An efficient and flexible synthesis of model lignin oligomers
作者:W. Graham Forsythe、Mark D. Garrett、Christopher Hardacre、Mark Nieuwenhuyzen、Gary N. Sheldrake
DOI:10.1039/c3gc41110a
日期:——
The use of model compounds in the development of selective lignin depolymerisation processes has been limited by the lack of complexity of these models compared with lignin itself. In this paper we report a convergent and efficient synthetic method for the flexible, multi-gram preparation of model lignin hexamers and octamers containing three of the most common connectivity motifs found within native lignin, namely β-O-4′, 5-5′ and β-5′, which will be used to further the mechanistic understanding of lignin depolymerisation processes.
Structural Transformation of 8–5-Coupled Dehydrodiferulates by Human Intestinal Microbiota
作者:Rachel R. Schendel、Cecile Karrer、Diana Bunzel、Melanie Huch、Andreas A. Hildebrand、Sabine E. Kulling、Mirko Bunzel
DOI:10.1021/acs.jafc.5b03234
日期:2015.9.16
Ingested dehydrodiferulates (DFAs) are partially released from cereal dietary fiber by human colonic microbiota, but little research has explored the further microbial metabolism of 8-5-coupled DFAs. This study investigated the in vitro microbial metabolism and elucidated major metabolites of free 8-5-DFAs (benzofuran and open forms) and an esterified analogue, 8-5-DFA diethyl ester (benzofuran). Synthesized standard compounds were incubated with fresh human fecal suspensions. Metabolites were isolated and structurally elucidated using high-resolution-LC-time-of-flight-(ToF)-MS, GC-MS, and NMR. Nine metabolite structures were unambiguously characterized with NMR, and four additional metabolites were tentatively identified to reveal structural conversion motifs: propenyl side chain hydrogenation (all substrates), O-demethylation and reductive ring-opening (8-5-DFA diethyl ester and free 8-5-DFA [benzofuran]), and de-esterification (8-5-DFA diethyl ester). A pathway of microbial 8-5-DFA metabolism was proposed based on metabolite formation kinetics. Importantly, deesterification of the 8-5-DFA diethyl ester occurred primarily after and/or concurrently with other metabolism steps. Cleavage to monomers was not observed.
Poacic Acid, a Plant-Derived Stilbenoid, Augments Cell Wall Chitin Production, but Its Antifungal Activity Is Hindered by This Polysaccharide and by Fungal Essential Metals
作者:Adi Yona、Micha Fridman
DOI:10.1021/acs.biochem.3c00595
日期:2024.4.16
Live cell fluorescence microscopy experiments revealed that PA increases chitinproduction and modifies itscellwall distribution. Chitinproduction and cell growth returned to normal after prolonged incubation. The antifungalactivity of PA was reduced in the presence of exogenous chitin, suggesting that the potentiation of chitinproduction is a stress response that helps the yeast cell overcome
气候和环境变化改变了真菌病原体的栖息地,对畜牧业和农作物生产造成了毁灭性的影响。此外,耐药真菌在全球范围内不断增加,这推动了寻找新的分子支架以开发人类、动物和植物抗真菌剂的迫切需求。苔藓酸 (PA) 是一种植物来源的二苯乙烯类化合物,最近被发现是一种新型分子支架,可抑制多种真菌的生长。它的抗真菌活性与真菌细胞壁 β-1,3-葡聚糖的产生/组装的扰动有关,但其作用方式尚未解决。在这项研究中,我们研究了 PA 及其衍生物在一组酵母上的抗真菌活性。PA 对酿酒酵母具有抑菌作用,对质膜损伤的白色念珠菌突变体具有杀真菌作用。活细胞荧光显微镜实验显示,PA 增加几丁质的产生并改变其细胞壁分布。长时间孵育后,几丁质生成和细胞生长恢复正常。在外源性几丁质存在下,PA 的抗真菌活性降低,表明甲壳素产生的增强是一种应激反应,可帮助酵母细胞克服这种抗真菌二苯乙烯的作用。金属离子也降低了生长抑制,表明 PA 影响金属稳态。这些发现表明