Fragrance material review on cinnamaldehyde

Antimicrobial and hydrophobic cellulose paper prepared by covalently attaching cinnamaldehyde for strawberries preservation

The demand for paper-based packaging materials as an alternative to incumbent disposable petroleum-derived polymers for food packaging applications is ever-growing. However, typical paper-based formats are not suitable for use in unconventional applications due to inherent limitations (e.g., excessive hydrophilicity, lack antimicrobial ability), and accordingly, enabling new capabilities is necessity. Herein, a simple and environmentally friendly strategy was proposed to introduce antimicrobial and hydrophobic functions to cellulose paper through successive chemical grafting of 3-aminopropyltriethoxysilane (APS) and cinnamaldehyde (CA). The results revealed that cellulose paper not only showed long-term antibacterial effect on different bacteria, but also inhibited a wide range of fungi. Encouragingly, the modified paper, which is fluorine-free, displays a high contact angle of 119.7°. Thus, even in the wet state, the modified paper can still maintain good mechanical strength. Meanwhile, the multifunctional composite papers have excellent biocompatibility and biodegradability. Compared with ordinary cellulose paper, multifunctional composite paper can effectively prolong the shelf life of strawberries. Therefore, the multifunctional composite paper represents good application potential as a fruit packaging material.

Cinnamaldehyde-enriched Pickering emulsions stabilized by modified cellulose I and II nanocrystals recycled from maple leaves for shrimp preservation

The utilization of biomass waste has attracted much interest, but such attention hasn't been paid to the abundant fallen maple leaves in Canada. Herein, we aim to obtain cellulose nanocrystals (CNCs) from maple leaves and explore their potential applications as sustainable stabilizers of Pickering emulsions for the preservation of food products with complicated structures. The results reveal that two types of CNCs were extracted from maple leaves at different alkaline conditions. Octenyl succinic anhydride was selected to modify rod-like CNCs, and the CNC-stabilized oil-in-water Pickering emulsions showed excellent stability. Cinnamaldehyde, a model antibacterial compound, was incorporated in the Pickering emulsions, which exhibited the improved storage stability and sustained antibacterial capacity towards both Gram-positive and Gram-negative bacteria. Shrimp was chosen as an example that has complicated surface structure and is hard to disinfect, and the CNC-stabilized Pickering emulsions could be easily sprayed on the surface of shrimp to inhibit the proliferation of bacteria and inactivate the psychrophilic bacteria responsible for shrimp spoilage at refrigerated condition, so as to preserve the quality of shrimp. Therefore, the current work suggests the possibility to utilize fallen maple leaves as a promising source of CNCs and the applications of CNC-stabilized Pickering emulsions in seafood preservation.

Green Alternatives as Antimicrobial Agents in Mitigating Periodontal Diseases: A Narrative Review

Periodontal diseases and dental caries are the most common infectious oral diseases impacting oral health globally. Oral cavity health is crucial for enhancing life quality since it serves as the entranceway to general health. The oral microbiome and oral infectious diseases are strongly correlated. Gram-negative anaerobic bacteria have been associated with periodontal diseases. Due to the shortcomings of several antimicrobial medications frequently applied in dentistry, the lack of resources in developing countries, the prevalence of oral inflammatory conditions, and the rise in bacterial antibiotic resistance, there is a need for reliable, efficient, and affordable alternative solutions for the prevention and treatment of periodontal diseases. Several accessible chemical agents can alter the oral microbiota, although these substances also have unfavorable symptoms such as vomiting, diarrhea, and tooth discoloration. Natural phytochemicals generated from plants that have historically been used as medicines are categorized as prospective alternatives due to the ongoing quest for substitute products. This review concentrated on phytochemicals or herbal extracts that impact periodontal diseases by decreasing the formation of dental biofilms and plaques, preventing the proliferation of oral pathogens, and inhibiting bacterial adhesion to surfaces. Investigations examining the effectiveness and safety of plant-based medicines have also been presented, including those conducted over the past decade.

Odorant-responsive biological receptors and electronic noses for volatile organic compounds with aldehyde for human health and diseases: A perspective review

Volatile organic compounds (VOCs) are gaseous chemicals found in ambient air and exhaled breath. In particular, highly reactive aldehydes are frequently found in polluted air and have been linked to various diseases. Thus, extensive studies have been carried out to elucidate disease-specific aldehydes released from the body to develop potential biomarkers for diagnostic purposes. Mammals possess innate sensory systems, such as receptors and ion channels, to detect these VOCs and maintain physiological homeostasis. Recently, electronic biosensors such as the electronic nose have been developed for disease diagnosis. This review aims to present an overview of natural sensory receptors that can detect reactive aldehydes, as well as electronic noses that have the potential to diagnose certain diseases. In this regard, this review focuses on eight aldehydes that are well-defined as biomarkers in human health and disease. It offers insights into the biological aspects and technological advances in detecting aldehyde-containing VOCs. Therefore, this review will aid in understanding the role of aldehyde-containing VOCs in human health and disease and the technological advances for improved diagnosis.

