Determination of membrane disruption and genomic DNA binding of cinnamaldehyde to Escherichia coli by use of microbiological and spectroscopic techniques

The influence of synergistic antibacterial saponins, sapindoside A and B, on the fatty acid composition and membrane properties of Micrococcus luteus

BACKGROUND

Saponins from Sapindus mukorossi Gaertn. are natural surfactants with excellent foaming ability, biodegradability, and safety. However, their applications in food have been rarely reported. The aim of this work was therefore to investigate the synergistic antibacterial roles of a combination of sapindoside A and B (SAB), which are major components of Sapindus saponins, in altering the properties and fatty acids (FAs) in the membrane of Micrococcus luteus, which has been identified as an opportunistic pathogen.

RESULTS

Microscopy showed that SAB destroyed the integrity of the cell membrane and internal structures and led to the leakage of the cell content. Further analysis indicated that the ratio of saturated FAs to unsaturated FAs was increased significantly, and the membrane fluidity, permeability, and integrity changed substantially. Although sapindoside A and B exerted similar synergistic effects on fatty acid composition and membrane fluidity, sapindoside A had a greater impact on membrane permeability and integrity, consistent with density functional theory.

CONCLUSION

The activity of M. luteus was inhibited more effectively by SAB than sapindoside A or B alone. It attacked cell membrane FAs, resulting in changing membrane fluidity, permeability, and integrity, eventually causing leakage of the cell contents, and ultimately cell death. This helped to provide evidence for the use of SAB as a natural antibacterial detergent additive in the food industry. © 2024 Society of Chemical Industry.

Advances in pharmacological effects and mechanism of action of cinnamaldehyde

Cinnamaldehyde is extracted from Cinnamomum cassia and other species, providing diverse sources for varying chemical properties and therapeutic effects. Besides natural extraction, synthetic production and biotechnological methods like microbial fermentation offer scalable and sustainable alternatives. Cinnamaldehyd demonstrates a broad pharmacological range, impacting various diseases through detailed mechanisms. This review aims to encapsulate the diverse therapeutic effects of cinnamaldehyde, its molecular interactions, and its potential in clinical applications. Drawing on recent scientific studies and databases like Web of Science, PubMed, and ScienceDirect, this review outlines cinnamaldehyde's efficacy in treating inflammatory conditions, bacterial infections, cancer, diabetes, and cardiovascular and kidney diseases. It primarily operates by inhibiting the NF-κB pathway and modulating pro-inflammatory mediators, alongside disrupting bacterial cells and inducing apoptosis in cancer cells. The compound enhances metabolic health by improving glucose uptake and insulin sensitivity and offers cardiovascular protection through its anti-inflammatory and lipid-lowering effects. Additionally, it promotes autophagy in kidney disease management. Preclinical and clinical research supports its therapeutic potential, underscoring the need for further investigation into its mechanisms and safety to develop new drugs based on cinnamaldehyde.

Inhibition mechanism of crude lipopeptide from Bacillus subtilis against Aeromonas veronii growth, biofilm formation, and spoilage of channel catfish flesh

Aeromonas veronii is associated with food spoilage and some human diseases, such as diarrhea, gastroenteritis, hemorrhagic septicemia or asymptomatic and even death. This research investigated the mechanism of the growth, biofilm formation, virulence, stress resistance, and spoilage potential of Bacillus subtilis lipopeptide against Aeromonas veronii. Lipopeptides suppressed the transmembrane transport of Aeromonas veronii by changing the cell membrane's permeability, the structure of membrane proteins, and Na+/K+-ATPase. Lipopeptide significantly reduced the activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) by 86.03% and 56.12%, respectively, ultimately slowing Aeromonas veronii growth. Lipopeptides also restrained biofilm formation by inhibiting Aeromonas veronii motivation and extracellular polysaccharide secretion. Lipopeptides downregulated gene transcriptional levels related to the virulence and stress tolerance of Aeromonas veronii. Furthermore, lipopeptides treatment resulted in a considerable decrease in the extracellular protease activity of Aeromonas veronii, which restrained the decomposing of channel catfish flesh. This research provides new insights into lipopeptides for controlling Aeromonas veronii and improving food safety.

