Effects Of Antimicrobial Compounds Research Articles

Antimicrobial phenolic metabolites from the aerial parts of Orthosiphon aristatus

Two new compounds oraristatin A (1) and oraristatinoside A (2), one new natural compound (2 S)-methyl-6,7-dihydroxytropate (3), and 11 known phenolic metabolites were isolated from the aerial parts of Orthosiphon aristatus. Their chemical structures were identified by 1D- and 2D NMR and HRESIMS spectroscopic analyses. The absolute configurations of 1 and 3 were determined by TD-DFT ECD spectroscopic analyses. Of the isolates, compound 2 weakly inhibited both Gram-positive and -negative bacteria (MIC = 150–300 μM), while 6 and 7 suppressed the growth of three Gram-positive bacteria and a yeast (MIC = 75–150 μM). This is the first report of the isolation of 6 − 9, 12, and 14 from the genus Orthosiphon and the antimicrobial effects of compounds 3, 7, 9, 12, and 14.

Antimicrobial secondary metabolites from the aerial parts of Perilla frutescens

Phytochemical research of Perilla frutescens aerial parts led to isolation of 12 secondary metabolites, including one new 3-benzoxepin glucoside, perillafrutoside A (1), one new megastigmane glycoside, perillafrutoside B (2), and 10 known compounds. Their chemical structures were identified based on 1D/2D NMR, HRESIMS, and ECD spectroscopic analyses. The structure of 2 was elucidated based on revision of the previously reported stereoisomer, (6R,9R)-blumenyl α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside. Evaluation of their antimicrobial effect revealed that compounds 1 and 5–11 inhibit Enterococcus faecalis growth, compounds 6, 7 and 9 suppress Staphylococcus aureus growth, whereas compounds 6 and 11 attenuate Candida albicans growth. This is the first report of the isolation of 3–5, 8–10 and 12 from the genus Perilla and the antimicrobial effect of compounds 3, 8 and 10.

Overview of rearing and testing conditions and a guide for optimizing Galleria mellonella breeding and use in the laboratory for scientific purposes.

The greater wax moth Galleria mellonella is an increasingly popular and consolidated alternative infection model to assess microbial virulence and the effectiveness of antimicrobial compounds. The lack of G.mellonella suppliers aiming at scientific purposes and a lack of well-established protocols for raising and testing these animals may impact results and reproducibility between different laboratories. In this review, we discuss the state of the art of rearing the larvae in situ, providing an overview of breeding and testing conditions commonly used and their influence on larval health and experiments results, from setting up the environment, providing the ideal diet, understanding the effects of pretreatments, choosing the best testing conditions, to exploring the most from the results obtained. Meanwhile, we guide the reader through the most practical ways of dealing with G.mellonella to achieve successful experiments.

Linking Antimicrobial Potential of Natural Products Derived from Aquatic Organisms and Microbes Involved in Alzheimer's Disease - A Review.

The following review is oriented towards microbes linked to Alzheimer's disease (AD) and antimicrobial effect of compounds and extracts derived from aquatic organisms against specific bacteria, fungi and viruses which were found previously in patients suffering from AD. Major group of microbes linked to AD include bacteria: Chlamydia pneumoniae, Helicobacter pylori, Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia, Actinomyces naeslundii, spirochete group; fungi: Candida sp., Cryptococcus sp., Saccharomyces sp., Malassezia sp., Botrytis sp., and viruses: herpes simplex virus type 1 (HSV-1), Human cytomegalovirus (CMV), hepatitis C virus (HCV). In the light of that fact, this review is the first to link antimicrobial potential of aquatic organisms against these sorts of microbes. This literature review might serve as a starting platform to develop novel supportive therapy for patients suffering from AD and to possibly prevent escalation of the disease in patients already having high-risk factors for AD occurrence.

