Multi-gram preparation of cinnamoyl tryptamines as skin whitening agents through a chemo-enzymatic flow process

Highly Efficient Synthesis of Cinnamamides from Methyl Cinnamates and Phenylethylamines Catalyzed by Lipozyme® TL IM under Continuous-Flow Microreactors

While a few derivatives of cinnamamides exhibited anti-inflammatory and/ or analgesic activity, in this study, we developed a highly efficient method for the synthesis of cinnamamides from methyl cinnamates and phenylethylamines catalyzed by Lipozyme® TL IM in continuous-flow microreactors. The reaction parameters and broad substrate range of the new method was studied. Maximum conversion (91.3%) was obtained under the optimal condition of substrate molar ratio of 1:2 (methyl 4-chlorocinnamate: phenylethylamine) at 45 °C for about 40 min. The remarkable features of this work include short residence time, mild reaction conditions, easy control of the reaction process, and that the catalyst can be recycled or reused, which provide a rapid and economical strategy for the synthesis and design of cinnamamide derivatives for further research on drug activity.

Efficient 2-Step Enzymatic Cascade for the Bioconversion of Oleuropein into Hydroxytyrosol

Among the plant bioactive components, oleuropein (OLE) is the most abundant phenolic compound in all parts of olive trees (Olea europaea L.), particularly concentrated in olive leaves. It has been shown to present various remarkable biological actions, such as antimicrobial, antioxidant, anticancer and anti-inflammatory ones. On the other hand, hydroxytyrosol (HT), the main degradation product of OLE, is considered one of the most powerful antioxidant agents, with higher beneficial properties than the OLE parent compound. In this work, oleuropein was efficiently transformed into hydroxytyrosol using a 2-step biotransformation involving a thermo-halophilic β-glucosidase from Alicyclobacillus herbarius (Ahe), which gave the corresponding aglycone with complete conversion (>99%) and rapid reaction times (30 min), and an acyltransferase from Mycobacterium smegmatis (MsAcT), here employed for the first time for its hydrolytic activity. After cascade completion, hydroxytyrosol was obtained in excellent yield (>99% m.c., 96% isolated yield) in 24 h. Starting from a natural substrate and employing enzymatic approaches, the final hydroxytyrosol can be claimed and commercialized as natural too, thus increasing its market value.

Biocatalyzed Synthesis of Vanillamides and Evaluation of Their Antimicrobial Activity

A series of vanillamides were easily synthesized, exploiting an acyltransferase from Mycobacterium smegmatis (MsAcT). After their evaluation as antimicrobial agents against a panel of Gram-positive and Gram-negative bacteria, three compounds were demonstrated to be 9-fold more effective toward Pseudomonas aeruginosa than the vanillic acid precursor. Taking into consideration the scarce permeability of the Gram-negative bacteria cell envelope when compared to Gram-positive strains or yeasts, these molecules can be considered the basis for the generation of new nature-inspired antimicrobials. To increase the process productivity and avoid any problem related to the poor water solubility of the starting material, a tailored flow biocatalyzed strategy in pure toluene was set up. While a robust immobilization protocol exploiting glyoxyl-agarose was employed to increase the stability of MsAcT, in-line work-up procedures were added downstream the process to enhance the system automation and reduce the overall costs.