Bioactive Compounds from Plant Origin as Natural Antimicrobial Agents for the Treatment of Wound Infections

The rising prevalence of drug-resistant bacteria underscores the need to search for innovative and nature-based solutions. One of the approaches may be the use of plants that constitute a rich source of miscellaneous compounds with a wide range of biological properties. This review explores the antimicrobial activity of seven bioactives and their possible molecular mechanisms of action. Special attention was focused on the antibacterial properties of berberine, catechin, chelerythrine, cinnamaldehyde, ellagic acid, proanthocyanidin, and sanguinarine against Staphylococcus aureus, Enterococcus spp., Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Serratia marcescens and Pseudomonas aeruginosa. The growing interest in novel therapeutic strategies based on new plant-derived formulations was confirmed by the growing number of articles. Natural products are one of the most promising and intensively examined agents to combat the consequences of the overuse and misuse of classical antibiotics.

Study of alkali-soluble curdlan/bacterial cellulose/cinnamon essential oil blend films with enhanced mechanical properties

In response to the growing demand for biodegraded film with high mechanical properties for complex preservation application scenarios, we developed a curdlan (CD) blended films with exceptional mechanical strength through an alkali dissolution method. Notably, the alkali-soluble CD film exhibited five-fold increase in tensile strength (TS) when compared to its water-soluble counterpart. Furthermore, the inclusion of 2 % bacterial cellulose (BC) resulted in a significant 41.1 % augmentation of the film's TS. Thermal stability improvements were observed through differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) results provided insights into alterations in film crystallinity and intermolecular interactions. Specifically, the incorporation of 10 % CEO led to an additional improvement in TS. Our experimental investigations involving the packaging of chilled fresh meat with these blended films unveiled their capacity to effectively inhibit microorganism growth, maintain meat color stability, delay protein decomposition and fat oxidation, and extend the storage time up to 9 days. Our study offers a promising solution for food packaging, emphasizing the development of a high-strength degradable CD/BC/CEO blended film, which holds potential for extending the shelf life of food products.

Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry

Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC50 and MIC90 of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 108 and 106 CFU/mL. At the cell density of 108 CFU/mL, MIC50 and MIC90 were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 106 CFU/mL, MIC50 and MIC90 were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC50 and MIC90 for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.

Study of antimicrobial activity and mechanism of vapor-phase cinnamaldehyde for killing Escherichia coli based on fumigation method

The vapor-phase antibacterial activity of essential oils makes them suitable for applications in air disinfection and other fields. At present, vapor-phase antibacterial activity of plant-based essential oils has rarely been reported. Herein, we report a new approach to investigate the antimicrobial activity and mechanism of vapor-phase cinnamaldehyde using Escherichia coli (E. coli) and three other pathogenic bacteria (Pseudomonas aeruginosa, Salmonella, Staphylococcus aureus) as model bacteria. Plate fumigation and agar block transfer techniques were used to determine the antimicrobial activities of vapor-phase cinnamaldehyde fumigation on the four types of bacteria, and the mechanism of action was determined by electrical conductivity (EC), OD260nm measurement, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and fluorescence spectroscopy. Cinnamaldehyde had good vapor-phase antibacterial activity against the four types of bacteria. The TEM, EC, and OD260nm measurements showed that after fumigation with cinnamaldehyde, the ultrastructures of the cells were damaged, and plasmolysis, cell collapse, and leakage of intracellular substances were observed. The FTIR and fluorescence spectroscopy analyses showed that the secondary and tertiary structures of bacterial membrane proteins were altered. These findings indicate that the cell membrane is an important target for plant-based essential oils to exert their vapor-phase antimicrobial effects. The results showed that plant-based essential oils can be developed as volatile broad-spectrum disinfection products and vapor-phase antiseptics.