Effect of organic compounds on dry anaerobic digestion of food and paper industry wastes

ABSTRACT Effects of antimicrobial compounds on dry anaerobic digestion (dry-AD) processes were investigated. Four compounds with known inhibition effects on traditional wet digestion, i.e. car-3-ene, hexanal, 1-octanol and phenol were selected and investigated at concentrations of 0.005%, 0.05% and 0.5%. Food waste (FW) and Paper waste (PW) were used as model substrates, all assays were running with the substrate to inoculum ratio of 1:1 (VS basis) corresponding to 15% TS in reactors. Generally, increasing concentrations of inhibitors resulted in decreasing methane yields with a few exceptions; in all these specific cases, long, lag phase periods (60 days) were observed. These adaptation periods made possible for the microbial systems to acclimatize to otherwise not preferred conditions leading to higher methane yields. Comparing the effects of the four different groups, phenols had the highest inhibitory effects, with no methane production at the highest amount added, while the lowest effects were obtained in cases of car-3-ene. Furthermore, the results showed that adding inhibitors up to a certain concentrations can repair the balance in AD process, slowing down the degradation steps, hence making it possible for the methanogens to produce a higher amount of methane. This phenomenon was not observed in case of PW, which is already a slow degradable substrate in its nature.

A simple and reliable method to assess the effects of antimicrobial compounds on phytoplasmas

A simple and reliable method to assess the effects of antimicrobial compounds on phytoplasmas

Synthesis of Tetra 3,4‐dimethoxyphenethoxy Peripheral Substituted Metallophthalocyanines and Investigation of Some Properties

AbstractThe synthesis and characterization of tetra 3,4‐dimethoxyphenethoxy substituted cobalt, zinc and copper phthalocyanines are reported. These compounds have been characterized by using electronic absorption, nuclear magnetic resonance spectroscopy, infrared spectroscopy, and elemental analysis. The aggregation behaviors were investigated in different concentrations phthalocyanine complexes. The photodegradation stabilities of pthalocyanine complexes 4–6 were determined in THF. The antioxidant activities of scavenging effect on 1,1‐Diphenyl‐2‐picryl‐hydrazyl (DPPH) radicals and ferrous chelating reducing power were also investigated. The antimicrobial effects of compounds were evaluated. In addition, DNA cleavage activities of the ligand and its phthalocyanine complexes were experimented on plasmid DNA (pBR322) using DNA gel electrophoresis and the complexes exhibited promising cleavage activity. Thermal properties of compounds were determined by thermogravimetric analysis(TG) and differential thermal analysis (DTA).

Uses and limitations of green fluorescent protein as a viability marker in Enterococcus faecalis: An observational investigation

Enterococci are capable of producing biofilms that are notoriously difficult to treat and remove, for instance in root canal infections. The tenacious nature of these organisms makes screening of known and novel antimicrobial compounds necessary. While traditionally growth and fluorescence-based screening methods have proven useful, these methods have their limitations when applied to enterococci (e.g. time consuming, no kinetic data, diffusion properties of the fluorescent dyes).The aim of this study was to develop and validate a GFP-based high-throughput screening system to assess the bactericidal activity of a broad range of antimicrobial agents on Enterococcus faecalis and its biofilms. The effect of antimicrobial compounds on cell viability and GFP fluorescence of enterococcal planktonic and biofilm cells was determined using colony forming unit counts, fluorescence spectrophotometry and real-time imaging devices.There was a linear correlation between cell viability and GFP fluorescence. The intensity of the GFP signal was effected by the extracellular pH. For a range of antimicrobials however, there was no correlation between these two parameters. In contrast, for oxidizing agents such as sodium hypochlorite, the antimicrobial of choice for root canal disinfection, there was a correlation between loss of fluorescence and loss of viability.To conclude, the use of a GFP-based system to monitor the antimicrobial activity of compounds on E. faecalis is possible despite significant limitations. This approach is useful for analysis of susceptibility to oxidizing agents. Using real-time measuring devices to follow GFP fluorescence it should be possible to investigate the mode of action and rate of diffusion of oxidizing agents in E. faecalis biofilm.

