Structure-activity relationships of some 4-quinazolylthiosemicarbazides and their triazolo derivatives

Eigh 4-quinazolylthiosemicarbazides and nine of their structural analogues have been tested for antibacterial effects and for structure activity relationships. 9-Chloro-5-morpholino-1,2,4-triazolo[4,3-c]quinazoline-3-thione has demonstrated the hightest antibacterial effect (MIC of 1 mg/L forE. coli andP. mirabilis and <1 mg/L forS. aureus andB. subtilis). The most effective derivatives have the carbon aromatic ring substituted with chlorine and the pyrimidine ring with morpholine or with secondary amine group.     

Growth of Escherichia coli, Pichia pastoris and Bacillus cereus in the Presence of the Ionic Liquids [BMIM][BF4] and [BMIM][PF6] and Organic Solvents

The influence of the two most commonly used ionic liquids (1-butyl-3-methyl imidazolium tetrafluoroborate, [BMIM][BF₄], 1-butyl-3-methyl imidazolium hexafluorophosphate, [BMIM][PF₆]) and three selected organic solvents (dimethylsulfoxide, ethanol, methanol) on the growth of Escherichia coli, Pichia pastoris and Bacillus cereus was investigated. [BMIM][BF₄] was toxic at 1% (v/v) on all three microorganisms. The minimal inhibitory concentration (MIC) of [BMIM][BF₄] on E. coli growth was between 0.7 and 1% (v/v). In contrast, [BMIM][PF₆] was less toxic for P. pastoris and B. cereus, whereas E. coli was not able to tolerate [BMIM][PF₆] (MIC value: 0.3–0.7% v/v). Growth of P. pastoris was unaffected by [BMIM][PF₆] at 10% (v/v). Similar results were found for dimethylsulfoxide. Thus, ionic liquids (ILs) can have substantial inhibitory effects on the growth of microorganisms, which should be taken into account for environmental reasons as well as for the use of ILs as co-solvents in biotransformations. Revisions requested 2 November 2005; Revisions received 20 December 2005     

Antibiotic activity of tigecycline against clinical pathogens by the micro dilution method

Resistant pathogens are the cause of clinical infections which threatening the patients lives and challenging the health systems through their economic importance. Therefore, new antibacterial agents with a broader spectrum of activity that protect against development of resistance are required. Tigecycline (Tygacil, Wyeth) is a relatively new FDA and EMEA approved glycylcycline antimicrobial with an expanded broad-spectrum activity against pathogens involved in complicated skin and skin structure infections. In this study we evaluated the in vitro activity of tigecycline in comparison to 14 other antibiotics against 182 clinical pathogens by use of the micro dilution method. In overall, tigecycline exhibited the lowest Minimum Inhibitory Concentration (MIC) values in almost all bacteria with a mean of 0.52 ± 1.25 mg/L, followed by meropenem and levofloxacin (mean MIC values 1.29 ± 2.52 and 1.45 ± 3.078 mg/L, respectively). MIC50 and MIC90 values of tigecycline were: 0.06 and 0.15 mg/L for E. coli, 0.12 and 1.00 mg/L for Klebsiella sp., 0.12 and 0.85 mg/L for various Enterobacter sp., 1.00 and 8.00 mg/L for Pseudomonas sp., 0.25 and 1.00 mg/L for Acinetobacter sp., 0.06 and 0.12 mg/L for Serratia sp., 0.12 and 0.25 mg/L for Staphylococcus aureus, 0.5 and 5.00 mg/L for Streptococcus sp. The MIC values recorded were among the lowest in recent literature for Acinetobacter sp. (included A. baumannii), and comparable to those obtained for Klebsiella, Serratia and Enterobacter indicating that tigecycline has a promising in vitro activity.     

Antibacterial effect of some substituted tricyclic quinazolines and their synthetic precursors

Eleven substituted tricyclic quinazolines and their synthetic precursors were tested for antibacterial effects. 3-Chloromethylcarbonyl-2-methylquinazolin-4-thione and 5-phenyl-2,3-dihydro-1,2,4-triazolo[4,3-c]quinazolin-3-one had the highest antibacterial effect againstBacillus subtilis, the MIC values being 50 mg/L. Two tested derivatives were more active againstPseudomonas aeruginosa than ampicillin, the IC₅₀ values being 80 and 100 mg/L. The most effective derivatives contained in the structure generally pharmacologically active chromophores—methyl group in position 2 and a chloromethyl configuration on the carbonyl group in position 3.     

