Cinnamaldehyde Research Articles

Trans-Cinnamaldehyde-Fighting Streptococcus mutans Using Nature.

Streptococcus mutans (S. mutans) is the main cariogenic bacterium with acidophilic properties, in part due to its acid-producing and -resistant properties. As a result of this activity, hard tooth structures may demineralize and form caries. Trans-cinnamaldehyde (TC) is a phytochemical from the cinnamon plant that has established antibacterial properties for Gram-positive and -negative bacteria. This research sought to assess the antibacterial and antibiofilm effects of trans-cinnamaldehyde on S. mutans. TC was diluted to a concentration range of 156.25-5000 μg/mL in dimethyl sulfoxide (DMSO) 0.03-1%, an organic solvent. Antibacterial activity was monitored by testing the range of TC concentrations on 24 h planktonic growth compared with untreated S. mutans. The subminimal bactericidal concentrations (MBCs) were used to evaluate the bacterial distribution and morphology in the biofilms. Our in vitro data established a TC MBC of 2500 μg/mL against planktonic S. mutans using a microplate spectrophotometer. Furthermore, the DMSO-only controls showed no antibacterial effect against planktonic S. mutans. Next, the sub-MBC doses exhibited antibiofilm action at TC doses of ≥625 μg/mL on hydroxyapatite discs, as demonstrated through biofilm analysis using spinning-disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). Our findings show that TC possesses potent antibacterial and antibiofilm properties against S. mutans. Our data insinuate that the most effective sub-MBC of TC to bestow these activities is 625 μg/mL.

Solvent effect in selective hydrogenation of cinnamaldehyde over Pd–Ni nanoclusters encapsulated within siliceous zeolite

Selective hydrogenation of unsaturated-organic compounds derived from biomass sources is a key step for producing chemicals and fuels, but it faces challenges in enhancing product selectivity and energy efficiency. Metal nanoparticles (NPs) encapsulated in zeolite crystals (metal@zeolite) are desirable and robust materials that can control catalytic activity and selectivity by tuning their structure. However, the solvent effect on selective hydrogenation over metal@zeolite has been unexplored, which plays a significant role in the reaction process. Here, the solvent effect on the selective hydrogenation of cinnamaldehyde (CAL), a representative substrate, over Pd–Ni bimetallic clusters encapsulated inside S-1 zeolite (Pd0.6Ni@S-1) was first reported. The results showed that Pd0.6Ni@S-1 effectively converted CAL into hydrocinnamaldehyde (HCAL) under mild conditions and that the product distribution was solvent-dependent by correlating the selectivity with solvent properties. The polarity of polar solvents affected the solvent-CAL interaction and thus the hydrogenation pathway. Our study reveals the importance of solvent engineering for selective hydrogenation over metal@zeolite catalysts and provides insights for designing efficient and robust materials for biomass conversion.

Effect of cinnamaldehyde on Rhizopus stolonifer and on the conservation of sweet potato

Abstract Objectives Rhizopus stolonifer, which causes soft rot of sweet potato, has resulted in substantial loss of economy postharvest. Materials and Methods The antifungal effect and mechanism of cinnamaldehyde (CIN) against R. stolonifer were explored by biochemical analysis and RNA-sequencing in this research, and the edible quality of CIN-treated sweet potato was evaluated. Results The results showed that CIN inhibited the growth of R. stolonifer and reduced the incidence of soft rot in sweet potato at a minimum inhibitory concentration of 1000 μL/L. The damage of the cell walls of R. stolonifer by CIN was associated with the upregulation of CHT1. Cytosolic leakage and malondialdehyde content increased following CIN-treatment, which was correlated with increased reactive oxygen species levels and decreased catalase activity. Upregulation of ERG genes and oxidative stress-related genes following CIN treatment was associated with impaired cell membrane integrity. The mitochondrial structure of R. stolonifer was damaged by CIN treatment resulting in decreased respiration rates and ATP production, which was correlated with lower expression levels of IDH1, COX4, and QCR7. Conclusions Our research suggests that the inhibition of CIN on R. stolonifer was related to the disruption of its normal gene expression network, and CIN maintained the nutritional and edible quality of sweet potato. This study provides valuable insights into the antifungal mechanism of CIN on R. stolonifer and the maintenance of root quality, which contributes to the efficient use of CIN for controlling soft rot in sweet potato.