Cinnamaldehyde causes developmental neurotoxicity in zebrafish via the oxidative stress pathway that is rescued by astaxanthin

Toxicology studies provide a reliable dose range for the use of compounds. Zebrafish show unique advantages in toxicology research. Cinnamaldehyde (Cin) is one of the main active compounds isolated from Cinnamon trees and other species of the genus Cinnamomum. In this study, we investigated the developmental neurotoxicity of cinnamaldehyde in zebrafish and preliminarily explored its underlying mechanism. Cinnamaldehyde causes developmental neurotoxicity in zebrafish, as evidenced by the damage to ventricular structures, eye malformations, shortened body length, trunk curvature, decreased neuronal fluorescence, and pericardial oedema. Moreover, it can induce abnormal behaviour and gene expression in zebrafish. After treatment with the oxidative stress inhibitor astaxanthin, the behaviour and abnormal gene expression were reversed. All of these data demonstrated that the developmental neurotoxicity of cinnamaldehyde might be attributed to oxidative stress. In addition, this study also confirmed that zebrafish is a reliable model for toxicity studies.

Homogeneity of Supported Single-Atom Active Sites Boosting the Selective Catalytic Transformations

Selective conversion of specific functional groups to desired products is highly important but still challenging in industrial catalytic processes. The adsorption state of surface species is the key factor in modulating the conversion of functional groups, which is correspondingly determined by the uniformity of active sites. However, the non-identical number of metal atoms, geometric shape, and morphology of conventional nanometer-sized metal particles/clusters normally lead to the non-uniform active sites with diverse geometric configurations and local coordination environments, which causes the distinct adsorption states of surface species. Hence, it is highly desired to modulate the homogeneity of the active sites so that the catalytic transformations can be better confined to the desired direction. In this review, the construction strategies and characterization techniques of the uniform active sites that are atomically dispersed on various supports are examined. In particular, their unique behavior in boosting the catalytic performance in various chemical transformations is discussed, including selective hydrogenation, selective oxidation, Suzuki coupling, and other catalytic reactions. In addition, the dynamic evolution of the active sites under reaction conditions and the industrial utilization of the single-atom catalysts are highlighted. Finally, the current challenges and frontiers are identified, and the perspectives on this flourishing field is provided.

Bio-based antibacterial food packaging films and coatings containing cinnamaldehyde: A review

As a typical bioactive compound from the bark and leaves of the trees of the genus Cinnamomum, cinnamaldehyde (CIN) is natural and safe. Its excellent antibacterial activity against various foodborne microorganisms is growingly regarded as a promising additive for improving and enhancing the properties of bio-based packaging films/coatings. This review systematically summarized the bio-based food packaging films/coatings containing CIN developed recently. The effects of CIN incorporation on physical and chemical properties of the antibacterial food packaging films/coatings, including thickness, color index, transparency, water content, water solubility, water contact angle, mechanical performances, water barrier performances, and antibacterial performances, were discussed. Simultaneously, this work also concluded that an explanation of the antibacterial mechanism of CIN and preparation methods of bio-based packaging films/coatings containing CIN/CIN carriers. Notably, the incorporation of CIN into the films/coatings could enhance their antibacterial performance extend the shelf-life of various foods, such as fish, meats, vegetables, fruits, and other perishable food, while improving their physical and chemical properties. Although incorporating CIN into food packaging films/coatings has been extensively studied, long-term follow-up research on the human safety of active food packaging films/coatings containing CIN needs to be carried out.

Cinnamaldehyde Relieves Induced Hepatocellular Carcinoma in Rat Model via Targeting Wnt/β-Catenin Pathway

Cinnamaldehyde (CA) is a natural compound that has promising biological activity. The current study investigates the antitumor activity of CA in thioacetamide induced hepatocellular carcinoma (HCC) in rats through targeting the Wnt/β-catenin pathway and evaluates the capability of CA to relieve hepatocytes oxidative stress in the HCC-rat model. After 16 weeks of HCC induction by thioacetamide (TAA), rats were treated for 7 consecutive weeks with CA daily; i.p. injection, Alpha-fetoprotein (AFP) level, necroinflammatory score and fibrosis percentage were measured to assess HCC development. The Wnt/β-catenin pathway was evaluated by measuring the hepatic protein level of Wnt-3a, β-catenin, cyclin D, matrix metalloproteinase-9 (MMP-9), and vascular endothelial growth factor (VEGF). Furthermore, hepatocytes’ oxidative stress was assessed by measuring hepatic GSH and MDA contents. Results showed that CA was significantly inhibiting the Wnt/β-catenin pathway through the downregulation of hepatic Wnt-3a, β-catenin, cyclin D, MMP-9, and VEGF. Moreover, CA ameliorates hepatocytes’ oxidative stress via lowering hepatic MDA content and rising hepatic GSH content. Thus, in conclusion, CA is a promising treatment for HCC. It not only has an effective antitumor activity but also ameliorates hepatocytes’ oxidative stress.

Analysis of Fragrance Allergens in Personal Care Products, Toys, and Water Samples: A Review

Fragrance allergens (FAs) refer to these volatile or semi-volatile fragrance compounds that can cause irritation and negative reactions. A large number of emerging FAs are widely used in household goods, and cause contact allergy or allergic contact dermatitis in eczema population and the general population. It shows an increasing prevalence and is regarded as a concern to public health. Recently, more and more studies have focused on the analytical methods of FAs in a variety of samples with different matrices. Therefore, a systematic and comprehensive overview of recent progress of analysis of FAs in various samples is needed. In this review, the physical and chemical properties, applications, hazards, and the recent advances of sample preparation and determination methods of common FAs in personal care products, toys, and water samples are systematically and comprehensively summarized. Meanwhile, this review also discusses the advantages and limitations of different sample pretreatment and detection methods, thus offering a deep-going discussion of the development and future trends in this area.