Aristatosides A-C, hederagenin-type triterpene saponins from Cephalaria aristata

Three hederagenin-type triterpene saponins; 3-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→3)-]-α-l-arabinopyranosyl hederagenin 28-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl ester (aristatoside A, 1), 3-O-α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-[-β-d-glucopyranosyl-(1→3)-]-α-l-arabinopyranosyl hederagenin 28-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl ester (aristatoside B, 2) and 3-O-β-d-xylopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-xylopyranosyl-(1→3)-α-l-rhamno-pyranosyl-(1→2)-α-l-arabinopyranosyl hederagenin (aristatoside C, 3) have been isolated together with ten known compounds including nine triterpenic and one steroidal glycosides from the aerial parts of Cephalaria aristata (Dipsacaceae). Two prosapogenins (1a–2a) were also obtained after alkaline hydrolysis of the bisdesmosidic compounds 1–2. The structures of all compounds were elucidated by extensive evaluation of the spectroscopic data (1D and 2D NMR, HR-ESI/MS), as well as the chemical examinations. The antimicrobial effects of compounds 1–3 and prosapogenins 1a–2a were evaluated against Gram-positive, Gram-negative bacteria and unicellular yeast C. albicans by MIC method.

Effect of antimicrobial compounds on cut Gerbera flowers: Poor relation between stem bending and numbers of bacteria in the vase water

Gerbera flowers (Gerbera jamesonii) often show stem bending. In four cultivars (Tamara, Liesbeth, Cora, and Mickey), we tested the effects on bending of antimicrobial compounds (chlorine bleach, a slow release chlorine compound, 8-hydroxyquinoline citrate [HQC], silver nitrate, carvacrol and thymol), some combined with sugars. At concentrations used for other cut flowers, inclusion in the vase solution of several of the antimicrobial compounds delayed bending, had no effect, or hastened bending. Hastening of bending was found at higher concentrations. It was accompanied with visible damage on the stem ends. Results with HQC indicated high toxicity as it did not delay bending at any of the concentration tested (100–400mgL−1). At 200mgL−1 HQC induced growth of bacteria that were not found in the controls. The number of bacteria in the vase water showed a low correlation with bending. Visible toxicity on the stem surface was often associated with a high bacteria count. However, at relatively high concentrations of the antimicrobial compounds stem bending was associated with a low count. This indicated an effect other than bacteria. Water uptake was low in stems that bent early. It is hypothesized that material from dead stem cells resulted in a xylem blockage which led to early bending. Sucrose at 15gL−1 in combination with an antimicrobial compound (slow release chlorine, HQC) resulted in the absence of stem damage and produced much less bending than the same concentration of the antimicrobial compounds alone. Sucrose apparently counteracted the toxic effects of the antimicrobial chemicals.

Nanomechanical response of bacterial cells to cationic antimicrobial peptides

The effectiveness of antimicrobial compounds can be easily screened, however their mechanism of action is much more difficult to determine. Many compounds act by compromising the mechanical integrity of the bacterial cell envelope, and our study introduces an AFM-based creep deformation technique to evaluate changes in the time-dependent mechanical properties of Pseudomonas aeruginosa PAO1 bacterial cells upon exposure to two different but structurally related antimicrobial peptides. We observed a distinctive signature for the loss of integrity of the bacterial cell envelope following exposure to the peptides. Measurements performed before and after exposure, as well as time-resolved measurements and those performed at different concentrations, revealed large changes to the viscoelastic parameters that are consistent with differences in the membrane permeabilizing effects of the peptides. The AFM creep deformation measurement provides new, unique insight into the kinetics and mechanism of action of antimicrobial peptides on bacteria.

Antimicrobial Triterpenoid Glycosides from Cephalaria scoparia

Five new oleanane-type triterpenoid glycosides (1-5), named scoposides A-E, along with one known bisdesmosidic triterpene glycoside, were isolated from the aerial parts of Cephalaria scoparia. Three prosapogenins (2a-4a) were also obtained after alkaline hydrolysis of the bisdesmosidic compounds 2-4. The structures of compounds 1-5 were determined by spectroscopic (1D and 2D NMR, HRESIMS) and chemical methods. The antimicrobial effects of compounds 1-5 were evaluated against a small panel of Gram-positive and Gram-negative bacteria.