Influence of PVA resin and cross-linking agent on the structure and properties of semi-refined carrageenan-based packaging films

For the high content of carrageenan in some seaweed and the low cost and easy availability of semi refined carrageenan (SRC), SRC resin powder was selected as our research object. Due to its water solubility, a solution casting method was adopted to form film, hoping to prepare food packaging materials that partially replace petroleum based resin. The pure SRC resin casting film is very brittle and cannot be formed. Therefore, 40wt% glycerol was added to the formula to plasticize and improve the flexibility and demoulding ability of SRC. The plasticized SRC film still has limitations. Soluble petroleum based polymer poly(vinyl alcohol) (PVA) resin was used as a blending modifier, cinnamaldehyde (CIN) as a crosslinking agent for acetal reaction with hydroxyl groups, boric acid (BA) as a provider of acidic environment and an auxiliary agent for generating partial hydrogen bonds with hydroxyl groups. Eight experimental research formulas were designed and FTIR, XRD, thermodynamic properties and mechanical properties of the modified films were analyzed. Both microscopic and macroscopic analyses have shown that under the acidic conditions of BA, CIN undergoes an acetal reaction with SRC and PVA, therefore mass ratio of the formula that SRC/glycerol/PVA/CIN/BA is 100/40/33.3/10/10, the film has the best tensile strength of 34.85Mpa, higher than that of other films. It has been proven that CIN does indeed act as a crosslinking agent in the formula, forming a network structure that enhances it.

Biological fate, functional properties, and design strategies for oral delivery systems for cinnamaldehyde.

Cinnamaldehyde (CA) is the main bioactive component extracted from the internal bark of cinnamon trees with many health benefits. In this paper, the bioavailability and biological activities of cinnamaldehyde, and the underlying molecular mechanism are reviewed and discussed, including antioxidant, cardioprotective, anti-inflammatory, anti-obesity, anticancer, and antibacterial properties. Common delivery systems that could improve the stability and bioavailability of CA are also summarized and evaluated, such as micelles, microcapsules, liposomes, nanoparticles, and nanoemulsions. This work provides a comprehensive understanding of the beneficial functions and delivery strategies of CA, which is useful for the future application of CA in the functional food industry.

An in situ-activated and chemi-excited photooxygenation system based on G-poly(thioacetal) for Aβ1-42 aggregates.

The abnormal aggregation of Aβ proteins, inflammatory responses, and mitochondrial dysfunction have been reported as major targets in Alzheimer's disease (AD). Photooxygenation of the amyloid-β peptide (Aβ) is viewed as a promising therapeutic intervention for AD treatment. However, the limitations of the depth of the external light source passing through the brain and the toxic side effects on healthy tissues are two significant challenges in the photooxidation of Aβ aggregates. We proposed a method to initiate the chemical stimulation of Aβ1-42 aggregate oxidation through H2O2 and correct the abnormal microenvironment of the lesions by eliminating the cascading reactions of oxidative stress. The degradable G-poly(thioacetal) undergoes cascade release of cinnamaldehyde (CA) and thioacetal triggered by endogenous H2O2, with CA in turn amplifying degradation by generating more H2O2 through mitochondrial dysfunction. A series of novel photosensitizers have been prepared and synthesized for use in the photodynamic oxidation of Aβ1-42 aggregates under white light activation. The nanoparticles (BD-6-QM/NPs) self-assembled from BD-6-QM, bis[2,4,5-trichloro-6-(pentoxycarbonyl) phenyl] ester (CPPO), and G-poly(thioacetal) not only exhibit H2O2-stimulated controlled release but also can be chemically triggered by H2O2 to generate singlet oxygen to inhibit Aβ1-42 aggregates, reducing the Aβ1-42-induced neurotoxicity.