Selective Rhodium-Catalyzed Hydroformylation of Terminal Arylalkynes and Conjugated Enynes to (Poly)enals Enabled by a π-Acceptor Biphosphoramidite Ligand

The hydroformylation of terminal arylalkynes and enynes offers a straightforward synthetic route to the valuable (poly)enals. However, the hydroformylation of terminal alkynes has remained a long-standing challenge. Herein, an efficient and selective Rh-catalyzed hydroformylation of terminal arylalkynes and conjugated enynes has been achieved by using a new stable biphosphoramidite ligand with strong π-acceptor capacity, which affords various important E-(poly)enals in good yields with excellent chemo- and regioselectivity at low temperatures and low syngas pressures.

Poly(ethylene glycol)s With a Single Cinnamaldehyde Acetal Unit for Fabricating Acid-Degradable Hydrogel

A synthetic route to prepare a poly(ethylene glycol) with a single cinnamaldehyde acetal unit in the polymer chain, was successfully established using a newly synthesized cinnamaldehyde acetal diethylene glycol (CADEG) as initiator. This HO-PEG(ca)-OH is non-toxic and would be degraded into a cinnamaldehyde and two PEG diols in acid environment. A whole polyethylene glycol based hydrogel was easily fabricated by thiol-ene “click” reaction in alkalescence aqueous solution using acrylate-PEG(ca)-acrylate and 4-arm PEG-SH as raw materials at room temperature. The gel time was dependent on the pH of the solution and its alkalinity can promote gel. The hydrogel can be degradable in acidic conditions and the stronger the acidity, the faster the degradation. This HO-PEG(ca)-OH also can be used in synthesis of cinnamaldehyde containing PEG derivatives, block copolymers or other acid degradable materials.

A Multi-Enzyme Cascade for the Production of High-Value Aromatic Compounds

Cascade reactions are the basis of life in nature and are adapted to research and industry in an increasing manner. The focus of this study is the production of the high-value aromatic ester cinnamyl cinnamate, which can be applied in flavors and fragrances. A three-enzyme cascade was established to realize the synthesis, starting from the corresponding aldehyde with in situ cofactor regeneration in a two-phase system. After characterization of the enzymes, a screening with different organic solvents was carried out, whereby xylene was found to be the most suitable solvent for the second phase. The reaction stability of the formate dehydrogenase (FDH) from Candida boidinii is the limiting step during cofactor regeneration. However, the applied enzyme cascade showed an overall yield of 54%. After successful application on lab scale, the limitation by the FDH was overcome by immobilization of the enzymes and an optimized downstream process, transferring the cascade into a miniplant. The upscaling resulted in an increased yield for the esterification, as well as overall yields of 37%.

Acaricidal activity of (E)-cinnamaldehyde and α-bisabolol on populations of Rhipicephalus microplus (Acari: Ixodidae) with different resistance profiles

This study aimed to investigate the acaricidal activity of (E)-cinnamaldehyde and α-bisabolol on populations of Rhipicephalus microplus with different resistance profiles. The adult immersion test (AIT) was used to characterize the susceptibility of tick populations (50 field populations) to synthetic acaricides: deltamethrin, amitraz, and chlorfenvinphos. The larval packet test (LPT) was used to determine the LC₅₀ values for (E)-cinnamaldehyde (populations 1-25) and α-bisabolol (populations 26-50) at the concentrations of 0.31, 0.62, 1.25, 2.0, 2.5, 5.0 and 10.0 mg/mL. The susceptible strain Porto Alegre (POA) was used as a reference for calculating the resistance ratio (RR). In the AIT, deltamethrin did not show efficacy >95 % for any of the populations, whereas amitraz and chlorfenvinphos have presented efficacy >95 % for three (6 %) and 15 (30 %) populations, respectively. In the LPT, the LC₅₀ values of (E)-cinnamaldehyde and α-bisabolol varied from 0.23 to 2.36 mg/mL and 1.57-3.01 mg/mL, respectively. The RR₅₀ for (E)-cinnamaldehyde showed 20 (80 %) populations with values <1.0 and no population with values>1.5. As for α-bisabolol, only two (8%) populations have presented RR₅₀ <1.0, whereas three (12 %) populations showed incipient resistance to this sesquiterpene (RR₅₀ between 1.5 and 2.0). The results indicate that all studied tick populations showed low susceptibility to at least one of the commercial acaricides tested. In addition, comparison between the LC₅₀ values of (E)-cinnamaldehyde and α-bisabolol for the field populations and the susceptible strain POA suggests that there is no cross-resistance of (E)-cinnamaldehyde and α-bisabolol for the tick populations evaluated, and that the differences in the LC₅₀ values are due to population variations.

