molecular weight copolymer.The best reaction parameters were found to be 80℃ and 6 hours and molecular weights increased proportionally with the amount of w-pentadecalactone(w-PDL).The molecular structure of copolymer with 75%weight ratio of w-PDL(Mn=19720 g/mol)was characterized by proton and carbon nuclear magnetic resonance spectroscopies(^1H-NMR and ^13C-NMR).Thermal properties of the same copolymer and homopolymers were investigated by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA).Improved thermal features were shown by addition of w-PDL to the structure and compared with poly(ε-caprolactone)(PCL).Consequently,poly(w-pentadecalactone-co-ε-caprolactone)copolymers were found to be good alternatives to widely used polyester,PCL,with their rapid polymerization tendency,higher molecular weights,and improved thermal features.

Study on Induction of Microcystis aeruginosa Cell Apoptosis by Signal Molecule N-acetyl-homoserine Lactones(AHLs)

[Objective]The relationship between signal molecule N-acety-homoserine lactones（AHLs） and Microcystis aeruginosa cell apoptosis was studied.[Method]With M.aeruginosa as the test materials treated by 5 μmol/L N-acety-homoserine lactones（AHLs）,the morphology of cell apoptosis was observed through staining with DAPI.[Result]Microcystis aeruginosa cell apoptosis was induced by signal molecule N-acetyhomoserine lactones（AHLs） with the concentration of 1 μmol/L to inhibit the growth and proliferation of Microcystis aeruginosa.[Conclusion] The results provided the important scientific basis and new management ideas for the treatment of water bloom of Microcystis aeruginosa.

Two New Lactones Metabolized from Isoline by Rat Liver Microsomes

Two new metabolites, namely bisline lactone and isolinecic acid lactone, were isolated from the resultant incubates after a scale-up incubation of isoline with rat liver microsomes. Their structures were determined by spectroscopic data, especially those from 1D and 2D NMR experiments.

Synthesis of Z and E-(2',5'-dimethoxyphenyl)-methylene-butyrolactones

A pair of Z and E isomers of cyclization of γ-ketoacid 7, which was prepared in six steps from 2,5-dimethoxyphenyl acetic acid 1, gave a pair of Z(20%) and E (4%) isomers of (2,5-dimethoxyphenyl)-methylene-butyrolactones

Sesquiterpene Lactones from Elephantopus scaber

A new germacranolide sesquiterpene lactone, isoscabertopin, was isolated from Elephantopus scaber together with the known scabertopin. Their structures were determined by spectroscopic methods.

A new cassane diterpenoid lactone from the seed of Caesalpinia minax

A new cassane diterpenoid lactone was isolated from the seed of Caesalpinia minax. On the basis of spectral evidences, its structure was established as 12α-methoxyl, 5α, 14β-dihydroxy-1α, 6α, 7β-triacetoxycass-13（15）-en-16, 12-olide.

A New Sesquiterpene Lactone from Ainsliaea bonatii

A new sesquiterpene lactone, Ainsliaolide A, was isolated from Ainsliaea bonatii. Thestructure was determined on the basis of spectral data.

Eupatoranolide, a New Sesquiterpene Lactone from Eupatorium adenophorum

A new sesquiterpene lactone eupatoranolide was isolated from the flowers of Eupatorium adenophorum, its structure was elucidated as 2 beta-acetoxy-(7 alpha, 9 beta H)-3.6(11)-cadinadien-12(7)-olide by spectral analysis.

Fenugreek lactone attenuates palmitate-induced apoptosis and dysfunction in pancreatic β-cells

AIM: To investigate the effect of fenugreek lactone(FL) on palmitate(PA)-induced apoptosis and dysfunction in insulin secretion in pancreatic NIT-1 β-cells. METHODS: Cells were cultured in the presence or absence of FL and PA(0.25 mmol/L) for 48 h. Then, lipid droplets in NIT-1 cells were observed by oil red O staining, and the intracellular triglyceride content was measured by colorimetric assay. The insulin content in the supernatant was determined using an insulin radioimmunoassay. Oxidative stress-associated parameters, including total superoxide dismutase, glutathione peroxidase and catalase activity and malondialdehyde levels in the suspensions were also examined. The expression of upstream regulators of oxidative stress, such as protein kinase C-α(PKC-α), phospho-PKC-α and P47 phox, were determined by Western blot analysis and real-time PCR. In addition, apoptosis was evaluated in NIT-1 cells by flow cytometry assays and caspase-3 viability assays.RESULTS: Our results indicated that compared to the control group, PA induced an increase in lipid accumulation and apoptosis and a decrease in insulin secretion in NIT-1 cells. Oxidative stress in NIT-1 cells was activated after 48 h of exposure to PA. However, FL reversed the above changes. These effects were accompanied by the inhibition of PKC-α, phosphoPKC-α and P47 phox expression and the activation of caspase-3. CONCLUSION: FL attenuates PA-induced apoptosis and insulin secretion dysfunction in NIT-1 pancreatic β-cells. The mechanism for this action may be associated with improvements in levels of oxidative stress.

A new ent-labdane diterpenoid lactone from Andrographis paniculata

A new ent-labdane diterpenoid lactone was isolated from Andrographis paniculata.Its structure was identified on the basis of spectral data including 2D NMR.

