Harigaya Sayoko, Honda Takayuki, Rong Lu, Miyakoshi Tetsuo, Chen Chen-Loung
Department of Applied Chemistry, Meiji University, Kawasaki 214-8571, Japan.
J Agric Food Chem. 2007 Mar 21;55(6):2201-8. doi: 10.1021/jf063161g. Epub 2007 Feb 24.
Fresh exudates from the lacquer tree, Rhus vernicifera DC, were extracted with acetone and the solution was chromatographed to isolate monomer, dimer, trimer, and oligomer fractions of urushiols. Constituents of the monomeric and dimeric fractions were then identified by two-dimensional (2D) 1H-13C heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond coherence (HMBC) NMR spectroscopic techniques. The results showed that the monomeric fraction contained 3-[8'Z,11'E,13'Z-pentadecatrienyl]catechol (1), 3-[8'Z,11'Z,14'-pentadecatrienyl]catechol (2), and 3-pentadecanyl]catechol (3), which was verified by HPLC analysis. The dimeric fraction contained 8'-(3' ',4' '-dihydroxy-5' '-alkenyl)phenyl-3-[9'E,11'E,13'Z-pentadecatrienyl]catechol (4), 14'-(3' ',4' '-dihydroxy-5' '-alkenyl)phenyl-3-[8'Z,10'E,12'E-pentadecatrienyl]catechol (5), 2-hydroxyl-3- or -6-alkenylphenyl ethyl ether (6), 14'-(3' ',4' '-dihydroxy-2' '-alkenyl)phenyl-3-[8'Z,10'E,12'E-pentadeca-trienyl]catechol (7), 15'-(2' '-hydroxy-3' '- or -6' '-alkenyl)phenyloxy-3-[8'Z,11'Z,13'E)-pentadecatrienyl]catechol (8), 14'-(2' ',3' '-dihydroxy-4' '-alkenyl)phenyl-3-[8'Z,10'E,12'E-pentadecantrienyl]catechol (9), 1,1',2,2'-tetrahydroxy-6,6'-dialkenyl-4,3'-biphenyl (10), 1,1',2,2'-tetrahydroxy-6,6'-dialkenyl-4,4'-biphenyl (11), 1,1',2,2'-tetrahydroxy-6,6'-dialkenyl-5,4'-biphenyl (12), and 1,2,1'-trihydroxy-6,6'-dialkenyldibenzofuran (13) as constituents. In addition, dimeric ethers and peroxides, such as compounds 14 and 15, were produced by autoxidation of monomeric urushiols in atmospheric air. The possible reaction mechanisms for the dehydrogenative polymerization of urushiols by Rhus laccase present in the fresh raw exudates under the atmospheric oxygen are discussed on the basis of structures identified. This is of primary importance because the use of the urushi exudates as coating materials does not involve organic solvents and is an environmentally friendly process.
从漆树（漆树科漆属植物，Rhus vernicifera DC）的新鲜渗出物中用丙酮提取，所得溶液经色谱分离，以分离漆酚的单体、二聚体、三聚体和低聚物馏分。然后通过二维（2D）1H-13C异核多量子相干（HMQC）和异核多键相干（HMBC）核磁共振光谱技术鉴定单体和二聚体馏分的成分。结果表明，单体馏分包含3-[8'Z,11'E,13'Z-十五碳三烯基]儿茶酚（1）、3-[8'Z,11'Z,14'-十五碳三烯基]儿茶酚（2）和3-十五烷基]儿茶酚（3），这通过高效液相色谱分析得到验证。二聚体馏分包含8'-（3''，4''-二羟基-5''-烯基）苯基-3-[9'E,11'E,13'Z-十五碳三烯基]儿茶酚（4）、14'-（3''，4''-二羟基-5''-烯基）苯基-3-[8'Z,10'E,12'E-十五碳三烯基]儿茶酚（5）、2-羟基-3-或-6-烯基苯基乙醚（6）、14'-（3''，4''-二羟基-2''-烯基）苯基-3-[8'Z,10'E,12'E-十五碳三烯基]儿茶酚（7）、15'-（2''-羟基-3''-或-6''-烯基）苯氧基-3-[8'Z,11'Z,13'E）-十五碳三烯基]儿茶酚（8）、14'-（2''，3''-二羟基-4''-烯基）苯基-3-[8'Z,10'E,12'E-十五碳三烯基]儿茶酚（9）、1,1',2,2'-四羟基-6,6'-二烯基-4,3'-联苯（10）、1,1',2,2'-四羟基-6,6'-二烯基-4,4'-联苯（11）、1,1',2,2'-四羟基-6,6'-二烯基-5,4'-联苯（12）和1,2,1'-三羟基-6,6'-二烯基二苯并呋喃（13）作为成分。此外，二聚体醚和过氧化物，如化合物14和15，是由单体漆酚在大气空气中自动氧化产生的。基于所鉴定的结构，讨论了新鲜生渗出物中存在的漆树漆酶在大气氧存在下使漆酚脱氢聚合的可能反应机制。这至关重要，因为将漆树渗出物用作涂料不涉及有机溶剂，是一个环保过程。
