In order to better understand the specific substituent effects on the electrochemical oxidation process of β-O-4 bond, a series of methoxyphenyl type β-O-4 dimer model compounds with different localized methoxyl gro...In order to better understand the specific substituent effects on the electrochemical oxidation process of β-O-4 bond, a series of methoxyphenyl type β-O-4 dimer model compounds with different localized methoxyl groups, including 2-(2-methoxyphenoxy)-1-phenylethanone, 2-(2-methoxyphenoxy)-1-phenylethanol, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanol, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanol have been selected and their electrochemical properties have been studied experimentally by cyclic voltammetry, and FT-IR spectroelectrochemistry. Combining with electrolysis products distribution analysis and density functional theory calculations, oxidation mechanisms of all six model dimers have been explored. In particular, a total effect from substituents of both para-methoxy(on the aryl ring closing to Cα) and Cα-OH on the oxidation mechanisms has been clearly observed, showing a significant selectivity on the Cα-Cβbond cleavage induced by electrochemical oxidations.展开更多
深入研究了β-O-4型木质素模型化合物———愈创木基丙三醇-β-愈创木基醚的合成新路线,并利用红外光谱和核磁共振谱对其化学结构进行了分析。采用由Cu2+/吡啶/过氧化氢组成的GIF(GIF sur YVETTE)型仿酶体系对这一木质素模型物进行了... 深入研究了β-O-4型木质素模型化合物———愈创木基丙三醇-β-愈创木基醚的合成新路线,并利用红外光谱和核磁共振谱对其化学结构进行了分析。采用由Cu2+/吡啶/过氧化氢组成的GIF(GIF sur YVETTE)型仿酶体系对这一木质素模型物进行了仿酶降解的研究,并采用GC-MS、13CNMR等方法分析了该β-O-4型木质素模型化合物在降解过程中的结构变化,在此基础上对这种仿酶降解的机理进行了探讨。研究结果表明:利用溴化铜对4-乙酰基愈创木酚进行溴化后很容易得到4-(α-溴化乙酰基)-愈创木酚中间体,从而提高了合成愈创木基丙三醇-β-愈创木基醚的效率。GIF仿酶降解体系对β-O-4型木质素模型物有较强的碎解能力,降解后产生一系列含羟基、醛基和羧基的芳香族低分子化合物,根据反应产物的结构可以说明β-O-4型木质素模型化合物的主要降解途径为:β-O-4醚键断裂、Cα—Cβ键断裂、Cβ—Cγ键断裂。本研究为该仿酶降解体系在无污染漂白工业上的应用提供理论依据。展开更多
目的:建立 RP-HPLC 法测定通光藤药材中11α-O-顺芷酰基-12β-O-乙酰基-通光藤苷元 B 的含量。方法:采用酸水解法降解通光藤 C_(21)甾体苷,以反相高效液相色谱法测定11α-O-顺芷酰基-12β-O-乙酰基-通光藤苷元 B 含量,色谱柱为 Diamonsi...目的:建立 RP-HPLC 法测定通光藤药材中11α-O-顺芷酰基-12β-O-乙酰基-通光藤苷元 B 的含量。方法:采用酸水解法降解通光藤 C_(21)甾体苷,以反相高效液相色谱法测定11α-O-顺芷酰基-12β-O-乙酰基-通光藤苷元 B 含量,色谱柱为 Diamonsil ODS(250 mm×4.6 mm,5 μm);柱温为16℃;流动相为乙腈-水(45:55);流速为0.8 mL·min^(-1);检测波长为220 nm。结果:11α-O-顺芷酰基-12β-O-乙酰基-通光藤苷元 B 进样量在1.016～5.080μg范围内与峰面积积分值呈良好的线性关系,r=0.9999(n=5);平均回收率(n=6)为98.8%,RSD=1.9%。结论:方法简便、快速、准确,为通光藤药材的质量评价和新药开发提供科学依据。展开更多
为了解木质素的热解机理,利用密度泛函理论B3LYP方法,在6-31++G(d,p)基组水平上对含有C_α位羰基的β-O-4型木质素二聚体模型化合物(3-羟基-1-(4-羟基苯基)-2-苯氧基-1-丙酮)的热解过程进行了理论计算和分析。结果表明,C_α位上的羰基...为了解木质素的热解机理,利用密度泛函理论B3LYP方法,在6-31++G(d,p)基组水平上对含有C_α位羰基的β-O-4型木质素二聚体模型化合物(3-羟基-1-(4-羟基苯基)-2-苯氧基-1-丙酮)的热解过程进行了理论计算和分析。结果表明,C_α位上的羰基取代基可大大降低C_β—O的键解离能,提高C_α—C_β的键解离能,使得C_β—O的键解离能比C_α—C_β低91.5 k J/mol,因此该二聚体主要通过C_β—O键均裂的方式发生热解反应,其主要酚类热解产物是苯酚和4-羟基苯甲醛,次要产物是4-羟基苯乙酮,生成4-羟基苯甲醛的动力学最优路径是R7-a,其反应能垒为236.6 k J/mol。展开更多
Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for de...Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone （2-PAP）, was investigated over several ce-sium-exchanged polyoxometalate （Cs-POM） catalysts. Decomposition of 2-PAP can follow two dif-ferent mechanisms： an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox proper-ties of the catalysts. The catalysts of POMs perform the following functions： promoting active hy-drogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen libera-tion and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP （〉99%） with excellent selectivities to the desired products （98.6% for phenol and 91.1% for acetophenone） can be achieved.展开更多
The world relies on nonrenewable fossil resources, which provide various fuels, chemicals and materials. Biomass is an-other storage form of carbon and solar energy that has attract-ed great interest, mainly because o...The world relies on nonrenewable fossil resources, which provide various fuels, chemicals and materials. Biomass is an-other storage form of carbon and solar energy that has attract-ed great interest, mainly because of its potential as a sustaina-ble source of chemicals and fuels [1,2]. Lignin is an attractive biomass feedstock. As shown in Fig. 1, three phenylpropane units assemble into lignin with a complex three-dimensional structure and different linkages in plants [3].展开更多
