Antibacterial and Antibiofilm Activities of Cinnamomum Sp. Essential Oil and Cinnamaldehyde: Antimicrobial Activities

Cinnamaldehyde effectively disrupts Desulfovibrio vulgaris biofilms: potential implication to mitigate microbiologically influenced corrosion

Microbiologically influenced corrosion poses significant challenges to various industries, as metal surfaces degrade due to the formation of microbial biofilms. Sulfate-reducing bacteria (SRB) are key contributors to this process in anoxic environments (e.g., oil and gas pipelines), mainly by producing highly corrosive hydrogen sulfide. Current prevention methods involving biocides often have drawbacks such as high toxicity and disposal costs, calling for novel environmentally friendly alternatives. Essential oils with their antimicrobial properties and biodegradability may represent promising candidates against microbial corrosion. In this study, cinnamaldehyde was selected both for its antimicrobial activity and its well-documented role as a corrosion inhibitor; then, its antibiofilm activity was investigated against Desulfovibrio vulgaris, in comparison with the well-known reference biocide glutaraldehyde. Both compounds were bactericidal against D. vulgaris at 12.5 µg/mL. D. vulgaris biofilms were developed and monitored by confocal microscopy, and then 72-h-old biofilms were exposed to serial cinnamaldehyde and glutaraldehyde concentrations (12.5-100 µg/mL) for a further 48 h, to evaluate their disruptive effects. Both compounds caused a significant disruption of pre-formed biofilms, at 50 µg/mL. The reduction compared to the untreated controls was ca. 90% vs 85% for biomass, 60% vs 45% for average thickness, and 85% vs 80% for surface area, respectively. Interestingly, cinnamaldehyde applied to a D. vulgaris biofilm grown on representative metal coupons completely inhibited the recovery of viable adherent cells. These data, altogether, highlight the potential of cinnamaldehyde as an effective alternative for controlling and mitigating microbiologically influenced corrosion, with comparable efficacy to glutaraldehyde.IMPORTANCEThe increasing environmental and health concerns associated with the use of conventional biocides to manage and control microbiologically influenced corrosion highlight the need for eco-friendly alternatives. Sulfate-reducing bacteria (SRB) represent the main players in this process, by adhering and proliferating as biofilms on metal infrastructures, producing metabolites that accelerate corrosion. Essential oils have long been regarded as potent antimicrobials endowed with low toxicity; however, there is limited knowledge about their potential use against anaerobic bacteria responsible for corrosion. This study focuses on the antimicrobial activity of cinnamaldehyde and shows its efficacy in eradicating biofilm-grown D. vulgaris, a model species to study SRB energy metabolism. Notably, cinnamaldehyde is also a well-known corrosion inhibitor, which makes it an appealing candidate for industrial applications, particularly where SRB-induced corrosion is prevalent. Altogether, our results pave the way for the future development of green sustainable strategies involving the use of cinnamaldehyde to mitigate microbiologically influenced corrosion.

Inhibition of Clinical Multidrug-Resistant Pseudomonas aeruginosa Biofilms by Cinnamaldehyde and Eugenol From Essential Oils: In Vitro and In Silico Analysis

Pseudomonas aeruginosa causes nosocomial infections and chronic diseases. Cinnamomum cassia and Syzygium aromaticum are used natural antimicrobials. Essential oil (EO) from C. cassia (CCEO) and S. aromaticum (CEO) was characterized using GC-MS analysis. Eugenol (82.31%), eugenol acetate (10.57%), and β-caryophyllene (3.41%) were major constituents in CEO while cinnamaldehyde (88.18%), cinnamyl acetate (2.85%) and 2-methoxy cinnamaldehyde (1.77%) were main components in CCEO. The EOs and major constituents exhibited good antimicrobial activity against clinical strains of P. aeruginosa. Cinnamaldehyde exhibited the best antimicrobial effect with minimal inhibitory concentration (MIC) as low as 0.031% ± 0.07% (v/v) and inhibition zones reaching 30 ± 0.5 mm diameter. Test samples showed antibiofilm activities against two culture types and seven clinical strains of P. aeruginosa at concentrations of 2MIC to MIC/4. CCEO and its major constituent cinnamaldehyde were more active, compared to CEO and its major constituent eugenol. Scanning electron microscopy images showed untreated colonies with well-developed biofilms while there was significant reduction of biofilms with distorted architecture and cell shrinkage upon treatment with test samples. In silico studies indicated great interactions between the major compounds, eugenol and cinnamaldehyde, with the receptor proteins of P. aeruginosa revealed by negative binding energies. Eugenol and cinnamaldehyde exhibited appreciable druglikeness.

Repurposing eugenol and cinnamaldehyde as potent antimicrobial agents: A comprehensive in-vitro and in-silico study

Multi-drug-resistant (MDR) pathogens represent a critical global health threat, necessitating the development of novel antimicrobial agents with broad-spectrum activity and minimal toxicity. This study investigates the antimicrobial and anti-biofilm properties of 4-Allyl-2-methoxyphenol (eugenol, EU) and (E)-3-Phenylprop-2-enal (cinnamaldehyde, CN) against 19 clinically significant pathogens through a combination of in-vitro assays and in-silico analyses. EU displayed remarkable activity, particularly against Aspergillus niger (20.5 ± 0.5 mm), and strong binding affinities with key protein targets, including peptide deformylase and β-carbonic anhydrase, with binding free energies (ΔG) ranging from -12.75 to -0.60 kcal/mol. CN exhibited exceptional activity against Staphylococcus epidermidis (29.6 ± 0.4 mm) and Candida albicans (36.6 ± 0.4 mm), supported by a significant binding affinity with β-carbonic anhydrase (ΔG: -5.23 kcal/mol). Dissociation constants (Kd) derived from MM-GBSA analyses indicated EU's strong inhibitory potential with nano- to picomolar Kd values, directly correlating with low IC50 values. CN demonstrated moderate inhibitory activity with Kd in the micromolar range. Molecular dynamics (MD) simulations confirmed the stability of these protein-ligand complexes, revealing critical hydrophobic interactions, such as those involving PHE122, that contributed to binding stabilization. ADMET profiling further underscored the favorable pharmacokinetics and safety of both compounds. These findings establish EU and CN as promising candidates for antimicrobial therapy, with potential applications in combating MDR pathogens and biofilm-associated infections. The complementary strengths of EU and CN warrant further structural optimization and combination studies, offering new avenues in the development of next-generation antimicrobial agents.

Antibacterial Activity of Selected Essential Oil Components and Their Derivatives: A Review

Essential oils (EOs) are gaining ground and have been intensively studied due to their widespread use in the pharmaceutical, food, and cosmetics industries. The essential components of EOs have been recognized for diverse therapeutic activities and have gained significant attention for their potential antibacterial activities. Despite the popularity of EOs and potent biological properties, their bioactive components and their derivatives are still not comprehensively characterized. This review explores the antibacterial efficacy of selected EO components and their derivatives, focusing on monoterpenes chosen (i.e., carvacrol, menthol, and thymol) and phenylpropanoids (i.e., cinnamaldehyde and eugenol). Furthermore, this review highlights recent advancements in developing derivatives of these EO components, which have shown improved antibacterial activity with reduced toxicity. By summarizing recent studies, this review reveals the potential of these natural compounds and their derivatives as promising candidates for pharmaceuticals, food preservation, and as alternatives to synthetic antibiotics in combating bacterial resistance.

Hidden Places for Foodborne Bacterial Pathogens and Novel Approaches to Control Biofilms in the Meat Industry

Biofilms are of great concern for the meat industry because, despite the implementation of control plans, they remain important hotspots of contamination by foodborne pathogens, highlighting the need to better understand the ecology of these microecosystems. The objective of this paper was to critically survey the recent scientific literature on microbial biofilms of importance for meat safety and quality, also pointing out the most promising methods to combat them. For this, the databases PubMed, Scopus, Science Direct, Web of Science, and Google Scholar were surveyed in a 10-year time frame (but preferably papers less than 5 years old) using selected keywords relevant for the microbiology of meats, especially considering bacteria that are tolerant to cleaning and sanitization processes. The literature findings showed that massive DNA sequencing has deeply impacted the knowledge on the species that co-habit biofilms with important foodborne pathogens (Listeria monocytogenes, Salmonella, pathogenic Escherichia coli, and Staphylococcus aureus). It is likely that recalcitrant commensal and/or spoilage microbiota somehow protect the more fastidious organisms from harsh conditions, in addition to harboring antimicrobial resistance genes. Among the members of background microbiota, Pseudomonas, Acinetobacter, and Enterobacteriales have been commonly found on food contact and non-food contact surfaces in meat processing plants, in addition to less common genera, such as Psychrobacter, Enhydrobacter, Brevundimonas, and Rothia, among others. It has been hypothesized that these rare taxa may represent a primary layer in microbial biofilms, offering better conditions for the adhesion of otherwise poor biofilm formers, especially considering their tolerance to cold conditions and sanitizers. Taking into consideration these findings, it is not only important to target the foodborne pathogens per se in cleaning and disinfection plans but the use of multiple hurdles is also recommended to dismantle the recalcitrant structures of biofilms. In this sense, the last part of this manuscript presents an updated overview of the antibiofilm methods available, with an emphasis on eco-friendly approaches.

