Controlled-Release of Plant Volatiles:New Composite Materials of Porous Carbon-Citral and Their Fungicidal Activity against Exobasidium vexans

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.

Overview of Research on Citral in Lauraceae Plants and Its Biological Activity

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.

Effect of Alkali Carbonate/Bicarbonate on Citral Hydrogenation over Pd/Carbon Molecular Sieves Catalysts in Aqueous Media

The efficient citral hydrogenation was achieved in aqueous media using Pd/CMS and alkali additives like K2CO3. 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.

柠檬醛对草莓贮藏期间品质和抗氧化能力的影响

目的探讨不同植物精油对草莓贮藏期间品质和抗氧化能力的影响。方法以“红颜”草莓为试材,分别用不同质量浓度(40、80、160和320μg/mL)的百里香精油、丁香花精油、肉桂精油、枯茗醛和柠檬醛进行处理,测定其在20℃贮藏期间的失重率、腐烂指数、理化性质、抗氧化物质含量和抗氧化酶活性等指标。结果柠檬醛在40μg/mL质量浓度时具有最佳保鲜效果,能够有效地降低草莓果实的失重率和腐烂指数,延缓可溶性固形物、可滴定酸和抗坏血酸含量的下降,维持较高的总酚和总黄酮含量,并提高果实对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基和羟基自由基的清除能力。此外,该处理还能显著提高过氧化氢酶、超氧化物歧化酶、抗坏血酸过氧化物酶等抗氧化酶的活性,且有效抑制丙二醛含量的升高。结论柠檬醛在草莓贮藏中具有良好的保鲜效果,能够保持其品质和营养价值,这为柠檬醛在水果贮藏保鲜中的应用提供了依据。

姜精油和柠檬醛对生姜枯萎病菌的抑菌作用及盆栽防效

生姜枯萎病是由尖孢镰刀菌(Fusarium oxysporum)引起的土传病害,防控极为困难。为了探究环境友好和安全的植物源生物农药,本研究利用平板抑菌试验和孢子萌发试验研究了姜精油和柠檬醛对生姜枯萎病菌尖孢镰刀菌的生长抑制作用,并通过盆栽试验进一步验证了姜精油和柠檬醛对生姜枯萎病菌尖孢镰刀菌的防控效果。结果显示,姜精油和柠檬醛处理可显著抑制生姜枯萎病菌尖孢镰刀菌的菌丝生长与孢子萌发,2 g·L^(−1)姜精油和0.5 g·L^(−1)柠檬醛对生姜枯萎病菌尖孢镰刀菌菌丝生长的抑制率分别为82.0%与100.0%,孢子萌发抑制率分别为34.7%与95.0%。扫描电镜结果表明,姜精油和柠檬醛处理生姜枯萎病菌尖孢镰刀菌菌丝体3 d后,其菌丝体表现出不同程度的弯曲、褶皱和凹陷;PI染色结果发现,姜精油和柠檬醛处理严重破坏了生姜枯萎病菌尖孢镰刀菌细胞膜的完整性和通透性,从而导致胞浆流失、胞外电导率、蛋白质、核酸与丙二醛含量急剧增加,麦角固醇含量减少,进而减弱了生姜枯萎病菌尖孢镰刀菌的致病力。接种生姜枯萎病菌尖孢镰刀菌15 d后,2 g·L^(−1)姜精油和0.5 g·L^(−1)柠檬醛处理对生姜枯萎病的防控效果分别为32.7%和42.3%,0.5 g·L^(−1)柠檬醛处理与8 g·L^(−1)百菌清防控效果(47.1%)无显著差异。综上,姜精油和柠檬醛对生姜枯萎病菌尖孢镰刀菌的生长有显著抑制作用,并对生姜枯萎病有较好的防治效果,研究结果可为开发新型植物源抑菌剂防控生姜枯萎病提供理论依据。

Selective Hydrogenation of Citral over a Carbon-titania Composite Supported Palladium Catalyst

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.

