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1.
Tertiary structure-related activity of tick defensin (persulcatusin) in the taiga tick, <Emphasis Type="Italic">Ixodes persulcatus</Emphasis> 总被引:1,自引:0,他引:1
Emiko Isogai Hiroshi Isogai Kazuhiko Okumura Hatsuhiro Hori Hiroki Tsuruta Yoichi Kurebayashi 《Experimental & applied acarology》2011,53(1):71-77
Defensins are small cysteine-rich cationic proteins found in both vertebrates and invertebrates constituting the front line
of host innate immunity. To examine the importance of the tertiary structure of tick defensin in its antimicrobial activity,
we synthesized two types of the peptides with tertiary structure or primary one on basis of the information of the sequence
in the defensin originated from the taiga tick, Ixodes persulcatus. Chemically synthesized peptides were used to investigate the activity spectrum against Staphylococcus aureus, Borrelia garinii and flora-associated bacteria. Both synthetic peptides showed antimicrobial activity against S. aureus in short-time killing within 1 h, but they do not show the activity against B. garinii, Stenotrophomonas maltophila and Bacillus spp., which were frequently isolated from the midgut of I. persulcatus. The teriary structure brought more potent activity to S. aureus than primary one in short-time killing. We also examined its antimicrobial activity by evaluation of growth inhibition in
the presence of the synthetic peptides. Minimum inhibitory concentration (MIC) was ranged from 1.2 to 5.0 μg/ml in tertiary
peptide and from 10 to 40 μg/ml in primary peptide, when 10 strains of S. aureus were used. From the curve of cumulative inhibition rates, MIC50 (MIC which half of the strains showed) to S. aureus is about 1.2 μg/ml in the peptide with tertiary structure and about 10 μg/ml in the linear one. Corynebacterium
renale is 10 times or more sensitive to tertiary peptide than primary one. In conclusion, the presence of 3 disulfide bridges, which
stabilize the molecule and maintain the tertiary structure, is considered to have an effect on their antimicrobial activities
against Gram-positive bacteria such as S. aureus. 相似文献
2.
Buatong Jirayu Phongpaichit Souwalak Rukachaisirikul Vatcharin Sakayaroj Jariya 《World journal of microbiology & biotechnology》2011,27(12):3005-3008
The aim of this work was to select endophytic fungi from mangrove plants that produced antimicrobial substances. Minimal inhibitory
concentrations (MIC) and minimal bactericidal concentrations (MBC) or minimal fungicidal concentrations (MFC) of crude extracts
from 150 isolates were determined against potential human pathogens by a colorimetric microdilution method. Ninety-two isolates
(61.3%) produced inhibitory compounds. Most of the extracts (28–32%) inhibited Staphylococcus aureus (MIC/MBC 4–200/64–200 μg ml−1). Only two extracts inhibited Pseudomonas aeruginosa (MIC/MBC 200/>200 μg ml−1). 25.5 and 11.7% inhibited Microsporum gypseum and Cryptococcus neoformans (MIC/MFC 4–200/8–200 μg ml−1 and 8–200/8–200 μg ml−1, respectively), while 7.5% were active against Candida albicans (MIC/MFC 32–200/32–200 μg ml−1). None of the extracts inhibited Escherichia coli. The most active fungal extracts were from six genera, Acremonium, Diaporthe, Hypoxylon, Pestalotiopsis, Phomopsis, and Xylaria as identified using morphological and molecular methods. Phomopsis sp. MA194 (GU592007, GU592018) isolated from Rhizophora apiculata showed the broadest antimicrobial spectrum with low MIC values of 8–32 μg ml−1against Gram-positive bacteria, yeasts and M. gypseum. It was concluded that endophytic fungi from mangrove plants are diverse, many produce compounds with antimicrobial activity
and could be suitable sources of new antimicrobial natural products. 相似文献
3.
