A review of cinnamaldehyde and its derivatives as antibacterial agents

Electrospinning Proteins for Wound Healing Purposes: Opportunities and Challenges

With the growth of the aging population worldwide, chronic wounds represent an increasing burden to healthcare systems. Wound healing is complex and not only affected by the patient's physiological conditions, but also by bacterial infections and inflammation, which delay wound closure and re-epithelialization. In recent years, there has been a growing interest for electrospun polymeric wound dressings with fiber diameters in the nano- and micrometer range. Such wound dressings display a number of properties, which support and accelerate wound healing. For instance, they provide physical and mechanical protection, exhibit a high surface area, allow gas exchange, are cytocompatible and biodegradable, resemble the structure of the native extracellular matrix, and deliver antibacterial agents locally into the wound. This review paper gives an overview on cytocompatible and biodegradable fibrous wound dressings obtained by electrospinning proteins and peptides of animal and plant origin in recent years. Focus is placed on the requirements for the fabrication of such drug delivery systems by electrospinning as well as their wound healing properties and therapeutic potential. Moreover, the incorporation of antimicrobial agents into the fibers or their attachment onto the fiber surface as well as their antimicrobial activity are discussed.

Protective Effects of Cinnamaldehyde against Mesenteric Ischemia-Reperfusion-Induced Lung and Liver Injuries in Rats

The aim of this study was to characterize and reveal the protective effects of cinnamaldehyde (CA) against mesenteric ischemia-reperfusion- (I/R-) induced lung and liver injuries and the related mechanisms. Sprague-Dawley (SPD) rats were pretreated for three days with 10 or 40 mg/kg/d, ig of CA, and then induced with mesenteric ischemia for 1 h and reperfusion for 2 h. The results indicated that pretreatment with 10 or 40 mg/kg of CA attenuated morphological damage in both lung and liver tissues of mesenteric I/R-injured rats. CA pretreatment significantly restored the levels of aspartate transaminase (AST) and alanine transaminase (ALT) in mesenteric I/R-injured liver tissues, indicating the improvement of hepatic function. CA also significantly attenuated the inflammation via reducing myeloperoxidase (MOP) activity and downregulating the expression of inflammation-related proteins, including interleukin-6 (IL-6), interleukin-1β (IL-1β), cyclooxygenase-2 (Cox-2), and tumor necrosis factor receptor type-2 (TNFR-2) in both lung and liver tissues of mesenteric I/R-injured rats. Pretreatment with CA significantly downregulated nuclear factor kappa B- (NF-κB-) related protein expressions (NF-κB p65, NF-κB p50, I kappa B alpha (IK-α), and inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ)) in both lung and liver tissues of mesenteric I/R-injured rats. CA also significantly downregulated the protein expression of p53 family members, including caspase-3, caspase-9, Bax, and p53, and restored Bcl-2 in both lung and liver tissues of mesenteric I/R-injured rats. CA pretreatment significantly reduced TUNEL-apoptotic cells and significantly inhibited p53 and NF-κB p65 nuclear translocation in both lung and liver tissues of mesenteric I/R-injured rats. CA neither induced pulmonary and hepatic histological alterations nor affected the parameters of inflammation and apoptosis in sham rats. We conclude that CA alleviated mesenteric I/R-induced pulmonary and hepatic injuries via attenuating apoptosis and inflammation through inhibition of NF-κB and p53 pathways in rats, suggesting the potential role of CA in remote organ ischemic injury protection.

Combination of ellagic acid and trans-cinnamaldehyde alleviates aging-induced cognitive impairment via modulation of mitochondrial function and inflammatory and apoptotic mediators in the prefrontal cortex of aged rats

Cognitive impairments are associated with advancing age. Trans-cinnamaldehyde (CIN) and ellagic acid (ELA) have multiplex activities to reduce various age-related cognitive disorders. In this study, we investigated the effects of these compounds separately or in combination on the cognitive outcomes, mitochondrial function, and inflammatory and apoptotic mediators in aged male Wistar rats. Thirty-two old (22 months old) and eight young (5 months old) rats were randomly allocated to five groups of young control, aged control, ELA-aged, CIN-aged, and ELA + CIN-aged. ELA (15 mg/kg, orally) and CIN (50 mg/kg, intraperitoneally) separately or in combination were administered for 1 month in aged animals. Spatial memory and cognitive activity were evaluated by the Barnes maze and novel object recognition tests. Mitochondrial function (its reactive oxygen species [ROS], mitochondrial membrane potential and ATP level), pro-inflammatory cytokines such as interleukin (IL)-1β and IL-6 and pro-apoptotic caspase 3 and Bax, and anti-apoptotic Bcl2 levels and their ratio were assessed in the prefrontal cortex. Behavioral results revealed that CIN separately or in combination with ELA significantly alleviates aging-induced memory impairment. Moreover, co-administration of agents effectively decreased inflammatory cytokines, cleaved-caspase 3, Bax and Bax/Bcl2 levels, mitochondrial ROS production, and mitochondrial membrane depolarization and increased Bcl2 and ATP level as compared with untreated aged control rats. Combination therapy was greater than those of individual treatments in all parameters. Therefore, combination therapy with CIN and ELA improved aging-induced cognitive impairment through anti-inflammatory, anti-apoptotic, and mitochondrial-boosting effects in aged rats.

