Citral(Eo)exhibits excellent fungicidal activities.However,it is difficult to maintain long-term fungicidal activity due to its strong volatility.Herein,a controlled-release strategy by using biomass-derived porous ca...Citral(Eo)exhibits excellent fungicidal activities.However,it is difficult to maintain long-term fungicidal activity due to its strong volatility.Herein,a controlled-release strategy by using biomass-derived porous carbon(BC)was developed to overcome the drawback of Eo.New composite materials were prepared by loading Eo on tea stem porous carbon(BC@Eo),and their controlled-release fungicidal activity against Exobasidium vexans was assessed.BC with a large specific surface area of 1001.6 m2/g and mesoporous structure was fabricated through carbonization tempera-ture of 700℃.The BC@Eo materials were characterized using Fourier-transform infrared spectroscopy and X-ray powder diffraction.The results suggested that chemical and physical interactions occurred in BC@Eo.The Eo release profile suggested a biphasic pattern with an initial fast release on days 1–14 and a subsequent controlled phase on days 14–30.The in vitro cumulative release percentage of Eo from BC@Eo was 51%during one month,and this result was significantly lower than that from free Eo(cumulative release percentage of Eo of 82%in one week).The anti-fungal activities of Eo and BC@Eo against E.vexans were determined using the inhibition zone method.The results indicated that Eo and BC@Eo formed large inhibition zones of 19.66±0.79 and 21.92±0.77 mm,respectively.The influence on the hyphal structure of E.vexans was observed by scanning electron microscopy on day 30.The hyphal structure of E.vexans treated with BC@Eo was more shrunken than that treated with Eo at 30 days,suggesting that BC@Eo prolongs the fungicidal activity against E.vexans.This study demonstrated that the encapsulation of Eo in BC for developing the BC@Eo materials could be a promising strategy to inhibit volatility and maintain the fungicidal activity of Eo and provide a potential alternative for the reuse of abundant tea biomass waste resources.展开更多
Citral is a monoterpene aldehyde,which is the main chemical component of essential oils from Litsea cubeba and Cymbopogon citratus,as well as one of the most important representatives of open-chain monoterpene compoun...Citral is a monoterpene aldehyde,which is the main chemical component of essential oils from Litsea cubeba and Cymbopogon citratus,as well as one of the most important representatives of open-chain monoterpene compounds.The lemon flavor released by citral is very strong,and thus,it is widely used in essence,spices,manufacturing of various foods and beauty and other industries.It has antibacterial,anti-inflammatory,antioxidant,anti-tumor,insecticidal and other biological activity.This paper reviewed citral in Lauraceae plants and its biological activity,in order to provide reference for the development and utilization of citral in Lauraceae plants and its diversified applications.展开更多
The efficient citral hydrogenation was achieved in aqueous media using Pd/CMS and alkali additives like K<sub>2</sub>CO<sub>3</sub>. The alkali concentrations, reaction temperature and the Pd m...The efficient citral hydrogenation was achieved in aqueous media using Pd/CMS and alkali additives like K<sub>2</sub>CO<sub>3</sub>. The alkali concentrations, reaction temperature and the Pd metal content were optimized to enhance the citral hydrogenation under aqueous media. In the absence of alkali, citral hydrogenation was low and addition of alkali promoted to ~92% hydrogenation without reduction in the selectivity to citronellal. The alkali addition appears to be altered the palladium sites. The pore size distribution reveals that the pore size of these catalysts is in the range of 0.96 to 0.7 nm. The palladium active sites are also quite uniform based on the TPR data. The catalytic parameters are correlated well with the activity data.展开更多
In this work, the Pd-based catalysts were designed via immobilizing Pd nanoparticles on graphite oxide (GO) modified with organic base, 1,1,3,3-tetramethylguanidine (TMG), which was used for the selective hydrogenatio...In this work, the Pd-based catalysts were designed via immobilizing Pd nanoparticles on graphite oxide (GO) modified with organic base, 1,1,3,3-tetramethylguanidine (TMG), which was used for the selective hydrogenation of citral. These catalysts were characterized by various techniques including IR, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was demonstrated that the Pd particles with size less than 5 nm were uniformly distributed throughout the support, and they were in the electron-deficient state due to the strong interactions with the modified support. The resultant Pd-TMG/GO catalyst displayed high efficiency for the selective hydrogenation of citral with a turnover frequency of 7100 h-1 as well as superior selectivity to citronellal of 89.6%. Moreover, the catalyst can be reused for five times without obvious activity loss, which may result from its stable structure.展开更多