Essential Oils as Alternative Green Broad-Spectrum Biocides

Natural compounds from plants represent suitable options to replace synthetic biocides when employed against microorganisms in various applications. Essential oils (EOs) have attracted increased interest due to their biocompatible and rather innocuous nature, and complex biological activity (fungicide, biocide and anti-inflammatory, antioxidant, immunomodulatory action, etc.). EOs are complex mixtures of derived metabolites with high volatility obtained from various vegetal parts and employed to a great extent in different healthcare (natural cures, nutrition, phyto- and aromatherapy, spices) and cosmetics applications (perfumery, personal and beauty care), as well as in cleaning products, agriculture and pest control, food conservation and active packaging, or even for restauration and preservation of cultural artifacts. EOs can act in synergy with other compounds, organic and synthetic as well, when employed in different complex formulations. This review will illustrate the employment of EOs in different applications based on some of the most recent reports in a systematic and comprehensive, though not exhaustive, manner. Some critical assessments will also be included, as well as some perspectives in this regard.

Antibacterial phenolic compounds from the flowering plants of Asia and the Pacific: coming to the light

CONTEXT

The emergence of pan-resistant bacteria requires the development of new antibiotics and antibiotic potentiators.

OBJECTIVE

This review identifies antibacterial phenolic compounds that have been identified in Asian and Pacific Angiosperms from 1945 to 2023 and analyzes their strengths and spectra of activity, distributions, molecular masses, solubilities, modes of action, structures-activities, as well as their synergistic effects with antibiotics, toxicities, and clinical potential.

METHODS

All data in this review was compiled from Google Scholar, PubMed, Science Direct, Web of Science, and library search; other sources were excluded. We used the following combination of keywords: 'Phenolic compound', 'Plants', and 'Antibacterial'. This produced 736 results. Each result was examined and articles that did not contain information relevant to the topic or coming from non-peer-reviewed journals were excluded. Each of the remaining 467 selected articles was read critically for the information that it contained.

RESULTS

Out of ∼350 antibacterial phenolic compounds identified, 44 were very strongly active, mainly targeting the cytoplasmic membrane of Gram-positive bacteria, and with a molecular mass between 200 and 400 g/mol. 2-Methoxy-7-methyljuglone, [6]-gingerol, anacardic acid, baicalin, vitexin, and malabaricone A and B have the potential to be developed as antibacterial leads.

CONCLUSIONS

Angiosperms from Asia and the Pacific provide a rich source of natural products with the potential to be developed as leads for treating bacterial infections.

Essential oils: a potential alternative with promising active ingredients for pharmaceutical formulations in chronic wound management

Chronic wound is a major clinical challenge that complicates wound healing, mainly associated with bacterial biofilms. Bacterial burden damages tissue and persists inflammation, failing to granulate, leading to morbidity and mortality. Various therapeutic strategies and approaches have been developed for chronic wound healing in clinical practice. As treating biofilm infection is crucial in chronic wounds, a potent antibiofilm agent, essential oils have been explored extensively for their therapeutic properties and as a replacement for antibiotic therapy. Currently, several studies on essential oils and their active compounds in therapeutics, such as adjunctive therapies, nanotechnology-based treatment and their drug delivery systems, help heal chronic wounds. The antimicrobial, anti-inflammatory and antioxidant properties of essential oils make them distinct and are renowned as natural remedies to improve the healing of infected chronic wounds. Consequently, it accelerates wound closure by reducing inflammation, increasing angiogenesis and tissue regeneration. This review focuses on different essential oils and their active compounds that are exploited for the treatment of biofilm infection, chronic inflammation and wound healing. Thus, an effective novel treatment can be developed to improve the current treatment strategy to overcome multidrug resistance bacteria or antibiotic resistance in various chronic wound infections that support wound healing.

Isolation of Thermophilic Bacteria Geobacillus subterraneus From Mount Tangkuban Perahu and the Novelty as a Candidate for Streptococcus mutans Anti-Biofilm

Thermophilic bacteria living in extreme areas with high temperatures are capable of producing secondary metabolites, such as antimicrobial peptides (AMPs). AMPs are stable at high temperatures and show good antibacterial activity. Therefore, this study aimed to identify thermophilic bacteria from the crater of Mount Tangkuban Perahu around West Java and assess antibacterial effectiveness of AMPs against Streptococcus mutans, which contribute to oral biofilm formation. The isolate obtained was identified using 16S ribosomal ribonucleic acid (rRNA) gene sequencing, and the supernatant of the isolate was tested against S. mutans American Type Culture Collection (ATCC) 25175 using the disc assay method. To determine AMPs-coding genes, its genome was uploaded to antibiotic and secondary metabolite analysis shell (antiSMASH) 5.0.0 platform and biofilm inhibition was tested using the microtiter plate technique (with a 96-well bottom). Subsequently, the results were assessed using a microplate reader operating at 595 nm wavelength. The isolate was identified as Geobacillus subterraneus, with antibacterial activity against S. mutans, and produced an inhibition zone of 8.40 mm at an optimum pH of 8. The output of AMPs-coding gene showed that AMPs of the isolate were a member of the lanthipeptide class I, or bacteriocin-I group. AMPs of G. subterraneus suppressed the growth of S. mutans biofilm at a supernatant concentration of 5%, with the lowest optical density (OD) value of 0.061 and the highest percentage of biofilm growth inhibition at 28.24%. Based on the results, G. subterraneus derived from the crater of Mount Tangkuban Perahu showed potent antibacterial properties against S. mutans, making it a promising novel S. mutans anti-biofilm candidate.

Combating bacterial biofilms and related drug resistance: Role of phyto-derived adjuvant and nanomaterials

The emergence of antimicrobial resistance (AMR) in clinical microbes has led to a search for novel antibiotics for combating bacterial infections. The treatment of bacterial infections becomes more challenging with the onset of biofilm formation. AMR is further accelerated by biofilm physiology and differential gene expression in bacteria with an inherent resistance to conventional antibiotics. In the search for innovative strategies to control the spread of AMR in clinical isolates, plant-derived therapeutic metabolites can be repurposed to control biofilm-associated drug resistance. Unlike antibiotics, designed to act on a single cellular process, phytochemicals can simultaneously target multiple cellular components. Furthermore, they can disrupt biofilm formation and inhibit quorum sensing, offering a comprehensive approach to combat bacterial infections. In bacterial biofilms, the first line of AMR is due to biofilms associated with the extracellular matrix, diffusion barriers, quorum sensing, and persister cells. These extracellular barriers can be overcome using phytochemical-based antibiotic adjuvants to increase the efficacy of antibiotic treatment and restrict the spread of AMR. Furthermore, phytochemicals can be used to target bacterial intracellular machinery such as DNA replication, protein synthesis, efflux pumps, and degrading enzymes. In parallel with pristine phytochemicals, phyto-derived nanomaterials have emerged as an effective means of fighting bacterial biofilms. These nanomaterials can be formulated to cross the biofilm barriers and function on cellular targets. This review focuses on the synergistic effects of phytochemicals and phyto-derived nanomaterials in controlling the progression of biofilm-related AMR. IT provides comprehensive insights into recent advancements and the underlying mechanisms of the use of phyto-derived adjuvants and nanomaterials.