The Cu(II)-tetraaza macrocyclic complex exhibited antimicrobial effects on bacteria, yeasts and filamentous fungi. The highest
antibacterial activity was found withB. subtilis andS. aureus, the respective IC50 values being 18 and 80 μg/L and the MIC values 50 and 1000 μg/L. A concentration of 1 mg/L exerted a bacteriocide effect
onS. aureus. The MIC value forB. subtilis was 250 times lower and forP. aeruginosa 10 times lower than the corresponding values for ampicillin. The Cu-complex was inactive against all tested yeasts. The strongest
antifungal effect was manifested forR. nigricans, with an IC50 value under 0.1 mg/L, whereas inA. alternata the IC50 was 13.5 mg/L. 相似文献
4.
Zi-gang Tian Tian-tang Dong Da Teng Ya-lin Yang Jian-hua Wang 《Applied microbiology and biotechnology》2009,82(6):1097-1103
The increasing problem of antibiotic resistance among pathogenic bacteria requires development of new antimicrobial agents.
The pivotal assets of the antimicrobial peptide include potential for rapid bactericidal activity and low propensity for resistance.
The four new antimicrobial hybrid peptides were designed based on peptides LFB15(W4,10), HP(2-20), and cecropin A according
to the structure–activity relationship of the amphipathic and cationic antimicrobial peptides. Their structural parameters
were accessed by bioinformatics tools, and then two hybrids with the most potential candidates were synthesized. The hybrid
peptide LH28 caused an increase in antibiotic activity (MIC50 = 1.56–3.13 μM) against given bacterial strains and did not cause obvious hemolysis of rabbit erythrocytes at concentration
of 3.13 μM with effective antimicrobial activity. The results demonstrate that evaluating the structural parameters could
be useful for designing novel antimicrobial peptides.
Zi-gang Tian and Tian-tang Dong contributed equally to this paper 相似文献
5.
Abiraj K. Prakasha Gowda A. S. Channe Gowda D. 《International journal of peptide research and therapeutics》2002,9(6):283-290
Summary Bactenecin7, a cationic antibacterial peptide, contains a repeating region of Xaa-Pro-Arg-Pro (Xaa=hydrophobic residues).
A series of peptides, Xaa-Pro-Arg-Pro (Xaa=D-Ala, D-Leu, D-Val, D-Phe and D-Lys) were synthesized to investigate the effect
of change ofN-terminal configuration on antimicrobial activity. The conformational preferences of these peptides in water and TFE were
examined by circular dichroism. All the synthetic peptides with D-amino acid substitution atN-terminal showed potent antifungal activity againstAspergillus niger, Aspergillus flavus andFusarium moniliforme at the concentration level of 8–10 μg ml−1. But the same tetrapeptides were unable to kill or suppress the growth of gram-negative and gram-positive bacteria such asEscherichia coli HB101,Pseudomonas aeruginosa, Klebsiella pneumoniae andStaphylococcus aureus even at the concentration level of 400 μg ml−1. The present study reveals that the change of configuration at theN-terminal of tetrapeptide has negative impact on antibacterial activity but enhanced antifungal activity. 相似文献
6.
Rasanthika Nayomi Jayatissa Rohan Prasantha Perera Chamari Madhu Hettiarachchi Pathum Manjula Weerawarna 《Indian journal of microbiology》2012,52(1):83-87
The continuing increase in the incidence of multi drug resistant pathogenic bacteria and shortage of new antimicrobial agents
are the prime driver in efforts to identify the novel antimicrobial classes. In vitro antibacterial activity of 4-phenyl-1-(2-phenylallyl)
pyridinium bromide was tested against Gram positive Staphylococcus aureus, Streptococcus species, Bacillus subtilis, and Gram negative Klebsiella aerogenes and Escherichia coli using disk diffusion method. Among them S. aureus showed strong antibacterial activity (21.99 ± 0.03 mm) while E. coli showed very little activity (8.97 ± 0.06 mm) towards the compound. The MIC of 4-phenyl-1-(2-phenyl-allyl)-pyridinium bromide
for 90% S. aureus was ≤20 μg/ml and was compared with phenoxymethylpenicillin, cloxacillin, erythromycin and vancomycin. When 4-phenyl-1-(2-phenyl-allyl)pyridinium
bromide showed MIC at ≤20 μg/ml, all others showed MIC at ≤100 μg/ml. Strong antibacterial activity of 4-phenyl-1-(2-phenyl-allyl)pyridinium
bromide against S. aureus indicates that there is a possibility to use it as an effective antibacterial agent. 相似文献
7.
