Conversion of gypenosides by enzymatic hydrolysis with β-glucanase

Hong-Yan ZHANG

ABSTRACT

Objective:

To investigate the enzymatic hydrolysis of gypenosides by β-glucanase 26130 CN to prepare some hydrolyzed secondary saponins, so as to provide material basis for further biological studies.

Methods:

Using β-glucanase 26130 CN, the total saponins from Herba Gynostemmatis were hydrolyzed with the enzyme catalysis, and the hydrolytic products were analyzed by ultra high- performance liquid chromatography coupled with quadrupole time- of- flight mass spectrometry(UHPLC- Q- TOF/MSE)to identify the converted products. Then, the main components of Herba Gynostemmatis, gypenosides XLIX and A, were used as substrates of the β-glucanase 26130 CN for convertsion to secondary saponin products. The products were separated by preparative highperformance liquid chromatography(HPLC)and identified by NMR and MS.

Results:

Twenty eight triterpenoid saponins were identified in the total saponin hydrolysate on the basis of their high-resolution MS data, by comparison with the data in the literature, and seven of them were validated to be the converted products. It was found that the β-glucanase 26130 CN could hydrolyze the glycosidic bond of terminal glucose or xylose in the molecule of gypenosides. By the enzymatic hydrolysis of gypenoside XLIX and gypenoside A, gypenoside I(the one glucosyl-lost gypenoside XLIX)and gypenoside UL1(the one xylosyl-lost gypenoside A)were obtained via the preparative HPLC separation of the gypenoside XLIX and gypenoside A hydrolysates, respectively.

Conclusion:

β-glucanase 26130 CN could effectively catalyze the hydrolysis of terminal glucosyl and xylosyl groups in gypenosides, with a relatively high hydrolytic conversion rate, which could be used to prepare some secondary saponins or aglycones.