DEGRADATION OF FLAVONOIDS BY Cryptococcus albidus α-L-RHAMNOSIDASE

Abstract

The aim of the work was to investigate the possibility of practical use substrate specificity of α-Lrhamnosidase Cryptococcus albidus. p-Nitrophenyl derivatives of monosaccharides were used to determine the activity and specificity of the enzyme. The ability to hydrolyze of natural substrates was evaluated by Davis and high-performance liquid chromatography methods. It was shown that the enzyme exhibits narrow specificity towards the glycon of synthetic substrates and hydrolyzes only p-nitrophenyl-α-L-rhamnopyranoside (Km 4.5 mM) and p-nitrophenyl-α-D-glucopyranoside (Km 10.0 mM). C. albidus α-L-rhamnosidase the most active degrades naringin (Km 0.77 mM), releasing prunin and naringenin. Km for neohesperidin was 3.3 mM. The efficacy of the naringin hydrolysis in grapefruit and pomelo juice was 98 and 94% in 60 min (40 оC, 2 U/ml). As the result of treatment by α -L-rhamnosidase of green tea and orange juice, there was a decrease in the content of rutin, narirutin and hesperidin, indicating that the α -1,2- and α -1,6-linked rhamnose can be cleaved from natural flavonoids. Thus, the study shows the efficiency of treating citrus juices and green tea with C. albidus α -L-rhamnosidase for the purpose of improving their taste qualities and obtaining bioavailable flavonoids glucosides.

Keywords

• specificity of Cryptococcus albidus
• α-L-rhamnosidase
• specificity naringin
• neohesperidin
• rutin
• flavonoids
• citrus juices
• green tea.