Natural Cinnamaldehyde and Its Derivatives Ameliorate Neuroinflammatory Pathways in Neurodegenerative Diseases

Neurodegenerative diseases are devastating and incurable disorders characterized by neuronal dysfunction. The major focus of experimental and clinical studies are conducted on the effects of natural products and their active components on neurodegenerative diseases. This review will discuss an herbal constituent known as cinnamaldehyde (CA) with the neuroprotective potential to treat neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). Accumulating evidence supports the notion that CA displays neuroprotective effects in AD and PD animal models by modulating neuroinflammation, suppressing oxidative stress, and improving the synaptic connection. CA exerts these effects through its action on multiple signaling pathways, including TLR4/NF-κB, NLRP3, ERK1/2-MEK, NO, and Nrf2 pathways. To summarize, CA and its derivatives have been shown to improve pathological changes in AD and PD animal models, which may provide a new therapeutic option for neurodegenerative interventions. To this end, further experimental and clinical studies are required to prove the neuroprotective effects of CA and its derivatives.

Surface Wiping Test to Study Biocide -Cinnamaldehyde Combination to Improve Efficiency in Surface Disinfection

Disinfection is crucial to control and prevent microbial pathogens on surfaces. Nonetheless, disinfectants misuse in routine disinfection has increased the concern on their impact on bacterial resistance and cross-resistance. This work aims to develop a formulation for surface disinfection based on the combination of a natural product, cinnamaldehyde, and a widely used biocide, cetyltrimethylammonium bromide. The wiping method was based on the Wiperator test (ASTM E2967−15) and the efficacy evaluation of surface disinfection wipes test (EN 16615:2015). After formulation optimization, the wiping of a contaminated surface with 6.24 log₁₀ colony-forming units (CFU) of Escherichia coli or 7.10 log₁₀ CFU of Staphylococcus aureus led to a reduction of 4.35 log₁₀ CFU and 4.27 log₁₀ CFU when the wipe was impregnated with the formulation in comparison with 2.45 log₁₀ CFU and 1.50 log₁₀ CFU as a result of mechanical action only for E. coli and S. aureus, respectively. Furthermore, the formulation prevented the transfer of bacteria to clean surfaces. The work presented highlights the potential of a combinatorial approach of a classic biocide with a phytochemical for the development of disinfectant formulations, with the advantage of reducing the concentration of synthetic biocides, which reduces the potentially negative environmental and public health impacts from their routine use.

Antibacterial and Cytotoxic Activities of Ten Commercially Available Essential Oils

There is a huge concern in the medical field concerning the emergence of bacterial resistance to antibiotics. Essential oils are a source of antibacterial compounds that can overcome this problem. Ten essential oils that are commercially available were investigated in the present study: ajowan, basil, German chamomile, Chinese cinnamon, coriander, clove, lemongrass, Spanish lavender, oregano and palmarosa. Their direct, synergistic and indirect antibacterial activities were evaluated against different human pathogenic Gram-positive and Gram-negative strains. To evaluate their possible use in clinics, the cytotoxicity of these essential oils was also tested on keratinocyte and epithelial cell lines. Except for the Chinese cinnamon, coriander and lemongrass, all other essential oils presented no cytotoxicity at 32 and 16 μg/mL. The highest indirect antibacterial activities were observed with the palmarosa and Spanish lavender in association with penicillin V. These two associations presented a 64-fold decrease against a resistant strain of Staphylococcus aureus, however, at a cytotoxic concentration. It can also be highlighted that when tested at a non-cytotoxic concentration, the activity of oregano in association with penicillin V presented an eight-fold decrease. These results show the interest to use essential oils in combination with antibiotics to reduce their concentrations inside drugs.