Phytochemical-mediated modulation of cancer-associated proteins: an integrated in-silico and in-vitro study

Cancer is a complex and widespread disease affecting various organs and tissues, with an expected significant increase in reported cases. Current treatments like chemotherapy and radiation therapy have limited efficacy and adverse side effects. This study investigated the multi-target therapeutic potential of seven phytochemicals against critical cancer-associated proteins. Computational docking studies analysed the binding interactions between phytochemicals and proteins, supported by in-vitro experiments on cancer cell lines. Vero cells assessed cytotoxicity, and the A549 cancer cell line evaluated anticancer activity. Cytotoxicity assessment on Vero cells revealed concentration-dependent effects of phytochemicals. Anticancer activity evaluation on the A549 cell line demonstrated the ability of certain phytochemicals to inhibit cancer cell proliferation and induce apoptosis. Cancer, Therapeutic agents, Phytochemicals, Computational docking studies, In-vitro experiments, Cytotoxicity, Anticancer activity, Chemotherapy, Vero cells, A549 cell line, multi-targeted therapeutic potential, Critical cancer-associated proteins.

Fabrication and Evaluation of a Soy Protein Isolate/Collagen/Sodium Alginate Multifunctional Bilayered Wound Dressing: Release of Cinnamaldehyde, Artemisia absinthium, and Oxygen

Chronic wounds, such as diabetic ulcers and pressure sores, pose significant challenges in modern healthcare due to their prolonged healing times and susceptibility to infections. This study aims to engineer a bilayered wound dressing (BLWD) composed of soy protein isolate/collagen with the ability to release Cinnamaldehyde, Artemisia absinthium (AA), and oxygen. Cinnamaldehyde, magnesium peroxide (MgO2), and AA extract were encapsulated. Nanoparticles were evaluated using scanning electron microscopy (SEM), dynamic light scattering, and ZETA potential tests. Swelling, degradation, water vapor penetration, tensile, MTT, SEM, oxygen release, AA extract release, and antibacterial properties were performed. An in vivo study was carried out to assess the final wound dressing under Hematoxiline&Eosin and Masson trichrome staining analysis and compared to a commercial product. According to the results, the synthesized nanoparticles had an average diameter of about 20 nm with a zeta potential in the range of -20 to -30 mV. The layers had uniform and dense surfaces. The maximum swelling and degradation of the dressing was about 130 and 13% respectively. Generally, better mechanical properties were observed in BLWD than in the single-layer case. More than 90% biocompatibility for the wound dressing was reported. The BLWD could inhibit the growth of Gram-positive and Gram-negative microorganisms. Histopathological analysis showed an acceptable wound-healing property. To sum up, the engineered wound dressing can be a good candidate for more clinical trials.

Antimicrobial Activity against Cronobacter of Plant Extracts and Essential Oils in a Matrix of Bacterial Cellulose

Bacterial cellulose (BC) is a biodegradable polymer resembling paper after being dried. It finds a growing number of applications in many branches of industry and in medicine. In the present study, BC was produced after Gluconacetobacter hansenii ATCC 23769 strain culture and used as a matrix for plant extracts (tulsi, brahmi, lemon, blackberry, nettle root, and nettle leave) and essential oils (cinnamon, sage, clove, mint, thyme, lemongrass, rosemary, lemon, anise, tea tree, lime, grapefruit, and tangerine), and the antimicrobial properties of these biomaterials was determined. The growth-inhibiting effects of plant extracts and essential oils combined with BC were analyzed against five Cronobacter species isolated from food matrix and two reference strains from the ATCC (513229 and 29544). Additional analyses were conducted for BC water activity and for its capability to absorb biologically active plant compounds. The cellulose matrix with a 50% extract from brahmi was found to effectively inhibit the growth of the selected Cronobacter strains. The other plant water extracts did not show any antimicrobial activity against the tested strains. It was demonstrated that BC soaked with thyme essential oil was characterized with the strongest antimicrobial activity in comparison to the other tested EOs. These study results indicate the feasibility of deploying BC impregnated with natural plant components as an active and environmentally-friendly packaging material.

Impact of the uninstructed use of a herbal, ayurvedic toothpaste on parameters of gingival health in periodontal aftercare patients: A randomized, double-blinded, two-arm parallel-group study

AIM

The aim of this study was to evaluate the impact of the uninstructed use of a toothpaste containing herbal ayurvedic ingredients on parameters of gingival health in a cohort of periodontal aftercare patients affected by gingival inflammation compared to the use of a standard, non-herbal toothpaste.

MATERIALS AND METHODS

The monocentric, randomized, double-blinded, two-arm parallel-group intervention was performed in a cohort of 88 periodontal aftercare patients with clinical signs of gingival inflammation. At baseline, bleeding on probing (BoP), gingival index (GI) and Quigley-Hein plaque index (QHI) were recorded. Subsequently, the study patients were randomly provided with a herbal ayurvedic toothpaste (n = 44) or a conventional, non-ayurvedic control toothpaste (n = 44) and without additional oral hygiene training instructed to use it 2× daily for the next 28 days. On day 28, BoP, GI and QHI were recorded again.

RESULTS

At baseline, there were no significant differences between both groups. On day 28, mean GI and BoP scores were significantly lower (p < 0.001) compared to baseline in both groups. Differences between the groups could not be verified. Mean QHI scores did not change significantly between day 0 and day 28 in both groups.

CONCLUSIONS

The impact of uninstructed toothbrushing with an ayurvedic toothpaste on the manifestation of gingival inflammation in periodontal aftercare patients is not significantly different to the use of a conventional, non-herbal toothpaste.

Spontaneous nanoemulsification of cinnamon essential oil: Formulation, characterization, and antibacterial and antibiofilm activity against fish spoilage caused by Serratia rubidaea BFMO8

The contemporary food industry's uses of nanoemulsions (NEs) include food processing, effective nutraceutical delivery, the development of functional chemicals, and the synthesis of natural preservatives, such as phytocompounds. Although cinnamon essential oil (CEO) is widely used in the cosmetic, pharmaceutical, and food industries, it is difficult to add to aqueous-based food formulations due to its weak stability and poor water solubility. This study describes the formulation of a CEO nanoemulsion (CEONE) by spontaneous emulsification and evaluates its antibacterial and antibiofilm properties against biofilm-forming Serratia rubidaea BFMO8 isolated from spoiled emperor fish (Lethrinus miniatus). Bacteria causing spoilage in emperor fish were isolated and identified as S. rubidaea using common morphological, cultural, and 16S RNA sequencing methods, and their ability to form biofilms and their susceptibility to CEONE were assessed using biofilm-specific methods. The spontaneous emulsification formulation of CEONE was accomplished using water and Tween 20 surfactant by manipulating organic and aqueous phase interface properties and controlling particle growth by capping surfactant increases. The best emulsification, with highly stable nano-size droplets, was accomplished at 750 rpm and a 1:3 ratio concentration. The stable CEONE droplet size, polydispersity index, and zeta potential values were 204.8 nm, 0.115, and -6.05 mV, respectively. FTIR and high-resolution liquid chromatography-mass spectrometry (HR-LCMS) analyses have revealed carboxyl, carbonyl, and phenol-like primary phytochemical functional groups in CEO and CEONE, which contribute to their antibacterial and antibiofilm properties.

Antibacterial effectiveness of trans-cinnamaldehyde against foodborne Enterobacteriaceae and its adjuvant effect with gentamicin

The Enterobacteriaceae family is recognized as a primary group of Gram-negative pathogens responsible for foodborne illnesses and is frequently associated with antibiotic resistance. The present study explores the natural-based compound trans-cinnamaldehyde (TC) against drug-resistant Enterobacteriaceae and its synergism with gentamicin (GEN) to address this issue. The research employs three strains of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae, previously isolated from shrimp. The antibacterial activity was evaluated by the disk diffusion method, microdilution test, kinetics of growth, and time-kill curve. In addition, the synergistic effect between TC/GEN was investigated by checkerboard assay. All strains showed sensitivity to TC with an inhibition zone diameter > 35 mm. The TC showed inhibitory and bactericidal action in the most tested bacteria around 625 μg/mL. Sub-inhibitory amounts (1/2 and 1/4 MIC) of TC interfered with the growth kinetics by lag phase extension and decreased the log phase. Time-kill curves show a reduction of viable cells after the first hour of TC treatment at bactericidal concentrations. The synergistic effect between TC/GEN was observed for E. coli and E. cloacae strains with FICi ranging from 0.15 to 0.50. These findings, therefore, suggest TC as a promising alternative in the fight against drug-resistant Enterobacteriaceae that can cause foodborne illnesses.

