Abstract

Quercetin, an aglycon of rutin, is widely applied as an important material in food and pharmaceutical industries. In the present study, in order to investigate the optimal reaction conditions for directional biosynthesis of quercetin by enzymatic hydrolysis of rutin catalyzed by snailase, the influences of temperature, substrate concentration and pH value on enzymatic hydrolysis of rutin were investigated by the conversion yield of quercetin from rutin with single-factor test. The results indicated that the crude snailase had good biocatalytic ability for selective hydrolysis of one rutinose from rutin. When the hydrolysis reaction conditions catalyzed by snailase were as follows: temperature 34°C, pH 6.2, and substrate concentration 0.0242 mg/ml, the highest conversion yield of quercetin was 98.18%. Moreover, selected metal ions (Cu²⁺, Ca²⁺, Mg²⁺, Fe²⁺, K⁺ and Na⁺) all had depressant effect on the conversation of quercetin from rutin with different strength. The hydrolysis product was purified by solvent extraction and crystallization, in which the chemical structure was identified as quercetin by ¹H-NMR and ¹³C-NMR. In conclusion, enzymatic conversion process of quercetin from rutin is simple, practical and can provide a reference in the trial production.

Key words: Rutin, quercetin, enzymatic hydrolysis, directional biosynthesis, snailase.