Control of pathogenic and spoilage bacteria in meat and meat products by high pressure: Challenges and future perspectives

High-pressure processing is among the most widely used nonthermal intervention to reduce pathogenic and spoilage bacteria in meat and meat products. However, resistance of pathogenic bacteria strains in meats at the current maximum commercial equipment of 600 MPa questions the ability of inactivation by its application in meats. Pathogens including Escherichia coli, Listeria, and Salmonelle, and spoilage microbiota including lactic acid bacteria dominate in raw meat, ready-to-eat, and packaged meat products. Improved understanding on the mechanisms of the pressure resistance is needed for optimizing the conditions of pressure treatment to effectively decontaminate harmful bacteria. Effective control of the pressure-resistant pathogens and spoilage organisms in meats can be realized by the combination of high pressure with application of mild temperature and/or other hurdles including antimicrobial agents and/or competitive microbiota. This review summarized applications, mechanisms, and challenges of high pressure on meats from the perspective of microbiology, which are important for improving the understanding and optimizing the conditions of pressure treatment in the future.

One-Step Dynamic Imine Chemistry for Preparation of Chitosan-Stabilized Emulsions Using a Natural Aldehyde: Acid Trigger Mechanism and Regulation and Gastric Delivery

Chitosan is a polysaccharide widely used as a structuring agent in foods and other materials because of its positive charge (amino groups). At present, however, it is difficult to form and stabilize emulsions using chitosan due to its high hydrophilicity. In this study, oil-in-water emulsions were prepared using a one-pot green-chemistry method. The chitosan and aldehyde molecules were in situ interfacially conjugated during homogenization, which promoted the adsorption of chitosan onto the oil droplet surfaces where they created a protective coating. The universality of this method was verified by using chitosan with different molecular weights and four kinds of natural aldehydes [cinnamaldehyde (CA), citral (CT), citronella (CN), and vanillin (VL)]. Chitosan with higher molecular weight facilitated the formation of emulsions. By harnessing the dynamic covalent nature of imine bonds, chitosan emulsions with an imine link display dynamic behavior with acid-catalyzed hydrolysis. The aldehyde structure could control the pH point of trigger for breakdown of emulsions, which was 1.0, 3.0, 4.0, and 4.0 for CA emulsion, CT emulsion, CN emulsion, and VL emulsion, respectively. At pH 6.5, aldehyde helped to decrease the interfacial tension of chitosan to about 10 mN/m, while this value would increase if the pH decreased by adding acid during the measurement. Chemical kinetics studies indicated that the hydrophobicity and conjugation effect of the aldehyde together determined the trigger points and properties of the emulsion. Finally, we used the optimized emulsions to encapsulate and control the release of curcumin. The gastric release behavior of the curcumin depended on aldehyde structure: VL > CN > CT ≈ CA. Hence, a tailor-made trigger release emulsion system can be achieved by rational selection and design of aldehyde structure to control hydrophobicity and conjugation effect of aldehydes.

Untargetted Metabolomic Exploration of the Mycobacterium tuberculosis Stress Response to Cinnamon Essential Oil

The antimycobacterial activity of cinnamaldehyde has already been proven for laboratory strains and for clinical isolates. What is more, cinnamaldehyde was shown to threaten the mycobacterial plasma membrane integrity and to activate the stress response system. Following promising applications of metabolomics in drug discovery and development we aimed to explore the mycobacteria response to cinnamaldehyde within cinnamon essential oil treatment by untargeted liquid chromatography–mass spectrometry. The use of predictive metabolite pathway analysis and description of produced lipids enabled the evaluation of the stress symptoms shown by bacteria. This study suggests that bacteria exposed to cinnamaldehyde could reorganize their outer membrane as a physical barrier against stress factors. They probably lowered cell wall permeability and inner membrane fluidity, and possibly redirected carbon flow to store energy in triacylglycerols. Being a reactive compound, cinnamaldehyde may also contribute to disturbances in bacteria redox homeostasis and detoxification mechanisms.

Antibacterial Activity of Commercial Phytochemicals against Aeromonas Species Isolated from Fish

Antimicrobial activities of phytochemicals-trans-cinnamaldehyde (TC), ferulic acid (FA), p-coumaric acid (p-CA), caffeic acid (CA), chlorogenic acid (CHA), Thymus vulgaris essential oil (TO), Eugenia caryophyllus essential oil (ECO), and Melaleuca alternifolia oil (TTO) against Aeromonas species-were assessed. Growth of all Aeromonas salmonicida subsp. salmonicida and almost all Aeromonas sobria strains was inhibited by TC at concentration 0.01 mg/mL, and for most Aeromonas hydrophila strains minimal inhibitory concentrations (MIC) ranged from 0.01 to 0.19 mg/mL. The inhibitory effect of TC against A. salmonicida subsp. salmonicida was comparable to the effect of oxytetracycline, and in the case of A. salmonicida subsp. salmonicida and A. sobria was higher compared to gentamicin. MIC of FA, p-CA, and CA for most strains ranged from 1.56 to 3.12 mg/mL, and MIC values of TO for most strains ranged from 0.39 to 0.78 mg/mL. TO and TC at the concentrations below ½ MIC values used in mixtures exhibited strong synergism. ECO and TC showed synergy in mixture of ⅛ MIC of ECO and ¼ MIC of TC. TC and TO exhibited the strongest inhibitory and bactericidal effect against investigated Aeromonas species, and they are a promising alternative to the use of antibiotics in controlling the growth of these fish pathogens.