Cinnamaldehyde ameliorates STZ-induced diabetes through modulation of autophagic process in adipocyte and hepatic tissues on rats

Type 2 diabetes mellitus is a worldwide public health issue. In the globe, Egypt has the ninth-highest incidence of diabetes. Due to its crucial role in preserving cellular homeostasis, the autophagy process has drawn a lot of attention in recent years, Therefore, the purpose of this study was to evaluate the traditional medication metformin with the novel therapeutic effects of cinnamondehyde on adipocyte and hepatic autophagy in a model of high-fat diet/streptozotocin-diabetic rats. The study was conducted on 40 male albino rats, classified into 2 main groups, the control group and the diabetic group, which was subdivided into 4 subgroups (8 rats each): untreated diabetic rats, diabetic rats received oral cinnamaldehyde 40 mg/kg/day, diabetic rats received oral metformin 200 mg/kg/day and diabetic rats received a combination of both cinnamaldehyde and metformin daily for 4 weeks. The outcomes demonstrated that cinnamaldehyde enhanced the lipid profile and glucose homeostasis. Moreover, Cinnamaldehyde had the opposite effects on autophagy in both tissues; by altering the expression of genes that control autophagy, such as miRNA 30a and mammalian target of rapamycin (mTOR), it reduced autophagy in adipocytes and stimulated it in hepatic tissues. It may be inferred that by increasing the treatment efficacy of metformin and lowering its side effects, cinnamaldehyde could be utilized as an adjuvant therapy with metformin for the treatment of type 2 diabetes.

Antimicrobial Activity of Individual Volatile Compounds from Various Essential Oils

Interest in natural remedies has grown recently due to a variety of public health concerns such as microbial antibiotic resistance. This global health concern necessitates innovative approaches to combat bacterial infections. Building upon established therapeutic uses of essential oils, this research focused on the volatile constituents of essential oils. The volatile antimicrobial activity of these constituents was studied by employing a derivative of a modified disk diffusion assay for quantitative comparisons. This study emphasizes the significance and value of exploring natural compounds as alternatives to traditional antibiotics and provides insights into their mechanisms and applications in contending with bacterial pathogens.

Inhibitory effect of natural compounds on quorum sensing system in Pseudomonas aeruginosa: a helpful promise for managing biofilm community

Pseudomonas aeruginosa biofilm is a community of bacteria that adhere to live or non-living surfaces and are encapsulated by an extracellular polymeric substance. Unlike individual planktonic cells, biofilms possess a notable inherent resistance to sanitizers and antibiotics. Overcoming this resistance is a substantial barrier in the medical and food industries. Hence, while antibiotics are ineffective in eradicating P. aeruginosa biofilm, scientists have explored alternate strategies, including the utilization of natural compounds as a novel treatment option. To this end, curcumin, carvacrol, thymol, eugenol, cinnamaldehyde, coumarin, catechin, terpinene-4-ol, linalool, pinene, linoleic acid, saponin, and geraniol are the major natural compounds extensively utilized for the management of the P. aeruginosa biofilm community. Noteworthy, the exact interaction of natural compounds and the biofilm of this bacterium is not elucidated yet; however, the interference with the quorum sensing system and the inhibition of autoinducer production in P. aeruginosa are the main possible mechanisms. Noteworthy, the use of different drug platforms can overcome some drawbacks of natural compounds, such as insolubility in water, limited oral bioavailability, fast metabolism, and degradation. Additionally, drug platforms can deliver different antibiofilm agents simultaneously, which enhances the antibiofilm potential of natural compounds. This article explores many facets of utilizing natural compounds to inhibit and eradicate P. aeruginosa biofilms. It also examines the techniques and protocols employed to enhance the effectiveness of these compounds.

Antibacterial effects of chitosan-based hydrogels containing Trachyspermum ammi essential oil on pathogens isolated from dogs with otitis externa

BACKGROUND

Growing antibiotic resistance has made treating otitis externa (OE) increasingly challenging. On the other hand, local antimicrobial treatments, especially those that combine essential oils (EOs) with nanoparticles, tend to be preferred over systemic ones. It was investigated whether Ajwain (Trachyspermum ammi) EO, combined with chitosan nanoparticles modified by cholesterol, could inhibit the growth of bacterial pathogens isolated from OE cases in dogs. In total, 57 dogs with clinical signs of OE were examined and bacteriologically tested. Hydrogels of Chitosan were synthesized by self-assembly and investigated. EO was extracted (Clevenger machine), and its ingredients were checked (GC-MS analysis) and encapsulated in chitosan-cholesterol nanoparticles. Disc-diffusion and broth Micro-dilution (MIC and MBC) examined its antimicrobial and therapeutic properties.

RESULTS

Staphylococcus pseudintermedius (49.3%) was the most common bacteria isolated from OE cases, followed by Pseudomonas aeruginosa (14.7%), Escherichia coli (13.3%), Streptococcus canis (9.3%), Corynebacterium auriscanis (6.7%), Klebsiella pneumoniae (2.7%), Proteus mirabilis (2.7%), and Bacillus cereus (1.3%). The investigation into the antimicrobial properties of Ajwain EO encapsulated in chitosan nanoparticles revealed that it exhibited a more pronounced antimicrobial effect against the pathogens responsible for OE.

CONCLUSIONS

Using chitosan nanoparticles encapsulated with EO presents an effective treatment approach for dogs with OE that conventional antimicrobial treatments have not cured. This approach not only enhances antibacterial effects but also reduces the required dosage of antimicrobials, potentially preventing the emergence of antimicrobial resistance.

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.

Biofilm busters: Exploring the antimicrobial and antibiofilm properties of essential oils against Salmonella Enteritidis

This study delves into an exploration of the antimicrobial and antibiofilm properties of the essential oils (EOs) of cinnamon, garlic, and onion on Salmonella Enteritidis. Firstly, disc diffusion and minimum inhibitory concentration (MIC) techniques were employed to assess the antibacterial activity of the EOs. Additionally, the study explored the effect of these EOs on both initial cell attachment and 24 h-preformed biofilms. The crystal violet assay was implemented to evaluate biofilm biomass. The findings revealed that cinnamon EO exhibited the highest anti-biofilm activity. Furthermore, initial cell attachment inhibition at MIC ranged between 50 and 65% for the three oils, while inhibition rates on preformed structures were lower than 40% for all EOs at this MIC concentration. The study also found that the effects of these oils were dosage- and time-dependent (p < 0.05), thereby urging the adoption of these natural extracts as effective strategies for combating Salmonella biofilms.

Cymbopogon citratus L. essential oil as a potential anti-biofilm agent active against antibiotic-resistant bacteria isolated from chronic rhinosinusitis patients

Chronic rhinosinusitis (CRS) is long-term inflammation of the sinuses that can be caused by infection due to antibiotic-resistant bacteria. Biofilm developed by microbes is postulated to cause antibiotic treatment failure. Thus, the anti-biofilm activities of seven Thai herbal essential oils (EOs) against antibiotic-resistant bacteria isolated from CRS patients was investigated. Lemongrass (Cymbopogon citratus L.) EO showed the most effective antibiofilm activity against Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus epidermidis grown as biofilm. GC-MS analysis found that myrcene was the major bioactive compound. Pretreatment with lemongrass EO significantly inhibited biofilm formation of all bacterial strains in more than 50% of cases. Furthermore, confocal microscopy analysis revealed the biofilm-disrupting activity of lemongrass EO against the biofilm matrix of all these bacterial species and also increased P. aeruginosa swarming motility with no toxicity to human cells. These results suggest that lemongrass EO has promising clinical applications as an anti-biofilm agent for CRS patients.

Study on the formation and anti-biofilm properties of cinnamon essential oil inclusion complexes by the structure of modified β-cyclodextrins

Essential oils (EOs), which are plant-oriented anti-biofilm agents, are extensively encapsulated by cyclodextrins to overcome their aqueous solubility and chemical instability, and achieve slow release during long-term storage. However, the biological activities of EOs decreased after initial encapsulation in CDs. In this study, modified-β-cyclodextrins (β-CDs) were screened as wall materials to maintained the initial anti-biofilm effect of pure CEO. The inhibitory and bactericidal activities of CEO encapsulated in five types of β-CDs with different substituents (primary hydroxyl, maltosyl, hydroxypropyl, methyl, and carboxymethyl) against Staphylococcus aureus biofilm were evaluated. Crystal violet assay and 3D-View observations suggested that CEO and its inclusion complexes (CEO-ICs) inhibited Staphylococcus aureus biofilm formation through the inhibition of colonising spreading, exopolysaccharide synthesis, and cell surface properties. Molecular docking revealed the causes of the decrease in the anti-biofilm effect after encapsulation, and quantitative structure-activity relationship assays provided MIC and MBIC prediction equation for modified-β-cyclodextrins inclusion complexes. Maltosyl-β-CD was screened as the best wall material to retained the anti-biofilm activities as pure cinnamon essential oil in initial stage, and its inclusion complexes can effectively inhibited biofilm formation in milk. This study provides a theoretical guidance for the selection β-CDs to encapsulate CEO as plant-oriented anti-biofilm agents to inhibit bacterial biofilm formation.