Ilkay Orhan Berrin Özçelik Sinem Aslan Murat Kartal Taner Karaoglu Bilge Şener Salih Terzioglu M. Iqbal Choudhary 《Phytochemistry Reviews》2007,6(1):189-196
Purpose of the present study was to evaluate antioxidant, antibacterial, antifungal, and antiviral activities of the petroleum
ether, chloroform, ethyl acetate and methanol extracts as well as the alkaloid fraction of Lycopodium clavatum L. (LC) from Lycopodiaceae growing in Turkey. Antioxidant activity of the LC extracts was evaluated by 1,1-diphenyl-2-picrylhydrazyl
(DPPH) radical-scavenging method at 0.2 mg/ml using microplate-reader assay. Antiviral assessment of LC extracts was evaluated
towards the DNA virus Herpes simplex (HSV) and the RNA virus Parainfluenza (PI-3) using Madin-Darby Bovine Kidney (MDBK) and Vero cell lines. Antibacterial and antifungal activities of the extracts
were tested against standard and isolated strains of the following bacteria; Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Acinobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis as well as the fungi; Candida albicans and C. parapsilosis. All of the extracts possessed noteworthy activity against ATCC strain of S. aureus (4 μg/ml), while the LC extracts showed reasonable antifungal effect. On the other hand, we found that only the chloroform
extract was active against HSV (16–8 μg/ml), while petroleum ether and alkaloid extracts inhibited potently PI-3 (16–4 μg/ml
and 32–4 μg/ml, respectively). However, all of the extracts had insignificant antiradical effect on DPPH. In addition, we
also analyzed the content of the alkaloid fraction of the plant by capillary gas chromatography-mass spectrometry (GC-MS)
and identified lycopodine as the major alkaloid. 相似文献
8.
Lactoferricin B (LfcinB), a 25 residue peptide derived from the N-terminal of bovine lactoferrin (bLF), causes depolarization
of the cytoplasmic membrane in susceptible bacteria. Its mechanism of action, however, still needs to be elucidated. In the
present study, synthetic LfcinB (without a disulfide bridge) and LfcinB (C–C; with a disulfide bridge) as well as three derivatives
with 15-, 11- and 9-residue peptides were prepared to investigate their antimicrobial nature and mechanisms. The antimicrobial
properties were measured via minimum inhibitory concentration (MIC) determinations, killing kinetics assays and synergy testing,
and hemolytic activities were assessed by hemoglobin release. Finally, the morphology of peptide-treated bacteria was determined
by atomic force microscopy (AFM). We found that there was no difference in MICs between LfcinB and LfcinB (C–C). Among the
derivatives, only LfcinB15 maintained nearly the same level as LfcinB, in the MIC range of 16–128 μg/ml, and the MICs of LfcinB11
(64–256 μg/ml) were 4 times more than LfcinB, while LfcinB9 exhibited the lowest antimicrobial activity. When treated at MIC
for 1 h, many blebs were formed and holes of various sizes appeared on the cell surface, but the cell still maintained its
integrity. This suggested that LfcinB had a major permeability effect on the cytoplasmic membrane of both Gram-positive and
Gram-negative bacteria, which also indicated it may be a possible intracellular target. Among the tested antibiotics, aureomycin
increased the bactericidal activity of LfcinB against E. coli, S. aureus and P. aeruginosa, but neomycin did not have such an effect. We also found that the combination of cecropin A and LfcinB had synergistic effects
against E. coli. 相似文献
9.
