表没食子儿茶素没食子酸酯(EGCG)自然氧化产物的分析
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摘要
【目的】茶多酚是茶叶中最重要的活性物质,而儿茶素含量占茶多酚总量70%以上。EGCG是儿茶素中最主要的活性物质,具有多种生物学活性,但其稳定性较差,在自然条件下容易发生氧化。目前,对其氧化产物的化学结构没有详细的报道。【方法】本研究使用ESI-MS、NMR等方法,鉴定EGCG的自然氧化产物,并检测不同反应条件(如时间、温度、pH值)下,EGCG主要自然氧化产物的变化规律。【结果】鉴定得到了2个主要的EGCG自然氧化产物:C-4位与C-8″连接的EGCG二聚化合物1;B-B″环间氧化的化合物2。【结论】确定了当自然氧化条件分别为氧化时间2 h、反应温度20℃、反应pH值8.0时,化合物2的生成占主导,且产率最高,可达到27~30μg/mL。
【Objective】The most important active substances in tea were tea polyphenols,more than 70 % of them were composed by catechins. EGCG was the majorbioactive compound in the catechins and had many biological activities. But its stability was poor and it was prone to oxidation under the normal conditions. At present,there was no detailed reports about the EGCG oxidation products' chemical structures.【Method】We used ESI-MS,NMR methods to identify the EGCG natural oxidation products and study the changes of EGCG major normal oxidation products' productivity in different reaction conditions( such as time,temperature,pH value).【Result】Two major EGCG normal oxidative products were identified,EGCG dimerization compound1 that connected with C-4 and C-8″. Compound 2 which was oxidated between B-B" ring.【Conclusion】We confirmed that the natural oxidation conditions were oxidation time 2 h,reaction temperature 20 ℃,pH value 8. 0. The production of compound 2 was dominant,and had the highest yield,could reach 27-30 μg/mL.
【Objective】The most important active substances in tea were tea polyphenols,more than 70 % of them were composed by catechins. EGCG was the majorbioactive compound in the catechins and had many biological activities. But its stability was poor and it was prone to oxidation under the normal conditions. At present,there was no detailed reports about the EGCG oxidation products' chemical structures.【Method】We used ESI-MS,NMR methods to identify the EGCG natural oxidation products and study the changes of EGCG major normal oxidation products' productivity in different reaction conditions( such as time,temperature,pH value).【Result】Two major EGCG normal oxidative products were identified,EGCG dimerization compound1 that connected with C-4 and C-8″. Compound 2 which was oxidated between B-B" ring.【Conclusion】We confirmed that the natural oxidation conditions were oxidation time 2 h,reaction temperature 20 ℃,pH value 8. 0. The production of compound 2 was dominant,and had the highest yield,could reach 27-30 μg/mL.
引文
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[7]Valcic S,Muders A,Jacobsen NE,et al.Antioxidant chemistry of green tea catechins.Identification of products of the reaction of(-)-epigallocatechingallate with peroxyl radicals[J].Chem.Res.Toxicol.,1999,12:382-386.
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[11]邓永亮,冯雷,吕才有.一种快速检测茶叶中儿茶素的HPLC方法[J].西南农业学报,2011,24(3):932-935.
[12]Nonaka G I,Muta M,Nishioka I.Myricatin,a galloylflavanonol sulfate and prodelphinidingallates from Myricarubra[J].Phytochemistry,1983,22:237-241.
[13]Valcic S,Muders A,Jacobsen N E,et al.Antioxidant chemistry of green tea catechins.Identification of productsof the reaction of(-)-epigallocatechingallate with peroxylradicals[J].Chem.Res.Toxicol,1999,12:382-386.
[14]Tanaka T,Matsuo Y,Kouno I.A novel black tea pigment and two new oxidation products of epigallocatechin-3-O-gallate[J].J Agric.Food Chem.,2005,53:7571-7578.
[15]Tanaka T,Watarumi S,Matsuo Y,et al.Production of theasinensins A and D,epigallocatechingallate dimers ofblack tea,by oxidation-reduction dismutation of dehydrotheasinensin A[J].Tetrahedron,2003,59:7939-7947.
[16]戚向阳.EGCG氧化产物制备新技术及结构鉴定[J].中国食品科学,2010(6):122-126.
[2]余志强,冯红钰,梁光志.桂香红美人茶加工工艺优化[J].南方农业学报,2015,46(8):1495-1499.
[3]宛晓春.茶叶生物化学[M].北京:中国农业出版社,2003:9-53.
[4]李春美,谢笔钧.儿茶素氧化聚合产物药理作用研究概况[J].茶叶,2001,27:28-34.
[5]Li C M,Xie B J.Evaluation of the antioxidant and pro-oxidant effects of tea catechin oxy-polymers[J].J Agric.Food Chem.,2000,12:6362-6366.
[6]李春美,谢笔钧.茶多酚及其氧化产物清除不同体系产生的活性氧自由基的分光光度法研究[J].精细化工,2000,4:241-244.
[7]Valcic S,Muders A,Jacobsen NE,et al.Antioxidant chemistry of green tea catechins.Identification of products of the reaction of(-)-epigallocatechingallate with peroxyl radicals[J].Chem.Res.Toxicol.,1999,12:382-386.
[8]Tanaka T,Watarumi S,Matsuo Y,et al.Kouno I.Produetion of theasinensins A and D,epigallocatechingallate dimers of black tea,by oxidation-reduction dismutation of dehydrotheasinensin A[J].Tetrahedron,2003,59:7939-794.
[9]Bailey R G,Nursten H E,Mcdowell I.Isolation and analysis of a polymeric thearubigin from tea[J].J Sci.Food Agric.,1992,59:365-375.
[10]夏涛.红茶色素形成机理的研究[J].茶叶科学,1999,19:139-144.
[11]邓永亮,冯雷,吕才有.一种快速检测茶叶中儿茶素的HPLC方法[J].西南农业学报,2011,24(3):932-935.
[12]Nonaka G I,Muta M,Nishioka I.Myricatin,a galloylflavanonol sulfate and prodelphinidingallates from Myricarubra[J].Phytochemistry,1983,22:237-241.
[13]Valcic S,Muders A,Jacobsen N E,et al.Antioxidant chemistry of green tea catechins.Identification of productsof the reaction of(-)-epigallocatechingallate with peroxylradicals[J].Chem.Res.Toxicol,1999,12:382-386.
[14]Tanaka T,Matsuo Y,Kouno I.A novel black tea pigment and two new oxidation products of epigallocatechin-3-O-gallate[J].J Agric.Food Chem.,2005,53:7571-7578.
[15]Tanaka T,Watarumi S,Matsuo Y,et al.Production of theasinensins A and D,epigallocatechingallate dimers ofblack tea,by oxidation-reduction dismutation of dehydrotheasinensin A[J].Tetrahedron,2003,59:7939-7947.
[16]戚向阳.EGCG氧化产物制备新技术及结构鉴定[J].中国食品科学,2010(6):122-126.