Differentiating True and False Cinnamon: Exploring Multiple Approaches for Discrimination

This study presents a comprehensive literature review that investigates the distinctions between true and false cinnamon. Given the intricate compositions of essential oils (EOs), various discrimination approaches were explored to ensure quality, safety, and authenticity, thereby establishing consumer confidence. Through the utilization of physical-chemical and instrumental analyses, the purity of EOs was evaluated via qualitative and quantitative assessments, enabling the identification of constituents or compounds within the oils. Consequently, a diverse array of techniques has been documented, encompassing organoleptic, physical, chemical, and instrumental methodologies, such as spectroscopic and chromatographic methods. Electronic noses (e-noses) exhibit significant potential for identifying cinnamon adulteration, presenting a rapid, non-destructive, and cost-effective approach. Leveraging their capability to detect and analyze volatile organic compound (VOC) profiles, e-noses can contribute to ensuring authenticity and quality in the food and fragrance industries. Continued research and development efforts in this domain will assuredly augment the capacities of this promising avenue, which is the utilization of Artificial Intelligence (AI) and Machine Learning (ML) algorithms in conjunction with spectroscopic data to combat cinnamon adulteration.

Injectable Chitosan-Based Hydrogels for Trans-Cinnamaldehyde Delivery in the Treatment of Diabetic Foot Ulcer Infections

Diabetic foot ulcers (DFU) are among the most common complications in diabetic patients and affect 6.8% of people worldwide. Challenges in the management of this disease are decreased blood diffusion, sclerotic tissues, infection, and antibiotic resistance. Hydrogels are now being used as a new treatment option since they can be used for drug delivery and to improve wound healing. This project aims to combine the properties of hydrogels based on chitosan (CHT) and the polymer of β cyclodextrin (PCD) for local delivery of cinnamaldehyde (CN) in diabetic foot ulcers. This work consisted of the development and characterisation of the hydrogel, the evaluation of the CN release kinetics and cell viability (on a MC3T3 pre-osteoblast cell line), and the evaluation of the antimicrobial and antibiofilm activity (S. aureus and P. aeruginosa). The results demonstrated the successful development of a cytocompatible (ISO 10993-5) injectable hydrogel with antibacterial (99.99% bacterial reduction) and antibiofilm activity. Furthermore, a partial active molecule release and an increase in hydrogel elasticity were observed in the presence of CN. This leads us to hypothesise that a reaction between CHT and CN (a Schiff base) can occur and that CN could act as a physical crosslinker, thus improving the viscoelastic properties of the hydrogel and limiting CN release.

trans-Cinnamaldehyde as a Novel Candidate to Overcome Bacterial Resistance: An Overview of In Vitro Studies

The increasing of drug-resistant bacteria and the scanty availability of novel effective antibacterial agents represent alarming problems of the modern society, which stimulated researchers to investigate novel strategies to replace or assist synthetic antibiotics. A great deal of attention has been devoted over the years to essential oils that contain mixtures of volatile compounds and have been traditionally exploited as antimicrobial remedies. Among the essential oil phytochemicals, remarkable antimicrobial and antibiotic-potentiating activities have been highlighted for cinnamaldehyde, an α,β-unsaturated aldehyde, particularly abundant in the essential oils of Cinnamomum spp., and widely used as a food additive in industrial products. In line with this evidence, in the present study, an overview of the available literature has been carried out in order to define the bacterial sensitizing profile of cinnamaldehyde. In vitro studies displayed the ability of the substance to resensitize microbial strains to drugs and increase the efficacy of different antibiotics, especially cefotaxime, ciprofloxacin, and gentamicin; however, in vivo, and clinical trials are lacking. Based on the collected findings, cinnamaldehyde appears to be of interest as an adjuvant agent to overcome superbug infections and antibiotic resistance; however, future more in-dept studies and clinical investigations should be encouraged to clarify its efficacy and the mechanisms involved.

Study of the Chemical Profile and Anti-Fungal Activity against Candida auris of Cinnamomum cassia Essential Oil and of Its Nano-Formulations Based on Polycaprolactone

BACKGROUND

Candida auris represents an emerging pathogen that results in nosocomial infections and is considered a serious global health problem. The aim of this work was to evaluate the in vitro antifungal efficacy of Cinnamomum cassia essential oil (CC-EO) pure or formulated in polycaprolactone (PCL) nanoparticles against ten clinical strains of C. auris.

METHODS

nanoparticles of PCL were produced using CC-EO (nano-CC-EO) and cinnamaldehyde (CIN) through the nanoprecipitation method. The chemical profile of both CC-EO and nano-CC-EO was evaluated using SPME sampling followed by GC-MS analysis. Micro-broth dilution tests were performed to evaluate both fungistatic and fungicidal effectiveness of CC-EO and CIN, pure and nano-formulated. Furthermore, checkerboard tests to evaluate the synergistic action of CC-EO or nano-CC-EO with micafungin or fluconazole were conducted. Finally, the biofilm disrupting activity of both formulations was evaluated.

RESULTS

GC-MS analysis shows a different composition between CC-EO and nano-CC-EO. Moreover, the microbiological analyses do not show any variation in antifungal effectiveness either towards the planktonic form (MIC_CC-EO = 0.01 ± 0.01 and MIC_nano-CC-EO = 0.02 ± 0.01) or the biofilm form. No synergistic activity with the antifungal drugs tested was found.

CONCLUSIONS

both CC-EO and nano-CC-EO show the same antimicrobial effectiveness and are potential assets in the fight against C. auris.

Cinnamomum sp. and Pelargonium odoratissimum as the Main Contributors to the Antibacterial Activity of the Medicinal Drink Horchata: A Study Based on the Antibacterial and Chemical Analysis of 21 Plants

Horchata, a herbal infusion drink from Ecuador containing a mixture of medicinal plants, has been reported to exhibit anti-inflammatory, analgesic, diuretic, and antioxidant activity. The antibacterial activity of each of the plants contained in the horchata mixture has not been fully evaluated. Thus, in this study, we analysed the antibacterial activity of 21 plants used in horchata, collected from the Ecuadorian Andes region, against bacterial strains of clinical importance. The methanolic extract of Cinnamomum sp. showed minimal inhibitory concentration (MIC) values of 250 µg/mL against Staphylococcus aureus ATCC25923 and Methicillin-resistant S. aureus (MRSA), while Pelargonium odoratissimum exhibited a MIC value of 500 µg/mL towards S. aureus ATCC25923. The high-performance liquid chromatography-diode array detector-tandem mass spectrometry (HPLC-DAD-MS/MS) analyses identified in Cinnamomum sp. epicatechin tannins, cinnamaldehyde, and prehelminthosporol molecules, whereas in P. odoratissimum, gallocatechin and epigallocatechin tannins, some flavonoids, and gallic acid and derivatives were identified. Finally, Cinnamomum sp. and P. odoratissimum showed partial inhibition of biofilm formation of S. aureus ATCC25923 and MRSA. Overall, our findings revealed which of the plants used in horchata are responsible for the antibacterial activity attributed to this herbal drink and exhibit the potential for Cinnamomum sp. and P. odoratissimum secondary metabolites to be explored as scaffolds in drug development.

Recent advances to combat ESKAPE pathogens with special reference to essential oils

Biofilm-associated bacteria, especially ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), are a serious challenge worldwide. Due to the lack of discovery of novel antibiotics, in the past two decades, it has become necessary to search for new antibiotics or to study synergy with the existing antibiotics so as to counter life-threatening infections. Nature-derived compounds/based products are more efficient than the chemically synthesized ones with less resistance and lower side effects. In this descriptive review, we discuss the most promising therapeutics for the treatment of ESKAPE-related biofilms. The first aspect includes different types of natural agents [botanical drugs, essential oils (EOs), antimicrobial peptides, bacteriophages, and endolysins] effective against ESKAPE pathogens. The second part of the review deals with special references to EOs/essential oil components (EOCs) (with some exclusive examples), mode of action (via interfering in the quorum-sensing pathways, disruption of biofilm and their inhibitory concentrations, expression of genes that are involved, other virulence factors), existing in literature so far. Moreover, different essential oils and their major constituents were critically discussed using in vivo models to target ESKAPE pathogens along with the studies involving existing antibiotics.