Organic acids as a substitute for monensin in diets for beef cattle

Feeding cattle high-grain diets has brought concurrent problems with ruminal acidosis. Grain overload in feedlot cattle has gained the most attention because of its economic impact. In fact, ruminal acidosis is second only to respiratory diseases, in depressing animal performance and production efficiency. Much of the past research has focused on effects of antimicrobial compounds (such as monensin) on ruminal fermentation; they have become management tools to prevent or to control ruminal acidosis. Despite beneficial effects of such compounds, in 2002 the European Commission proposed to ban on antibiotic growth promotants including monensin. This legislation has important economic implications in production cost of beef. Several nutritional alternatives to monensin have been studied in vitro with diverse results. This paper provides an overview of research with organic acids (malate and fumarate) for beef cattle as a substitute for monensin. Although these organic acids may be considered as feed additives, more research is needed about the effects of malate and (or) fumarate on beef cattle performance. Dietary factors such as forage:concentrate ratio, and forage or cereal grain type may alter the response to these additives. In addition, appropriate timing for supplementing with malate or fumarate must be studied.

Effects of antimicrobial compounds on the postharvest life of rose.

Effects of antimicrobial compounds on the postharvest life of rose.

Effect of antimicrobial compounds on the number of bacteria in stems of cut rose flowers

The presence of chlorine in solution (bleach), a slow release chlorine (DICA), a quaternary ammonium compound (benzalkonium chloride), a hydroxyquinoline compound (HQC), or aluminium sulphate in the vase water decreased the number of bacteria in stems of cut ‘Sonia’roses, with respect to untreated controls. However, when the concentration of the antimicrobial compound was high enough to reduce the number of bacteria in stems (measured after 7 d of vase life) to below the detection limit, the roses showed severe leaf chlorosis and leaf abscission. Benzalkonium chloride resulted in damage at a concentration just enough to reduce the number of bacteria in stems. Effects of HQC, aluminium sulphate, and silver nitrate on the number of bacteria were variable. In experiments in which HQC was relatively ineffective, only one bacterial strain was found in the stem. This strain grew on HQC concentrations as high as 400 mg/l, and was identified as Pseudomonas fluorescens. and accepted 8 June 1989

The effect of antimicrobial compounds on the gastrointestinal microflora of rainbow trout, Salmo gairdneri Richardson

Populations of aerobic and anaerobic heterotrophic bacteria occurring in the gastrointestinal tract of healthy rainbow trout were estimated using a dilution plate technique. Data revealed a progressive decline in numbers of aerobic bacteria along the digestive tract from oesophagus to lower intestine. However, the highest numbers were recovered from the intestinal contents and faeces. Anaerobes were generally restricted to the upper intestine and intestinal contents. The aerobic component of the bacterial microflora from the digestive tract was equated with Acinetobacter calcoaceticus, Aeromonas hydrophila, Bacillus circulans, Bac. megaterium, coryneforms, Grampositive irregularly shaped rods, Flavobacterium sp., Kurthia sp., Microhacterium sp., Providencia stuartii, Pseudomonas spp., Ps.fluorescens and Ps. pseudoalcaligenes. Evidence from scanning electron microscopy pointed to a general lack of colonization of the gut wall: instead, microorganisms were abundant in the intestinal contents. Antimicrobial compounds, i.e. oxolinic acid, oxytetracycline and sulphafurazole (which are commonly used to combat infections by Gramnegative bacterial fish pathogens), caused an increase in bacterial numbers throughout the digestive tract, with maximal numbers in the lower intestine. The bacteria, comprising an essentially different range of taxa, were generally resistant to the antibiotics in use. Conversely, erythromycin and penicillin G, which are used to treat some diseases caused by Gram‐positive bacteria, caused a rapid reduction in bacterial numbers within the gastrointestinal tract.