N. I. Gerasimenko E. L. Chaykina N. G. Busarova M. M. Anisimov 《Applied Biochemistry and Microbiology》2010,46(4):426-430
Antimicrobial and hemolytic activity of ethanol extract of brown seaweed Laminaria cichorioides (Miyabe), its lipophilic fractions, various classes of substances of lipophilic fraction, such as chlorophylls, fucoxanthin,
monogalactosyldiacylglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols, and fatty acids were investigated.
The antimicrobial activity was studied by means of yeast cells Safale S-04 and Candida albicans KMM 455, fungi Aspergillus niger KMM 4634 and Fusarium oxysporum KMM 4639, bacteria Staphylococcus aureus ATCC 21027 (gram-positive) and Escherichia coli ATCC 15034 (gram-negative) which demonstrated selective sensitivity to the studied substances. Hemolytic activity was investigated
at concentrations of substances in the range of 0.2–200 μg/ml at different pH of erythrocyte suspension. All investigated
substances caused hemolysis. The dependence of hemolytic activity of substances on pH of media was determined. 相似文献
10.
Jiřina Slaninová Helena Putnová Lenka Borovičková Pavel Šácha Václav Čeřovský Lenka Monincová Vladimír Fučík 《Central European Journal of Biology》2011,6(2):150-159
As the occurrence of Candida species infections increases, so does resistance against commonly-used antifungal agents. It is therefore necessary to look
for new antifungal drugs. This study investigated the antifungal activity of recently isolated, synthesized and characterized
antimicrobial α-helical amphipathic peptides (12–18 amino acids long) from the venom of hymenoptera (melectin, lasioglossins
I, II, and III, halictines I and II) as well as a whole series of synthetic analogs. The minimal inhibitory concentrations
(MICs) against different Candida species (C. albicans, C. krusei, C. glabrata, C. tropicalis and C. parapsilosis) of the natural peptides amounted to 4–20 μM (7–40 mg/l). The most active were the synthetic analog all-D-lasioglossin III
and lasioglossin III analog KNWKK-Aib-LGK-Aib-IK-Aib-VK-NH2. As shown using a) colony forming unit determination on agar plates, b) the efflux of the dye from rhodamine 6B-loaded cells,
c) propidium iodide and DAPI staining, and d) fluorescently labeled antimicrobial peptide (5(6)-carboxyfluorescein lasioglossin-III),
the killing of fungi by the peptides studied occurs within minutes and might be accompanied by a disturbance of all membrane
barriers. The peptides represent a promising lead for the development of new, effective antifungal drugs. 相似文献
11.
The investigation of the recombinant bovine lactoferrin-derived antimicrobial protein (rBLfA) demonstrates that the inter-lobe
region of bovine lactoferrin contributes to iron binding stability and antimicrobial activity against Staphylococcus aureus. rBLfA containing N-lobe (amino acid residues 1–333) and inter-lobe region (residues 334–344) was expressed in Pichia pastoris at shaking flask and fermentor level. The recombinant intact bovine lactoferrin (rBLf) and N-lobe (rBLfN) were expressed
in the same system as control. The physical–chemical parameters of rBLfA, rBLfN and rBLf including amino acid residues, molecular
weight, isoelectric point, net positive charge and instability index were computed and compared. The simulated tertiary structure
and the calculated surface net charge showed that rBLfA maintained original structure and exhibited a higher cationic feature
than rBLf and rBLfN. The three proteins showed different iron binding stability and antimicrobial activity. rBLfA released
iron in the pH range of 7.0–3.5, whereas rBLfN lost its iron over the pH range of 7.0–4.0 and iron release from rBLf occurred
in the pH range of 5.5–3.0. However, the minimum inhibition concentration of rBLfA against S. aureus ATCC25923 was 6.5 μmol/L, compared with 12.5 and 25 μmol/L that of rBLfN and rBLf, respectively. These results revealed that
S. aureus was more sensitive to rBLfA than rBLfN and rBLf. It appeared that the strong cationic character of inter-lobe region related
positively to the higher anti-S. aureus activity. 相似文献
12.
