Lipase-Catalyzed One-Step and Regioselective Synthesis of Clindamycin Palmitate

Chemical synthesis of clindamycin palmitate, a prodrug with taste greatly improved more than that of clindamycin, involves laborious steps of protection and deprotection to achieve the monoacylation only at 2-hydroxyl group of clindamycin and gives an overall yield below 50%. Here we report the first example of one-step synthesis of clindamycin palmitate with high regioselectivity using immobilized Candida antarctica lipase B (Novozym 435) as the catalyst. The lipase-catalyzed synthesis reached a conversion above 90% in 12 h using toluene as solvent and, moreover, a highly regioselective acylation at the 2-hydroxyl of clindamycin. The significantly improved conversion achieved at an excellent regioselectivity makes this enzymatic process attractive for the synthesis of clindamycin ester derivatives

Catalytic <i>In Situ</i> Hydrogenation of Fatty Acids into Fatty Alcohols over Cu-Based Catalysts with Methanol in Hydrothermal Media

The catalytic hydrogenation of fatty acids has witnessed rapid development in recent years. However, the conventional hydrogenation process often requires high-pressure hydrogen. This paper describes a novel protocol to produce fatty alcohols via an <i>in situ</i> hydrogenation of fatty acids in water and methanol using Cu-based catalysts. Cu/ZrO₂, Cu/MgO, and Cu/Al₂O₃ were prepared by the co-precipitation method. All Cu-based catalysts exhibited excellent activity for <i>in situ</i> hydrogenation of fatty acids, and the stability of Cu/ZrO₂ was the best. The structures and properties of Cu-based catalysts are demonstrated by transmission electron microscopy, X-ray diffraction, H₂ temperature-programmed reduction, N₂ adsorption–desorption, CO temperature-programmed desorption, and CO₂ temperature-programmed desorption. The stability of Cu/ZrO₂ is caused by the good hydrothermal stability and tetragonal phase formation of ZrO₂, which strongly binds to active Cu. The better activity over Cu/Al₂O₃ is caused by the larger surface area, higher Cu dispersion, smaller Cu particle size, and stronger basicity of Cu/Al₂O₃. Furthermore, the effects of the reaction time, catalyst loading, methanol loading, carbon number, and types of hydrogen donor on <i>in situ</i> hydrogenation of the fatty acids were investigated to demonstrate the reaction behaviors

MOESM1 of Process optimization for enhancing production of cis-4-hydroxy-l-proline by engineered Escherichia coli

Additional file 1. Additional tables and figures

Data_Sheet_1_One-pot biosynthesis of N-acetylneuraminic acid from chitin via combination of chitin-degrading enzymes, N-acetylglucosamine-2-epimerase, and N-neuraminic acid aldolase.docx

N-acetylneuraminic acid (Neu5Ac) possesses the ability to promote mental health and enhance immunity and is widely used in both medicine and food fields as a supplement. Enzymatic production of Neu5Ac using N-acetyl-D-glucosamine (GlcNAc) as substrate was significant. However, the high-cost GlcNAc limited its development. In this study, an in vitro multi-enzyme catalysis was built to produce Neu5Ac using affordable chitin as substrate. Firstly, exochitinase SmChiA from Serratia proteamaculans and N-acetylglucosaminosidase CmNAGase from Chitinolyticbacter meiyuanensis SYBC-H1 were screened and combined to produce GlcNAc, effectively. Then, the chitinase was cascaded with N-acetylglucosamine-2-epimerase (AGE) and N-neuraminic acid aldolase (NanA) to produce Neu5Ac; the optimal conditions of the multi-enzyme catalysis system were 37°C and pH 8.5, the ratio of AGE to NanA (1:4) and addition of pyruvate (70 mM), respectively. Finally, 9.2 g/L Neu5Ac could be obtained from 20 g/L chitin within 24 h along with two supplementations with pyruvate. This work will lay a good foundation for the production of Neu5Ac from cheap chitin resources.</p

MOESM1 of Process optimization for enhancing production of cis-4-hydroxy-l-proline by engineered Escherichia coli

Additional file 1. Additional tables and figures

MOESM4 of Molecular characterization of a novel chitinase CmChi1 from Chitinolyticbacter meiyuanensis SYBC-H1 and its use in N-acetyl-d-glucosamine production

Additional file 4: Figure S4. MS of profile of the GlcNAc product

MOESM2 of Molecular characterization of a novel chitinase CmChi1 from Chitinolyticbacter meiyuanensis SYBC-H1 and its use in N-acetyl-d-glucosamine production

Additional file 2: Figure S2. Determination of Km and Vm of the CmChi1 using p-NP-(GlcNAc)2 as the substrate

MOESM3 of Molecular characterization of a novel chitinase CmChi1 from Chitinolyticbacter meiyuanensis SYBC-H1 and its use in N-acetyl-d-glucosamine production

Additional file 3: Figure S3. HPLC profile of the GlcNAc product. Numbers 1 to 6 represent GlcNAc to (GlcNAc)6. (a): standard samples; (b): product

MOESM1 of Molecular characterization of a novel chitinase CmChi1 from Chitinolyticbacter meiyuanensis SYBC-H1 and its use in N-acetyl-d-glucosamine production

Additional file 1: Figure S1. Determination of Km and Vm of the CmChi1 using CC as the substrate

Role of Solvent in Catalytic Conversion of Oleic Acid to Aviation Biofuels

The role of solvents in the conversion of oleic acid over Pt/C was studied. Three solvent systems (solvent-free, water, and dodecane systems) were employed for the conversion of oleic acid over Pt/C at 350 °C. Decarboxylation, hydrogen transfer, and aromatization were observed in these three reaction systems. In comparison to the non-solvent reaction system, much slower decarboxylation and aromatization rates and fewer heptadecane and aromatic products were observed in the hydrothermal and dodecane reaction systems. The decarboxylation and aromatization rates and yields of heptadecane and aromatics decreased with increased dodecane loading in the dodecane reaction system, and the decarboxylation and aromatization rates and yields of heptadecane and aromatics significantly decreased with the increase of water in the hydrothermal reaction system. The effects of solvent loading, catalyst loading, and reaction time on the reactions (decarboxylation, hydrogen transfer, and aromatization) were investigated. The reaction behaviors of 1-heptadecene with different solvents were studied, and N₂ adsorption–desorption and thermogravimetric analysis of fresh and spent Pt/C in the three reaction systems were also performed. The results indicate that the competition of dodecane for the Pt/C active sites is mainly responsible for the slow decarboxylation and aromatization rates. In addition to the similar influencing factor to that in the dodecane system, H⁺ released from water and hydrogen bonding, which inhibited the ionization of carboxyl groups, was the key influencing factor for the slower decarboxylation and aromatization rates obtained under hydrothermal conditions