Facile and Efficient Acylation of Bioflavonoids Using Whole-Cell Biocatalysts in Organic Solvents

Abstract

Bioflavonoids have many biological and pharmacological activities, but many of them display low bioavailability after oral administration owing to poor lipophilicity of glycoside forms. To improve their lipophilicity, as well as their bioactivity, a new efficient approach was developed for fatty acyl-modification of four vitamin P-like bioflavonoids (troxerutin, rutin, hesperidin, and naringin) using whole-cell biocatalysts in binary solvent systems. Using troxerutin as a typical important bioflavonoid, the acylation activities of 15 strains of different sources were evaluated and Pseudomonas aeruginosa GIM 1.46 showed the highest acylation activity in nonaqueous mediums. 13C NMR, ESI-MS, and FT-IR analysis confirmed that P. aeruginosa catalyzed acylation of troxerutin to produce troxerutin monopropionate (dominant product) and troxerutin dipropionate. In a binary system of n-heptane and pyridine, the cells showed much higher catalytic activity and operational stability than in other solvents, attributing to a proper increase in permeability of cell envelopes and cell viability by using the binary organic solvents. The optimal n-heptane concentration, molar ratio of vinyl propionate to troxerutin, catalyst dosage, and reaction temperature were found as 35%, 30:1, 50 mg/mL, and 40 °C, respectively, under which the troxerutin conversion and the monoester yield reached 94% and 81.1%, respectively.

Biocatalytic synthesis of acylated derivatives of troxerutin: their bioavailability and antioxidant properties in vitro

“…In our previous study, whole cells of P. aeruginosa GIM 1.46 and P. stutzeri GIM 1.273 were found to be capable of catalyzing acylation of troxerutin, giving two products (the monoester TME and diester TDE). Figure 1 a shows that two types of Pseudomonas whole cells had similar catalytic activities and efficiencies considering their similar initial rates (2.55 and 2.76 mmol/L h) and substrate conversions (94.1% and 91.3%) in the acylation of troxerutin under the optimal reaction conditions [ 17 ]. These values were much higher than those in previous reports using chemical (substrate conversion of 57%) [ 6 ] or enzymatic methods (ester yield of 59.2%) [ 10 ].…”

“…The yield of rutin monoester was significantly lower than that of troxerutin monoester; this might be related to the absence of the primary hydroxyl group in rutin. However, in our previous study, rutin was also relatively good substrate for P. aeruginosa GIM 1.46 cells to synthesize 4‴-O-propionyl rutin with yield of 61.5% in the same reaction conditions [ 17 ], showing the P. aeruginosa cells have high catalytic activity and regioselectivity.…”

“…In our previous study, we screened whole-cell biocatalysts from various microbial sources. Whole cells of Pseudomonas aeruginosa GIM 1.46 and P. stutzeri GIM 1.273 were capable of synthesizing troxerutin-acylated derivatives [ 17 ]. In the present study, we developed a new whole-cell biocatalytic method for producing mono- or di-esters of troxerutin using the two Pseudomonas strains (Scheme 1 ).…”

Efficient acylation of gastrodin byAspergillus oryzaewhole-cells in non-aqueous media

“…6A2-H2). The SEM analysis conrmed that strongly polar organic solvents such as pyridine led to distortion of cell shape and wrinkling of cell surfaces, 41 as the water molecules inside the cells gradually migrated into the polar pyridine by passive diffusion. The addition of ILs, especially the water immiscible ILs, into polar solvent increased the hydrophobicity of the whole reaction systems, reduced the water migration from cells into the outer environment and maintained the natural morphology of the cells. ]…”

Biocatalytic Synthesis of Lipophilic Baicalin Derivatives as Antimicrobial Agents

“…The chemically acetylated baicalin showed low or even no biological activity due to the nonselective acylation on its hydroxyl groups . Undoubtedly, enzyme catalysis can well circumvent this drawback and has more advantages compared with chemical synthesis, including the higher selectivity, environmental friendliness, fewer side reactions, and milder reaction conditions . Moreover, the immobilization technology improves the stability and catalytic activity of enzymes in anhydrous media, especially in organic solvents, as well as their separability and recyclability .…”