Trans-cinnamaldehyde potently kills Enterococcus faecalis biofilm cells and prevents biofilm recovery

Enterococcus faecalis is a biofilm-forming, nosocomial pathogen that is frequently isolated from failed root canal treatments. Contemporary root canal disinfectants are ineffective in eliminating these biofilms and preventing reinfection. As a result, there is a pressing need to identify novel and safe antibiofilm molecules. The effect of short-term (5 and 15 min) and long-term (24 h) treatments of trans-cinnamaldehyde (TC) on the viability of E. faecalis biofilms was compared with currently used root canal disinfectants. Treatment for 15 min with TC reduced biofilm metabolic activity as effective as 1% sodium hypochlorite and 2% chlorhexidine. Treatment with TC for 24 h was significantly more effective than 2% chlorhexidine in reducing the viable cell counts of biofilms. This serendipitous effect of TC was sustained for 10 days under growth-favoring conditions. For the first time, our study highlights the strong antibacterial activity of TC against E. faecalis biofilms, and notably, its ability to prevent biofilm recovery after treatment.

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.

In vitro antifungal activity of Cinnamomum zeylanicum bark and leaf essential oils against Candida albicans and Candida auris

Candida infections are a significant source of patient morbidity and mortality. Candida albicans is the most common pathogen causing Candida infections. Candida auris is a newly described pathogen that is associated with multi-drug-resistant candidiasis and candidaemia in humans. The antifungal effects of various essential oils and plant compounds have been demonstrated against human pathogenic fungi. In this study, the effect of cinnamon leaf and bark essential oils (CEOs) was determined against both C. albicans and C. auris. The disc diffusion (direct and vapour) and broth microdilution method was used to determine antifungal activity of the EOs against selected strains (C. albicans ATCC 10231, C. albicans ATCC 2091 and C. auris NCPF 8971) whilst the mode of action and haemolysin activity of the CEOs were determined using electron microscopy and light microscopy. Direct and vapour diffusion assays showed greater inhibitory activity of bark CEO in comparison with leaf CEO. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of bark CEO for all tested strains was below 0.03% (v/v), which was lower than the MICs of the leaf CEO (0.06–0.13%, v/v) dependent on the strain and the MFCs at 0.25% (v/v). In the morphological interference assays, damage to the cell membrane was observed and both CEOs inhibited hyphae formation. The haemolysin production assay showed that CEOs can reduce the haemolytic activity in the tested C. albicans and C. auris strains. At low concentrations, CEOs have potent antifungal and antihaemolytic activities in vitro against C. albicans and C. auris.

Key points

• Essential oils from Cinnamomum zeylanicum Blume bark and leaf (CBEO and CLEO) demonstrated fungicidal properties at very low concentrations.

• The antifungal activity of CBEO was greater than that of CLEO consistent with other recent published literature.

• The mode of action of CBEO and CLEO was damage to the membrane of C. albicans and C. auris.

• Both CBEO and CLEO inhibited the formation of hyphae and reduced haemolysin production in C. albicans and C. auris.

Development and Validation of a UPLC-DAD Method for Quantitative Analysis of Coumarin, trans-Cinnamic Acid, trans-Cinnamaldehyde, and Eugenol in Encapsulated Cinnamon Flavoring Powder

BACKGROUND

Cinnamon is a popular spice used in food products. Its flavor varies by its chemical profile. Cinnamon flavoring powder is a unique form of material with essential oil encapsulated in wall material, which improves the stability and homogeneity but also increases the difficulties for analysis. A specific and rapid method is needed to analyze the main components for its quality and safety.

OBJECTIVE

An analytical method for the quantification of cinnamon flavoring powder was developed and validated. The characteristic components for analysis were selected as coumarin, trans-cinnamic acid, trans-cinnamaldehyde, and eugenol.

METHODS

This quantitation method with ultra-performance liquid chromatography coupled with diode array detector analysis was achieved by material extraction followed by chromatographic separation on C18 columns eluted with a gradient acetonitrile-water mobile phase. The detected wavelength was determined as 280 nm.

RESULTS

Linear regression of calibration curves for each component was validated (R2 > 0.9995). The specificity, LOD and LOQ, precision, accuracy, and ruggedness of the developed method were also evaluated.

CONCLUSIONS

Such an approach is applicable for the simultaneous determination of these four characteristic constituents in cinnamon flavoring powder used in manufacturing and quality control of nutritional products.

HIGHLIGHTS

This study describes the selection of four components for analysis, the efficient extraction of them from cinnamon flavoring powder, and the rapid quantitation of these four characteristic components in these materials.