Antibacterial effect of substituted 4-quinazolylhydrazines and their arylhydrazones determined by a modified microdilution method

Eight 4-quinazolylhydrazines and eleven their arylhydrazones have been tested for antibacterial effects and for structure-activity relationships by a modifed microdilution method. The derivative 6-chloro-2-morpholino-4-quinazolyl-5′-nitro-2′-furylhydrazone had the highest antibacterial effect, the MIC values being 100 mg/L forE. fœcalis, 250 mg/L forS. aureus, 200 mg/L forP. aeruginosa and 350 mg/L forE. coli. The most effective derivatives were those with the benzene ring substituted with chlorine or methyl group in position 6 or 8 and with pyrimidine ring substituted with a secondary amine in position 2. The modified microdilution method did not give rise to any statistically significant deviations in the MIC values for ampicillin in comparison with reported reference collection values. Dedicated to Professor Vladimír Betina, DSc. on the occasion of his 65th birthday     

Benzo{a}pyrene-induced DNA damage in Mytilus galloprovincialis: measurement of bulky DNA adducts and DNA oxidative damage in terms of 8-oxo-7,8-dihydro-2´-deoxyguanosine formation

Bulky DNA adducts and 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodGuo) were measured in gill DNA of benzo[a]pyrene (B[a]P)-exposed mussels (50 mg kg^-1 dw day^-1), respectively by the ³²P-post-labelling technique and high performance liquid chromatography coupled to electrochemical detection assay. A time-course study was performed for both biomarkers and their potential use for marine biomonitoring discussed for the sentinel species studied. In gills, B[a]P-related DNA adducts were positively correlated with B[a     

Shoot initiation by humic acids of selected tropical crops grown in tissue culture

Summary The effect of humic acid on shoot development from nodal segments in tissue culture was tested. The species wereGnetum gnemon, Elletaria cardamomum, andPogostemon cablin. Humic acids were extracted from a peat soil sampled from South Sumatra, Indonesia. Alkaline extraction was conducted on two series of 12-hour agitations followed by centrifugation and sedimentation at pH below 2. Explants were 1-cm long single nodes ofG. gnemon andP. cablin, and lateral buds ofE. cardamomum on MS medium. Benzyladenine was added at 0.1 mg/L for the first two and at 0.3 mg/L for the latter. The treatments included six, seven, and eight levels of humic acid concentrations for the respective species in a completely randomized design with 10 replicates. Effect of the treatment was evaluated on the basis of the initiation period of shoots and/or roots, and the number and height of the shoots. The initiation period of the shoots was significantly shortened in the presence of humic acids. Root initiation was significantly induced especially when humic acids were used in liquid medium. In combinations with BA, the addition of humic acids at 400 mg/L, 40 mg/L, and 300 mg/L yielded the fastest growth ofG. gnemon, E. cardamomum, andP. cablin, respectively.Abbreviations HA humic acids - BA benzyladenine - MS Murashige & Skoog     

Antimicrobial effects of the macrocyclic Cu(II)-tetraanhydroaminobenzaldehyde complex

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.     

Inhibitory effects on microbial growth of Botrytis cinerea and Erwinia carotovora on potato using of a biopolymer chitosan at different molecular weights

The antimicrobial efficiency of chitosan at different molecular weights (5, 37, 57 and 290 kDa) against Botrytis cinerea and Erwinia carotovora on potato (Solanum tuberosum L.) was investigated. In vitro study showed that chitosan of 37 kDa was the most active against E. carotovora (minimum inhibitory concentration (MIC) = 950 mg/L), whereas 5 kDa chitosan was the most active against B.cinerea. Coating of potato tubers with 100, 250 and 500 mg/L significantly decreased the rate of weight loss and chitosan of 37 kDa showed the best effect. The in vivo antibacterial effect indicated that all treatments (500, 1000 and 2000 mg/L) significantly inhibited the growth of E. carotovora compared with the control. The lowest decay incidence was observed with 37 kDa chitosan. However, the antifungal activity against B. cinerea inoculated of leaves showed no decay incidence at 500 and 1000 mg/L with 57 kDa chitosan after 48 h.     

