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1.
AbstractThis work investigated chloroform extracts from culture supernatants of two human probiotic bacteria, Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730 for the production of virulence factors and quorum sensing (QS) interference against three Pseudomonas aeruginosa strains. Both extracts inhibited biofilm biomass (up to 50%), biofilm metabolic activity (up to 39%), the production of the enzyme elastase (up to 63%) and pyocyanin (up to 77%), and decreased QS, without presenting any antibacterial acgivity. In addition, the chloroform extracts of both strains disrupted preformed biofilms of the three strains of P. aeruginosa analyzed (up to 40%). GC-MS analysis revealed that the major compounds detected in the bioactive extracts were four diketopiperazines. This study suggests that the metabolites of L. casei and L. acidophilus could be a promising alternative to combat the pathogenicity of P. aeruginosa. 相似文献
2.
Daniel Samson Daniel Rentsch Marco Minuth Thomas Meier Günther Loidl 《Journal of peptide science》2019,25(7)
Aspartimide (Asi) formation is a notorious side reaction in peptide synthesis that is well characterized and described in literature. In this context, we observed significant amounts of chain termination in Fmoc‐SPPS while synthesizing the N‐terminal Xaa‐Asp‐Yaa motif. This termination was caused by the formation of piperazine‐2,5‐diones. We investigated this side reaction using a linear model peptide and independently synthesizing its piperazine‐2,5‐dione derivative. Nuclear magnetic resonance (NMR) data of the side product present in the crude linear peptide proves that exclusively the six‐membered ring is formed whereas the theoretically conceivable seven‐membered 1,4‐diazepine‐2,5‐dione is not found. We propose a mechanism where nucleophilic attack of the N‐terminal amino function takes place at the α‐carbon of the carbonyl group of the corresponding Asi intermediate. In addition, we systematically investigated the impact of (a) different adjacent amino acid residues, (b) backbone protection, and (c) side chain protection of flanking amino acids. The side reaction is directly related to the Asi intermediate. Hence, hindering or avoiding Asi formation reduces or completely suppresses this side reaction. 相似文献
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Lind H Sjögren J Gohil S Kenne L Schnürer J Broberg A 《FEMS microbiology letters》2007,271(2):310-315
Antifungal compounds from cultures of five type strains of dairy propionibacteria, as well as from the cultivation medium, were studied. Cell-free supernatants and medium were fractionated by C(18) solid phase extraction. The aqueous 95% acetonitrile fractions were analyzed by GC-MS or subjected to reversed-phase HPLC, to identify, quantify or isolate antifungal substances. The resulting HPLC fractions were screened for antifungal activity against the mold Aspergillus fumigatus and the yeast Rhodotorula mucilaginosa. Active fractions were further separated by HPLC and the structures of the compounds were determined by spectroscopic and chromatographic methods. All five strains produced 3-phenyllactic acid, at concentrations ranging from 1.0 microg mL(-1) (Propionibacterium freudenreichii ssp. shermanii) to 15.1 microg mL(-1) (Propionibacterium thoenii), and at L/D -ratios ranging from 2 : 3 (Propionibacterium acidipropionici) to 9 : 1 (Propionibacterium freudenreichii). A number of active compounds found in cultures of propionibacteria were also present in noninoculated growth medium: two antifungal diketopiperazines, cyclo(L-Phe-L-Pro) and cyclo(L-Ile-L-Pro), and seven antifungal linear peptides. Three of the linear peptides corresponded to sequences found in the medium component casein, suggesting their origin from this component, whereas the diketopiperazines were suggested to be formed from medium peptides by heat treatment. 相似文献
4.
The Yamato-791198 and Murchison carbonaceouschondrites were analyzed for dipeptides anddiketopiperazines as well as amino acids and hydantoins bygas chromatography combined with mass spectrometry. Glycylglycine (gly-gly) and cyclo(gly-gly) were detected atthe concentrations of 11 and 18 pmol g-1, respectively,in Yamato-791198, and 4 and 23 pmol g-1, respectively,in Murchison. No other dipeptide and diketopiperazine weredetected. Five hydantoins were detected at 8 to 65 pmolg-1 in Yamato-791198 and seven in Murchison at 6 to 104pmol g-1. Total concentration of the glycine (gly)dimers is approximately four orders of magnitude less thanthe concentration of free gly in Yamato-791198, and threeorders of magnitude less than that in Murchison. Theabsence of L- and LL-stereoisomers of dipeptides consistingof protein amino acids indicates that gly-gly andcyclo(gly-gly) detected are native to the chondrites and not fromterrestrial contaminants. A possibility was discussed thatthe gly dimers might have been formed by condensation of glymonomers but not formed through N-carboxyanhydrides of gly. 相似文献
5.