Synaptic and blood-brain barrier structural changes in a rat epilepsy model induced by coriaria lacton Replication experiment with animals

BACKGROUND： Structural and functional synaptic changes, as well as blood-brain barrier （BBB） changes, affect the micro-environment of nervous tissue and excitation, both of which play an important role in epilepsy. OBJECTIVE： To observe synaptic and BBB ultrastructural changes in the motor cortex of a rat epilepsy model induced by coriaria lacton, and to investigate the synaptic and BBB effects on the mechanism of epilepsy. DESIGN： A randomized controlled animal experiment. SETTING： Department of Histology and Embryology, Luzhou Medical College; and Electron Microscopy Laboratory, Luzhou Medical College. MATERIALS： Twenty healthy male Sprague Dawley rats, aged 8 weeks, were chosen for this study. The rats weighed （280 ± 50） g and were supplied by the Experimental Animal Center of Luzhou Medical College. Experimentation was performed in accordance with the ethical guidelines for the use and care of animals. The animals were randomly divided into a control group and an epilepsy group, with 10 rats in each group. METHODS： This study was performed at the Department of Histology and Embryology, and Electron Microscopy Laboratory, Luzhou Medical College between February and December 2006. According to the protocol, the epilepsy group was injected with 10 μ L/100 g coriaria lacton into the lateral ventricles to establish an epileptic model. The control group rats were not administered anything. Eight days after the model was established, all rats were anesthetized with ether. The motor cortex was removed and sectioned into ultrathin sections. Synaptic and BBB ultrastructural changes were observed by electron microscopy. MAIN OUTCOME MEASURES： （1）Structural changes of three different parts of the synapses, synaptic cleft width, postsynaptic density thickness, proportion of perforation synapses, curvature of synaptic interface, and length of active zones. （2）Capillary and BBB changes （endothelium, basement membrane, pericyte, and the astrocyte endfeet）. RESULTS： （1）Curvature of synaptic interface, length of active zones, thickness of postsynaptic density, and percentage of perforation synapses increased significantly. （2）There was significant edema in the endothelium, basement membrane, and the pericyte of the epilepsy group; the electron density of the basement membrane was reduced. CONCLUSION： （1） The coriaria lacton treatment altered synaptic ultrastructure, as well as BBB characteristics, in the epileptic rat model, and also improved synaptic transmission efficiency, as well as BBB permeability; （2）Synaptic and BBB ultrastructural changes might play an important role in the mechanism of epilepsy.

A new nor-sesquiterpene lactone from Ainsliaea fulvioides

A new nor-sesquiterpene lactone ainsliatone A （1） was isolated from the aerial parts of Ainsliaeafulvioides. Its structure was established by the basis of spectroscopic methods and single-crystal X-ray diffraction analysis.

A new nine-membdered lactone from a marine fungus Cladosporium sp.F14

A new nine-membered lactone,cladospolide E（1）,was isolated from a culture broth of a marine fungus Cladosporium sp.F14. The structure of compound 1 was determined on the basis of extensive spectroscopic analysis,including 1D and 2D NMR data.

Effects of coriaria lactone-activated,astrocyte-conditioned medium on estrogen receptor and progesterone receptor expression in rat cortical and hippocampal neurons

BACKGROUND： Coriaria lactone-activated astrocytes released bioactive substances that eventually caused epilepsy. OBJECTIVE： It has been suggested that activated astrocytes alter the expression of the estrogen receptor and progesterone receptor by releasing bioactive substances during epilepsy, thereby affecting neuronal activity in the brain. This study was designed to observe the expression of the estrogen receptor and the progesterone receptor in rat brain following lateral ventricle injection of coriaria lactone-activated, astrocyte-conditioned medium. DESIGN AND SETTING： This immunohistochemical, randomized, controlled, animal study was conducted at the Department of Pathology, Hospital Affiliated to Binzhou Medical College, China. MATERIAL： Coriaria lactone was provided by Huaxi Pharmaceutical Factory, China. METHODS： Forty adult, healthy, male, Sprague Dawley rats were randomly assigned into two groups. Astrocyte-conditioned medium （10 μ L） was injected into rat lateral ventricle in the control group （n = 8）. Coriaria lactone-activated, astrocyte-conditioned medium （10 μL） was infused into the rat lateral ventricle in the coriaria lactone group （n = 32）. At 2, 4, 8 and 12 hours following injection, rats were sacrificed and subjected to immunohistochemistry. Eight rats were studied at each time point. MAIN OUTCOME MEASURES： Behavioral changes were observed in rats of both groups. Expression of the estrogen receptor and the progesterone receptor in rat cortical and hippocampal neurons was measured using immunohistochemistry. RESULTS： Four hours after injection, estrogen receptor levels in rat cortical and hippocampal neurons were significantly higher in the coriaria lactone group than in the control group （P 〈 0.05）. Progesterone receptor levels were significantly lower in the coriaria lactone group than in the control group （P 〈 0.05）. Seizures were not observed in the control group. In the coriaria lactone group, convulsions appeared 30 minutes after injection; seizures reached grade Ⅲ at 45 minutes rat behavior was nearly normal at 2 hours. CONCLUSION： Activated astrocytes can induce seizures in the rat by enhancing estrogen receptor expression and decreasing progesterone receptor expression in cerebral cortical and hippocampal neurons.

A new ent-labdane eiterpenoid lactone from Andrographis paniculata

A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR.

New Sesquiterpene Lactones from Carpesium Lipskyi

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Sesquiterpene Lactone Glycosides from Carpesium macrocephalum

Two new sesquiterpene lactone glycosides were isolated from the seeds of Carpesium macrocephalum. Their structures were elucidated as 2-O--D-glucopyranosy-5? 11?H- eudesma-4 (15)-en-12, 8?olide and 2 ?O--D-glucopyranosy-5?H-eudesma-4 (15), 11 (13)- dien-12, 8?olide by spectral methods (HRMS, 1 D and 2 D NMR).