Cooperative Reinforcement of Ionic Liquid and Reactive Solvent on Enzymatic Synthesis of Caffeic Acid Phenethyl Ester as an In Vitro Inhibitor of Plant Pathogenic Bacteria

Abstract

It is widely believed that lipases in ionic liquids (ILs) possess higher enzyme activity, stability and selectivity; however, reaction equilibrium is always limited by product inhibition, and the product is difficult to separate from non-volatile ILs using distillation. To solve this problem, using trialkylphosphine oxide (TOPO) as a complexing agent, a novel biphase of reactive solvent and IL was firstly reported for caffeic acid phenethyl ester (CAPE) production from methyl caffeate (MC) and 2-phenylethanol (PE) catalyzed by lipase via transesterification. The effects of the reaction parameters and their action mechanism were investigated, and the inhibition of CAPE against bacterial wilt pathogen Ralstonia solanacearum was firstly measured. The MC conversion of 98.83% ± 0.76% and CAPE yield of 96.29% ± 0.07% were obtained by response surface methodology in the 25 g/L TOPO-cyclohexane/[Bmim][Tf2N] (1:1, v/v); the complex stoichiometry calculation and FTIR spectrum confirmed that the reversible hydrogen-bond complexation between TOPO and caffeates significantly enhances the cooperative effect of two phases on the lipase-catalyzed reaction. The temperature was reduced by 14 °C; the MC concentration increased by 3.33-fold; the ratio of catalyst to donor decreased by 4.5-fold; and Km decreased 1.08-fold. The EC50 of CAPE against R. solanacearum was 0.17–0.75 mg/mL, suggesting that CAPE is a potential in vitro inhibitor of plant pathogenic bacteria.

A Highly Regioselective and Practical Synthesis of α‐Aryl Ketones under a Cooperative Cascade Effect of an Ionic Liquid and Tetrabutylammonium Fluoride

“…As a reaction media they have been utilized for oxidation processes including Pd‐catalysed Wacker‐type reaction using [bmim]X (X=BF 4 or PF 6 ) . Moreover, the remarkable synergistic cooperative effect of ionic liquid in conjunction with chemo/biocatalyst have emerged as a promising strategy for highly efficient and selective route towards genesis of complex molecules.…”

A novel nanoparticle loaded with methyl caffeate and caffeic acid phenethyl ester against Ralstonia solanacearum—a plant pathogenic bacteria

“…Caffeate derivatives such as MC and CAPE were prepared by our group. 21,23 SYBR premix Ex Tap™ II (Tli RNaseH Plus), primer script RT reagent kit with gDNA eraser (Perfect Real Time), DEPC water, and isopropanol were purchased from Takara. The total RNA extraction reagent TRIzol and PCR kit were purchased from Sangon Biotech.…”

“…RS-5 R. solanacearum strains were used, which were isolated from mulberry roots. 21 All the primers were synthesized by Shanghai Biotech; the primer sequences were synthesized as described elsewhere, 18 as listed in Table 1.…”

“…The standard curve formulas of MC and CAPE are shown in eqn (3) and (4), and the measurement methods were carried out in accordance with an earlier research. 21 MC standard curve line:…”

“…Among them, caffeic acid phenethyl ester (CAPE), which is considered to be one of the most popular compounds for the development of new drugs 20 and has been the main active ingredient isolated from propolis residues, has shown toxic effects toward R. solanacearum. 21 Methyl caffeate (MC) has many pharmacological activities, and it is a synthetic intermediate of many natural drugs and food additives, such as propyl caffeate (PC); CAPE can be prepared by the transesterication of MC with the corresponding alcohol. 22 Recently, PLGA particles loaded with CAPE were successfully prepared, 20 which demonstrated the feasibility of fabricating PLGA particles loaded with caffeic acid and its derivatives.…”