Limited Role of Rhamnolipids on Cadmium Resistance for an Endogenous-Secretion Bacterium

Rhamnolipids, a type of biosurfactant, represent a potential strategy for both enhancing organismic resistance and in situ remediation of heavy metals contaminations. In-depth study of the mechanism of rhamnolipids synthesis in response to heavy metals stress, is indispensable for a wide use of biosurfactant-secreting microbes in bioremediation. In this study, we employed the wild-type and the rhlAB deficient strain (ΔrhlAB) of Pseudomonas aeruginosa, a prototypal rhamnolipids-producing soil microorganism, to investigate its responses to cadmium resistance based on its physicochemical, and physiological properties. Compared with the wild-type strain, the ΔrhlAB were more sensitive to Cd-stress at low Cd concentration (<50 mg/L), whereas there was little difference in sensitivity at higher Cd concentrations, as shown by spot titers and cell viability assays. Secreted rhamnolipids reduced intracellular Cd²⁺ accumulation to alleviate Cd²⁺ stress, whereas endogenous rhamnolipids played a limited role in alleviating Cd²⁺ stress. Synthesized rhamnolipids exhibited a higher critical micelle concentration (CMC) (674.1 mg/L) and lower emulsification index (4.7%) under high Cd-stress, while these parameters showed no obvious changes. High Cd-stress resulted in high hydrophilic wild-type bacterial surface and lower bioremediation ability. This study could advance a deeper understanding of the mechanism of cadmium resistance and provide a theoretical foundation for the application of biosurfactant and biosurfactant-secreted bacterium in contaminant bioremediation.

Synergistic antibacterial combination of Sapindoside A and B changes the fatty acid compositions and membrane properties of Cutibacterium acnes

Sapindus saponins extracted from S. mukorossi have been reported to exert antibacterial activities against skin pathogenic bacteria, but their antibacterial mechanism is still at an exploratory stage. The objective of this study was to explore the synergistic antibacterial mechanism of the combination of two Sapindus saponins, namely Sapindoside A and B (SAB) against Cutibacterium acnes (C. acnes) 6919 via targeting the fatty acid compositions and membrane properties. After exposure to SAB, C. acnes cells increased the cell surface hydrophobicity and reduced the cell membrane fluidity by changing the composition of membrane fatty acids. In the fatty acid compositions, the content of two main fatty acids 12-methyl-tetradecanoic acid (isoC15:0) and octadecanoic acid (C18:0) reduced and improved respectively with the addition of SAB, and fatty acid biosynthesis-related genes were significantly down-regulated (p < 0.05). Further, molecular docking demonstrated that SAB interacted with FabD, which is an essential enzyme for bacterial type II fatty acid synthesis, via hydrogen bonds and hydrophobic interactions. In the above results, the contribution of SA to SAB was greater than that of SB. In summary, the results revealed that SAB changed the fatty acid compositions of C. acnes, further disrupting the cell membrane properties, and SA played a major role, suggesting that SAB could be a natural antiacne additive against C. acnes-associated infections.

Antibacterial Mechanism of Cinnamaldehyde: Modulation of Biosynthesis of Phosphatidylethanolamine and Phosphatidylglycerol in Staphylococcus aureus and Escherichia coli

Cinnamaldehyde is a natural antimicrobial food preservative. Previous studies have suggested that cinnamaldehyde interacts with the cell membrane, but the molecular targets of cinnamaldehyde action on foodborne pathogens are still unclear. In this study, the structural changes of Staphylococcus aureus and Escherichia coli cells were observed after cinnamaldehyde treatment. Then, quantitative real-time polymerase chain reaction (PCR) and parallel reaction monitoring were used for determining the effects of cinnamaldehyde treatment of these bacteria on the expression of genes and proteins associated with glycerophospholipid biosynthesis. Changes in fatty acids (raw materials for the biosynthesis of glycerophospholipids) and glycerophospholipids in S. aureus and E. coli after cinnamaldehyde treatment were analyzed to confirm the results of gene and protein expression experiments. Cinnamaldehyde regulated the glycerophospholipid biosynthesis pathways of these foodborne pathogens, mainly targeting phosphatidylglycerol and phosphatidylethanolamine, which resulted in the disruption of cell membrane integrity.