Obesity is crucially involved in many metabolic diseases,such as type 2 diabetes,cardiovascular disease and cancer.Regulating the number or size of adipocytes has been suggested to be a potential treatment for obesity...Obesity is crucially involved in many metabolic diseases,such as type 2 diabetes,cardiovascular disease and cancer.Regulating the number or size of adipocytes has been suggested to be a potential treatment for obesity.In this study,we investigated the effect of pyrocincholic acid 3β-O-β-D-quinovopyranosyl-28-O-β-D-glucopyranoside(PAQG),a 27-nor-oleanolic acid saponin extracted from Metadina trichotoma,on adipogenesis and lipid metabolism in 3T3-L1 adipocytes.The 3T3-L1 pre-adipocytes were incubated with vehicle or PAQG for 6 days in differentiation process.PAQG significantly reduced the adipogenesis,adiponectin secretion and the expression level of key transcription factors related to adipogenesis,such as PPARc,C/EBPb,C/EBPa,and FABP4.Moreover,PAQG increased the levels of FFA and glycerol in medium and reduced TG level in mature adipocytes.Interestingly,PAQG not only promoted the activation of AMPK and genes involved in fatty oxidation including PDK4 and CPT1a,but also inhibited those genes involved in fatty acid biosynthesis,such as SREBP1c,FAS,ACCa and SCD1.In conclusion,PAQG inhibits the differentiation and regulates lipid metabolism of 3T3-L1 cells via AMPK pathway,suggesting that PAQG may be a novel and promising natural product for the treatment of obesity and hyperlipidemia.展开更多
目的建立能同时测定冠心安口服液中蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷含量的HPLC分析方法。方法Capcell Pak UG C_(18)色谱柱分离;蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷检测...目的建立能同时测定冠心安口服液中蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷含量的HPLC分析方法。方法Capcell Pak UG C_(18)色谱柱分离;蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷检测波长分别设定为334、281、320 nm;柱温为室温;进样体积为10μL;以乙腈为流动相A,1 mL·L^(−1)磷酸溶液(三乙胺调节pH至6.0)为流动相B,梯度洗脱。结果蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷的质量浓度分别在0.0245~2.4500、0.0457~4.5700、0.0474~4.7400μg·mL^(−1)范围内线性良好;平均回收率分别为100.8%、99.9%、101.4%;精密度和重复性RSD值(n=6)均在5.0%以内;供试品溶液在24 h内稳定。结论此方法具有前处理简单、分析时间短和检测结果准确等优点,适用于冠心安口服液制剂的质量控制。展开更多
基金The authors gratefully acknowledge the financial support of the Natural Science Foundation of China,China(Grant No.21975082 and 21736003)the Guangdong Basic and Applied Basic Research Foundation(Grant Number:2019A1515011472 and 2022A1515011341)the Science and Technology Program of Guangzhou(Grant Number:202102080479).
文摘In order to better understand the specific substituent effects on the electrochemical oxidation process of β-O-4 bond, a series of methoxyphenyl type β-O-4 dimer model compounds with different localized methoxyl groups, including 2-(2-methoxyphenoxy)-1-phenylethanone, 2-(2-methoxyphenoxy)-1-phenylethanol, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanol, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanol have been selected and their electrochemical properties have been studied experimentally by cyclic voltammetry, and FT-IR spectroelectrochemistry. Combining with electrolysis products distribution analysis and density functional theory calculations, oxidation mechanisms of all six model dimers have been explored. In particular, a total effect from substituents of both para-methoxy(on the aryl ring closing to Cα) and Cα-OH on the oxidation mechanisms has been clearly observed, showing a significant selectivity on the Cα-Cβbond cleavage induced by electrochemical oxidations.