The effects of cinnamaldehyde on acute or chronic stress-induced anxiety-related behavior and locomotion in male mice

Anxiety and stress are considered as universal psychiatric exhibitions of the present societies and lifestyles. Several experiments have been conducted to examine natural anxiolytic agents to find out an alternative to synthetic anxiolytic drugs. The present study investigated the anxiolytic effects of cinnamaldehyde (Cin) on mice behavior in the elevated plus maze (EPM) and open field (OF) tests. Sixty male Swiss mice, weighing 20-30 g, were divided into six groups including: acute stress + mazola oil; chronic stress + oil; acute stress + Cin (20 mg/kg); chronic stress + Cin; non-stress + oil; and non-stress + Cin groups. The groups were administered for seven days (once a day). The acute stress + Cin group showed a meaningful rise in the percentage of entries into the open arms compared to the acute stress + oil group (p <.05). The percentage of time spent in the open arms in the chronic stress + Cin group was significantly higher compared to the chronic stress + oil group (p < .01). The percentage of entries into the open arms increased significantly (p < .01) in the chronic stress + Cin group in comparison with the chronic stress + oil group. The Cin treated groups showed significant increases in the time spent in the center area and in the number of entries into the center area compared with the oil treated groups in OF test. The number of entries into the arms (total activity), as well as locomotor activity was not significant among groups. The results of the present study indicated that Cin, as a natural product, might have anxiolytic effects in mice behavior in the EPM and OF tests. Lay summary  The results demonstrated that the administration of cinnamaldehyde (Cin) produced anxiolytic effects in mice. Natural antioxidant products have been reported effective for anxiety. Synthetic medications have notable adverse effects. Therefore, these natural substances with broad therapeutic applicability are able to reduce anxiety-related behavior with rare side effects. According to the results, Cin could decrease anxiety-related behavior in mice.

Dehydrogenative β-Arylation of Saturated Aldehydes Using Transient Directing Groups

An unprecedented cross-dehydrogenative-coupling (CDC) reaction of saturated aldehyde β-C-H with arenes to form cinnamaldehydes via the cleavages of four C-H bonds has been developed. The reaction possesses complete E-stereoselectivity for the C═C double bond. The protocol is featured by atom and step economy, mild reaction conditions, and convenient operation.

Modular synthesis of (E)-cinnamaldehydes directly from allylarenes via a metal-free DDQ-mediated oxidative process

An efficient synthesis of (E)-cinnamaldehydes by a metal-free DDQ-mediated oxidative transformation of allylarenes was developed. The protocol provides a practical method to prepare diverse (E)-cinnamaldehydes with broad functional group tolerance in good to excellent yields, including easy access to natural products randainal and geranyloxy sinapyl aldehyde from plant extracts. Finally, the mechanism of a single-electron transfer process was proposed.

Antibacterial effects of 18 medicinal plants used by the Khyang tribe in Bangladesh

CONTEXT

The resistance of bacteria to antibiotics is raising serious concern globally. Asian medicinal plants could improve the current treatment strategies for bacterial infections. The antibacterial properties of medicinal plants used by the Khyang tribe in Bangladesh have not been investigated.

OBJECTIVE

The present study examines the antibacterial properties of 18 medicinal plants used by the Khyang tribe in day-to-day practice against human pathogenic bacteria.

MATERIALS AND METHODS

Leaves, bark, fruits, seeds, roots and rhizomes from collected plants were successively extracted with hexane, ethyl acetate and ethanol. The corresponding 54 extracts were tested against six human pathogenic bacteria by broth microdilution assay. The antibacterial mode of actions of phytoconstituents and their synergistic effect with vancomycin and cefotaxime towards MRSA was determined by time-killing assay and synergistic interaction assay, respectively.

RESULTS AND DISCUSSION

Hexane extract of bark of Cinnamomum cassia (L.) J. Presl. (Lauraceae) inhibited the growth of MRSA, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii with MIC values below 100 µg/mL. From this plant, cinnamaldehyde evoked at 4 × MIC in 1 h an irreversible decrease of MRSA count Log10 (CFU/mL) from 6 to 0, and was synergistic with vancomycin for MRSA with fractional inhibitory concentration index of 0.3.

CONCLUSIONS

Our study provides evidence that the medicinal plants in Bangladesh have high potential to improve the current treatment strategies for bacterial infection.

Novel cinnamaldehyde-based aspirin derivatives for the treatment of colorectal cancer

Colorectal cancer (CRC) is a leading cause of mortality worldwide. Current treatments of CRC involve anti-cancer agents with relatively good efficacy but unselectively target both cancer and non-cancer cells. Thus, there is a need to discover and develop novel CRC therapeutics that have potent anti-cancer effects, but show reduced off-target cell effects. Here, a novel series of cinnamaldehyde-based aspirin derivatives were designed and synthesized. Biological evaluation indicated that the most active compound 1f exhibited more than 10-fold increase in the anti-proliferation efficacy in HCT-8 cells compared to the parent compounds. Its effects were similarly reproduced in another CRC cell line, DLD-1, but with 7- to 11-fold less inhibitory activity in non-tumorigenic colon cells. Flow cytometry analysis showed that 1f induced cell cycle arrest and apoptosis, which was further validated with immunoblot analysis of the relative protein levels of cleaved caspase 3 and PARP as well as the ROS production in CRC cells. More so, 1f significantly inhibited the growth of implanted CRC in vivo in mouse xenograft model. Taken together, our results show that cinnamaldehyde-based aspirin derivatives such as 1f show promise as novel anti-CRC agent for further pharmaceutical development.