Synergistic Action of Cinnamomum verum Essential Oil with Sertraline

Cinnamomum verum L. essential oil (CEO), commonly known as Ceylon cinnamon or cinnamon tree, is regarded as one of the most employed essential oils in the field of aromatherapy. It is usually applied externally as astringent, antipruritic, rubefacient, and anti-septic agent. Furthermore, both in vitro and in vivo research have demonstrated its numerous pharmacological effects, including the potentiality for treating neuralgia, myalgia, headache, and migraine. Several pieces of research also corroborated its significant antiviral and antimicrobial properties. Cinnamaldehyde, eugenol, caryophyllene, cinnamyl acetate, and cinnamic acid are the most representative compounds that are generally found in greater quantities in CEO and play a pivotal role in determining its pharmacological activities. Due to the global antibiotic resistance scenario and the dwindling amount of funding dedicated to developing new antibiotics, in recent years research has concentrated on exploring specific economic approaches against microbial infections. In this context, the purpose of this study was the investigation of the synergistic antibacterial activities of commercially available and chemically characterized CEO in combination with sertraline, a selective serotonin reuptake inhibitor (SSRI), whose repositioning as a non-antibiotic drug has been explored over the years with encouraging results. In vitro effects of the titled combination were assessed toward a wide panel of both Gram-positive and Gram-negative bacteria. The antimicrobial efficacy was investigated by using the checkerboard microdilution method. The interesting preliminary results obtained suggested a synergistic effect (fractional inhibitory index, FICI < 0.5) of sertraline in combination with CEO, leading to severe growth inhibition for all bacterial species under investigation.

Recent advances in essential oil complex coacervation by efficient physical field technology: A review of enhancing efficient and quality attributes

Although complex coacervation could improve the water solubility, thermal stability, bioavailability, antioxidant activity and antibacterial activity of essential oils (EOs). However, some wall materials (such as proteins and polysaccharides) with water solubility and hydrophobic nature limited their application in complex coacervation. In order to improve the properties of EO complex coacervates, some efficient physical field technology was proposed. This paper summarizes the application and functional properties of EOs in complex coacervates, formation and controlled-release mechanism, as well as functions of EO complex coacervates. In particular, efficient physical field technology as innovative technology, such as high pressure, ultrasound, cold plasma, pulsed electric fields, electrohydrodynamic atomization and microwave technology improved efficient and quality attributes of EO complex coacervates are reviewed. The physical fields could modify the gelling, structural, textural, emulsifying, rheological properties, solubility of wall material (proteins and polysaccharides), which improve the properties of EO complex coacervates. Overall, EOs complex coacervates possess great potential to be used in the food industry, including high bioavailability, excellent antioxidant capacity and gut microbiota in vivo, masking the sensation of off-taste or flavor, favorable antimicrobial capacity.

Antibacterial activity of essential oils for combating colistin-resistant bacteria

OBJECTIVES

Colistin (polymyxin E) is a bactericidal antibiotic used to treat severe infections caused by multidrug-resistant Gram-negative bacteria. The product of the mcr1 gene generates transferable plasmid-mediated colistin resistance, which has arisen as a worldwide health-care problem. This study aimed to isolate and identify colistin-resistant bacteria, and evaluate the ability of essential oils in its fights.

METHODS

Twenty-seven bacterial isolates were collected from patients who were admitted to the National Cancer Institute, Cairo, Egypt, and processed using standard microbiological methods. Essential oils were purchased from AB Chem Company, Egypt, screened for antibacterial, cytotoxic activity, and (GC-MS) analysis.

RESULTS

A total of 5 bacterial isolates were resistant to colistin with minimum inhibitory concentration (MIC) ranging from 6.25->200 µg/ml. Cinnamon oil exhibited the highest activity against colistin-resistant strains followed by thyme and eucalyptus oil. The (MIC) of cinnamon oils against resistant strains ranged from 4.88 to 312.5 µg/ml. Moreover, mcr-1 gene expression was extremely down-regulated after the treatment of bacterial strains with cinnamon oil and decreased to 20-35-fold. Examination of treated bacterial cells with sub-inhibitory concentrations under transmission electron microscopy showed various abnormalities occurred in most of these cells.

CONCLUSIONS

Cinnamon oil exhibits antibacterial activity against colistin-resistant strains, showing it as a promising natural alternative in clinical therapy.

trans-Cinnamaldehyde-encapsulated zeolitic imidazolate framework-8 nanoparticle complex solutions to inactivate Escherichia coli O157:H7 on fresh spinach leaves

This study synthesized and characterized ZIF-8 nanoparticles encapsulated with trans-cinnamaldehyde oil (TC) and evaluated their antimicrobial effectiveness against Escherichia coli O157:H7 on fresh spinach leaves. The antimicrobial activity of different mass ratios of TC-encapsulated ZIF-8 against E. coli O157:H7 (ATCC 43895) strain was assessed and the best mass ratio of 1:2 TC to ZIF-8 identified. Spinach leaves were treated with (1) 0.5TC@ZIF-8_PL nanoparticle complexes solution, (2) 200 ppm chlorine, (3) free TC, and (4) sterilized distilled water (control). All sample groups were rinsed for 1 min, dried in a biosafety cabinet, weighted, and packed in sterilized Whirl-pk^TM Stand-Up sampling bags, and stored at 4°C for 15 days for shelf life studies. Samples were dipped into a solution of nanoparticles and another group was sprayed. The quality of spinach samples was assessed by monitoring changes in moisture content (MC), water activity (Aw), color, pH, texture (firmness and work), vitamin C content, total carotenoid, and chlorophyll content. Spinach leaves treated with 0.5TC@ZIF-8_PL had less (p < 0.05) water, total chlorophyll, and total carotenoid losses, with minimal changes in pH. However, treatment did not prevent the color degradation (p > 0.05) and adversely affected spinach firmness. The spinach samples treated with 200 ppm chlorine and free TC had higher (p < 0.05) total chlorophyll degradation than the samples treated with the nanoparticles. The mass ratio of TC-encapsulated ZIF-8 must be readjusted to reduce potential toxicity issues while maintaining the antimicrobial properties. PRACTICAL APPLICATION: Zeolitic imidazolate framework-8 (ZIF-8) nanoparticle complex can be used to encapsulate natural antimicrobials to inhibit growth of pathogens on fresh produce. A 2-log reduction in populations of Escherichia coli O157:H7 on fresh spinach leaves was achieved using trans-cinnamaldehyde at low concentrations. The results can be used to embed the compounds into polymeric films for antimicrobial packaging applications.

Extraction, Chemical Compositions and Biological Activities of Essential Oils of Cinnamomum verum Cultivated in Vietnam

Cinnamomum verum (Cinnamomum genus) essential oil is commonly used in food preparation and traditional medicines, with a broad spectrum of biological activities. However, research on the extraction of essential oils (EOs) from C. verum cultivated locally in Vietnam is currently limited. Therefore, in this study, the chemical compositions and bioactivities of EOs from the bark and leaves of C. verum collected from the Thai Nguyen and Yen Bai provinces of Vietnam were investigated. The EOs samples were extracted by using water distillation, organic solvent (n-hexane) and ultrasound-assisted (in n-hexane solvent) extraction methods. The chemical composition of the obtained EOs were analyzed by GC-FID and GC/MS analyses. Results showed that the major chemical compositions of C. verum EOs were: (E)-cinnamaldehyde, trans-cinnamic acid, cinnamyl acetate, and benzaldehyde. Furthermore, C. verum EOs exhibited inhibitory activities against two tested cancer cell lines and four bacterial strains. These findings provide essential knowledge about the potential application of C. verum EOs cultivated in Vietnam for the pharmaceutical industry.

