Antimicrobial Activities of Ellagitannins against Clostridiales perfringens, Escherichia coli, Lactobacillus plantarum and Staphylococcus aureus

In this study, we tested the growth inhibition effect of 22 individual ellagitannins and of pentagalloylglucose on four bacterial species, i.e.,Clostridiales perfringens, Escherichia coli, Lactobacillus plantarumandStaphylococcus aureus. All tested compounds showed antimicrobial effects againstS. aureus, and almost all againstE. coliandC. perfringens. ForL. plantarum, no or very weak growth inhibition was detected. The level of inhibition was the greatest forS. aureusand the weakest forC. perfringens. ForS. aureus, the molecular size or flexibility of ellagitannins did not show a clear relationship with their antimicrobial activity, even though rugosins E and D and pentagalloylglucose with four or five free galloyl groups had a stronger growth inhibition effect than the other ellagitannins with glucopyranose cores but with less free galloyl groups. Additionally, our results withS. aureusshowed that the oligomeric linkage of ellagitannin might have an effect on its antimicrobial activity. ForE. coli, the molecular size, but not the molecular flexibility, of ellagitannins seemed to be an important factor. ForC. perfringens, both the molecular size and the flexibility of ellagitannin were important factors. In previous studies, corilagin was used as a model for ellagitannins, but our results showed that other ellagitannins are much more efficacious; therefore, the antimicrobial effects of ellagitannins could be more significant than previously thought

Ellagitannin-Lipid Interaction by HR-MAS NMR Spectroscopy

Ellagitannins have antimicrobial activity, which might be related to their interactions with membrane lipids. We studied the interactions of 12 different ellagitannins and pentagalloylglucose with a lipid extract of Escherichia coli by high-resolution magic angle spinning NMR spectroscopy. The nuclear Overhauser effect was utilized to measure the cross relaxation rates between ellagitannin and lipid protons. The shifting of lipid signals in 1H NMR spectra of ellagitannin-lipid mixture due to ring current effect was also observed. The ellagitannins that showed interaction with lipids had clear structural similarities. All ellagitannins that had interactions with lipids had glucopyranose cores. In addition to the central polyol, the most important structural feature affecting the interaction seemed to be the structural flexibility of the ellagitannin. Even dimeric and trimeric ellagitannins could penetrate to the lipid bilayers if their structures were flexible with free galloyl and hexahydroxydiphenoyl groups

Antimicrobial activities of ellagitannins against Clostridiales perfringens, Escherichia coli, Lactobacillus plantarum and Staphylococcus aureus

In this study, we tested the growth inhibition effect of 22 individual ellagitannins and of pentagalloylglucose on four bacterial species, i.e., Clostridiales perfringens, Escherichia coli, Lactobacillus plantarum and Staphylococcus aureus. All tested compounds showed antimicrobial effects against S. aureus, and almost all against E. coli and C. perfringens. For L. plantarum, no or very weak growth inhibition was detected. The level of inhibition was the greatest for S. aureus and the weakest for C. perfringens. For S. aureus, the molecular size or flexibility of ellagitannins did not show a clear relationship with their antimicrobial activity, even though rugosins E and D and pentagalloylglucose with four or five free galloyl groups had a stronger growth inhibition effect than the other ellagitannins with glucopyranose cores but with less free galloyl groups. Additionally, our results with S. aureus showed that the oligomeric linkage of ellagitannin might have an effect on its antimicrobial activity. For E. coli, the molecular size, but not the molecular flexibility, of ellagitannins seemed to be an important factor. For C. perfringens, both the molecular size and the flexibility of ellagitannin were important factors. In previous studies, corilagin was used as a model for ellagitannins, but our results showed that other ellagitannins are much more efficacious; therefore, the antimicrobial effects of ellagitannins could be more significant than previously thought

The impact of light intensity on metabolomic profile of Arabidopsis thaliana wild type and reticulata mutant by NMR spectroscopy

Light acclimation involves biochemical, metabolic and developmental adjustments that allow plants to cope with a vast range of growth environments. Arabidopsis thaliana mutants with photoperiod-dependent defects in leaf development and metabolism have been instrumental in deciphering the interlinked regulatory networks in plants. The reticulata (re) mutant displays dark green veins and pale green mesophyll tissues when grown under long day conditions. RE is a chloroplast envelope membrane protein of unknown function and is required for accurate primary metabolism and leaf development under long photoperiod, while its functional significance under short photoperiods has remained poorly understood. In the present study we assessed whether RE impacts primary metabolism or leaf development when Arabidopsis plants acclimate to different light intensities under short photoperiod. We show that growth under short day conditions annuls the metabolic and developmental defects of re mutants, suggesting that RE does not significantly modulate leaf development or primary metabolism under short photoperiod. Based on proton nuclear magnetic resonance spectroscopy (H-1 NMR) and statistical analysis, however, the metabolite profiles of differentially light-acclimated short-day-grown plants differ with respect to sugars (glucose, fructose and sucrose), TCA cycle intermediates (fumaric, malic, citric and succinic acids) and fatty acids, which become more abundant under high light. Moreover, in contrast to isoleucine, leucine, valine, threonine, serine, tyrosine and phenylalanine, which show increased abundance in highlight-acclimated plants, the contents of alanine, glutamine, glutamic acid and aspartic acid are higher when plants grow under normal growth light. These findings indicate that NMR can detect high-light-induced metabolic adjustments that arise upon plant acclimation to light stress

