Initial steps of the peroxidase-catalyzed polymerization of coniferyl alcohol and/or sinapyl aldehyde: capillary zone electrophoresis study of pH effect

Capillary zone electrophoresis has been used to monitor the first steps of the dehydrogenative polymerization of coniferyl alcohol, sinapyl aldehyde, or a mixture of both, catalyzed by the horseradish peroxidase (HRP)-H(2)O(2) system. When coniferyl alcohol was the unique HRP substrate, three major dimers were observed (beta-5, beta-beta, and beta-O-4 interunit linkages) and their initial formation velocity as well as their relative abundance varied with pH. The beta-O-4 interunit linkage was thus slightly favored at lower pH values. In contrast, sinapyl aldehyde turned out to be a very poor substrate for HRP except in basic conditions (pH 8). The major dimer observed was the beta,beta'-di-sinapyl aldehyde, a red-brown exhibiting compound which might partly participate in the red coloration usually observed in cinnamyl alcohol dehydrogenase-deficient angiosperms. Finally, when a mixture of coniferyl alcohol and sinapyl aldehyde was used, it looked as if sinapyl aldehyde became a very good substrate for HRP. Indeed, coniferyl alcohol turned out to serve as a redox mediator (i.e. "shuttle oxidant") for the sinapyl aldehyde incorporation in the lignin-like polymer. This means that in particular conditions the specificity of oxidative enzymes might not hinder the incorporation of poor substrates into the growing lignin polymer.     

阿魏酸钠对肺结核模型小鼠免疫功能及肺泡巨噬细胞吞噬功能的调控作用研究

摘要 目的：探讨与分析阿魏酸钠对肺结核模型小鼠免疫功能及肺泡巨噬细胞吞噬功能的调控作用。方法：肺结核模型小鼠(n=36)随机分为模型组、利福平组、阿魏酸钠组,每组各12只。利福平组、阿魏酸钠组分别给予100 mg/kg剂量的利福平与阿魏酸钠,模型组小鼠灌胃等量生理盐水,1次/d,给药6周,观察与记录所有小鼠的一般特征;分别于给药第2周、第4周、第6周,HE染色观察小鼠的病理特征;MDA检测试剂盒和总SOD活性检测试剂盒测定肺组织MDA水平与SOD活性;流式细胞仪检测小鼠T淋巴细胞亚群-CD3⁺T淋巴细胞、CD4⁺T淋巴细胞水平;酶联免疫法检测血清IL-6、IL-8含量;AnnexinV-FITC检测肺泡巨噬细胞凋亡率。结果：利福平组、阿魏酸钠组给药第2周、第4周、第6周的肺组织丙二醛（Malondialdehyde,MDA）水平低于模型组（P<0.05）,超氧化物岐化酶（superoxide dismutase,SOD）活性高于模型组（P<0.05）,利福平组与阿魏酸钠组对比也有明显差异（P<0.05）。利福平组、阿魏酸钠组给药第2周、第4周、第6周的血液CD3⁺T淋巴细胞、CD4⁺T淋巴细胞比例明显高于模型组（P<0.05）,阿魏酸钠组也高于利福平组（P<0.05）。利福平组、阿魏酸钠组给药第2周、第4周、第6周的血清IL-6、IL-8含量明显低于模型组（P<0.05）,阿魏酸钠组也低于利福平组（P<0.05）。利福平组、阿魏酸钠组给药第2周、第4周、第6周的肺泡灌洗液（broncho alveolar lavage fluid,BALF）巨噬细胞凋亡率明显低于模型组（P<0.05）,阿魏酸钠组也明显低于利福平组（P<0.05）。结论：阿魏酸钠在肺结核模型小鼠的应用可抑制炎症因子的表达,并改善氧化状况,还能增强小鼠的免疫功能,降低肺泡灌洗液巨噬细胞凋亡率。     

阿魏酸钠诱导分化的PC12细胞裂解液的无细胞滤液的抗抑郁样效果

阿魏酸(ferulic acid,FA)是一种广泛存在的低毒酚酸,阿魏酸钠(sodium ferulate,SF)则是其钠盐。先前的研究已经证实,阿魏酸钠具有显著的神经保护和神经发生增强作用及抗抑郁效果。该研究的目的在于探讨阿魏酸钠诱导分化的PC12细胞裂解液的无细胞滤液可能的抗抑郁效果。PC12细胞在含80μmol/L阿魏酸钠的DMEM培养基中孵育6d,无菌条件下制备阿魏酸钠诱导分化的PC12细胞液的无细胞滤液,测定PC12细胞裂解液无细胞滤液中残留的阿魏酸钠量。以慢性不可预期的多种刺激制造大鼠抑郁模型,用行为学、形态学、免疫组织化学和BrdU掺入等方法观察并检测阿魏酸钠诱导分化的PC12细胞裂解液的无细胞滤液对慢性应激大鼠抑郁模型行为学、海马的组织病理学、海马和大脑皮质的神经生长因子(nerve growth factor,NGF)及脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)的表达及神经发生的影响。实验证实,阿魏酸钠诱导分化的PC12细胞裂解液的无细胞滤液能改善抑郁症样模型大鼠的行为学障碍,上调其海马和大脑皮质NGF和BNDF的表达,增加海马神经干细...     