Selective hydrogenation of citral over Au-based bimetallic catalysts in supercritical carbon dioxide

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.

Inhibition of citral nanoemulsion to growth,spoilage ability and Al-2/luxS quorum sensing system of Shewanella putrefaciens CN-32:a study on bacteriostasis from in vitro culture and gene expression analysis

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.

ANTIMICROBIAL ACTIVITY OF CYMBOPOGON CITRATUS ESSENTIAL OIL AND CITRAL THIOSEMICARBAZONE AGAINST MYCOBACTERIUM TUBERCULOSIS

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

Pd nanoparticles immobilized on graphite oxide modified with a base: Highly efficient catalysts for selective hydrogenation of citral

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.

柠檬醛纳米乳对壳聚糖涂膜性能和保鲜效果的影响

为全面地探究柠檬醛纳米乳/壳聚糖复合涂膜对柑橘果实的保鲜机理,研究首先表征了柠檬醛纳米乳添加量(10%、20%和30%,质量分数)对壳聚糖平板膜拉伸性能和透过性能,以及膜液在果实表皮润湿性能的影响,然后测定了复合涂膜对蜜桔果实贮藏品质的影响。结果表明,柠檬醛纳米乳可增强壳聚糖膜的塑性,提高薄膜的水蒸气透过系数与氧气透过系数;添加10%的纳米乳使得涂膜液在蜜桔果皮表面的接触角由纯壳聚糖膜液的80.49°降至66.2°,铺展系数则由-53.48 mN/m提升至-23.02 mN/m,较好地改善了涂膜液对蜜桔果皮的润湿性,提高了二者的界面相互作用。将柠檬醛纳米乳/壳聚糖复合涂膜用于蜜桔保鲜时,可较好地抑制果实的腐烂,降低其呼吸强度并维持较为稳定的营养物质含量。其中,纳米乳添加量为20%的涂膜对果实腐烂的抑制效果最好,贮藏19 d后该组果实的腐烂率仅为16.67%,而对照组的腐烂率已超过30%。因此,柠檬醛纳米乳的添加既可提高涂膜在果皮表面的铺展性能以改善涂膜结构,同时也可通过柠檬醛的释放来减少微生物对果实的侵染,进而显著提高果实的贮藏品质,在果实采后保鲜中具有良好的应用潜力。

柠檬醛和丁香酚对黄曲霉生长的协同抑菌作用研究

为了降低抑菌剂的用量及成本,同时达到更好的抑菌效果,分别检测麝香草酚、香芹酚、邻香兰素、柠檬醛和丁香酚的最小抑菌浓度(MIC),通过棋盘法筛选到具有协同抑菌作用的复配组合为柠檬醛和丁香酚,进一步研究其抑菌机制。测定柠檬醛和丁香酚协同处理下黄曲霉菌丝干重变化,通过碘化丙啶染色试验测定细胞内容物释放、相对电导率和pH值变化,检测其对细胞膜完整性的影响,通过荧光白染色试验研究其对隔膜的影响,最后评估其在花生中的抑菌效果。结果表明:麝香草酚、香芹酚、柠檬醛和丁香酚的MIC分别为135、47、71、43μg/mL,通过联合抑菌法得出当1/4 MIC柠檬醛+1/4 MIC丁香酚时,具有协同抑菌作用;柠檬醛和丁香酚协同处理能完全抑制菌丝生长、破坏黄曲霉细胞膜的完整性,细胞外pH值依次降低,相对电导率依次升高,黄曲霉菌丝内的隔膜被破坏;柠檬醛和丁香酚对黄曲霉的抗真菌活性与细胞膜通透性和细胞壁完整性受损有关;1/4 MIC柠檬醛+1/4 MIC丁香酚处理完全抑制了黄曲霉孢子在花生上的萌发。柠檬醛和丁香酚处理在防控黄曲霉污染中展示了良好的效果,同时协同处理方式降低了天然化合物的用量和成本。