Synthesis of molecularly imprinted polymer with a methacrylate derivative monomer for the isolation of ethyl p-methoxycinnamate as an active compound from Kaempferia galanga L. extracts.

Kaempferia galanga rhizome is traditionally used as a treatment for various diseases. Ethyl p-methoxycinnamate (EPMC), which constitutes up to 31.77% of the total essential oil, is the main/marker compound. EPMC is responsible for various pharmacological activities of Kaempferia galanga rhizome. According to the existing research, the isolation yield of EPMC is still meager, namely 0.50-2.50%; thus, a new EPMC isolation method is needed to produce better results. In this study, after determining the association constant and obtaining the Jobs plot between methacrylate derivative monomers and EPMC, a molecularly imprinted polymer for solid phase extraction (MI-SPE) was synthesized through bulk polymerization with EPMC as a template, methacrylic acid as a monomer, TRIM/EDGMA as a crosslinker in a ratio of 1 : 4 : 20 (MIP1) or 1 : 7 : 20 (MIP2). BPO was used as an initiator and n-hexane was used as a porogen. The synthesis of the NIP was also conducted using the same ratio but without the template. The MIPs were then characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) measurements, and their analytical performance was evaluated through adsorption capacity and selectivity. The results indicate that MIP2 exhibits better analytical performance with an adsorption capacity value of 0.0813 mg g-1. The selectivity of MIP2 was tested using EPMC analog compounds, namely ethyl cinnamic (EC), cinnamaldehyde (CD), and kaempferol (KF), with imprinting factor (IF) values of 17.436, 1.539, and 0.06, respectively. Lastly, MIP2 was applied to the SPE cartridge for the isolation of EPMC from Kaempferia galanga rhizome extract, and showed a percentage recovery of 82.40% for the ethanol extract, 68.05% for the ethyl acetate extract, and 65.27% for the n-hexane extract. MI-SPE 2 gives high purity results for the ethanol, ethyl acetate, and n-hexane extracts, with purities of 97.00%, 97.63%, and 99.59%, respectively. These results indicate that the MI-SPE technique shows great potential as a new method for isolating EPMCs with high yield and purity.

Co–Fe catalyst supported on acidified bentonite for selective hydrogenation of cinnamaldehyde

Acidified bentonite supported Co and Fe catalyst (Co–Fe/ACBT) with abundant strong Lewis acid sites was used for cinnamaldehyde selective hydrogenation, which showed a great catalytic activity with 90.5% CAL conversion and 86.8% COL selectivity.

Enhanced Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Silica-Coated Pt-CoxOy Hybrid Nanoparticles.

Selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) is difficult due to the intrinsic difficulty with thermodynamically easier hydrogenation of C═C bonds. In this work, Pt-CoxOy hybrid nanoparticles encapsulated in mesoporous silica nanospheres (Pt-CoxOy@mSiO2) were synthesized by a sol-gel method, which showed greatly improved COL selectivity for hydrogenation of CAL. At 80 °C and 1.0 MPa of H2, Pt-CoxOy@mSiO2 achieved a CAL conversion of 98.7% with a COL selectivity of 93.5%. In contrast, Pt@mSiO2 yields 3-phenylpropanol (HCOL) as the major product with HCOL selectivity of 67.2%, while PtCo@mSiO2 yields 3-phenylpropionaldehyde with selectivity of 51.8% under the same conditions. The enhanced catalytic performance of Pt-CoxOy@mSiO2 for hydrogenation of CAL to COL is ascribed to the Pt surface electron deficiency induced by metal-oxide interaction, and the protection of active NPs by silica shells results in good catalytic stability.