Can the epoxides of cinnamyl alcohol and cinnamal show new cases of contact allergy?

BACKGROUND

Cinnamyl alcohol is considered to be a prohapten and prehapten with cinnamal as the main metabolite. However, many individuals who are allergic to cinnamyl alcohol do not react to cinnamal. Sensitizing epoxides of cinnamyl alcohol and cinnamal have been identified as metabolites and autoxidation products of cinnamyl alcohol.

OBJECTIVE

To investigate the clinical relevance of contact allergy to epoxycinnamyl alcohol and epoxycinnamal.

METHODS

Irritative effects of the epoxides were investigated in 12 dermatitis patients. Epoxycinnamyl alcohol and epoxycinnamal were patch tested in 393 and 390 consecutive patients, respectively. In parallel, cinnamyl alcohol and cinnamal were patch tested in 607 and 616 patients, respectively.

RESULTS

Both epoxides were irritants, but no more positive reactions were detected than when testing was performed with cinnamyl alcohol and cinnamal. Late allergic reactions to epoxycinnamyl alcohol were observed. In general, patients with late reactions showed doubtful or positive reactions to cinnamal and fragrance mix I at regular patch testing.

CONCLUSION

The investigated epoxides are not important haptens in contact allergy to cinnamon fragrance. The high frequency of fragrance allergy among patients included in the irritancy study showed the difficulty of suspecting fragrance allergy on the basis of history; patch testing broadly with fragrance compounds is therefore important.

An approach to testing undiluted e-cigarette aerosol in vitro using 3D reconstituted human airway epithelium

The data presented here show that to provide an estimate of the relative cytotoxicity and therefore potency of e-cigarettes, undiluted aerosol techniques can be used. With the emergence of electronic nicotine delivery systems, fit-for-purpose in vitro screening methods are required. Reconstituted 3D human airway epithelium, was exposed to undiluted aerosols at the air-liquid interface, using a Vitrocell VC 10. TEER, cilia beat frequency and cytotoxic responses were assessed. Using two smoking regimes (ISO and HCI) a 3R4F reference cigarette, produced IC₅₀s of 5.2 and 2.1 min, 1458 ng/mL and 1640 ng/mL nicotine respectively. Using an open tank e-cigarette device, a full cytotoxicity dose-response curve was obtained giving an IC₅₀ of 30 min with corresponding nicotine of 10,957 ng/mL, 6-14 times less cytotoxic than cigarette smoke. A commonly used e-liquid flavourant cinnamaldehyde and known skin sensitizer was added to the standard e-liquid formulation and used as an aerosolised positive control, at 0.1, 0.025, 0.01 and 0%, demonstrating a full dose response. The delivery of undiluted aerosols in vitro has resulted in increased method sensitivity, throughput and quantitative e-cigarette comparisons. A positive control aerosol generated from a 'safe' e-liquid benchmark can inform risk assessments on supportable levels of flavour ingredients.

Antibacterial effects of cinnamon (Cinnamomum zeylanicum) bark essential oil on Porphyromonas gingivalis

The objective of this study was to investigate the antibacterial effects of cinnamon (Cinnamomum zeylanicum) bark essential oil (CBEO) and its principal constituent cinnamaldehyde against Porphyromonas gingivalis and to elucidate the antibacterial mechanism. GC-MS analysis showed that cinnamaldehyde was the major constituent in CBEO (57.97%). The minimum inhibition concentrations (MICs) of CBEO and cinnamaldehyde were 6.25 μg/mL and 2.5 μM for P. gingivalis, respectively. Nucleic acid and protein leakage was observed with increasing concentrations of CBEO and cinnamaldehyde. Additionally, propidium iodide uptake assays revealed CBEO and cinnamaldehyde at 1 × MIC impaired P. gingivalis membrane integrity by enhancing cell permeability. Morphological changes in P. gingivalis cells were observed by scanning electron microscopy, which indicated cell membrane destruction. To further determine the anti-biofilm effect, relative biofilm formation and established biofilms were examined, which demonstrated that both CBEO and cinnamaldehyde at sub-MIC levels inhibited P. gingivalis biofilm formation by 74.5% and 67.3% separately, but only CBEO slightly decreased established biofilms by 33.5% at 4 × MIC. These results suggest the potential of CBEO as a natural antimicrobial agent against periodontal disease. Furthermore, cinnamaldehyde was confirmed to be the antibacterial substance of CBEO with inhibitory action against P. gingivalis.

In Situ Interfacial Conjugation of Chitosan with Cinnamaldehyde during Homogenization Improves the Formation and Stability of Chitosan-Stabilized Emulsions

The emulsifying properties of a natural cationic polysaccharide (chitosan) were improved by in situ conjugation with a natural essential oil (cinnamaldehyde, CA) during homogenization. In the absence of CA, chitosan-coated medium-chain triglyceride droplets were highly susceptible to creaming and coalescence at pH values ranging from 1 to 6.5. However, incorporation of relatively low levels of CA in the oil phase greatly improved the formation and stability of oil-in-water emulsions. These effects were attributed to two main factors: (i) covalent binding of lipophilic CA moieties to hydrophilic chitosan chains leading to conjugates with a good surface activity and (ii) interfacial cross-linking of adsorbed chitosan layers by CA leading to the formation of a rigid polymeric coating around the lipid droplets, which improved their stability against coalescence. The encapsulation technique developed in this study may be useful for applications in a range of commercial products; regulatory and flavor issues associated with chitosan and CA would have to be addressed.