Combinatorial effects of trans-cinnamaldehyde with fluoride and chlorhexidine on Streptococcus mutans

AIMS

The aim of this study was to investigate the effects of trans-cinnamaldehyde (TC) and its synergistic activity with chlorhexidine (CHX) and fluoride against Streptococcus mutans.

METHODS AND RESULTS

Streptococcus mutans UA159 was treated with TC alone and in combination with CHX or sodium fluoride. The synergy profile was analysed using the Zero Interaction Potency model. TC showed strong synergism (synergy score of 21·697) with CHX, but additive effect (synergy score of 5·298) with fluoride. TC and the combinations were tested for acid production (glycolytic pH drop) and biofilm formation by S. mutans, and nitric oxide production in macrophages. TC significantly inhibited sucrose-dependent biofilm formation and acid production by S. mutans. Mechanistic studies were carried out by qRT-PCR-based transcriptomic studies which showed that TC acts by impairing genes related to metabolism, quorum sensing, bacteriocin expression, stress tolerance and biofilm formation.

CONCLUSIONS

trans-Cinnamaldehyde potentiates CHX and sodium fluoride in inhibiting S. mutans biofilms and virulence through multiple mechanisms. This study sheds significant new light on the potential to develop TC as an anti-caries treatment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oral diseases were classified as a 'silent epidemic' in the US Surgeon General's Report on Oral Health. Two decades later, >4 billion people are still affected worldwide by caries, having significant effects on the quality of life. There is an urgent need to develop novel compounds and strategies to combat dental caries. Here, we prove that TC downregulates multiple pathways and potentiates the CHX and fluoride to prevent S. mutans biofilms and virulence. This study sheds significant new light on the potential to develop TC in combination with CHX or fluoride as novel treatments to arrest dental caries.

Comparative antidandruff efficacy of plant extracts prepared from conventional and supercritical fluid extraction method and chemical profiling using GCMS

BACKGROUND

To combat dandruff associated pathogens, supercritical fluid extraction (SFE) can be used as an alternative eco-friendly technique to obtain antimicrobial plant extracts over conventional methods.

OBJECTIVES

The purpose of the study was to compare the yield and antimicrobial potential of extracts obtained by different extraction methods.

METHODS

Extraction was carried out by cold percolation method using ethyl acetate (EA) and SFE using CO₂. Antimicrobial activity was studied against dandruff causing microbes; Malassezia furfur, Propionibacterium acne, and Staphylococcus epidermidis by agar well diffusion and micro broth dilution method. Statistical evaluation was done by principal component analysis (PCA).

RESULTS

The yield was found higher in the ethyl acetate extracts. PCA indicated that among the sixteen extracts, SFE extract of Azadirachta indica leaves was the most influential with the highest F1 score and maximum antimicrobial activity. Cinnamomum zeylanicum SFE extract demonstrated the lowest MIC against P. acne and M. furfur. GC-MS analysis of A. indica extract inferred that ganoderic acid, 13,14-epoxyoleanan-3-ol acetate, henicosanal, 2-heptadecycloxirane were the major phytoconstituents whereas cinnamaldehyde, α- muurolene and caffeic acid were primarily found in cinnamon.

CONCLUSION

Bioactive compounds identified in the extracts of A. indica and C. zeylanicum can be used in natural antidandruff products.

Immunomodulatory effects of thymol and cinnamaldehyde in chicken cell lines

Thymol and cinnamaldehyde are phytogenic feed additives that have been developed to improve gut health, immunity and growth performance in poultry and swine. This study evaluated the immune modulating effects of a thymol and cinnamaldehyde blend (TCB) in the intestinal system of poultry in vitro, using two chicken cell lines, LMH (liver cell line) which has been used to mimic epithelial cell responses, and HD-11 (monocyte/macrophage-like). Cells with high viability (>95%) from established cell lines were cultured in the presence of TCB at concentrations ranging from 1 ng/ml to 100 ng/ml. The viability, transepithelial electrical resistance (TEER) and phagocytic capacity of co-cultured LMH cells, with or without stimulation with lipopolysaccharide (LPS), was subsequently evaluated. The expression of cytokines, chemokines and pattern recognition receptors by HD-11 monocytes/macrophages was measured by RT-PCR and by proteomic analysis. TCB was well tolerated by both cell lines (cell viability >90% after co-culture with TCB at 100 ng/ml for 48 h with or without LPS). Epithelial integrity of LMH cells (as assessed by TEER) was increased by TCB (10 ng/ml) after 4 h incubation, versus untreated controls, and phagocytic capacity of HD-11 cells was increased, in a dose-dependent manner (P<0.05). In HD-11 cells, TCB (10 ng/ml) downregulated the relative expression of pro-inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8 and the transcription factor cyclooxygenase-2 and upregulated expression of anti-inflammatory IL-10, versus untreated controls (P<0.05). In summary, under the tested conditions, TCB enhanced the epithelial barrier integrity of poultry hepatocytes, increased phagocytic activity and production of anti-inflammatory cytokines by monocytes and macrophages. These results indicated how supplementing TCB in poultry diets can increase bird performance, by increasing in vivo cell membrane integrity (especially important in the gut) and assisting in immune responses, which can liberate energy for growth.