Rizwan Aslam Céline Marban Christian Corazzol Fran?ois Jehl Fran?ois Delalande Alain Van Dorsselaer Gilles Prévost Youssef Ha?kel Corinne Taddei Francis Schneider Marie-Hélène Metz-Boutigue 《PloS one》2013,8(7)
Innate immunity involving antimicrobial peptides represents an integrated and highly effective system of molecular and cellular mechanisms that protects host against infections. One of the most frequent hospital-acquired pathogens, Staphylococcus aureus, capable of producing proteolytic enzymes, which can degrade the host defence agents and tissue components. Numerous antimicrobial peptides derived from chromogranins, are secreted by nervous, endocrine and immune cells during stress conditions. These kill microorganisms by their lytic effect at micromolar range, using a pore-forming mechanism against Gram-positive bacteria, filamentous fungi and yeasts. In this study, we tested antimicrobial activity of chromogranin A-derived peptides (catestatin and cateslytin) against S. aureus and analysed S. aureus-mediated proteolysis of these peptides using HPLC, sequencing and MALDI-TOF mass spectrometry. Interestingly, this study is the first to demonstrate that cateslytin, the active domain of catestatin, is active against S. aureus and is interestingly resistant to degradation by S. aureus proteases. 相似文献
13.
A bacterium identified as Pseudomonas fluorescence was isolated from Taxus baccata rhizosphere. Ethyl acetate extract from its culture filtrate yielded an active antimicrobial compound that was purified by
TLC. The active metabolites were resolved by column chromatography on silica gel (60–120 mesh). The compound was further characterized
on the basis of spectral data (UV, IR and 1HNMR), which indicated the presence of an aromatic ring and phenolic functionality. The compound showed significant antimicrobial
activity against two-gram positive bacteria (B. subtilis and S. aureus), four-gram negative bacteria (E. coli, K. pneumoniae, S. flexneri and P. aeruginosa), and one pathogenic fungus (Candida albicans). The minimum inhibitory concentration (MIC) of the compound ranged between 75μg to 250 μg/ml. 相似文献
14.
Yavin Eran J. Yan Lin Desiderio Dominic M. Pontet Michel Fridkin Mati 《International journal of peptide research and therapeutics》1997,4(3):157-166
Summary Extended peptides that derive from the primary sequence of the acute phase reactant C-reactive protein (CRP) are shown to
inhibit in vitro the enzymatic activities of human leukocyte elastase (hLE) and human leukocyte cathepsin G (hCG), which are
associated with the tissue damage that occurs during the course of several chronic inflammatory conditions. Major inhibitory
activity was observed in the peptides CRP70–98 and CRP50–98 towards hLE (Ki=4.0μ M) and hCG (Ki=1.4 μM), respectively. In contrast to the inability of intact CRP pentamers to inhibit both enzymes, CRP subunits (monomers)
inhibited hLE (3.0 μM) and hCG (3.6 μM) activity. 相似文献
15.
Qingtian Li Yuhua Zhou Ke Dong Xiaokui Guo 《Applied microbiology and biotechnology》2010,86(1):305-309
To enhance the potential therapeutic efficacy of an antimicrobial peptide human β-defensin 3, two fusion peptides, a bactericidal–immunomodulatory
fusion peptide human β-defensin 3-mannose-binding lectin and a bactericidal–bactericidal fusion peptide human β-defensin 3-lysozyme
were synthesized and the bactericidal activities in vitro and in vivo against methicillin-resistant Staphylococcus aureus N315 were demonstrated in this study. Peptide human β-defensin 3-lysozyme showed the best bactericidal activity in vitro,
but human β-defensin 3-mannose-binding lectin showed a significant improvement in angiogenesis and tissue reconstruction.
Our results illustrated that outstanding bactericidal activity in vitro is not essential in the development of antimicrobial
peptides. Fusion strategy and immunomodulatory factors should be utilized in novel antimicrobial peptide development. 相似文献
16.