Cinnamaldehyde-Based Self-Nanoemulsion (CA-SNEDDS) Accelerates Wound Healing and Exerts Antimicrobial, Antioxidant, and Anti-Inflammatory Effects in Rats’ Skin Burn Model

Cinnamaldehyde, the main phytoconstituent of the cinnamon oil, has been reported for its potential wound healing activity, associated to its antimicrobial and anti-inflammatory effects. In this study, we are reporting on the cinnamaldehyde-based self-nanoemulsifying drug delivery system (CA-SNEDDS), which was prepared and evaluated for its antimicrobial, antioxidant, anti-inflammatory, and wound healing potential using the rat third-degree skin injury model. The parameters, i.e., skin healing, proinflammatory, and oxidative/antioxidant markers, were evaluated after 3 weeks of treatment regimens with CA-SNEDDS. Twenty rats were divided randomly into negative control (untreated), SNEDDS control, silver sulfadiazine cream positive control (SS), and CA-SNEDDS groups. An aluminum cylinder (120 °C, 10-s duration) was used to induce 3rd-degree skin burns (1-inch square diameter each) on the rat’s dorsum. At the end of the experiment, skin biopsies were collected for biochemical analysis. The significantly reduced wound size in CA-SNEDDS compared to the negative group was observed. CA-SNEDDS-treated and SS-treated groups demonstrated significantly increased antioxidant biomarkers, i.e., superoxide dismutase (SOD) and catalase (CAT), and a significant reduction in the inflammatory marker, i.e., NAP-3, compared to the negative group. Compared to SNEDDS, CA-SNEDDS exhibited a substantial antimicrobial activity against all the tested organisms at the given dosage of 20 µL/disc. Among all the tested microorganisms, MRSA and S. typhimurium were the most susceptible bacteria, with an inhibition zone diameter (IZD) of 17.0 ± 0.3 mm and 19.0 ± 0.9 mm, respectively. CA-SNEDDS also exhibited strong antifungal activity against C. albicans and A. niger, with IZD of 35.0 ± 0.5 mm and 34.0 ± 0.5 mm, respectively. MIC and MBC of CA-SNEDDS for the tested bacteria ranged from 3.125 to 6.25 µL/mL and 6.25 to 12.5 µL/mL, respectively, while the MIC and MBC for C. albicans and A. niger were 1.56 µL/mL and 3.125 µL/mL, respectively. The MBIC and MBEC of CA-SNEDDS were also very significant for the tested bacteria and ranged from 6.25 to 12.5 µL/mL and 12.5 to 25.0 µL/mL, respectively, while the MBIC and MBEC for C. albicans and A. niger were 3.125 µL/mL and 6.25 µL/mL, respectively. Thus, the results indicated that CA-SNEDDS exhibited significant wound healing properties, which appeared to be attributed to the formulation’s antimicrobial, antioxidant, and anti-inflammatory effects.

Antibacterial, Antibiofilm, and Antioxidant Activity of 15 Different Plant-Based Natural Compounds in Comparison with Ciprofloxacin and Gentamicin

Plant-based natural compounds (PBCs) are comparatively explored in this study to identify the most effective and safe antibacterial agent/s against six World Health Organization concern pathogens. Based on a contained systematic review, 11 of the most potent PBCs as antibacterial agents are included in this study. The antibacterial and antibiofilm efficacy of the included PBCs are compared with each other as well as common antibiotics (ciprofloxacin and gentamicin). The whole plants of two different strains of Cannabis sativa are extracted to compare the results with sourced ultrapure components. Out of 15 PBCs, tetrahydrocannabinol, cannabidiol, cinnamaldehyde, and carvacrol show promising antibacterial and antibiofilm efficacy. The most common antibacterial mechanisms are explored, and all of our selected PBCs utilize the same pathway for their antibacterial effects. They mostly target the bacterial cell membrane in the initial step rather than the other mechanisms. Reactive oxygen species production and targeting [Fe-S] centres in the respiratory enzymes are not found to be significant, which could be part of the explanation as to why they are not toxic to eukaryotic cells. Toxicity and antioxidant tests show that they are not only nontoxic but also have antioxidant properties in Caenorhabditis elegans as an animal model.

Assessment of the antioxidant, antimicrobial and antibiofilm activities of essential oils for potential application of active chitosan films in food preservation

In the food industry, the development of microbial biofilms is a serious problem that leads to the contamination and deterioration of food products. To overcome that, our aim consists of searching for natural antimicrobial and non-toxic compounds (essential oils EOs), which might be used alone or adsorbed on natural biopolymer films (chitosan). In this work, the antioxidant activity of eight EOs was evaluated by DPPH radical-scavenging method while their antibacterial activity was determined by diffusion on agar and microdilution methods. Among all tested EOs, Eugenia caryophyllus, Cinnamomum zeylanicum Blume and Thymus satureioides Cosson showed high antioxidant activities at the concentration of 25.6 mg/mL, with respective values of (86.26%, 81.75%, and 76%), and strong antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Enterococcus hirae, with (MIC) values ≤ 4 µL/mL. At the concentration of 1 µL/mL, these EOs tested alone, showed values of antibiofilm-forming activity ranging from 79.43 to 99.33% and from 44.18 to 94.17%, when they are adsorbed onto chitosan film. These promising results confirm that these three EOs have a good potential for an eventual application in the food industry, as antimicrobial and antioxidant agents, or as active biodegradable food packaging, if combined with chitosan.

Cinnamomum: The New Therapeutic Agents for Inhibition of Bacterial and Fungal Biofilm-Associated Infection

Due to the potent antibacterial properties of Cinnamomum and its derivatives, particularly cinnamaldehyde, recent studies have used these compounds to inhibit the growth of the most prevalent bacterial and fungal biofilms. By inhibiting flagella protein synthesis and swarming motility, Cinnamomum could suppress bacterial attachment, colonization, and biofilm formation in an early stage. Furthermore, by downregulation of Cyclic di‐guanosine monophosphate (c‐di‐GMP), biofilm-related genes, and quorum sensing, this compound suppresses intercellular adherence and accumulation of bacterial cells in biofilm and inhibits important bacterial virulence factors. In addition, Cinnamomum could lead to preformed biofilm elimination by enhancing membrane permeability and the disruption of membrane integrity. Moreover, this substance suppresses the Candida species adherence to the oral epithelial cells, leading to the cell wall deformities, damage, and leakages of intracellular material that may contribute to the established Candida’s biofilm elimination. Therefore, by inhibiting biofilm maturation and destroying the external structure of biofilm, Cinnamomum could boost antibiotic treatment success in combination therapy. However, Cinnamomum has several disadvantages, such as poor solubility in aqueous solution, instability, and volatility; thus, the use of different drug-delivery systems may resolve these limitations and should be further considered in future investigations. Overall, Cinnamomum could be a promising agent for inhibiting microbial biofilm-associated infection and could be used as a catheter and other medical materials surface coatings to suppress biofilm formation. Nonetheless, further in vitro toxicology analysis and animal experiments are required to confirm the reported molecular antibiofilm effect of Cinnamomum and its derivative components against microbial biofilm.

Contribution of Aldehydes and Their Derivatives to Antimicrobial and Immunomodulatory Activities

Essential oils (EOs) are intricate combinations of evaporative compounds produced by aromatic plants and extracted by distillation or expression. EOs are natural secondary metabolites derived from plants and have been found to be useful in food and nutraceutical manufacturing, perfumery and cosmetics; they have also been found to alleviate the phenomenon of antimicrobial resistance (AMR) in addition to functioning as antibacterial and antifungal agents, balancing menstrual cycles and being efficacious as an immune system booster. Several main aldehyde constituents can be found in different types of EOs, and thus, aldehydes and their derivatives will be the main focus of this study with regard to their antimicrobial, antioxidative, anti-inflammatory and immunomodulatory effects. This brief study also explores the activity of aldehydes and their derivatives against pathogenic bacteria for future use in the clinical setting.

Antimicrobial and Antibiofilm Activity of Cinnamon (Cinnamomum burmanii) Extract on Periodontal Pathogens—An in vitro study

Objective  The aim of this study was to analyze the antibiofilm effectiveness of cinnamon ( Cinnamomum burmanii ) ethanol extract against Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans in vitro .

Material and   Methods Phytochemical tests were done to identify the cinnamon extract active substances. Furthermore, a crystal violet biofilm assay was used to analyze biofilm detachment after treatment with different concentrations (15, 10, 7.5, 5, and 2.5%) of cinnamon. Biofilm turbidity was measured at 595-nm wavelength using a microplate reader. Additionally, MTT assay was done to analyze the toxicity level of cinnamon extract on fibroblast cells.

Statistical Analysis  The obtained data were analyzed for normality using the Kolmogorov–Smirnov test. The differences between each group were analyzed using a one-way analysis of variance statistical test, with a significance level of p <0.05.

