Sun Meina, Nie Kaili, Wang Fang, Deng Li
Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beijing, China.
Amoy-BUCT Industrial Bio-technovation Institute, Xiamen, China.
Front Bioeng Biotechnol. 2020 Jan 22;7:486. doi: 10.3389/fbioe.2019.00486. eCollection 2019.
Ceramides and their analogs have a regulatory effect on inflammatory cytokines expression. It was found that a kind of ceramides analog synthesized from phenylglycinol could inhibit the production of cytokine TNF-α. However, two active hydrogen groups are present in the phenylglycinol molecule. It is difficult to control the process without hydroxyl group protection to dominantly produce amide in the traditional chemical synthesis. A selective catalytic the amidation route of phenylglycinol by lipases was investigated in this research. The results indicated that the commercial immobilized lipase Novozym 435 has the best regio-selectivity on the amide group. Based on the experimental results and simulation, it was found that the mechanism of specific N-acyl selectivity of lipase was not only from intramolecular migration and proton shuttle mechanism, but also from the special structure of active site of enzyme. The optimal reaction yield of aromatic amide compound in a solvent-free system with lipase loading of 15 wt% (to the weight of total substrate) reached 89.41 ± 2.8% with very few of byproducts detected (0.21 ± 0.1% ester and 0.64 ± 0.2% diacetylated compound). Compare to other reported works, this work have the advantages such as low enzyme loading, solvent free, and high N-acylation selectivity. Meanwhile, this Novozym 435 lipase based synthesis method has an excellent regio-selectivity on most kinds of amino alcohol compounds. Compared to the chemical method, the enzymatic synthesis exhibited high regio-selectivity, and conversion rates. The method could be a promising alternative strategy for the synthesis of aromatic alkanolamides.
神经酰胺及其类似物对炎症细胞因子的表达具有调节作用。研究发现，一种由苯甘氨醇合成的神经酰胺类似物能够抑制细胞因子TNF-α的产生。然而，苯甘氨醇分子中存在两个活性氢基团。在传统化学合成中，若不进行羟基保护，很难控制反应过程以主要生成酰胺。本研究考察了脂肪酶催化苯甘氨醇的选择性酰胺化路线。结果表明，市售固定化脂肪酶Novozym 435对酰胺基团具有最佳的区域选择性。基于实验结果和模拟发现，脂肪酶特定N-酰基选择性的机制不仅源于分子内迁移和质子穿梭机制，还源于酶活性位点的特殊结构。在无溶剂体系中，脂肪酶负载量为15 wt%（相对于总底物重量）时，芳香酰胺化合物的最佳反应产率达到89.41±2.8%，检测到的副产物极少（酯为0.21±0.1%，二乙酰化化合物为0.64±0.2%）。与其他已报道的工作相比，本工作具有酶负载量低、无溶剂以及N-酰化选择性高的优点。同时，这种基于Novozym 435脂肪酶的合成方法对大多数氨基醇化合物具有优异的区域选择性。与化学方法相比，酶促合成表现出高区域选择性和转化率。该方法可能是合成芳香链烷醇酰胺的一种有前景的替代策略。