Biswajit Mishra Vipul Kumar Srivastava Rama Chaudhry Rishi Kumar Somvanshi Abhay Kumar Singh Kamaldeep Gill Ramesh Somvanshi Ishan Kumar Patro Sharmistha Dey 《Amino acids》2010,39(5):1493-1505
Anti-bacterial drug resistance is one of the most critical concerns among the scientist worldwide. The novel antimicrobial
decapeptide SD-8 is designed and its minimal inhibitory concentration and therapeutic index (TI) was found in the range of
1–8 μg/ml and 45–360, respectively, against major group of Gram positive pathogens (GPP). The peptide was also found to be
least hemolytic at a concentration of 180 μg/ml, i.e., nearly 77 times higher than its average effective concentration. The
kinetics assay showed that the killing time is 120 min for methicillin-sensitive Staphylococcus aureus (MSSA) and 90 min for methicillin-resistant S. aureus (MRSA). Membrane permeabilization is the cause of peptide antimicrobial activity as shown by the transmission electron microscopy
studies. The peptide showed the anti-inflammatory property by inhibiting COX-2 with a K
D and K
i values of 2.36 × 10−9 and 4.8 × 10−8 M, respectively. The peptide was also found to be effective in vivo as derived from histopathological observations in a Staphylococcal
skin infection rat model with MRSA as causative organism. 相似文献
17.
Wang H Meng XL Xu JP Wang J Wang H Ma CW 《Applied microbiology and biotechnology》2012,94(4):1031-1039
Antimicrobial peptides (AMPs) are widely expressed and play an important role in innate immune defense against infectious
agents such as bacteria, viruses, fungi, and parasites. Cecropins are a family of AMPs synthesized in the fat body of insects
that have proven effective at killing specific pathogens. In order to fulfill their clinical potential as antimicrobial drugs,
a simple, cost-effective method to express AMPs is sorely needed. In this study, we expressed and characterized the cecropin
from Plutella xylostella (pxCECA1) using an intein-dependent expression system in Escherichia coli. We cloned the pxCECA1 gene from larva by RT-PCR and fused the encoding sequence of mature pxCECA1 with an intein gene and
a chitin-binding domain gene (CBD) in pTWIN1 plasmid. The fusion protein CBD–intein–pxCECA1 was expressed in E. coli BL21 (DE3) and separated by flowing cell extracts through a chitin column. Subsequently, self-cleavage of the intein at its
C-terminus was induced in a temperature- and pH-dependent manner, resulting in the release of mature pxCECA1. The optimal
conditions for self-cleavage were determined to be pH 6.0 for 48 h at 4°C, under which 12.3 mg of recombinant pxCECA1 could
be recovered from 1 l of E. coli culture. The purified pxCECA1 displayed antimicrobial activity against a broad variety of gram-positive and gram-negative
bacteria. This preparation was especially effective against Staphylococcus aureus, including methicillin-resistant strains. Catalase release assays demonstrated that pxCECA1 acts as a microbicidal agent.
These results show for the first time that the IMPACT-TWIN expression system is an efficient, cost-effective way to produce
fully functional AMPs and that the AMP pxCECA1 is a novel microbicidal agent with promising therapeutic applications. 相似文献
18.