多糖稳定柠檬醛及其在食品领域的应用研究进展

柠檬醛因具有柠檬香气和抗菌生物活性而被应用于食品领域,但因其对酸、氧、光敏感,易发生酸催化环化、氧化和光化学降解而导致生物活性降低,其应用受到极大限制,采用多糖封装是提高柠檬醛物理、化学稳定性和延缓降解的有效方式。本文综述了柠檬醛的结构性质及其在食品饮料、保鲜抗菌方面的应用及局限性,总结了多糖用于封装稳定柠檬醛的方法,包括乳液系统、自组装、水凝胶及喷雾干燥,同时概述了这些方法稳定柠檬醛的应用现状,最后指出该研究领域存在的问题和未来的研究方向,旨在为提高柠檬醛生物活性、拓展其在食品领域中的应用提供理论参考。

假性紫罗兰酮的合成研究

以柠檬醛和乙酰乙酸酯类化合物为原料,以仲胺类有机碱为缩合催化剂,制得中间体2-乙酰基-5,9-二甲基-葵-2,4,8-三烯酸酯类化合物及其烯醇式衍生物;将中间体混合物在稀的碳酸氢钠水溶液中进行水解脱羧反应制得假性紫罗兰酮.本文研究了乙酰乙酸酯和仲胺的种类对反应的影响,通过正交实验,优化反应条件,筛选更优异的合成工艺:以二乙胺为碱性缩合剂,柠檬醛与乙酰乙酸甲酯在20℃温度下缩合反应1.5 h,收率为98.8%,脱羧反应收率98.0%,两步总收率96.8%,产品气相含量97%.工艺具有收率高、操作简便、废水少等特点,具有工业化前景.

基于灰色关联度分析的荜澄茄药材质量评价

目的评价不同产地荜澄茄药材的质量。方法收集14个产区荜澄茄药材样品,根据2020年版《中国药典(四部)》检查方法测定水分、总灰分、浸出物,采用高效液相色谱法测定药材样品中柠檬醛和芦丁的含量。以上述5个指标为考察对象,采用灰色关联度分析法构建荜澄茄药材质量评价模型,并与主成分分析法结果比较。结果灰色关联度分析法结果显示,福建建阳产药材样品与最优参考序列的相对关联度(0.66)最高,质量最优;广西苍梧产药材与最优参考序列的相对关联度(0.30)最低,质量最差。主成分分析法与灰色关联分析法的结果基本一致。结论所建立模型可用于荜澄茄药材的质量评价,建议将柠檬醛、芦丁含量测定纳入质量标准。

山苍子对水生浮游动物的毒性影响探究

山苍子治疗水霉病的病鱼有很好的疗效,但对水体中浮游动物的影响未知,因而探究山苍子对水生生态系统影响具有重要意义。以大型蚤为受试生物,设置山苍子浓度分别为0.02 mg/mL、0.1 mg/mL、0.5 mg/mL的实验组以及空白,每组3个平行,记录14天内大型蚤的体长、退壳数、产蚤数、存活数等指标。山苍子的使用浓度低于0.02 mg/mL有利于蚤的生长和繁殖,浓度大于0.1 mg/mL时对蚤的生长和繁殖有一定影响,高于0.5 mg/mL时严重威胁蚤的健康。山苍子对大型蚤的生长有一定的促进作用,但是浓度过高时对蚤的长期影响还有待进一步研究。