Microencapsulated phytogenic in dog feed modulates immune responses, oxidative status and reduces bacterial (Salmonella and Escherichia coli) counts in feces

Improving the health and immunity of pets is a concern of the guardians, while maintaining the health of the animals directly impacts the owners' health and public health. The objective of this study was to produce a dog feed containing a microencapsulated phytogenic blend, as well as determine the impact of the additive on animal health and its intestinal microbiota. The composition included microencapsulated thymol, carvacrol, and cinnamaldehyde, at 300 mg/kg of feed. Ten male beagle dogs were divided into two groups, identified as follows: the control group (C; ingested the feed without the additive) and the treated group (T; consumed feed containing the phytogenic blend). The dogs received 300 g of feed/day divided into two meals. Greater neutrophil counts in group T and lymphocyte counts were observed at the end of the experiment, as well as levels of α2-globulins and γ-globulin, while β1 and β2-globulins levels were lower in group T. Serum nitrogen oxide levels were higher in group T. Levels of reactive oxygen species were lower in group T at days 30 and 45, unlike activity of glutathione peroxidase that was higher. We found less bacterial contamination in the feces of dogs in group T, i.e., total bacterial count, total coliform counts, and counts of Salmonella and Escherichia coli were lower on days 30 and 45. Phytogenic blend intake reduces bacterial counts in stool and improves antioxidant/oxidative status and immune responses.

Impact of long-term quorum sensing inhibition on uropathogenic Escherichia coli

BACKGROUND

Quorum sensing is an extracellular bacterial communication system used in the density-dependent regulation of gene expression and development of biofilms. Biofilm formation has been implicated in the establishment of catheter-associated urinary tract infections and therefore quorum sensing inhibitors (QSIs) have been suggested as anti-biofilm catheter coating agents. The long-term effects of QSIs in uropathogens is, however, not clearly understood.

OBJECTIVES

We evaluated the effects of repeated exposure to the QSIs cinnamaldehyde, (Z)-4-bromo-5(bromomethylene)-2(5H)-furanone-C30 (furanone-C30) and 4-fluoro-5-hydroxypentane-2,3-dione (F-DPD) on antimicrobial susceptibility, biofilm formation and relative pathogenicity in eight uropathogenic Escherichia coli (UPEC) isolates.

METHODS

MICs, MBCs and minimum biofilm eradication concentrations and antibiotic susceptibility were determined. Biofilm formation was quantified using crystal violet. Relative pathogenicity was assessed in a Galleria mellonella model. To correlate changes in phenotype to gene expression, transcriptomic profiles were created through RNA sequencing and variant analysis of genomes was performed in strain EC958.

RESULTS

Cinnamaldehyde and furanone-C30 led to increases in susceptibility in planktonic and biofilm-associated UPEC. Relative pathogenicity increased after cinnamaldehyde exposure (4/8 isolates), decreased after furanone-C30 exposure (6/8 isolates) and varied after F-DPD exposure (one increased and one decreased). A total of 9/96 cases of putative antibiotic cross-resistance were generated. Exposure to cinnamaldehyde or F-DPD reduced expression of genes associated with locomotion, whilst cinnamaldehyde caused an increase in genes encoding fimbrial and afimbrial-like adhesins. Furanone-C30 caused a reduction in genes involved in cellular biosynthetic processes, likely though impaired ribonucleoprotein assembly.

CONCLUSIONS

The multiple phenotypic adaptations induced during QSI exposure in UPEC should be considered when selecting an anti-infective catheter coating agent.