Results  The results showed that the ethanol extract of cinnamon contains active compounds of flavonoids, alkaloids, saponins, tannins, quinones, and terpenoids. MTT result showed the cinnamon extract to be nontoxic. The biofilm assay results showed that all cinnamon concentrations exhibited an antibiofilm effect against P. gingivalis and A. actinomycetemcomitans in all incubation time compared with a negative control ( p <0.05).

Conclusions  Cinnamon extracts were effective in inhibiting biofilm of periodontal pathogens. Cinnamon extract might be useful as an alternative therapy for periodontal diseases. Future studies are still needed to confirm this result in vivo to analyze the efficacy of this extract as mouthwash.

Appraisal of Cinnamaldehyde Analogs as Dual-Acting Antibiofilm and Anthelmintic Agents

Cinnamaldehyde has a broad range of biological activities, which include antibiofilm and anthelmintic activities. The ever-growing problem of drug resistance and limited treatment options have created an urgent demand for natural molecules with antibiofilm and anthelmintic properties. Hence, we hypothesized that molecules with a scaffold structurally similar to that of cinnamaldehyde might act as dual inhibitors against fungal biofilms and helminths. In this regard, eleven cinnamaldehyde analogs were tested to determine their effects on fungal Candida albicans biofilm and nematode Caenorhabditis elegans. α-Methyl and trans-4-methyl cinnamaldehydes efficiently inhibited C. albicans biofilm formation (>90% inhibition at 50 μg/mL) with minimum inhibitory concentrations (MICs) of ≥ 200 μg/mL and 4-bromo and 4-chloro cinnamaldehydes exhibited anthelmintic property at 20 μg/mL against C. elegans. α-Methyl and trans-4-methyl cinnamaldehydes inhibited hyphal growth and cell aggregation. Scanning electron microscopy was employed to determine the surface architecture of C. albicans biofilm and cuticle of C. elegans, and confocal laser scanning microscopy was used to determine biofilm characteristics. The perturbation in gene expression of C. albicans was investigated using qRT-PCR analysis and α-methyl and trans-4-methyl cinnamaldehydes exhibited down-regulation of ECE1, IFD6, RBT5, UCF1, and UME6 and up-regulation of CHT4 and YWP1. Additionally, molecular interaction of these two molecules with UCF1 and YWP1 were revealed by molecular docking simulation. Our observations collectively suggest α-methyl and trans-4-methyl cinnamaldehydes are potent biofilm inhibitors and that 4-bromo and 4-chloro cinnamaldehydes are anthelmintic agents. Efforts are required to determine the range of potential therapeutic applications of cinnamaldehyde analogs.

Exploring the potential of Cinnamomum zeylanicum oil against drug resistant Helicobacter pylori-producing cytotoxic genes

Thirty-one of sixty dyspeptic patients tested positive for Helicobacter pylori colonization in this study, as determined by histopathology and 16S rRNA. The cytotoxin-associated gene A (cagA) and vacuolating cytotoxin A (vacA) genes were found in 67.7 and 93.5% of H. pylori patients, respectively. The cagA gene was found to be associated with 100% of patients with duodenal erosion and ulceration identified via endoscopy examination. In addition, 86.7% of patients with cancerous and precancerous lesions, glandular atrophy, and intestinal metaplasia identified via histopathology examination. The vacA s1m1 mutation was associated with more severe forms of gastric erosion and ulceration, as well as the presence of precancerous and cancerous lesions. Eighteen (64.3%) of the twenty-eight isolates were classified as multi-drug resistant (MDR) or pan-drug resistant (PDR) H. pylori. Due to a resurgence of interest in alternative therapies derived from plants as a result of H. pylori resistance to the majority of commonly used antibiotics, the inhibitory activity of five essential oils extracted from some commonly used medicinal plants was evaluated in vitro against drug-resistant H. pylori clinical isolates. Cinnamomum zeylanicum essential oil demonstrated the highest anti-H. pylori activity when compared to the other essential oils tested. Cinnamaldehyde was the most abundant compound in C. zeylanicum (65.91%). The toxicological evaluation established the safety of C. zeylanicum oil for human use. As a result, C. zeylanicum essential oil may represent a novel antibacterial agent capable of combating drug-resistant H. pylori carrying cytotoxin genes.

Enhancement of Biofunctionalization by Loading Manuka Oil on TiO2 Nanotubes

Metallic implants (mesh) for guided bone regeneration can result in foreign body reactions with surrounding tissues, infection, and inflammatory reactions caused by micro-organisms in the oral cavity after implantation. This study aimed to reduce the possibility of surgical failure caused by microbial infection by loading antibacterial manuka oil in a biocompatible nanostructure surface on Ti and to induce stable bone regeneration in the bone defect. The manuka oil from New Zealand consisted of a rich β-triketone chemotype, leptospermone, which showed strong inhibitory effects against several bacteria, even at very low oil concentrations. The TiO₂ nanotubular layer formed by anodization effectively enhanced the surface hydrophilicity, bioactivity, and fast initial bone regeneration. A concentration of manuka oil in the range of 0.02% to less than 1% can have a synergistic effect on antibacterial activity and excellent biocompatibility. A manuka oil coating (especially with a concentration of 0.5%) on the TiO₂ nanotube layer can be expected not only to prevent stenosis of the connective tissue around the mesh and inflammation by microbial infection but also to be effective in stable and rapid bone regeneration.

Cinnamaldehyde as antimicrobial in cellulose-based dental appliances

AIMS

In the context of minor orthodontic intervention using clear aligner technologies, we determined antimicrobial properties of a cellulose-based material loaded with essential oils such as cinnamaldehyde.

METHODS AND RESULTS

Isothermal microcalorimetry was used to assess the growth of bacterial biofilms at the interface between the tested material and the solid growth medium. The calorimetric data were analyzed using conventional growth models (Gompertz and Richards), and inhibition at 12 and 24 h was calculated.

CONCLUSIONS

The tested material showed antimicrobial properties against Staphylococcus epidermidis as well as Streptococcus mutans and Streptococcus mitis clinical isolates. The inhibition was more pronounced against S. epidermidis, for which growth rate was reduced by 70% and lag phase was extended by 12 h. For S. mutans and S. mitis, the decrease in growth rate was 20% and 10%, and the lag phase increased by 2 and 6 h, respectively.

SIGNIFICANCE AND IMPACT

Clear aligners for minor teeth alignment are becoming very popular. As they must be worn for at least 22 h per day for up to 40 weeks, it is important that they remain clean and do not promote caries formation or other oral infections. Therefore, introducing material with antimicrobial properties is expected to maintain oral hygiene during the aligner therapy. Here, we demonstrate the use of cinnamaldehyde for reducing microbial growth and biofilm formation on cellulose-based dental clear aligners.

Essential oils as antimicrobial and anti-adhesion agents against bacteria Salmonella Typhimurium and Staphylococcus aureus, and yeasts Candida albicans and Saccharomyces cerevisiae

A serious global problem with the increasing resistance of microorganisms to currently used antimicrobials has opened up the promotional research in the identification of new, more effective drugs with a broad spectrum of antimicrobial activities. Plant essential oils, due to the large biological and structural diversity of their components, are known to have many potential benefits. This study aimed to evaluate the antimicrobial and anti-adhesion activity of fifteen essential oils and their compounds against two bacterial and two yeast species responsible for food spoilage and infectious diseases. Antimicrobial activity was determined by testing the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC) and the minimum fungicidal concentration (MFC) of essential oils and compounds. The essential oils of Cinnamomum zeylanicum and Eugenia caryophyllus showed the highest antimicrobial activity with MICs ranging from 0.078 to 1.25 mg/mL, and 0.039 to 1.25 mg/mL, respectively. On the other hand, essential oils of Eucalypti aetheroleum and Salvia officinalis had significantly weaker antimicrobial properties than the others. Further, MICs were used to assess the inhibition of adhesion of bacteria Salmonella Typhimurium ATCC 25923 and Staphylococcus aureus ATCC 14208, and yeasts Candida albicans ATCC 10231 and Saccharomyces cerevisiae ATCC 9763 in a microtiter plate using the crystal violet staining method. Based on the percentage of adhesion inhibition, yeast S. cerevisiae ATCC 9763 showed a high level of antimicrobial resistance. E. caryophyllus had the strongest effect with inhibition up to 73%. Consistent with the antimicrobial susceptibility results, the most active anti-adhesion compounds were carvacrol and thymol. Considering the role of biofilm in food spoilage and clinical diseases, inhibition of the initial phase of biofilm formation by natural antimicrobial agents may be an alternative to commonly used synthetic ones.