Mechanism Of Antimicrobial Effect Research Articles

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review.

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs’ antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Algae Polyphenolic Compounds and Modern Antibacterial Strategies: Current Achievements and Immediate Prospects.

The increasing drug resistance of pathogenic microorganisms raises concern worldwide and necessitates the search for new natural compounds with antibacterial properties. Marine algae are considered a natural and attractive biotechnological source of novel antibiotics. The high antimicrobial activity of their polyphenolic compounds is a promising basis for designing innovative pharmaceuticals. They can become both a serious alternative to traditional antimicrobial agents and an effective supplement to antibiotic therapy. The present review summarizes the results of numerous studies on polyphenols from algae and the range of biological activities that determine their biomedical significance. The main focus is put on a group of the polyphenolic metabolites referred to as phlorotannins and, particularly, on their structural diversity and mechanisms of antimicrobial effects. Brown algae are an almost inexhaustible resource with a high biotechnological potential for obtaining these polyfunctional compounds. An opinion is expressed that the effectiveness of the antibacterial activity of phlorotannins depends on the methods of their extraction aimed at preserving the phenolic structure. The use of modern analytical tools opens up a broad range of opportunities for studying the metabolic pathways of phlorotannins and identifying their structural and functional relationships. The high antimicrobial activity of phlorotannins against both Gram-positive and Gram-negative bacteria provides a promising framework for creating novel drugs to be used in the treatment and prevention of infectious diseases.

Advances in Biogenic Nanoparticles and the Mechanisms of antimicrobial Effects

Innovations in the nanotechnological arena have paved a path leading to nano-revolution, which has most recently unfurled the role of plants in the biogenic synthesis of nanoparticles. Though synthesis of nanoparticles can be accomplished through physical and chemical techniques, biological course of synthesis has proficiently proved competent over other techniques. The problem of evolving multidrug resistant bacteria, due to irrational use of antibiotics, makes the biogenically synthesized nanoparticles attractive, due to their promising efficacy with negligible side effects. Consequently, the nanoparticles becoming better substitutes for conventional treatment besides overcoming all the limitations. Nanoparticles have great stability and potent antibacterial activity. The uniqueness lies in their size (10 and 500 nm) and dimension offers these particles to dynamically communicate with biomolecules on the cell surfaces and within the cells, so proficiently to decode and designate various biochemical and physiochemical properties of the cells. The present review aims to recapitulate various emerging efforts in the biogenic synthesis of nanoparticles, most significantly their unique mechanisms of action with different approaches as well as the factors that may add up to their antimicrobial activity.

Evaluation of Antibacterial Activity of Nanostructured Copolymers of Poly (Naphthylamine)

The present preliminary investigation highlights for the first time the antibacterial activity of copolymers of nanostructured poly (naphthylamine) (PNA) with aniline (PNA-co-PANI) and o-toluidine (PNA-co-POT) against E. coli and S. aureus. The antibacterial effect of these nanosized polymers was found to be much higher than that reported for pristine polyaniline. The chemical structure and morphology of the copolymers was found to play a significant role in deciding the antimicrobial efficiency of the copolymers. A proposed mechanism of antimicrobial effect has also been suggested. Our results indicate that the antimicrobial effects of the copolymers could be useful ingredients for biomaterials used in the development of food packaging and medical devices.

Epithelium of human fresh amniotic membrane has antimicrobial effects in vitro

This study was carried out to investigate the antimicrobial effects of human fresh amniotic membrane and human amniotic homogenate supernatant (HAHS) in vitro. Fresh human amniotic membranes were harvested and used to make a cellular amniotic membranes (fresh amniotic membranes without the epithelium) and HAHS. Then, the antimicrobial effects of both the fresh human amniotic membrane with the epithelium and fresh amniotic membranes without the epithelium were observed. The antimicrobial effects of fresh HAHS were examined with Kirby-Bauer method. The antimicrobial capacity was compared with ten antibiotics with the Broth Micro-dilution Method, and the impacts of temperatures and pH values and preserved time of HAHS on the antimicrobial capacity were investigated. Finally, transmission electron microscopy (TEM) was used to explore the possible mechanism of the antibiosis of HAHS. Human fresh amniotic membrane with the epithelium had antimicrobial effects, while fresh amniotic membrane without the epithelium did not have any antimicrobial activities. HAHS showed antimicrobial activities for the three standard strains:Staphylococcus aureus ATCC, Escherichia coli, Pseudomonas aeruginosa; four clinically isolated sensitive bacterial strains: Streptococcus pneumonia, Staphylococcus epidermidis,Staphylococcus haemolyticus, and Proteus mirabilis; three clinically isolated fungal strains:Blastomyces albicans, Fusarium solani, Aspergillus fumigatus; and one clinically isolated multi-drug-resistant strain: Enterococcus faecalis. The minimum inhibitory concentration (MIC) of HAHS for Staphylococcus aureus was less than that of Chloramphenicol, equal to that of Clindamycin, greater than that of Penicillin, Rifampicin, and Levofloxacin. Fresh amniotic membrane with epithelium and HAHS had antimicrobial activities, and fresh amniotic membrane without the epithelium did not, indicating that antimicrobial activities are related with the epithelium. HAHS had broad antimicrobial activities and stable characteristics. The mechanism of antimicrobial effect of HAHS was probably interacting with the plasma membrane of the bacteria. Key words: Human amniotic membrane, antimicrobial effects, amniotic homogenate supernatant, minimum inhibitory concentration, minimal bactericidal concentration.