As a nutritious cold chain food,cheese is susceptible to Listeria monocytogenes contamination.In order to prevent and control Listeria monocytogenes in cheese safely and efficiently,maintain the sensory quality during...As a nutritious cold chain food,cheese is susceptible to Listeria monocytogenes contamination.In order to prevent and control Listeria monocytogenes in cheese safely and efficiently,maintain the sensory quality during sale,this paper developed a novel nanofiber membrane with good mechanical strength,hydrophobicity,thermal stability,release performance and bacteriostatic performance as food active packaging.In this study,zein was introduced and electrospun to form a reliable carrier to embed and deliver citral in the cavity of HP-β-CD(Hydroxypropyl-β-cyclodextrin).We found that the zein-based nanofiber membranes showed preferable tensile properties and hydrophobicity with 4%(w:v)addition of citral/HP-β-CD inclusion complex.Meanwhile,the thermal stability and release property of citral were significantly improved by embedding in HP-β-CD and loading into zein-base nanofiber membranes.Moreover,after packaged by Zein nanofiber membrane encapsulated with citral/HP-β-CD inclusion complex under the storage conditions of 4℃ and 12℃,the growth of Listeria monocytogenes in four kinds of cheeses was inhibited to a certain degree.The texture and sensory quality of the four cheeses at the two temperatures and the color quality under the low temperature condition of 4℃ did not change significantly.In summary,Zein nanofiber membranes encapsulated with citral/HP-β-CD inclusion complex has potential application prospects in the field of food active packaging.展开更多
Citral,a natural antimicrobial agent,has been found to induce severe membrane damage resulting in bacterial death.Despite its effectiveness,there is a lack of in-depth research on its interaction with bacterial cells,...Citral,a natural antimicrobial agent,has been found to induce severe membrane damage resulting in bacterial death.Despite its effectiveness,there is a lack of in-depth research on its interaction with bacterial cells,espe-cially at low concentrations.This work aimed to investigate the impact of citral concentration on its antibacterial effect against Staphylococcus aureus(S.aureus)and to analyze the relevance between membrane damage and cell death.In this study,the minimal inhibitory concentration of citral against S.aureus was measured at 0.25 mg/mL.At a concentration of 0.5 mg/mL,citral significantly disturbed the cell membrane fluidity and permeability,leading to the leakage of intracellular macromolecules and rapid cell death.However,when the concentration was decreased to 0.25 mg/mL,the membrane damage was greatly reduced,and a complex biological process between citral and membrane components was found.Under continuous drug exposure,the cell membrane underwent gradual rigidification,concomitant with the loss of membrane function,ultimately causing cell death.Despite the fact that no notable disturbance to membrane functions was discovered,the presence of 0.125 mg/mL citral could still weaken the metabolic vitality and growth of S.aureus.Therefore,it was suggested that there could be multiple mechanisms of citral action on S.aureus cells,with drug concentration being a critical factor affecting the mode of action.Overall,the findings of this study provide valuable insights into the antibacterial mechanisms of natural compounds and broaden the potential applications of citral as a natural antimicrobial.展开更多