Chemistry, Antimicrobial Mechanisms, and Antibiotic Activities of Cinnamaldehyde against Pathogenic Bacteria in Animal Feeds and Human Foods

Cinnamaldehyde is a major constituent of cinnamon essential oils produced by aromatic cinnamon plants. This compound has been reported to exhibit antimicrobial properties in vitro in laboratory media and in animal feeds and human foods contaminated with disease-causing bacteria including Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Listeria monocytogenes, and Salmonella enterica. This integrated review surveys and interprets our current knowledge of the chemistry, analysis, safety, mechanism of action, and antibiotic activities of cinnamaldehyde in food animal (cattle, lambs, calves, pigs, poultry) diets and in widely consumed liquid (apple, carrot, tomato, and watermelon juices, milk) and solid foods. Solid foods include various fruits (bayberries, blueberries, raspberries, and strawberries), vegetables (carrots, celery, lettuce, spinach, cucumbers, and tomatoes), meats (beef, ham, pork, and frankfurters), poultry (chickens and turkeys), seafood (oysters and shrimp), bread, cheese, eggs, infant formula, and peanut paste. The described findings are not only of fundamental interest but also have practical implications for food safety, nutrition, and animal and human health. The collated information and suggested research needs will hopefully facilitate and guide further studies needed to optimize the use of cinnamaldehyde alone and in combination with other natural antimicrobials and medicinal antibiotics to help prevent and treat food animal and human diseases.

Interactions of cinnamaldehyde and its metabolite cinnamic acid with human serum albumin and interference of other food additives

Considering the adverse effect of food additives on humans, thorough research of their physiological effects at the molecular level is important. The interactions of cinnamaldehyde (CNMA), a food perfume, and its major metabolite cinnamic acid (CA) with human serum albumin (HSA) were examined by multiple-spectroscopies. NMR analysis revealed CNMA and CA both bound to HSA, and STD-NMR experiments established CNMA and CA primarily interacted with site I and site II of HSA, respectively. The ligands caused strong quenching of HSA fluorescence through a static quenching mechanism, with hydrophobic and electrostatic interaction between CNMA/CA and HSA, respectively. UV-vis absorption and CD results showed ligands induced secondary structure changes of HSA. Binding configurations were proved by docking method. Furthermore, binding constants of CNMA/CA-HSA systems were influenced by the addition of four other food additives. These studies have increased our knowledge regarding the safety and biological action of CNMA and CA.

The reaction of cinnamaldehyde and cinnam(o)yl derivatives with thiols

Spurred by the alleged relevance of the thia-Michael reaction in the bioactivity of various classes of cinnam(o)yl natural products and by the development of a quick NMR assay to study this reaction, we have carried out a systematic study of the "native" reactivity of these compounds with dodecanethiol and cysteamine as models, respectively, of simple thiols and reactive protein thiols that can benefit from iminium ion catalysis in Michael reactions. Cinnamoyl esters and amides, as well as cinnamyl ketones and oximes, did not show any reactivity with the two probe thiols, while cinnamaldehyde (1a) reacted with cysteamine to afford a mixture of a thiazoline derivative and compounds of multiple addition, and with aliphatic thiols to give a single bis-dithioacetal (6). Chalchones and their vinylogous C5-curcuminoid derivatives were the only cinnamoyl derivatives that gave a thia-Michael reaction. From a mechanistic standpoint, loss of conjugation in the adduct might underlie the lack of a native Michael reactivity. This property is restored by the presence of another conjugating group on the carbonyl, as in chalcones and C5-curcuminoids. A critical mechanistic revision of the chemical and biomedical literature on cinnamaldehyde and related compounds seems therefore required.

Theoretical and experimental studies on the separation of cinnamyl acetate and cinnamaldehyde by adsorption onto a β-cyclodextrin polyurethane polymer

CAc and CA were separated using CDPU as adsorbent, and the mechanism was proposed through DFT calculations and experimental analyses.

Cinnamaldehyde Inhibits Staphylococcus aureus Virulence Factors and Protects against Infection in a Galleria mellonella Model

Bacterial resistance to the available marketed drugs has prompted the search of novel therapies; especially in regards of anti-virulence strategies that aim to make bacteria less pathogenic and/or decrease their probability to become resistant to therapy. Cinnamaldehyde is widely known for its antibacterial properties through mechanisms that include the interaction of this compound with bacterial cell walls. However, only a handful of studies have addressed its effects on bacterial virulence, especially when tested at sub-inhibitory concentrations. Herein, we show for the first time that cinnamaldehyde is bactericidal against Staphylococcus aureus and Enterococcus faecalis multidrug resistant strains and does not promote bacterial tolerance. Cinnamaldehyde actions were stronger on S. aureus as it was able to inhibit its hemolytic activity on human erythrocytes and reduce its adherence to latex. Furthermore, cinnamaldehyde enhanced the serum-dependent lysis of S. aureus. In vivo testing of cinnamaldehyde in Galleria mellonella larvae infected with S. aureus, showed this compound improves larvae survival whilst diminishing bacterial load in their hemolymph. We suggest that cinnamaldehyde may represent an alternative therapy to control S. aureus-induced bacterial infections as it presents the ability to reduce bacterial virulence/survival without promoting an adaptive phenotype.