The Effects of Nine Compounds on Aldehyde-Oxidase-Related Genes in Bactrocera dorsalis (Hendel).

Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) (B. dorsalis) is an important agricultural, major invasive, and quarantine pest that can cause significant damage to the economic value of the fruit and vegetable industry. Male bait is one of the most effective methods of surveying, monitoring, and controlling B. dorsalis. In our study, we constructed cDNA libraries using total RNA extracted independently from the antennae, mouthparts, and thoracic legs of male and female adults and the ovipositors of female adults and screened out four aldehyde-oxidase-related genes (AOX-related), C58800, C66700, C67485, and C67698. Molecular docking predictions showed that eight compounds, including 3,4-dimethoxycinnamyl alcohol, 3,4-dimethoxy-cinnamaldehyde, deet, ethyl N-acetyl-N-butyl-β-alaninate, n-butyl butyrate, n-butyl butyrate, ethyl butyrate, methyl eugenol, and ethyl acetate, could combine with proteins encoded by the four B. dorsalis AOX-related genes. Furthermore, QPCR was performed to confirm that four compounds, including 3,4-dimethoxy cinnamic aldehyde, butyl levulinic acid ethyl ester (mosquito repellent), butyl butyrate, and methyl eugenol, induced significant changes in the AOX-related genes of B. dorsalis. These results provide useful information and guidance for the batch screening of potentially useful compounds and the search for effective attractants of B. dorsalis.

Dietary supplementation of cinnamaldehyde positively affects the physiology, feed utilization, growth, and body composition of striped catfish Pangasianodon hypophthalmus.

The study evaluated the effects of diverse cinnamaldehyde (CIN) supplementation doses on the physiological attributes, feed utilization, growth, and body composition of striped catfish Pangasianodon hypophthalmus. The study incorporated five doses of CIN supplementation, namely 0, 0.5, 1, 1.5, and 2gkg-1 feed, with four replicates per group. Commercial extruded isonitrogenous and isoenergetic feeds with crude protein and gross energy levels of 28.46% ± 0.23% and 3858.70 ± 18.06kcalkg-1, respectively, were used as test feeds. The initial weight of striped catfish was 5.57 ± 0.02g, and 30 fish were maintained in each cage (2 × 1 × 1 m3) for 60days. The results illustrated that the incorporation of CIN into the diet increases amylase and lipase levels and the ability of striped catfish to accumulate glucose, as the glucose tolerance test revealed that CIN 1.0 and 1.5gkg-1 reduced glucose content to its basal level at 3-4 h postinjection and upregulated the insulin receptor, hexokinase, and hormone-sensitive lipase genes. CIN 1.5gkg-1 also increased plasma total protein and high-density lipoprotein levels and reduced triglyceride and cholesterol levels. CIN 1.0-2.0 g kg-1 increased antioxidant capacity by increasing the levels of superoxide dismutase and glutathione and decreasing malondialdehyde levels. CIN 1.5gkg-1 was the best treatment for increasing final weight, the specific growth rate, protein retention, and the protein efficiency ratio and for decreasing the feed conversion ratio. CIN additionally increased meat protein and decreased meat and liver lipid content. This study concluded that 1.24gkg-1 is the optimal CIN dose calculated from the equation Y = - 0.1487x2 + 0.3702x + 5.0724 (R2 = 0.71) to increase growth and feed efficiency in striped catfish by increasing nonprotein catabolism and exerting antioxidant effects.