A novel carbon-titania composite material, C/TiO2, has been prepared by growing carbon nanofibers （CNFs） on TiO2 surface via methane decomposition using Ni-Cu as a catalyst. The C/TiO2 was used for preparing support...A novel carbon-titania composite material, C/TiO2, has been prepared by growing carbon nanofibers （CNFs） on TiO2 surface via methane decomposition using Ni-Cu as a catalyst. The C/TiO2 was used for preparing supported palladium catalyst, Pd/C/TiO2. The support and Pd/C/TiO2 catalyst were characterized by BET, SEM, XRD and TG-DTG. Its catalytic performance was evaluated in selective hydrogenation of citral to citronellal, and compared with that of activated carbon supported Pd catalyst. It was found that the Pd/C/TiO2 catalyst contains 97% of mesopores. And it exhibited 88% of selectivity to citronellal at citral conversion of 90% in citral hydrogenation, which was much higher than that of activated carbon supported Pd catalyst. This result may be attributed to elimination of internal diffusion limitations, which were significant in activated carbon supported Pd catalyst, due to its microporous structure.展开更多
Selective hydrogenation of citral was investigated over Au-based bimetallic catalysts in the environmentally benign supercritical carbon dioxide (scCO_(2)) medium.The catalytic performances were different in citral hy...Selective hydrogenation of citral was investigated over Au-based bimetallic catalysts in the environmentally benign supercritical carbon dioxide (scCO_(2)) medium.The catalytic performances were different in citral hydrogenation when Pd or Ru was mixed (physically and chemically) with Au.Compared with the corresponding monometallic catalyst,the total conversion and the selectivity to citronellal (CAL) were significantly enhanced over TiO2 supported Pd and Au bimetallic catalysts (physically and chemically mixed);however,the conversion and selectivity did not change when Ru was physically mixed with Au catalyst compared to the monometallic Ru/TiO2,and the chemically mixed Ru-Au/TiO2 catalyst did not show any activity.The effect of CO_(2) pressure on the conversion of citral and product selectivity was significantly different over the Au/TiO2,Pd-Au/TiO2,and Pd/TiO2 catalysts.It was assumed to be ascribed to the difference in the interactions between Au,Pd nanoparticles and CO_(2) under different CO_(2) pressures.展开更多
Objectives:The bacteriostatic effects of a citral nanoemulsion against Shewanella putrefaciens CN-32(SHP CN-32)were investigated using in vitro culture and gene expression analysis,forbuilding a potential application ...Objectives:The bacteriostatic effects of a citral nanoemulsion against Shewanella putrefaciens CN-32(SHP CN-32)were investigated using in vitro culture and gene expression analysis,forbuilding a potential application in spoilage microorganism control and aquatic products quality maintenance.Materials and Methods:SHP CN-32 was treated by prepared citral nanoemulsion when the minimal inhibitory concentration(MIC)was verified.The growth curve,membrane integrity,scanning electron microscope(SEM)observation,biofilm formation and quorum sensing(QS)signaling molecule Al-2 content were evaluated in different MIC treatment groups(0 to 1.00 MIC).The gene expression status of SHP CN-32 in O and 0.50 MIC groups were compared using transcriptome sequencing and quantitative polymerase chain reaction(PCR).Results:The in vitro culture revealed that the citral nanoemulsion could inhibit the growth of SHP CN-32 with MIC of approximately 200μg/mL.Images of membrane integrity.SEM and biofilm formation suggested significant biological structure damage in bacteria after treatment.Meanwhile,the Qs signaling molecule Al-2 content showed a decline with increasing treatment concentration.Transcriptome sequencing and quantitative PCR revealed that the majority genes related diversified functional metabolic pathways of SHP CN-32 were downregulated at varying degree.Conclusion:A significant bacteriostasis of citral nanoemulsion against SHP CN-32 was verified via the results of growth inhibition,structural destruction,signal molecular decrease and gene expression downregulation of strains.These synergies significantly affect the characteristic expression of SHP CN-32,revealing the application potential as bacteriostat,QS inhibitor and preservative in aquatic products.展开更多
Introduction:Tuberculosis,caused by Mycobacterium tuberculosis became more prevalent due to drug resistance.Cymbopogon citratus,a crop from the African flora contains an essential oil rich in carbonyl compounds.Conden...Introduction:Tuberculosis,caused by Mycobacterium tuberculosis became more prevalent due to drug resistance.Cymbopogon citratus,a crop from the African flora contains an essential oil rich in carbonyl compounds.Condensation of carbonyl compounds with thiosemicarbazides gave thiosemicarbazones which exhibit rather展开更多
基金Supported by National Modern Agricultural Industry Technology System,Youth Science and Technology Fund of Guizhou Academy of Agricultural Sciences No.[2020]02,Guiding Project of Guizhou Academy of Agricultural Sciences No.[2018]01.