Role of manganese superoxide dismutase (Mn-SOD) against Cr(III)-induced toxicity in bacteria

The toxicity of Cr(VI) was widely investigated, but the defense mechanism against Cr(III) in bacteria are seldom reported. Here, we found that Cr(III) inhibited bacterial growth and induced reactive oxygen species (ROS). After exposure to Cr(III), loss of sodA not only led to the excessive generation of ROS, but also enhanced the level of lipid peroxidation and reduced the GSH level, indicating that the deficiency of Mn-SOD decreased the bacterial resistance ability against Cr(III). The adverse effects of oxidative stress caused by Cr(III) could be recovered by the rescue of Mn-SOD in the sodA-deficient strain. Besides the oxidative stress, Cr(III) could cause the bacterial morphology variation, which was distinct between the wild-type and the sodA-deficient strains due to the differential expressions of Z-ring division genes. Moreover, Mn-SOD might prevent Cr(III) from oxidation on the bacterial surface by combining with Cr(III). Taken together, our results indicated that the Mn-SOD played a vital role in regulating the stress resistance, expression of cell division-related genes, bacterial morphology, and chemistry valence state of Cr. Our findings firstly provided a more in-depth understanding of Cr(III) toxicity and bacterial defense mechanism against Cr(III).

A review of cinnamaldehyde and its derivatives as antibacterial agents

There is a continuing rise in the occurrence of multidrug-resistant bacterial infections. Antibiotic resistance to currently available antibiotics has become a global health issue leading to an urgent need for alternative antibacterial strategies. There has been a renewed interest in the development of antibacterial agents from natural sources, and trans-cinnamaldehyde is an example of a naturally occurring compound that has received significant attention in recent years. Trans-Cinnamaldehyde has been shown to possess substantial antimicrobial activity, as well as an array of other medicinal properties, and represents an intriguing hit compound from which a number of derivatives have been developed. In some cases, these derivatives have been shown to possess improved activity, not only compared to trans-cinnamaldehyde but also to commonly used antibiotics. Therefore, understanding the antibacterial mechanisms of action that these compounds elicit is imperative in order to facilitate their development and the development of new antibacterial agents that could exploit similar mechanistic approaches. The purpose of this review is to provide an overview of current knowledge on the antibacterial activity and mechanisms of action of cinnamaldehyde and its derivatives, and to highlight significant contributions made in this research area. It is hoped that the findings presented in this work will aid the future development of new antibacterial agents.

Cinnamaldehyde Induces Expression of Efflux Pumps and Multidrug Resistance in Pseudomonas aeruginosa

Essential oils or their components are increasingly used to fight bacterial infections. Cinnamaldehyde (CNA), the main constituent of cinnamon bark oil, has demonstrated interesting properties in vitro against various pathogens, including Pseudomonas aeruginosa In the present study, we investigated the mechanisms and possible therapeutic consequences of P. aeruginosa adaptation to CNA. Exposure of P. aeruginosa PA14 to subinhibitory concentrations of CNA caused a strong albeit transient increase in the expression of operons that encode the efflux systems MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY/OprM. This multipump activation enhanced from 2- to 8-fold the resistance (MIC) of PA14 to various antipseudomonal antibiotics, including meropenem, ceftazidime, tobramycin, and ciprofloxacin. CNA-induced production of pump MexAB-OprM was found to play a major role in the adaption of P. aeruginosa to the electrophilic biocide, through the NalC regulatory pathway. CNA was progressively transformed by bacteria into the less toxic metabolite cinnamic alcohol (CN-OH), via yet undetermined detoxifying mechanisms. In conclusion, the use of cinnamon bark oil or cinnamaldehyde as adjunctive therapy to treat P. aeruginosa infections may potentially have antagonistic effects if combined with antibiotics because of Mex pump activation.