Daniel Farran Delphine Echalier Jean Martinez Georges Dewynter 《Journal of peptide science》2009,15(7):474-478
The electrophilic reactivity of Boc‐DKPs has been studied. Thanks to Boc activation, the opening ability of carbonyl lactam groups is enhanced. According to experimental conditions, this enabled the synthesis of Boc‐amino acid derivatives or original dipeptides via a regioselective and sequential way. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
6.
【目的】利用超高效液相色谱与串联四级杆飞行时间质谱仪联用技术(ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry,UPLC-Q-TOF-MS/MS)结合质谱裂解规律分析,靶向分离Alternaria panax发酵液粗提物中次生代谢产物。【方法】用马铃薯葡萄糖(potato dextrose broth,PDB)培养基液体发酵A.panax 14 d,将滤液用乙酸乙酯萃取后减压浓缩得粗提物;基于UPLC-Q-TOF-MS/MS方法(高分辨质谱、分子式与碎片峰等)分析粗提物化学成分及质谱裂解规律;采用半制备高效液相色谱(high-performance liquid chromatography,HPLC)方法进一步分离纯化;结合核磁共振波谱(nuclear magnetic resonance,NMR)和质谱(mass spectrometry,MS)等谱学技术以及与文献数据对照确定化合物结构。【结果】利用UPLC-Q-TOF-MS/MS技术分析出... 相似文献
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8.
A.M. Tamburro V. Guantieri A. Scatturin 《International journal of biological macromolecules》1982,4(2):126-127
Circular dichroism measurements on methionyl-containing diketopiperazines have shown that the thioether side chain favours the appearance of fold conformations in the ring. A solvent-dependent conformational distribution has been also found in the case of l-methionylglycine diketopiperazzine. 相似文献
9.
AbstractA novel approach to the diazabicyclo[2.2.2]octane core of prenylated bridged diketopiperazine alkaloids is described by direct oxidative cyclizations of functionalized diketopiperazines mediated by ferrocenium hexafluorophosphate or the Mn(OAc)3?2H2O/Cu(OTf)2 system. Divergent reaction pathways take place depending on the substitution pattern of the substrates and the oxidation conditions such as temperature or the presence or absence of persistent radical TEMPO. For ester-substituted diketopiperazines, the ester group exerts a significant influence on the reaction outcome and stereochemistry of the radical cyclizations. 相似文献
10.
Lijian Ding Peng Xu Weiyan Zhang Ye Yuan Xiaoping He Dengquan Su Yutong Shi C. Benjamin Naman Xiaojun Yan Bin Wu J. Enrico H. Lazaro Shengying Li Shan He 《化学与生物多样性》2020,17(7)
The in situ application of iChip cultivation in mangrove sediment from Hainan province, China, led to the isolation of a novel bacterial species Gallaecimonas mangrovi HK‐28. The extract of G. mangrovi HK‐28 exhibited antibiotic activity against the aquatic pathogen Vibrio harveyi, and its chemical constituents were further investigated by bioactivity‐guided isolation. Three new diketopiperazines, gallaecimonamides A–C, were accordingly isolated from the AcOEt extract of the fermentation broth of G. mangrovi HK‐28. The planar structures of gallaecimonamides A–C were determined using HR‐ESI‐MS together with 1D‐ and 2D‐NMR. The absolute configurations of gallaecimonamides A–C were assigned by optical rotation, NOESY experiment and TDDFT ECD calculations. The in vitro antibacterial and antimalarial activities of gallaecimonamides A–C were assessed. Gallaecimonamide A was found to display antibacterial activity against V. harveyi with a MIC value of 50 μm . However, gallaecimonamides B and C showed no antibacterial activity against V. harveyi (MIC >300 μm ). In addition, all the isolates did not exhibit any inhibitory activities against V. parahaemolyticus (MIC>300 μm ) and Plasmodium falciparum W2 (EC50>100 μg/mL). 相似文献