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Amphipatic compounds exhibit an antimicrobial action both on bacteria and fungi. It is caused by a penetrative property of hydrophobic carbon chain of the compuound into a plasma membrane as well as by additional interaction of membrane elements and a hydrophilic amphipathic compound head. Bactericidal and fungicidal activity of this compound strongly depends on chemical environmental factors. In general, microorganisms are not as sensitive in a full medium as in a minimal one and the level of sensitivity rises when the amphipatic compounds are presend in destilled water. Similarly, the sensitivity is stronger in fluid than on solid medium. Our researches revealed however that some aminoacids, although they are complex organic compounds, increase the microbial sensitivity to some tested compound. This efect depends on a microorganism and on a kind of compound. The highest hipersensitivity has been observed against yeast-like fungi when arginine was a cooperating aminoacid. The effect concerns Trichosporon but not E.coli, not occurs in relation to SDS, quaternary ammonium salt IA, and bisammonium salts. Certainly the effect exhibit QAS, which have simple composition of hydrophilic „head” consisting only of methyl group, attaching to alkilic chain possessing keton group, build of 14 or 16 carbon atoms.
Background. Problems in substantial under recovery of Pseudomonas aeruginosa and Candida albicans from carriers have been demonstrated for laboratories performing phase 2, step 2 efficacy tests on disinfectants relative to levels required by the EN 13697 standard. It was thus necessary to determine recoveries of these microorganisms following procedural losses incurred during drying and to optimise drying conditions such that recoveries then complied with the standard. Objectives. The aim of the study was to establish optimal drying conditions for the recovery of Candida albicans ATCC 10231 from carriers. Materials and Methods. The evaluation was performed according to the EN 13697:2001 standard procedure. A test suspension of Candida albicans and interfering substance were inoculated onto the surface of carriers (2 cm diameter stainless steel discs) and then dried under different conditions consisting of: a 37°C incubation with and without an incubator fan as well as at 23°C (room temperature) in a laminar air flow cabinet. Carriers were dried until the surfaces appeared visibly dry and the number of surviving organisms then recovered from the surface were quantified. The following were calculated for colony forming units (cfu); N (log10 cfu in a 0.05 ml test suspension), NC (the control log10 cfu in neutralizing medium), Nts (cfu numbers remaining on the surface) and the N-NC difference which should not exceed 2 log10 when microorganism recoveries are adequate and without any toxicity effects of the neutralising medium. Experiments was conducted using validating procedure (NC) which is performed with distilled water. Results. Drying at 37°C adversely affected the survival of Candida albicans and prevented the levels of microbial recovery from carriers to reach those specified by the EN 13697 standard. However, drying at around room temperatures of 23°C reduced Candida albicans mortality and increased recoveries from the carrier to levels compliant with the standard, where the N-NC differences were not greater than 2 log10. Conclusions. The viability of Candida albicans ATCC 10231 is sufficiently improved when carriers are dried at 23°C, even if the drying time exceeds 60 minutes. The density of the initial test suspension (N) should also be increased.
Fungicidal properties of 4-(1,3,4-thiadiazol-2-yl)benzene-1,3-diols set under in vitro conditions against five phytopathogenic fungi have been evaluated. The substitution panel includes amino-, alkyl-, alkoxyl-, aryl- and heteroarylderivatives. The most active compound with the benzyl substituent exhibits fungistatic effects amounting to 90-100% with the concentration of 20 μg mL-1 against R. solani, similar to the standard fungicides. The derivatives with amine moiety generally display lower activity than other analogues. F. culmorum seems to be the most refractory fungus compared to studied compounds. The influence of substitution of C-5 at the constant fragment at C-2 of 1,3,4-thiadiazole ring on the antifungal effect is discussed. To explain differences in the activity the quantum-chemical calculations were made.
To explore new antifungal agents for rice blast control, the antifungal activity of a series of novel 1,2,4-triazole derivatives against Magnaporthe oryzae has been evaluated. The antifungal activity was determined by using in vitro mycelial growth inhibition tests. Among the 19 test compounds, we found that the compound 1-(4-phenoxymethyl-2-phenyl-[1,3]dioxolan-2-ylmethyl)-1H-1,2,4- triazole (Gj) displayed potent antifungal activity against M. oryzae. The IC50 value was found approximately 3.8±0.5 μM and the IC50 value of propiconazole was found to be approximately 3.7±0.2 μM, respectively. Structure-activity relationship studies on aromatic ring structures provided insight and information about the structural requirements for antifungal activity of this synthetic series against M. oryzae.
The activity of picoxystrobin and its mixtures with standard fungicides against isolates of eyespot cereal disease agents was estimated in laboratory in vitro tests. The tested Ramulispora herpotrichoides and R. acuformis isolates differed in response to carbendazim. Picoxystrobin at concentration from 0.05 to 50 mg/L not totally inhibited the mycelium growth of tested pathogens on PDA medium. But carbendazim sensitive R. herpotrichoides isolates were a little more susceptible to strobilurin derivate than carbendazim resistant R. herpotrichoides isolate and R. acuformis strains. The effect of picoxystrobin at concentration 0.5 mg/L as partner in mixture with standard fungicide at concentration 0.1 mg/L (carbendazim, prochloraz or cyprodinil) was assessed as the additive. It was relatively most noticeably in tests with R. acuformis and picoxystrobin plus cyprodinil mixture that was for mixture recommended as tank-mix or as manufacture product.
This particular study deals with the impact of pre-sowing nanotube-based seed treatment technology on rapeseed (Brassica napus) growth and yield. During field tests we identified a significant yield increase as a result of applying the pre-sowing nanotube-based seed treatment technology. The main treatment agents were physiologically active nanochips consisting of carrier matrix nanotubes with eliciting activity ("Taunit", "Taunit-M", "Taunit-MD", and graphene). Enriching nanochips with insecticide-fungicide Kruizer-rape for guaranteed seed protection from crucifer flea allowed to raise the yield up to 8.08 t / ha - 12.28 t / ha.
N-Methyl-W-D-fructosyl amphotericin B methyl ester (MFAME) is a semisynthetic de­rivative of the antifungal antibiotic amphotericin B (AMB). In contrast to the parent antibiotic, the derivative is characterised by low toxicity to mammalian cells and good solubility in water of its salts. Comparative studies on biological properties of free MFAME, AMB and their liposomal formulations were performed. To obtain liposomal forms, the antibiotics were incorporated into small unilamellar vesicles composed of dimyristoyl phos- phatidylcholine (DMPC) and DMPC: cholesterol or ergosterol, 8:2 molar ratio. The effectivity of the liposomal and free forms of AMB and MFAME were compared by de­termination of fungistatic and fungicidal activity against Candida albicans ATCC 10261, potassium release from erythrocytes, and haemolysis. The results obtained indicate that in contrast to AMB, incorporation of MFAME into liposomes did not further improve its selective toxicity. Studies on the antagonistic effect of ergosterol and cholesterol on the antifungal ac­tivity of the antibiotics indicated that sterol interference was definitely less pro­nounced in the case of MFAME than in the case of AMB.
Several new 3-substituted isoxazolecarboxamides have been prepared from aromatic and aliphatic aldehydes. A key step was a 1,3-dipolar cycloaddition of nitrile oxides to ethyl acrylate or methacrylate esters. Some of the amides showed high fungicidal activities against Alternaria alternate, Botrytis cinerea, Rhizoctonia solani, Fusarium culmorum, and Phytophthora cactorum strains.
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