文摘Citral(Eo)exhibits excellent fungicidal activities.However,it is difficult to maintain long-term fungicidal activity due to its strong volatility.Herein,a controlled-release strategy by using biomass-derived porous carbon(BC)was developed to overcome the drawback of Eo.New composite materials were prepared by loading Eo on tea stem porous carbon(BC@Eo),and their controlled-release fungicidal activity against Exobasidium vexans was assessed.BC with a large specific surface area of 1001.6 m2/g and mesoporous structure was fabricated through carbonization tempera-ture of 700℃.The BC@Eo materials were characterized using Fourier-transform infrared spectroscopy and X-ray powder diffraction.The results suggested that chemical and physical interactions occurred in BC@Eo.The Eo release profile suggested a biphasic pattern with an initial fast release on days 1–14 and a subsequent controlled phase on days 14–30.The in vitro cumulative release percentage of Eo from BC@Eo was 51%during one month,and this result was significantly lower than that from free Eo(cumulative release percentage of Eo of 82%in one week).The anti-fungal activities of Eo and BC@Eo against E.vexans were determined using the inhibition zone method.The results indicated that Eo and BC@Eo formed large inhibition zones of 19.66±0.79 and 21.92±0.77 mm,respectively.The influence on the hyphal structure of E.vexans was observed by scanning electron microscopy on day 30.The hyphal structure of E.vexans treated with BC@Eo was more shrunken than that treated with Eo at 30 days,suggesting that BC@Eo prolongs the fungicidal activity against E.vexans.This study demonstrated that the encapsulation of Eo in BC for developing the BC@Eo materials could be a promising strategy to inhibit volatility and maintain the fungicidal activity of Eo and provide a potential alternative for the reuse of abundant tea biomass waste resources.
基金Supported by Changsha Science and Technology Program (kh2101007).
文摘Citral is a monoterpene aldehyde,which is the main chemical component of essential oils from Litsea cubeba and Cymbopogon citratus,as well as one of the most important representatives of open-chain monoterpene compounds.The lemon flavor released by citral is very strong,and thus,it is widely used in essence,spices,manufacturing of various foods and beauty and other industries.It has antibacterial,anti-inflammatory,antioxidant,anti-tumor,insecticidal and other biological activity.This paper reviewed citral in Lauraceae plants and its biological activity,in order to provide reference for the development and utilization of citral in Lauraceae plants and its diversified applications.
文摘The efficient citral hydrogenation was achieved in aqueous media using Pd/CMS and alkali additives like K<sub>2</sub>CO<sub>3</sub>. The alkali concentrations, reaction temperature and the Pd metal content were optimized to enhance the citral hydrogenation under aqueous media. In the absence of alkali, citral hydrogenation was low and addition of alkali promoted to ~92% hydrogenation without reduction in the selectivity to citronellal. The alkali addition appears to be altered the palladium sites. The pore size distribution reveals that the pore size of these catalysts is in the range of 0.96 to 0.7 nm. The palladium active sites are also quite uniform based on the TPR data. The catalytic parameters are correlated well with the activity data.
基金financially supported by the National Natural Science Foundation of China (20903105, 21073202)Chinese Academy of Sciences (KJXC2.YW.H30)
文摘In this work, the Pd-based catalysts were designed via immobilizing Pd nanoparticles on graphite oxide (GO) modified with organic base, 1,1,3,3-tetramethylguanidine (TMG), which was used for the selective hydrogenation of citral. These catalysts were characterized by various techniques including IR, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was demonstrated that the Pd particles with size less than 5 nm were uniformly distributed throughout the support, and they were in the electron-deficient state due to the strong interactions with the modified support. The resultant Pd-TMG/GO catalyst displayed high efficiency for the selective hydrogenation of citral with a turnover frequency of 7100 h-1 as well as superior selectivity to citronellal of 89.6%. Moreover, the catalyst can be reused for five times without obvious activity loss, which may result from its stable structure.