柠檬醛通过MDM2/p53信号通路对小鼠B细胞淋巴瘤38B9细胞增殖、细胞周期及凋亡的影响

目的:探讨柠檬醛(citral)对小鼠B细胞淋巴瘤38B9细胞的作用和机制。方法:采用不同质量浓度(0~120 mg/L)的柠檬醛处理38B9细胞,通过CCK-8法检测细胞活力,并计算柠檬醛的半数抑制浓度(IC_(50))。根据IC_(50)值设置低、中、高三个浓度(5、10、20 mg/L)处理38B9细胞,并检测柠檬醛对38B9细胞增殖的影响。采用瑞氏-吉姆萨染色观察38B9细胞形态变化。通过流式细胞术检测38B9细胞凋亡及细胞周期。利用RT-qPCR和Western blot检测38B9细胞凋亡及细胞周期相关因子的mRNA和蛋白表达水平,小鼠抑瘤实验观察柠檬醛对38B9细胞生长的作用。通过PubChem在线预测柠檬醛可能的靶点,并绘制蛋白质互作网络图。使用ClusterProfile对结果进行GO富集分析并使用ggplot2绘制可视化柱状图。利用Western blot检测38B9细胞MDM2/p53信号通路相关蛋白的表达水平。结果:柠檬醛能有效抑制小鼠B细胞淋巴瘤38B9细胞的活力,诱导其凋亡并阻滞其细胞周期,促进Puma、Noxa、Bax和p21的mRNA和蛋白表达(P<0.05或P<0.01),抑制Bcl-2和CDK2的mRNA和蛋白表达(P<0.05或P<0.01),抑制MDM2的蛋白表达(P<0.05),促进p53的蛋白表达(P<0.05)。结论:柠檬醛能够显著抑制小鼠B细胞淋巴瘤38B9细胞的增殖,同时诱导细胞凋亡并引起细胞周期阻滞,其机制可能与MDM2/p53信号通路有关。

二异丙基氨基锂催化柠檬醛合成假性紫罗兰酮研究

目的:研究二异丙基氨基锂(LDA)催化山苍子油中的柠檬醛合成假性紫罗兰酮。方法:在冰水浴条件下,选取LDA和柠檬醛用量比、丙酮和柠檬醛的用量比、反应时间三个因素为实验影响因素,进行单因素试验,分别研究这三个因素对假性紫罗兰酮合成的影响。根据实验结果在三个因素中各取三个合理水平进行L_(9)(3^(4))正交试验,根据极差分析,得出最优工艺条件。结果:正交实验表明在LDA和柠檬醛用量比2∶1、丙酮和柠檬醛的用量比6.0、反应时间3.5h下,柠檬醛转化率为95.41%,假性紫罗兰酮得率为86.36%。结论:该假性紫罗兰酮合成工艺简单,产率较高,可进行工业化。

柠檬醛对黄曲霉质膜损伤机制的初步研究

与正常生长的黄曲霉对照 ,通过测定经柠檬醛毒化的菌丝体对还原糖和蛋白质利用率、[Na+ ,K+ ] ATPase分解ATP活性、细胞电解质渗出率、并结合扫描电镜和快速显微多道分光光度法观察菌丝体细胞及孢子形态变化 ,结果表明经该醛MIC毒化后 ,菌丝体细胞及孢子表面疏松而粗糙 ;隘痕缩小并关闭 ;电导率增加 5 2 8% ;对还原糖和蛋白质的利用速率分别下降 6 1 5 %和 44 3 % ;孢子萌发率下降至 6 1 4% ;该醛能明显改变细胞质膜的分子结构 ,使其失去选择通透性而抑制菌丝体生长和孢子萌发率。

微波法从山苍子中提取柠檬醛及其测定研究(英文)

讨论了采用微波辐照从山苍子中提取制备柠檬醛 ,精油的得率较传统的直接水蒸气蒸馏法平均提高 2 .4 8%以上。用程序升温毛细管柱气相色谱归一化法测定山苍子精油中的柠檬醛 ,获得了山苍子精油中柠檬醛含量为 68.64 % ,回收率为 10 1.3 % ,相对标准偏差为 0 .2 8% ,线性相关系数为 0 .9997,准确性与内标法相一致的实验结果 ,而且操作较内标法和GB 1142 4 - 89法更为方便。