Prevalence of Ile-460-Val/ParE Substitution in Clinical Streptococcus pneumoniae Isolates That Were Less Susceptible to Fluoroquinolones

A total of 73 clinical isolates of Streptococcus pneumoniae were measured for susceptibilities to nine fluoroquinolones, and nucleotide sequences of the quinolone resistance-determining regions (QRDRs) were determined. MIC₉₀s of sparfloxacin, tosufloxacin, grepafloxacin, and gatifloxacin were less than 0.5 mg/L and the MIC₉₀ of ciprofloxacin was 2 mg/L, although MIC values of some isolates to ciprofloxacin were more than 2 mg/L. We found that 60 of 73 isolates had only Ile-460-Val/ParE substitution and two isolates had an additional substitution of Ser-114-Gly/GyrA, while none of the isolates had any other substitutions in QRDRs of either ParC/E or GyrA/B. The isolates carrying Ile-460-Val/ParE substitution were more resistant to the fluoroquinolones norfloxacin and ciprofloxacin than the isolates with no amino acid substitution and the differences in MIC values were significant, suggesting that Ile-460-Val/ParE substitution in recent clinical S. pneumoniae isolates should be involved in the low-level fluoroquinolone resistance.     

Effect of structure on antibiotic action of new 9-(ethylthio)acridines

Six new 9-(ethylthio)acridine derivatives were examined for antibacterial and antifungal activities with 10 bacterial and 8 yeast strains. The only active compounds were 2-and 3-amino derivatives. The observed MICs (mg/L) for 2-amino-9-(ethylthio)acridine (possessing the highest biological activity) were 12 (P. mirabilis), 30 (B. subtillis), 60 (C. freundii), 90 (E. coli), 128 (E. vulneris) and 500 (S. marcescens andS. aureus). Both amino derivatives have also lowest half-wave potential (E _1/2) and field Swain-Lupton constants (describing oxidoreduction behavior) what supports the importance of acridine ion formation in the mechanism of antimicrobial action.     

Hydrophobicity and outer membrane proteins ofShigella dysenteriae type 1 after treatment with subinhibitory concentrations of aminoglycosides

Hydrophobicity and profiles of outer membrane proteins ofShigella dysenteriae type 1 after treatment with subinhibitory concentrations (1/2 or 1/4 of the MIC) of aminoglycosides were studied. The antimicrobial activity of the antibiotics tested was 3.12 mg/L (amikacin, tobramycin) and 6.25 mg/L (gentamicin). The hydrophobicity of the cell surface ofS. dysenteriae type 1 was decreased after exposure to all aminoglycosides at a concentration of 1/2 of the MICs; 1/4 of the MICs of the antibiotics did not affect bacterial aggregation in the presence of ammonium sulfate. SDS-polyacrylamide gel electrophoresis showed that the profiles of outer membrane proteins of the strain treated with aminoglycosides at both subinhibitory concentrations were not changed as compared to the control.     

Fluorinated Phthalocyanine/Silver Nanoconjugates for Multifunctional Biological Applications

In this study, a new phthalonitrile derivative namely 4-[(2,4-difluorophenyl)ethynyl]phthalonitrile ( 1 ) and its metal phthalocyanines ( 2 and 3 ) were synthesized. The resultant compounds were conjugated to silver nanoparticles and characterized using transmission electron microscopy (TEM) images. The biological properties of compounds ( 1 – 3 ), their nanoconjugates ( 4 – 6 ), and silver nanoparticles ( 7 ) were examined for the first time in this study. The antioxidant activities of biological candidates ( 1 – 7 ) were studied by applying the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The highest antioxidant activity was obtained 97.47 % for 200 mg/L manganese phthalocyanine-silver nanoconjugates ( 6 ). The antimicrobial and antimicrobial photodynamic therapy (APDT) activities of biological candidates ( 1 – 7 ) were examined using a micro-dilution assay. The highest MIC value was obtained 8 mg/L for nanoconjugate 6 against E. hirae. The studied compounds and their silver nanoconjugates exhibited high APDT activities against all the studied microorganisms. The most effective APDT activities were obtained 4 mg/L for nanoconjugates ( 5 and 6 ) against L. pneumophila and E. hirae, respectively. All the studied biological candidates displayed high cell viability inhibition activities against E. coli cell growth. The biofilm inhibition activities of the tested biological candidates were also investigated against S. aureus and P. Aeruginosa. Biological candidates ( 1 – 6 ) can be considered efficient metal nanoparticle-based materials for multi-disciplinary biological applications.     