Antimicrobial Edible Apple Films Inactivate Antibiotic Resistant and Susceptible Campylobacter jejuni Strains on Chicken Breast

Campylobacter jejuni is the leading cause of bacterial diarrheal illness worldwide. Many strains are now becoming multidrug resistant. Apple-based edible films containing carvacrol and cinnamaldehyde were evaluated for bactericidal activity against antibiotic resistant and susceptible C. jejuni strains on chicken. Retail chicken breast samples inoculated with D28a and H2a (resistant strains) and A24a (a sensitive strain) were wrapped in apple films containing cinnamaldehyde or carvacrol at 0.5%, 1.5%, and 3% concentrations, and then incubated at 4 or 23 °C for 72 h. Immediately after wrapping and at 72 h, samples were plated for enumeration of viable C. jejuni. The antimicrobial films exhibited dose- and temperature-dependent bactericidal activity against all strains. Films with ≥1.5% cinnamaldehyde reduced populations of all strains to below detection at 23 °C at 72 h. At 4 °C with cinnamaldehyde, reductions were variable for all strains, ranging from 0.2 to 2.5 logs and 1.8 to 6.0 logs at 1.5% and 3.0%, respectively. Films with 3% carvacrol reduced populations of A24a and H2a to below detection, and D28a by 2.4 logs at 23 °C and 72 h. A 0.5-log reduction was observed for both A24a and D28a, and 0.9 logs for H2a at 4 °C at 3% carvacrol. Reductions ranged from 1.1 to 1.9 logs and 0.4 to 1.2 logs with 1.5% and 0.5% carvacrol at 23 °C, respectively. The films with cinnamaldehyde were more effective than carvacrol films. Reductions at 23 °C were greater than those at 4 °C. Our results showed that antimicrobial apple films have the potential to reduce C. jejuni on chicken and therefore, the risk of campylobacteriosis. Possible mechanisms of antimicrobial effects are discussed. Apple antimicrobial films could potentially be used in retail food packaging to reduce C. jejuni commonly present on food.

Diethyl pyrocarbonateの殺菌作用機作(第1報)

食品防腐剤として研究開発されているDEPCの殺菌メカエズムを解明する目的で,パン酵母を1%DEPC水溶液で処理し,酵母細胞に起る変化をしらべた. (1) 室温で1時間処理した酵母細胞は,顕微鏡的には(MB染色においても)対照と差異が認められなかった. (2) 処理後調製した圧搾酵母は, 外観など対照と差異がなかったが,これを30°Cに貯蔵すると一般に2～3日で軟化した.このようにDEPC処理は,圧搾酵母の軟化を促進したが,溶出アミノ態窒素量からすると,自己消化の速度には大した影響を及ぼさないものと考えられる. (3) DEPC処理1時間で醗酵力は全く消失した. (4) DEPC処理酵母を通風乾燥すると,水分含量40%から10%への脱水で急激にMB染色性が増加し, 10%の乾燥酵母では全細胞がMBにより染色された. DEPC処理は,酵母細胞の耐乾燥性を著しく損傷するものと考えられる.

Mechanism of Antimicrobial Effect of Quinone Compounds

The qualitative change and quantitative change of p-benzoquinone were followed in yeast suspension to obtain the information on the mechanism of the antimicrobial effect of quinone compounds. When the quinone concentration was below 0.16 mM, the quinone was found to be continuously reduced to hydroquinone by the yeast in the presence of energy substrate, whereas the concentration exceeded 0.16 mM, the reduction ability was rapidly destroyed even in the presence of energy substrate.The critical concentration for destruction of the reduction ability was considered to be related to the toxic effect of the quinone on the yeast.