[Enzymatic reaction pattern of saponins in Gynostemma pentaphyllum and identification of their transformed products]

The activity of rare saponins is generally better than that of their prototypes. There are significant differences in the proportions and pharmacological effects of rare saponins/prototype saponins in Gynostemma pentaphyllum samples dried with different methods, which may be related to the reaction catalyzed by glucosidase. To explore the pattern of the enzymatic reaction catalyzed by glucosidase during the processing of G. pentaphyllum and provide technical support for the green production of rare saponins, this experiment extracted glucosidase from fresh leaves of G. pentaphyllum, constructed a simulated reaction system, and conducted in vitro simulation reactions with the prototype saponins extract of G. pentaphyllum. Ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry was employed to detect the substrates, intermediate products, and final products of the reaction. Furthermore, traditional Chinese medicine chemical methods were used to purify and identify some substrates and products, on the basis of which the enzymatic reaction pattern was explored. The results confirmed the role of gypenoside-β-glucosidase in the enzymatic reaction and identified a total of 15 saponins, including PPD neutral saponins and acidic saponins(acetyl saponins, malonyl saponins, etc.,) in 4 groups during the reaction process. Four substrates and products were purified and identified, and it was clarified that gypenoside-β-glucosidase had selectivity. The enzymatic reaction pattern was summarized as follows.(1)The enzyme only hydrolyzed neutral saponins, while acidic saponins such as acetyl and malonyl saponins were not easily hydrolyzed.(2)The hydrolysis occurred at the glucosyl group at the C-3 position, while the glucosyl group at the C-20 position was not easily hydrolyzed. The enzymatic reaction of G. pentaphyllum can be employed to generate rare saponins, and the findings of this study can help expand and enhance the utilization value of G. pentaphyllum.