基金financially supported by State Key Laboratory of Utilization of Woody Oil Resource(Grant no.2019XK 2002)National Natural Science Foundation of China(Grant no.31972172)+1 种基金Natural Science Foundation of Jiangsu Province(Grant no.BK20201417)Jiangsu Province Research Fund(Grant no.JNHB-131).
文摘As a nutritious cold chain food,cheese is susceptible to Listeria monocytogenes contamination.In order to prevent and control Listeria monocytogenes in cheese safely and efficiently,maintain the sensory quality during sale,this paper developed a novel nanofiber membrane with good mechanical strength,hydrophobicity,thermal stability,release performance and bacteriostatic performance as food active packaging.In this study,zein was introduced and electrospun to form a reliable carrier to embed and deliver citral in the cavity of HP-β-CD(Hydroxypropyl-β-cyclodextrin).We found that the zein-based nanofiber membranes showed preferable tensile properties and hydrophobicity with 4%(w:v)addition of citral/HP-β-CD inclusion complex.Meanwhile,the thermal stability and release property of citral were significantly improved by embedding in HP-β-CD and loading into zein-base nanofiber membranes.Moreover,after packaged by Zein nanofiber membrane encapsulated with citral/HP-β-CD inclusion complex under the storage conditions of 4℃ and 12℃,the growth of Listeria monocytogenes in four kinds of cheeses was inhibited to a certain degree.The texture and sensory quality of the four cheeses at the two temperatures and the color quality under the low temperature condition of 4℃ did not change significantly.In summary,Zein nanofiber membranes encapsulated with citral/HP-β-CD inclusion complex has potential application prospects in the field of food active packaging.
基金financially supported by State Key Laboratory of Utilization of Woody Oil Resource(Grant no.2019XK 2002)National Natural Science Foundation of China(Grant no.31972172)+1 种基金Natural Science Foundation of Jiangsu Province(Grant no.BK20201417)Jiangsu Province Research Fund(Grant no.JNHB-131).
文摘Citral,a natural antimicrobial agent,has been found to induce severe membrane damage resulting in bacterial death.Despite its effectiveness,there is a lack of in-depth research on its interaction with bacterial cells,espe-cially at low concentrations.This work aimed to investigate the impact of citral concentration on its antibacterial effect against Staphylococcus aureus(S.aureus)and to analyze the relevance between membrane damage and cell death.In this study,the minimal inhibitory concentration of citral against S.aureus was measured at 0.25 mg/mL.At a concentration of 0.5 mg/mL,citral significantly disturbed the cell membrane fluidity and permeability,leading to the leakage of intracellular macromolecules and rapid cell death.However,when the concentration was decreased to 0.25 mg/mL,the membrane damage was greatly reduced,and a complex biological process between citral and membrane components was found.Under continuous drug exposure,the cell membrane underwent gradual rigidification,concomitant with the loss of membrane function,ultimately causing cell death.Despite the fact that no notable disturbance to membrane functions was discovered,the presence of 0.125 mg/mL citral could still weaken the metabolic vitality and growth of S.aureus.Therefore,it was suggested that there could be multiple mechanisms of citral action on S.aureus cells,with drug concentration being a critical factor affecting the mode of action.Overall,the findings of this study provide valuable insights into the antibacterial mechanisms of natural compounds and broaden the potential applications of citral as a natural antimicrobial.
基金Project supported by the National Natural Science Foundation of China （No. 20976076） and the Natural Science Foundation of Jiangsu Province （No. BK2009536）.
