Esculin derivative esters obtained by biocatalysis reaction using commercial lipase

Cardiovascular diseases, such as thrombosis and cerebrovascular accidents, constitute a worrying situation of public health, and are currently one of the leading cause of mortality in whole world (NASCIMENTO et al, 2018). The main treatment against these pathologies are conducting by anticoagulation therapy, however, the medicines available nowadays cause a large of side effects, requiring constant monitoring of their use. Novel anticoagulants from natural sources seem to be an interesting alternative to these problems, considering the high potential and the variety of chemical structures, especially the coumarin derivatives. They act as vitamin K antagonists since they compete for the active site of the enzyme γ-glutamyl carboxylase, preventing the formation of the coagulation cascade (ROSSELI et al, 2006). This work, therefore aims to increase the potential anticoagulant effect of esculin, a natural glycose-bonded coumarin, through the formation of esterified derivatives by enzymatic transesterification reactions using the commercial lipase Novozyme®435 as biocatalyst. Initially, the substrate esculin was solubilized in tetrahydrofuran (500 µL) and acetone (500 µL) onto a 10 mL glass vial. In each vial, 1 mL of different vinyl esters were added, such as: vinyl acetate, vinyl laurate, vinyl propionate, vinyl pivalate, vinyl benzoate, vinyl butyrate and the lipase Novozyme (10% in relation to the total substrate mass). The glasses were disposed on a shaker at 60 ° C and 200 rpm. Every 24 hours the reactions were sampling (two times - 50 μL), totalizing 96 h. The products were monitored by thin-layer chromatography (TLC) in a solvent system containing ethyl acetate:hexane:methanol:acetic acid (25:45:10:10), and silica gel as stationary phase, followed by ultraviolet chamber development at 365 nm. The Rf values was calculated. After that, the products were analyzed by HPLC/DAD under monitoring at 274 nm. The kinetic profile of the reactions concerning the products formation were proposed calculating the peak areas (λmax 225 - 330 nm) in each chromatogram (0 - 96 h). The results showed that all esters investigated were produced in the first 24 hours, with different conversion rates. The Rf values found for esculin acetates were: product 1 (mono)= 0.67; product 2 (di)= 0.83; esculine propionates: product 1 (mono)= 0.75; product 2= 0.83 (di); esculin laurate: product 1=0.83 (mono); esculin benzoate: product 1= 0.67 (mono); esculin cynammate is under analysis. Esculin butyrate product was not formed under the experimental conditions analyzed. Esculin acetates were obtained in 100 % conversion in the first 24 h while esculin propionates were obtained in 75 %. The conversion of the other products are under quantification. That results means good prospects for the esterified molecules proposed. However, further studies need to be done, including the isolation of the products followed by their structural elucidation by NMR spectroscopic. Finally, the evaluation for the biological potential as anticoagulants.