Aqueous phase selective C[dbnd]O hydrogenation of cinnamaldehyde over bimetallic RuCo catalysts with electronic and geometric modification

Aqueous phase selective hydrogenation of cinnamaldehyde (CALD), as a representative α,β-unsaturated aldehyde, into cinnamyl alcohol (CALA) has been investigated over monometallic Ru and bimetallic RuCo catalysts on pristine h-BN support. Using water as the solvent, the optimal 0.5%Ru-1.1%Co/h-BN catalyst exhibits 510 h−1 specific reaction rate and 78.9 % CALA selectivity as well as good recycling stability at 100 °C. Based on the structure characterizations of catalysts, metal nanoparticles consisting of metallic Ru0 and partially oxidized Ruδ+ sites are uniformly dispersed on h-BN thin sheets. In comparison to monometallic catalysts, additive Co metals in bimetallic RuCo/h-BN catalysts play significant geometric and electronic modification roles on Ru active sites depending on the Ru/Co ratio, and therefore remarkably enhances the preferential activation of CALD CO bond and selectivity of CALA product as well as accelerates the catalytic reaction. Furthermore, the hydrogen dissociative activation ability of various Ru and RuCo catalysts was evaluated, while the superior catalytic performance in water than other commonly used solvents was also clarified and discussed.

A polylactide based multifunctional hydrophobic film for tracking evaluation and maintaining beef freshness by an electrospinning technique.

A nanofiber film was prepared by a facile electrospinning technique using polylactide (PLA), butterfly pea flower extract (BPA) and cinnamaldehyde (CIN). The as-prepared film shows the prominent antioxidative, antibacterial, colorimetric and hydrophobic properties so that the beef freshness can be monitored and maintained up to 6days at 4°C simultaneously. Besides, the nanofiber structure endows the film with a fast color responsiveness under acidic-alkaline atmospheres with different concentrations. Moreover, this film exhibits higher tensile strength (9.56 Mpa) than that of the pure PLA electrospinning film (4.40 Mpa). Especially the introduction of the BPA effectively boosts the antimicrobial ability of the CIN. The freshness, sub-freshness and spoilage levels of the beef can be easily testified by observing the color difference change of the film. So the polylactide based multifunctional film as an intelligent packaging has an excellent potential for the sub-freshness detection of meat.

Antibacterial effects and microarray-based molecular mechanisms of trans-cinnamaldehyde against Porphyromonas gingivalis

Porphyromonas gingivalis (P. gingivalis) is one of the keystone pathogenic bacteria of periodontitis and peri-implantitis. This study aimed to investigate the antibacterial effects and molecular mechanisms of trans-cinnamaldehyde (TC), a safe extract from natural plants, on P. gingivalis. Minimum inhibitory and minimum bactericidal concentrations (MIC and MBC) of TC were determined, and scanning and transmission electron microscopies were used to assess the morphological changes. The overall biomass was estimated, and the metabolic activity of biofilms was determined at different TC concentrations. A microarray-based bioinformatics analysis was performed to elucidate the underlying molecular mechanisms of TC-inhibited P. gingivalis, and significant differences among groups were determined. TC showed an inhibitory effect on the proliferation and survival of planktonic P. gingivalis, of which the MIC and MBC were 39.07 μg/mL and 78.13 μg/mL, respectively. TC also significantly suppressed the formation and metabolic activity of P. gingivalis biofilm. The results of the significant pathways and gene ontology (GO) analyses revealed that TC treatment inhibited two metabolic pathways, accompanied by the downregulation of relative genes of nitrogen metabolism (NrfA, NrfH, and PG_2213) and starch and sucrose metabolism (PG_1681, PG_1682, and PG_1683). Thus, this study confirmed TC to be a natural antimicrobial agent against P. gingivalis and further demonstrated that TC suppressed the microbial activity on P. gingivalis through the disruption of physiological metabolism, which might inhibit the growth and the biofilm formation of P. gingivalis.

The Temporal Dynamics of Sensitivity, Aflatoxin Production, and Oxidative Stress of Aspergillus flavus in Response to Cinnamaldehyde Vapor.