文摘A novel carbon-titania composite material, C/TiO2, has been prepared by growing carbon nanofibers （CNFs） on TiO2 surface via methane decomposition using Ni-Cu as a catalyst. The C/TiO2 was used for preparing supported palladium catalyst, Pd/C/TiO2. The support and Pd/C/TiO2 catalyst were characterized by BET, SEM, XRD and TG-DTG. Its catalytic performance was evaluated in selective hydrogenation of citral to citronellal, and compared with that of activated carbon supported Pd catalyst. It was found that the Pd/C/TiO2 catalyst contains 97% of mesopores. And it exhibited 88% of selectivity to citronellal at citral conversion of 90% in citral hydrogenation, which was much higher than that of activated carbon supported Pd catalyst. This result may be attributed to elimination of internal diffusion limitations, which were significant in activated carbon supported Pd catalyst, due to its microporous structure.
基金supported by the One Hundred Talents Program and YW.H16 from the Chinese Academy of Sciencesthe National Natural Science Foundation of China (20573104)the CAS-JSPS International Joint Project GJHZ05
文摘Selective hydrogenation of citral was investigated over Au-based bimetallic catalysts in the environmentally benign supercritical carbon dioxide (scCO_(2)) medium.The catalytic performances were different in citral hydrogenation when Pd or Ru was mixed (physically and chemically) with Au.Compared with the corresponding monometallic catalyst,the total conversion and the selectivity to citronellal (CAL) were significantly enhanced over TiO2 supported Pd and Au bimetallic catalysts (physically and chemically mixed);however,the conversion and selectivity did not change when Ru was physically mixed with Au catalyst compared to the monometallic Ru/TiO2,and the chemically mixed Ru-Au/TiO2 catalyst did not show any activity.The effect of CO_(2) pressure on the conversion of citral and product selectivity was significantly different over the Au/TiO2,Pd-Au/TiO2,and Pd/TiO2 catalysts.It was assumed to be ascribed to the difference in the interactions between Au,Pd nanoparticles and CO_(2) under different CO_(2) pressures.
基金supported by the Hainan Provincial Natural Science Foundation of China (321CXTD1012)the National Natural Science Foundation of China (NSFC31871868)the Scientific Research Foundation of Hainan Tropical Ocean University (RHDRC202117),China.
文摘Objectives:The bacteriostatic effects of a citral nanoemulsion against Shewanella putrefaciens CN-32(SHP CN-32)were investigated using in vitro culture and gene expression analysis,forbuilding a potential application in spoilage microorganism control and aquatic products quality maintenance.Materials and Methods:SHP CN-32 was treated by prepared citral nanoemulsion when the minimal inhibitory concentration(MIC)was verified.The growth curve,membrane integrity,scanning electron microscope(SEM)observation,biofilm formation and quorum sensing(QS)signaling molecule Al-2 content were evaluated in different MIC treatment groups(0 to 1.00 MIC).The gene expression status of SHP CN-32 in O and 0.50 MIC groups were compared using transcriptome sequencing and quantitative polymerase chain reaction(PCR).Results:The in vitro culture revealed that the citral nanoemulsion could inhibit the growth of SHP CN-32 with MIC of approximately 200μg/mL.Images of membrane integrity.SEM and biofilm formation suggested significant biological structure damage in bacteria after treatment.Meanwhile,the Qs signaling molecule Al-2 content showed a decline with increasing treatment concentration.Transcriptome sequencing and quantitative PCR revealed that the majority genes related diversified functional metabolic pathways of SHP CN-32 were downregulated at varying degree.Conclusion:A significant bacteriostasis of citral nanoemulsion against SHP CN-32 was verified via the results of growth inhibition,structural destruction,signal molecular decrease and gene expression downregulation of strains.These synergies significantly affect the characteristic expression of SHP CN-32,revealing the application potential as bacteriostat,QS inhibitor and preservative in aquatic products.
文摘Introduction:Tuberculosis,caused by Mycobacterium tuberculosis became more prevalent due to drug resistance.Cymbopogon citratus,a crop from the African flora contains an essential oil rich in carbonyl compounds.Condensation of carbonyl compounds with thiosemicarbazides gave thiosemicarbazones which exhibit rather