文摘 深入研究了β-O-4型木质素模型化合物———愈创木基丙三醇-β-愈创木基醚的合成新路线,并利用红外光谱和核磁共振谱对其化学结构进行了分析。采用由Cu2+/吡啶/过氧化氢组成的GIF(GIF sur YVETTE)型仿酶体系对这一木质素模型物进行了仿酶降解的研究,并采用GC-MS、13CNMR等方法分析了该β-O-4型木质素模型化合物在降解过程中的结构变化,在此基础上对这种仿酶降解的机理进行了探讨。研究结果表明:利用溴化铜对4-乙酰基愈创木酚进行溴化后很容易得到4-(α-溴化乙酰基)-愈创木酚中间体,从而提高了合成愈创木基丙三醇-β-愈创木基醚的效率。GIF仿酶降解体系对β-O-4型木质素模型物有较强的碎解能力,降解后产生一系列含羟基、醛基和羧基的芳香族低分子化合物,根据反应产物的结构可以说明β-O-4型木质素模型化合物的主要降解途径为:β-O-4醚键断裂、Cα—Cβ键断裂、Cβ—Cγ键断裂。本研究为该仿酶降解体系在无污染漂白工业上的应用提供理论依据。
文摘为了解木质素的热解机理,利用密度泛函理论B3LYP方法,在6-31++G(d,p)基组水平上对含有C_α位羰基的β-O-4型木质素二聚体模型化合物(3-羟基-1-(4-羟基苯基)-2-苯氧基-1-丙酮)的热解过程进行了理论计算和分析。结果表明,C_α位上的羰基取代基可大大降低C_β—O的键解离能,提高C_α—C_β的键解离能,使得C_β—O的键解离能比C_α—C_β低91.5 k J/mol,因此该二聚体主要通过C_β—O键均裂的方式发生热解反应,其主要酚类热解产物是苯酚和4-羟基苯甲醛,次要产物是4-羟基苯乙酮,生成4-羟基苯甲醛的动力学最优路径是R7-a,其反应能垒为236.6 k J/mol。
基金supported by the National Key Basic Research Program of China(973 program,2013CB934101)National Natural Science Foundation of China(21433002,21573046)+1 种基金China Postdoctoral Science Foundation(2016M601492)International Science and Technology Cooperation Projects of Guangxi(15104001-5)~~
文摘Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone （2-PAP）, was investigated over several ce-sium-exchanged polyoxometalate （Cs-POM） catalysts. Decomposition of 2-PAP can follow two dif-ferent mechanisms： an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox proper-ties of the catalysts. The catalysts of POMs perform the following functions： promoting active hy-drogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen libera-tion and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP （〉99%） with excellent selectivities to the desired products （98.6% for phenol and 91.1% for acetophenone） can be achieved.
文摘The world relies on nonrenewable fossil resources, which provide various fuels, chemicals and materials. Biomass is an-other storage form of carbon and solar energy that has attract-ed great interest, mainly because of its potential as a sustaina-ble source of chemicals and fuels [1,2]. Lignin is an attractive biomass feedstock. As shown in Fig. 1, three phenylpropane units assemble into lignin with a complex three-dimensional structure and different linkages in plants [3].
文摘Obesity is crucially involved in many metabolic diseases,such as type 2 diabetes,cardiovascular disease and cancer.Regulating the number or size of adipocytes has been suggested to be a potential treatment for obesity.In this study,we investigated the effect of pyrocincholic acid 3β-O-β-D-quinovopyranosyl-28-O-β-D-glucopyranoside(PAQG),a 27-nor-oleanolic acid saponin extracted from Metadina trichotoma,on adipogenesis and lipid metabolism in 3T3-L1 adipocytes.The 3T3-L1 pre-adipocytes were incubated with vehicle or PAQG for 6 days in differentiation process.PAQG significantly reduced the adipogenesis,adiponectin secretion and the expression level of key transcription factors related to adipogenesis,such as PPARc,C/EBPb,C/EBPa,and FABP4.Moreover,PAQG increased the levels of FFA and glycerol in medium and reduced TG level in mature adipocytes.Interestingly,PAQG not only promoted the activation of AMPK and genes involved in fatty oxidation including PDK4 and CPT1a,but also inhibited those genes involved in fatty acid biosynthesis,such as SREBP1c,FAS,ACCa and SCD1.In conclusion,PAQG inhibits the differentiation and regulates lipid metabolism of 3T3-L1 cells via AMPK pathway,suggesting that PAQG may be a novel and promising natural product for the treatment of obesity and hyperlipidemia.
文摘目的建立能同时测定冠心安口服液中蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷含量的HPLC分析方法。方法Capcell Pak UG C_(18)色谱柱分离;蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷检测波长分别设定为334、281、320 nm;柱温为室温;进样体积为10μL;以乙腈为流动相A,1 mL·L^(−1)磷酸溶液(三乙胺调节pH至6.0)为流动相B,梯度洗脱。结果蒙花苷、延胡索乙素和2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷的质量浓度分别在0.0245~2.4500、0.0457~4.5700、0.0474~4.7400μg·mL^(−1)范围内线性良好;平均回收率分别为100.8%、99.9%、101.4%;精密度和重复性RSD值(n=6)均在5.0%以内;供试品溶液在24 h内稳定。结论此方法具有前处理简单、分析时间短和检测结果准确等优点,适用于冠心安口服液制剂的质量控制。