NMR metabolomics and DNA sequencing of Escherichia coli and Staphylococcus aureus cultures treated with hydrolyzable tannins

Escherichia coli and Staphylococcus aureus are globally among the most prominent bacterial strains associated with antibacterial resistance-caused deaths. Naturally occurring polyphenols, such as hydrolyzable tannins, have been shown to potently inhibit E. coli and S. aureus. The current study investigated the metabolome changes of E. coli and S. aureus cultures after treatments with different hydrolyzable tannins using an NMR metabolomics approach. Additionally, the effect of these tannin treatments influencing a more complex bacterial system was studied in a biomimetic setting with fecal samples inoculated into the growth medium. Metabolite concentration changes were observed in all three scenarios: E. coli, S. aureus, and fecal batch culture. The metabolome of E. coli was more altered by the tannin treatments than S. aureus when compared to control cultures. A dimeric hydrolyzable tannin, rugosin D, was found to be the most effective of the studied compounds in influencing bacterial metabolome changes and in inhibiting E. coli and S. aureus growth. It was also observed that the tannin structure should have both hydrophobic and hydrophilic regions to efficiently influence E. coli and S. aureus growth

NMR metabolome of Borrelia burgdorferi in vitro and in vivo in mice

Lyme borreliosis (LB), caused by bacteria of the Borrelia burgdorferi sensu lato (Borrelia) species, isthe most common tick-borne infection in the northern hemisphere. LB diagnostics is based on clinicalevaluation of the patient and on laboratory testing, where the main method is the detection of Borreliaspecific antibodies in patient samples. There are, however, shortcomings in the current serology basedLB diagnostics, especially its inability to differentiate ongoing infection from a previously treated one.Identification of specific biomarkers of diseases is a growing application of metabolomics. One of themain methods of metabolomics is nuclear magnetic resonance (NMR) spectroscopy. In the presentstudy, our aim was to analyze whether Borrelia growth in vitro and infection in vivo in mice causesspecific metabolite differences, and whether NMR can be used to detect them. For this purpose,we performed NMR analyses of in vitro culture medium samples, and of serum and urine samples ofBorrelia infected and control mice. The results show, that there were significant differences in theconcentrations of several amino acids, energy metabolites and aromatic compounds between Borreliaculture and control media, and between infected and control mouse serum and urine samples. Forexample, the concentration of L-phenylalanine increases in the Borrelia growth medium and in serum ofinfected mice, whereas the concentrations of allantoin and trigonelline decrease in the urine of infectedmice. Therefore, we conclude that Borrelia infection causes measurable metabolome differences in vitroand in Borrelia infected mouse serum and urine samples, and that these can be detected with NMR.</p

Synthesis of medronic acid monoesters and their purification by high-performance countercurrent chromatography or by hydroxyapatite

We achieved the synthesis of important medronic acid monoalkyl esters via the dealkylation of mixed trimethyl monoalkyl esters of medronic acid. Two methods were developed for the purification of medronic acid monoesters: 1) small scale (10–20 mg) purification by using hydroxyapatite and 2) large scale (tested up to 140 mg) purification by high-performance countercurrent chromatography (HPCCC)

Ellagitannin–Lipid Interaction by HR-MAS NMR Spectroscopy

Ellagitannins have antimicrobial activity, which might be related to their interactions with membrane lipids. We studied the interactions of 12 different ellagitannins and pentagalloylglucose with a lipid extract of Escherichia coli by high-resolution magic angle spinning NMR spectroscopy. The nuclear Overhauser effect was utilized to measure the cross relaxation rates between ellagitannin and lipid protons. The shifting of lipid signals in 1H NMR spectra of ellagitannin&ndash;lipid mixture due to ring current effect was also observed. The ellagitannins that showed interaction with lipids had clear structural similarities. All ellagitannins that had interactions with lipids had glucopyranose cores. In addition to the central polyol, the most important structural feature affecting the interaction seemed to be the structural flexibility of the ellagitannin. Even dimeric and trimeric ellagitannins could penetrate to the lipid bilayers if their structures were flexible with free galloyl and hexahydroxydiphenoyl groups

Structural Requirements for Bisphosphonate Binding on Hydroxyapatite: NMR Study of Bisphosphonate Partial Esters

Eighteen different bisphosphonates, including four clinically used bisphosphonate acids and their phosphoesters, were studied to evaluate how the bisphosphonate structure affects binding to bone. Bisphosphonates with weak bone affinity, such as clodronate, could not bind to hydroxyapatite after the addition of one ester group. Medronate retained its ability to bind after the addition of one ester group, and hydroxy-bisphosphonates could bind even after the addition of two ester groups. Thus, several bisphosphonate esters are clearly bone binding compounds. The following conclusions about bisphosphonate binding emerge: (1) a hydroxyl group in the geminal carbon takes part in the binding process and increases the bisphosphonate’s ability to bind to bone; (2) the bisphosphonate’s ability to bind decreases when the amount of ester groups increases; and (3) the location of the ester groups affects the bisphosphonate’s binding ability