L. D. Sette M. R. Z. Passarini C. Delarmelina F. Salati M. C. T. Duarte 《World journal of microbiology & biotechnology》2006,22(11):1185-1195
Endophytic filamentous fungi from coffee plants (Coffea arabica and C. robusta) deposited in the Brazilian Collection of Environmental and Industrial Microorganisms (CBMAI) were characterized taxonomically by using molecular tools and investigated concerning their antimicrobial activity against different human pathogenic bacteria. Thirty-seven out of 39 CBMAI strains investigated were identified to at least at genus level by ITS and rDNA D1/D2 sequencing and phylogenetic analyses. Bioactivity screening of fungal extracts against Salmonella choleraesuis (CBMAI 484), Staphylococcus aureus (CBMAI 485), Pseudomonas aeruginosa (CBMAI 489) and against four different Escherichia coli serotypes showed that 17 fungi inhibited at least one of the bacteria studied. The endophytic fungi Trichoderma harzianum (CBMAI 43), Guignardia sp. (CBMAI 69) and Phomopsis sp. (CBMAI 164) inhibited from four to five bacterial species, while five fungi were active against all pathogenic bacteria tested and were identified as Aspergillus
versicolor (CBMAI 46), Fusarium oxysporum (CBMAI 53), Glomerella sp. (CBMAI 63) and Cladosporium spp. (CBMAI 64 and CBMAI 66). The Minimal Inhibitory Concentration (MIC) for the fungus extracts varied from 0.025 to 1.0 mg ml−1, demonstrating antimicrobial potential of some of these fungi. 相似文献
19.
In vitro activity of a new triazole antifungal agent,Sch 56592, against clinical isolates of filamentous fungi 总被引:6,自引:0,他引:6
Sch 56592 is a new triazole derivative that possesses potent, broad-spectrum antifungal activity. We evaluated the in vitroactivity
of Sch 56592 compared with that of itraconazole, amphotericin B and 5-fluorocytosine against 51 clinical isolates of filamentous
fungi, including Aspergillus flavus(10), A. fumigatus(12), Fusariumspp. (13), Rhizopus spp. (6), Pseudallescheria boydii(5),
and one isolate each of Acremoniumspp., A. niger, A. terreus, Paecilomycesspp., and Trichodermaspp. In vitrosusceptibility
testing was performed using the microdilution broth method outlined in the NCCLS 27-A document. Sch 56592 was highly active
against A. flavus(MIC90, 0.25 μg/ml), A. fumigatus(MIC90, 0.12 μg/ml), P. boydii(MIC50, 1 μ/ml) and Rhizopusspp (M1C50, 1 μg/ml). By comparison with itraconazole, Sch 56592 was four- to eight-fold more active against isolates of Aspergillusand
both compounds showed equipotent in vitroactivity against P. boydiiand Rhizopusspp. Sch 56592 was four- to 16-fold more active
than amphotericin B against Aspergillusspp. and P. boydiiand both antifungal drugs displayed similar activity against Rhizopusspp.
Overall, Sch 56592 showed good in vitroactivity against all isolates tested (MIC, ≤ 2 μg/ml) except isolates of Fusarium(MIC
range, 1–>4 μg/ml). On the basis of these data Sch 56592 has promising activity against Aspergillus spp. and other species
of filamentous fungi that are likely to be encountered clinically. Additional in vitroand in vivostudies are warranted.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
Surfactin is a lipopeptide produced by Bacillus subtilis which possesses antimicrobial activity. We have studied the leakage and lysis of POPC vesicles induced by surfactin using
calcein fluorescence de-quenching, isothermal titration calorimetry and 31P solid state NMR. Membrane leakage starts at a surfactin-to-lipid ratio in the membrane, R
b ≈ 0.05, and an aqueous surfactin concentration of C
Sw ≈ 2 μM. The transient, graded nature of leakage and the apparent coupling with surfactin translocation to the inner leaflet
of the vesicles, suggests that this low-concentration effect is due to a bilayer-couple mechanism. Different permeabilization
behaviour is found at R
b ≈ 0.15 and attributed to surfactin-rich clusters, which can induce leaks and stabilize them by covering their hydrophobic
edges. Membrane lysis or solubilization to micellar structures starts at R
bsat = 0.22 and C
Sw = 9 μM and is completed at R
msol = 0.43 and C
Sw = 11 μM. The membrane–water partition coefficient of surfactin is obtained as K = 2 × 104 M−1. These data resolve inconsistencies in the literature and shed light on the variety of effects often referred to as detergent-like
effects of antibiotic peptides on membranes. The results are compared with published parameters characterizing the hemolytic
and antibacterial activity.
Dedicated to Prof. K. Arnold on the occasion of his 65th birthday. 相似文献