Cinnamaldehyde (CA), a natural plant extract, possesses notable antimicrobial properties and the ability to inhibit mycotoxin synthesis. This study investigated the effects of different concentrations of gaseous CA on A. flavus and found that higher concentrations exhibited fungicidal effects, while lower concentrations exerted fungistatic effects. Although all A. flavus strains exhibited similar responses to CA vapor, the degree of response varied among them. Notably, A. flavus strains HN-1, JX-3, JX-4, and HN-8 displayed higher sensitivity. Exposure to CA vapor led to slight damage to A. flavus, induced oxidative stress, and inhibited aflatoxin B1 (AFB1) production. Upon removal of the CA vapor, the damaged A. flavus resumed growth, the oxidative stress weakened, and AFB1 production sharply increased in aflatoxin-producing strains. In the whole process, no aflatoxin was detected in aflatoxin-non-producing A. flavus. Moreover, the qRT-PCR results suggest that the recovery of A. flavus and the subsequent surge of AFB1 content following CA removal were regulated by a drug efflux pump and velvet complex proteins. In summary, these findings emphasize the significance of optimizing the targeted concentrations of antifungal EOs and provide valuable insight for their accurate application.

Integrated Metabolomics and Gut Microbiome Analysis Reveals the Efficacy of a Phytochemical Constituent in the Management of Ulcerative Colitis.

Cinnamaldehyde (CAH), a phytochemical constituent isolated from cinnamon, is gaining attention due to its nutritional and medicinal benefits. This study aimed to investigate the potential role of CAH in the treatment of ulcerative colitis (UC). Integrated metabolomics and gut microbiome analysis are performed for 2,4,6-trinitrobenzenesulfonic acid (TNBS) induced UC rats. The effect of CAH on colonic inflammation, lipid peroxidation, metabolic profiles, and gut microbiota is systematically explored. It finds that CAH improves the colitis-related symptoms, decreases disease activity index, increases the colon length and body weight, and alleviates histologic inflammation of UC rats. These therapeutic effects of CAH are due to suppression of inflammation and lipid peroxidation. Moreover, multi-omics analysis reveals that CAH treatment cause changes in plasma metabolome and gut microbiome in UC rats. CAH regulates lipid metabolic processes, especially phosphatidylcholines, lysophosphatidylcholines, and polyunsaturated fatty acids. Meanwhile, CAH modulates the gut microbial structure by restraining pathogenic bacteria (such as Helicobacter) and increasing probiotic bacteria (such as Bifidobacterium and Lactobacillus). These results indicate that CAH exerts a beneficial role in UC by synergistic modulating the balance in gut microbiota and the associated metabolites, and highlights the nutritional and medicinal value of CAH in UC management.

Performance analysis and structural characterization of flaxseed gum/chitosan/cinnamaldehyde composite films

The low mechanical strength, water deficiency, and oxidative protection of organic membranes impede their use as food-grade packaging materials. Cinnamaldehyde (CIN) tends to lose its activity owing to its instability. In this study, CIN was added to flaxseed gum (FG)/chitosan (CS) films prepared in a “sandwich” structure. The influence of CIN dosage on the properties of the composite films was studied, and the film formation mechanism of the membrane was explored. The elongation at break, water vapor permeability, oxygen permeability, and light transmittance of the composite film with 1.5% CIN were lower than those of the FG/CS/FG film. Supplementation of the composite membrane with CIN generated new hydrogen bonds, electrostatic interactions, and C-O-C bonds, which converted the structure of the composite film into a sheet and increased its crystallinity without markedly affecting its thermal stability. Therefore, CIN is an extremely useful additive for improving the applicability of flaxseed gum/CS membranes as food-grade packaging films.

Inhibitory effect of temozolomide on apoptosis induction of cinnamaldehyde in human glioblastoma multiforme T98G cell line.