Insights into the Relationships Between Herbicide Activities, Molecular Structure and Membrane Interaction of Cinnamon and Citronella Essential Oils Components

Since the 50's, the massive and "environmental naïve" use of synthetic chemistry has revolutionized the farming community facing the dramatic growth of demography. However, nowadays, the controversy grows regarding the long-term harmful effects of these products on human health and the environment. In this context, the use of essential oils (EOs) could be an alternative to chemical products and a better understanding of their mode of biological action for new and optimal applications is of importance. Indeed, if the biocidal effects of some EOs or their components have been at least partly elucidated at the molecular level, very little is currently known regarding their mechanism of action as herbicides at the molecular level. Here, we showed that cinnamon and Java citronella essential oils and some of their main components, i.e.,, cinnamaldehyde (CIN), citronellal (CitA), and citronellol (CitO) could act as efficient herbicides when spread on A. thaliana leaves. The individual EO molecules are small amphiphiles, allowing for them to cross the mesh of cell wall and directly interact with the plant plasma membrane (PPM), which is one of the potential cellular targets of EOs. Hence, we investigated and characterized their interaction with biomimetic PPM while using an integrative biophysical approach. If CitO and CitA, maintaining a similar chemical structure, are able to interact with the model membranes without permeabilizing effect, CIN belonging to the phenylpropanoid family, is not. We suggested that different mechanisms of action for the two types of molecules can occur: while the monoterpenes could disturb the lipid organization and/or domain formation, the phenylpropanoid CIN could interact with membrane receptors.

Impedimetric analysis on the mass transfer properties of intact and competent E. coli cells

Competent Escherichia coli cells are commonly used in bacterial transformation owing to its high permeability for bioorganic macromolecules like plasmid DNA. However, the mass transfer property of competent E. coli cell has not fully investigated. In the present study, mass transfer coefficients of competent and intact E. coli cells in deionized water were evaluated by impedimetric analysis of the release of cytoplasmic compounds. Because competent cells have a higher permeability after chemical treatment, the lumped mass transfer coefficient of a competent cell was approximately 6.5 times larger than that of an intact cell at room temperature. Release of cytoplasmic components was accelerated at an elevated temperature of 42 °C, which is the heat shock temperature used during bacterial transformation. At this elevated temperature, assessed lumped mass transfer coefficients of intact and competent E. coli cells were 9.28 × 10^-4 min^-1 and 97.10 × 10^-4 min^-1, respectively. Significant increase in the mass transfer coefficient of the competent cell is caused by cytolysis of cells. The double layer capacitances were also assessed from the electrochemical spectra confirming the enhanced ion release from E. coli cells and rupture of the competent cell under prolonged exposure at the elevated temperature. Impedimetric detection of the ion release with analyses using an equivalent circuit model provides a method to evaluate mass transfer properties of biomolecules.

Cinnamaldehyde inhibit Escherichia coli associated with membrane disruption and oxidative damage

In this study, the antimicrobial mechanism of cinnamaldehyde (CIN) against Gram-negative Escherichia coli ATCC 25922 (E. coli) based on membrane and gene regulation was investigated. Treatment with low concentration (0, 1/8, 1/4, 3/8 MIC) of CIN can effectively suppress the growth of E. coli by prolonging its lag phase and Raman spectroscopy showed obvious distinction of the E. coli after being treated with these concentration of CIN. The determination of relative conductivity indicated that CIN at relatively high concentration (0, 1, 2, 4 MIC) can increase the cell membrane permeability, causing the leakage of cellular content. Besides, the content of malondialdehyde (MDA) and the activity of total superoxide dismutase (SOD) of E. coli increased with increasing treatment concentration of CIN, implying that CIN can cause oxidative damage on E. coli cell membrane and induce the increase of total SOD activity to resist this oxidative harm. Moreover, quantitative real-time RT-PCR (qRT-PCR) analysis revealed the relationship between expression of antioxidant genes (SODa, SODb, SODc) and treatment CIN concentration, suggesting that SOD, especially SODc, played a significant role in resistance of E. coli to CIN. The underlying inactivation processing of CIN on E. coli was explored to support CIN as a potential and natural antimicrobial agent in food industry.