Antibacterial and antifungal activity of ethanolic extracts from eleven spice plants

Eleven ethanolic extracts from spices of Melissa officinalis, Mentha piperita, Laurus nobilis, Rhus coriaria, Dianthus coryophyllum, Piper nigrum, Capsicum annum, Juniperus oxycedrus, Erica arborea, Colutea arborescens, and Cuminum cyminum collected from various regions of Turkey and local markets were assayed for the in vitro antibacterial activity against 3 Gram-positive (Bacillus subtilis, Staphylococcus aureus and S. epidermidis) and 2 Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), using agar dilution methods. In addition, their possible toxicity to Candida albicans and Aspergillus niger was determined, using both agar dilution and disc-diffusion methods. The minimum inhibition concentration (MIC) of the M. piperita, L. nobilis and J. oxycedrus ethanolic extracts was 5 mg/mL for all the microorganisms tested. P. aeruginosa was the most sensitive bacterial strain to P. nigrum and E. arborea extracts among both Gram-positive and Gram-negative bacteria tested with MIC of 5 mg/mL. The extracts of L. nobilis, D. coryophyllum, J. oxycedrus and C. arborescens showed higher inhibitory activity against the yeast C. albicans and the fungus A. niger than the standard antifungal nystatin.     

Antimicrobial activity of the extracts from fruits of <Emphasis Type="Italic">Rumex</Emphasis> L. species

This study was designed primarily to investigate the antibacterial and antifungal activity of the extracts from fruits of six Rumex L. species: R. acetosa L., R. acetosella L., R. confertus Willd., R. crispus L., R. hydrolapathum Huds. and R. obtusifolius L. The 7 Grampositive and 7 Gram-negative bacteria strains and 5 fungal ones were tested by agar and broth dilution method. Determination of minimal inhibitory concentration (MIC) revealed that the extracts from R. confertus, R. crispus, R. hydrolapathum and R. obtusifolius exerted differential inhibitory effect on the growth of Gram-positive bacteria — staphylococci (MIC=62.5–125 μg/mL) and Gramnegative bacteria — Escherichia coli ATCC 3521, Proteus mirabilis, Pseudomonas aeruginosa (MIC=125→500 μg/mL); MIC values determined by agar dilution method were somewhat higher. The same extracts inhibited also the growth of fungi — Candida spp. or Trichophyton mentagrophytes ATCC 9533 (MIC=250–500 μg/mL), as found by agar dilution method. The total content of polyphenols (11.66–78.36 mg/g), anthracene derivatives (0.26–12.93 mg/g) and tannins (4.00–11.16%) was also determined.     

The production of lactic acid from whey permeate byLactobacillus helveticus

Summary The effect of pH on growth and lactic acid production ofLactobacillus helveticus was investigated in a continuous culture using supplemented whey ultrafiltrate. Maximum lactate productivity of 5 gl^–1h^–1 occurred at pH 5.5. Whey permeates concentrated up to four times were fermented using batch cultures. Maximum lactic acid concentration of 95 gl^–1 was attained, but residual sugars indicated a possible limitation in growth factors.Nomenclature D Dilution rate [h^–1] - X Biomass [gl^–1] - Glu Glucose consentration [gl^–1] - Gal Galactose consentration [gl^–1] - S Substrate, Lactose consentration [gl^–1] - P Product, Lactate consentration [gl^–1] - Y_p/s Yield, defined as P/S [gg^–1] - r_i Rate of synthesis or consumption of i [gl^–1h^–1]     