Oxidation of isoeugenol and coniferyl alcohol catalyzed by laccases isolated from Rhus vernicifera Stokes and Pycnoporus coccineus

Laccases isolated from Rhus vernicifera Stokes (tree) and Pycnoporus coccineus (fungus) catalyzed the oxidation of isoeugenol (1) and coniferyl alcohol (5) in acetone–water (1:1, v/v). These oxidations follow a first order rate law. In general, the rates of Pycnoporus laccase-catalyzed oxidation of 1 and 5 are approximately three and seven times faster than the corresponding rates of Rhus laccase-catalyzed oxidation, respectively. Thus, synthesis for 2-(4-hydroxyphenyl)coumaran type compounds, such as dehydrodiconiferyl alcohol, can be accomplished by Rhus laccase-catalyzed dehydrogenative polymerization of the corresponding 1-(4-hydroxyphenyl)–1-propene derivatives. The reaction proceeds under very mild reaction conditions. The resulting reaction mixtures are chromatographed on a silica gel column to isolate the products in approximately 30–40% yield.     

Regulation of Syringyl to Guaiacyl Ratio in Lignin Biosynthesis

p -hydroxyphenyl (H)-, guaiacyl (G)- and syringyl (S) propane, in situ is described. New pathways that regulate the ratio of S to G moieties operating at the stages of cinnamoyl CoA, cinnamyl aldehyde and cinnamyl alcohol are introduced. The roles of monolignol glucoside in the lignification of tree xylem are discussed. The results of gene manupulations that alter the lignin structures are also introduced. Received 15 September 2001/ Accepted in revised form 16 October 2001     

The degradation of coniferyl alcohol and the complementary production of chlorogenic acids in the growth culture of Streptomyces albogriseolus KF977548 isolated from decaying wood residues

Coniferyl alcohol is one of the major precursors of lignin; the most abundant aromatic compound and a natural resource currently receiving attention because of the value-added metabolites resulting from its degradation. Growth study of Streptomyces albogriseolus KF977548 (strain AOB) isolated from decaying wood residues in a tropical estuarine ecosystem was carried out using coniferyl alcohol as a sole carbon source. Cell growth and metabolite production were monitored at 24 h interval by dry weight measurements and HPLC, LC–MS-DAD analyses. Biochemical and PCR assays were carried out to detect the major catabolic enzymes of interest. Strain AOB utilized coniferyl alcohol completely within 72 h (μ = 0.204 h⁻¹, T_d = 3.4 h). Laccase and peroxidase were released into the growth medium up to 0.099 and 98 μmol/mL respectively. Protocatechuate 3, 4-dioxygenase and demethylase were detected in the genome whilst ortho-adipate pathway was clearly indicated. Growth on coniferyl alcohol or caffeic acid as mono substrates resulted in the production of secondary metabolites identified by HPLC–MS as 1-caffeoylquinic and 3,4,5-tricaffeoylquinic acids, known as chlorogenic acids, in the culture medium. The microbial production of chlorogenic acids from a lignin-related substrate base by strain AOB could arouse a plausible biotechnological process.     

Genetic and molecular basis of grass cell-wall degradability. I. Lignin-cell wall matrix interactions

Lignification limits grass cell-wall digestion by herbivores. Lignification is spatially and temporally regulated, and lignin characteristics differ between cell walls, plant tissues, and plant parts. Grass lignins are anchored within walls by ferulate and diferulate cross-links, p-coumarate cyclodimers, and possibly benzyl ester and ether cross-links. Cell-wall degradability is regulated by lignin concentration, cross-linking, and hydrophobicity but not directly by most variations in lignin composition or structure. Genetic manipulation of lignification can improve grass cell-wall degradability, but the degree of success will depend on genetic background, plant modification techniques employed, and analytical methods used to characterize cell walls.     

Phytochemical constituents of leaves and twigs of Elaeagnus umbellata

A phytochemical study of the leaves and twigs of Elaeagnus umbellata Thunb. has led to the isolation and identification of 12 compounds, including two flavonoid coumaroyl glycosides (1 and 2), two simple phenolic compounds (3 and 4), one coniferyl alcohol derivative (5), one monoterpene (6), two pairs of enantiomeric neolignans (7a/7b and 8a/8b), and a pair of enantiomeric sesquineolignans (9a/9b). The structures of these compounds were elucidated through the analysis of their MS, ECD, and 1D/2D NMR spectra as well as comparison with previously reported data. This is the first time that 1 and 2 have been isolated from this species, and the first time that 5, 6, 7a, 7b, 8a, 8b, 9a, and 9b have been identified in the Elaeagnaceae family.     

Ferulate–coniferyl alcohol cross-coupled products formed by radical coupling reactions

Radical coupling reactions between ethyl ferulate (Et-FA), a simple model for feruloyl polysaccharides in planta, and coniferyl alcohol (CA), a monolignol, were studied in order to better understand the polymer cross-coupling interactions among polysaccharides and monolignols or lignin, mediated by ferulate (FA), in plant cell walls. Cross-coupled FA/CA dimers produced in an aqueous buffer (pH 5.0) containing peroxidase/hydrogen peroxide were isolated and characterized by NMR. The total coupling products were characterized by 2D ¹³C–¹H correlation (HSQC) NMR spectroscopy and GC–MS. Results from this study showed that ferulate readily cross-couples with coniferyl alcohol through free radical coupling mechanisms producing a series of cross-coupled FA/CA dimers with β-O-4-, β-5-/8-5-, and 8-β-linkages; the syntheses and isolation of β-5- and 8-5-cross-coupled dimers are reported here. The transformation from 8-β-coupled FA/CA hydroxyl esters into lactones through intramolecular transesterification is demonstrated for the first time and mechanisms behind these transformations are discussed. The finding of both β-5- and 8-5-cross-coupled dimers in this study suggests that analogs of both may be present in plant cell walls. Finally it is suggested that ferulates in plants indeed react with monolignols through free radical mechanisms producing a more diverse array of cross-coupled dimers than previously reported.