Traditional uses, phytochemistry and pharmacological activities of the genus Cinnamomum (Lauraceae): A review

Species of Cinnamomum exhibit excellent economic and medicinal value, and have found use in traditional medicine, are consumed as a spice, as well as being cultivated as landscape plants. Investigations into the pharmacological activities of the genus Cinnamomum revealed that it manifested a wide range of pharmacological properties including antimicrobial, antioxidant, anti-inflammatory and analgesic, antitumor, anti-diabetic and anti-obesity, immunoregulation, insecticidal and acaricidal, cardiovascular protective, cytoprotective, as well as neuroprotective properties both in vivo and in vitro. In the past five years, approximately 306 chemical constituents have been separated and identified from the genus Cinnamomum, covering 111 terpenes, 44 phenylpropanoids, 51 lignans, 17 flavonoids, 53 aromatic compounds, 17 aliphatic compounds, four coumarins, two steroids. This article highlights the traditional uses, phytochemistry and pharmacological properties of the few studied taxa of Cinnamomum through searching for the pieces of literature both at home and abroad, which would provide a reference for the pharmaceutical research and clinical application of this genus.

"Smart" Antimicrobial Nanocomplexes with Potential to Decrease Surgical Site Infections (SSI)

The emergence of resistant pathogens is a burden on mankind and threatens the existence of our species. Natural and plant-derived antimicrobial agents need to be developed in the race against antibiotic resistance. Nanotechnology is a promising approach with a variety of products. Biosynthesized silver nanoparticles (AgNP) have good antimicrobial activity. We prepared AgNPs with trans-cinnamic acid (TCA) and povidone-iodine (PI) with increased antimicrobial activity. We synthesized also AgNPs with natural cinnamon bark extract (Cinn) in combination with PI and coated biodegradable Polyglycolic Acid (PGA) sutures with the new materials separately. These compounds (TCA-AgNP, TCA-AgNP-PI, Cinn-AgNP, and Cinn-AgNP-PI) and their dip-coated PGA sutures were tested against 10 reference strains of microorganisms and five antibiotics by zone inhibition with disc- and agar-well-diffusion methods. The new compounds TCA-AgNP-PI and Cinn-AgNP-PI are broad spectrum microbicidal agents and therefore potential coating materials for sutures to prevent Surgical Site Infections (SSI). TCA-AgNP-PI inhibits the studied pathogens stronger than Cinn-AgNP-PI in-vitro and on coated sutures. Dynamic light scattering (DLS), ultraviolet-visible spectroscopy (UV-Vis), Fourier Transform infrared spectroscopy (FT-IR), Raman, x-ray diffraction (XRD), microstructural analysis by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) confirmed the composition of TCA-AgNP-PI and Cinn-AgNP-PI. Smart solutions involving hybrid materials based on synergistic antimicrobial action have promising future perspectives to combat resistant microorganisms.

Azole Based Acetohydrazide Derivatives of Cinnamaldehyde Target and Kill Candida albicans by Causing Cellular Apoptosis

Opportunistic fungal pathogens including Candida albicans are responsible for the alarming rise in hospital acquired infections and millions of deaths worldwide. The current treatment modalities are not enough to handle this situation, and therefore, new treatment modalities and strategies are desperately needed. In this direction, we synthesized a series of azole based acetohydrazide derivatives of cinnamaldehyde and subjected it to antifungal activity evaluation. Preliminary antifungal activity evaluation revealed tremendous antifungal potential of some of the derivatives against fluconazole susceptible and resistant clinical isolates of Candida albicans. Although all the compounds in the series are structurally similar except for the presence of different substituents on the phenyl ring of the acetohydrazide pendent, they sharply differed in their activity profile. Further mechanism of action studies revealed that these compounds have an apoptotic effect on C. albicans confirmed via Annexin V-FITC staining and TUNEL assay.