In Situ Metabolism of Cinnamyl Alcohol in Reconstructed Human Epidermis: New Insights into the Activation of This Fragrance Skin Sensitizer

Chemical modification of epidermal proteins by skin sensitizers is the molecular event which initiates the induction of contact allergy. However, not all chemical skin allergens react directly as haptens with epidermal proteins but need either a chemical (prehaptens) or metabolic (prohaptens) activation step to become reactive. Cinnamyl alcohol has been considered a model prohapten, as this skin sensitizer has no intrinsic reactivity. Therefore, the prevailing theory is that cinnamyl alcohol is enzymatically oxidized into the protein-reactive cinnamaldehyde, which is the sensitizing agent. Knowing that reconstructed human epidermis (RHE) models have been demonstrated to be quite similar to the normal human epidermis in terms of metabolic enzymes, use of RHE may be useful to investigate the in situ metabolism/activation of cinnamyl alcohol, particularly when coupled with high-resolution magic angle spinning nuclear magnetic resonance. Incubation of carbon-13 substituted cinnamyl derivatives with RHE did not result in the formation of cinnamaldehyde. The metabolites formed suggest the formation of an epoxy-alcohol and an allylic sulfate as potential electrophiles. These data suggest that cinnamyl alcohol is inducing skin sensitization through a route independent of the one involving cinnamaldehyde and should therefore be considered as a skin sensitizer on its own.

Involvement of TRPA1 in the cinnamaldehyde-induced pulpal blood flow change in the feline dental pulp

Objectives

The purpose of this study was to investigate the involvement of TRPA1 in the cinnamaldehyde-induced pulpal blood flow (PBF) change in the feline dental pulp.

Materials and Methods

Mandibles of eight cats were immobilized and PBF was monitored with a laser Doppler flowmetry at the mandibular canine tooth. To evaluate the effect of cinnamaldehyde on PBF, cinnamaldehyde was injected into the pulp through the lingual artery at a constant rate for 60 seconds. As a control, a mixture of 70% ethanol and 30% dimethyl sulfoxide (DMSO, vehicle) was used. To evaluate the involvement of transient receptor potential ankyrin 1 (TRPA1) in PBF change, AP18, a specific TRPA1 antagonist, was applied into the pulp through the Class V dentinal cavity followed by cinnamaldehyde-administration 3 minutes later. The paired variables of experimental data were statistically analyzed using paired t-test. A p value of less than 0.05 was considered as statistically significant.

Results

Administration of cinnamaldehyde (0.5 mg/kg, intra-arterial [i.a.]) induced significant increases in PBF (p < 0.05). While administration of a TRPA1 antagonist, AP18 (2.5 - 3.0 mM, into the dentinal cavity [i.c.]) caused insignificant change of PBF (p > 0.05), administration of cinnamaldehyde (0.5 mg/kg, i.a.) following the application of AP18 (2.5 - 3.0 mM, i.c.) resulted in an attenuation of PBF increase from the control level (p < 0.05). As a result, a TRPA1 antagonist, AP18 effectively inhibited the vasodilative effect of cinnamaldehyde (p < 0.05).

Conclusions

The result of the present study provided a functional evidence that TRPA1 is involved in the mechanism of cinnamaldehyde-induced vasodilation in the feline dental pulp.

Oxidation of cinnamyl alcohol using bimetallic Au–Pd/TiO2 catalysts: a deactivation study in a continuous flow packed bed microreactor

Deactivation of Au–Pd/TiO₂ catalyst during oxidation in flow is attributed to Pd leaching and a complex effect of oxygen.

Dose-dependent DNA adduct formation by cinnamaldehyde and other food-borne α,β-unsaturated aldehydes predicted by physiologically based in silico modelling

Genotoxicity of α,β-unsaturated aldehydes shown in vitro raises a concern for the use of the aldehydes as food flavourings, while at low dose exposures the formation of DNA adducts may be prevented by detoxification. Unlike many α,β-unsaturated aldehydes for which in vivo data are absent, cinnamaldehyde was shown to be not genotoxic or carcinogenic in vivo. The present study aimed at comparing dose-dependent DNA adduct formation by cinnamaldehyde and 18 acyclic food-borne α,β-unsaturated aldehydes using physiologically based kinetic/dynamic (PBK/D) modelling. In rats, cinnamaldehyde was predicted to induce higher DNA adducts levels than 6 out of the 18 α,β-unsaturated aldehydes, indicating that these 6 aldehydes may also test negative in vivo. At the highest cinnamaldehyde dose that tested negative in vivo, cinnamaldehyde was predicted to form at least three orders of magnitude higher levels of DNA adducts than the 18 aldehydes at their respective estimated daily intake. These results suggest that for all the 18 α,β-unsaturated aldehydes DNA adduct formation at doses relevant for human dietary exposure may not raise a concern. The present study illustrates a possible use of physiologically based in silico modelling to facilitate a science-based comparison and read-across on the possible risks posed by DNA reactive agents.