多环芳烃降解菌的筛选、鉴定及降解特性

【目的】多环芳烃(PAHs)是一类普遍存在于环境中且具有高毒性的持久性有机污染物,高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。研究拟从供试菌株中筛选多环芳烃高效降解菌,并分析其降解特性,为多环芳烃污染环境的微生物修复提供资源保障和科学依据。【方法】采用平板法从25株供试菌株中筛选出以菲和芘为唯一碳源和能源的高效降解菌,经16S rRNA基因序列进行初步鉴定,通过单因素实验法分析其在液体培养基中的降解特性。【结果】筛选出的3株多环芳烃高效降解菌SL-1、02173和02830经16S rRNA基因序列分析,02173和02830分别与假单胞菌属中的Pseudomonas alcaliphila和Pseudomonas corrugate同源性最近,SL-1为本课题组发表新类群Rhizobium petrolearium的模式菌株;降解实验表明,菌株SL-1 3 d内对单一多环芳烃菲(100 mg/L)和芘(50 mg/L)的降解率分别达到100%和48%,5 d后能够降解74%的芘;而其3 d内对混合PAHs中菲和芘的降解率分别为75.89%和81.98%。菌株02173和02830 3 d内对混合多环芳烃中萘(200 mg/L)、芴(50 mg/L)、菲(100 mg/L)和芘(50 mg/L)的降解率均分别超过97%。【结论】筛选出的3株PAHs降解菌SL-1、02173和02830不仅可以高效降解低分子量PAHs,还对高分子量PAHs具有很好的降解潜力。研究表明,由于共代谢作用低分子量多环芳烃可促进高分子量多环芳烃的降解,而此时低分子量多环芳烃的降解将受到抑制。     

Interference betweenSalsola kali L. seedlings: Implications for plant succession

Studies were conducted to determine the cause of the decline of the early successional species,Salsola kali L., in the years following its colonization of disturbed soils in arid regions of the western United States. DriedS. kali plant material significantly stimulated the growth ofS. kali but had no effect on the growth or levels of mycorrhizal infection ofAgropyron smithii, a later successional grass. In contrast, root leachates fromS. kali caused a depression in the growth ofS. kali, but had no effect on the growth or mycorrhizal infection ofA. smithii. In the reciprical experiment, root leachates fromA. smithii had no effect on mycorrhizal fungi,S. kali, orA. smithii. This study contradicts earlier studies of the allelopathic potential ofS. kali litter and supports the importance of direct interference betweenS. kali seedling as the cause of the die-off ofS. kali during secondary succession.     

Photosynthetic responses of two eucalypts to industrial‐age changes in atmospheric [CO2] and temperature

The unabated rise in atmospheric [CO₂] is associated with increased air temperature. Yet, few CO₂‐enrichment studies have considered pre‐industrial [CO₂] or warming. Consequently, we quantified the interactive effects of growth [CO₂] and temperature on photosynthesis of faster‐growing Eucalyptus saligna and slower‐growing E. sideroxylon. Well‐watered and ‐fertilized tree seedlings were grown in a glasshouse at three atmospheric [CO₂] (290, 400, and 650 µL L^?1), and ambient (26/18 °C, day/night) and high (ambient + 4 °C) air temperature. Despite differences in growth rate, both eucalypts responded similarly to [CO₂] and temperature treatments with few interactive effects. Light‐saturated photosynthesis (A_sat) and light‐ and [CO₂]‐saturated photosynthesis (A_max) increased by ～50% and ～10%, respectively, with each step‐increase in growth [CO₂], underpinned by a corresponding 6–11% up‐regulation of maximal electron transport rate (J_max). Maximal carboxylation rate (V_cmax) was not affected by growth [CO₂]. Thermal photosynthetic acclimation occurred such that A_sat and A_max were similar in ambient‐ and high‐temperature‐grown plants. At high temperature, the thermal optimum of A_sat increased by 2–7 °C across [CO₂] treatments. These results are the first to suggest that photosynthesis of well‐watered and ‐fertilized eucalypt seedlings will remain strongly responsive to increasing atmospheric [CO₂] in a future, warmer climate.     

Growth and amino acid contents of<Emphasis Type="Italic">Spirulina platensis</Emphasis> with different nitrogen sources

The growth and amino acid contents of the cyanobacterium,Spirulina platensis strain NIES 46, were investigated using ammonium, nitrate, nitrite, or urea as the sole nitrogen source in a batch culture. Chlorophylla concentration was highest at 2,096 μg/L in the nitrate group after 10 days of cultivation, while the dry weight ofS. platensis was highest at 4.5 g/L in the ammonium group after 30 days of cultivation. The total amino acid content was highest at 174 mg/g dry weight ofS. platensis in the urea group at the end of the cultivation period, yet the amino acid patterns forS. platensis were similar for all the experimental groups. Therefore, it seemed that the growth and amino acid composition ofS. platensis varied depending on the type of nitrogen sources, while the amino acid patterns were not changed. Also, the most efficient harvesting time forS. platensis seemed to be approximately 10 days after cultivation.