Glioblastoma is the most common primary malignant brain tumor in adults. Temozolomide (TMZ) is an FDA-approved drug used to treat this type of cancer. Cinnamaldehyde (CIN) is a derivative of cinnamon extract and makes up 99% of it. The aim of this study was to investigate the in vitro combined effect of CIN and TMZ on human glioblastoma multiforme T98G cell line viability. In this study, we used 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl-tertazolium bromide (MTT) method to evaluate the extent of IC50, acridine orange, Giemsa and Hoechst staining to evaluate the manner of apoptosis and the Western blotting method to examine the expression change of apoptotic proteins. Our results show that TMZ has an inhibitory effect on CIN when both used in combination at concentrations of 300 and 100 μM (P<0.05) and has a cytotoxic effect when used alone at the same concentrations (P<0.05). The western blotting result showed that TMZ at concentrations of 2,000 and 1,000 μM significantly increased Bax expression and decreased Bcl2 expression (P<0.05), indicating that TMZ induced apoptosis through the mitochondrial pathway. However, CIN had no effect on Bax and Bcl2 expressions, thus causing apoptosis from another pathway. Also, the Bax:Bcl2 expression ratio at concentrations combined was lower than that for TMZ 1,000 μM and higher than that for CIN 150 and 100 μM (P<0.05), which confirms the inhibitory effect of TMZ on CIN. From the present study, we conclude that TMZ in combination with CIN has an inhibitory effect on increasing the cytotoxicity rate.

ZIF-8 decorated Au/Al2O3 hybrid material for highly selective hydrogenation of cinnamaldehyde

Recycling of supported Au catalysts is challenging because of aggregation or loss of Au. Here, we report a strategy for introducing ZIF-8 into traditional Au/Al2O3 surface. The introduction of ZIF-8 can not only provide higher selectivity for the reaction products, but also prevent the loss or aggregation of the Au catalyst. From a series of characterizations, it can be seen that the ZIF-8 decorated Au/Al2O3 hybrid material Au@ZA (Z refers to ZIF-8, A refers to Al2O3) was successfully prepared. Au nanoparticles have better dispersion on the composite carrier, and the particle size is smaller. In the hydrogenation reaction of cinnamaldehyde (CAL), the Au@ZA composite catalyst has both the high chemical stability and the high selectivity of cinnamyl alcohol (COL) due to the micropore size effect of ZIF-8. The Au@ZA catalyst has ∼ 85 % COL selectivity when the CAL conversion is close to 100 %. And after 8 times of repeated use, the conversion of CAL and the selectivity of COL did not decrease significantly. It should be noted that just when a small amount of ZIF-8 is present, the synergistic catalytic effect mentioned above can be produced.

Fabrication of a cinnamaldehyde-based bi-DOPO flame retardant with excellent glass transition temperature, fire safety and mechanical properties for epoxy resins

Manufacturing fire-resistant, tough, and durable epoxy resin (EP) is a challenging task. Traditional flame retardants derived from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) tend to aggregate and plasticize, causing a decline in glass transition temperature (Tg) and mechanical properties of EP. To overcome this issue, a bulky aromatic DOPO-based derivative called PPCANT was synthesized successfully using biomass-derived cinnamaldehyde (CA). The steric hindrance and intermolecular interactions (π-π stacking) of PPCANT's mitigated Tg deterioration and significantly improved mechanical properties. Incorporating 5 wt% PPCANT into the EP (EP/PPCANT-5) achieved a limiting oxygen index (LOI) of 32.6% and UL-94 V-0 rating, reducing both total heat release and smoke production. Moreover, PPCANT endowed the EP with exceptional char-forming ability. Analysis of the flame retardant mechanism indicated that the PPCANT structure imparted an ideal flame quenching mechanism, characterized by the instantaneous extinction of flames caused by the blowout of PO·/PO2 radicals, and a dilution effect of free radicals from non-flammable gases. In addition, the incorporation of nitro and amino groups in PPCANT facilitates the formation of hydrogen bonds with the hydroxyl groups generated in the ring-opened EP, leading to a significant decrease in the hydrophilicity of EP. These findings highlight PPCANT as a promising flame retardant that simultaneously enhances flame retardancy, mechanical strength, and hydrophobicity in EP materials.