[Comparison of saponins from Gynostemma pentaphyllum leaves prepared by different processing methods]

Abstract

To investigate the differences of chemical compositions in Gynostemma pentaphyllum leaves prepared by different processing methods. Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS) was used to compare the chemical compositions between shade-dried processing and drum-dried processing. Forty six gypenosides were identified by control comparison， liquid chromatography-mass spectrometry(LC-MSn) fragmentation information， and literature data. The mass spectral peak area statistics was combined with principal component analysis(PCA)， and the results showed that eight batches of Gynostemma pentaphyllum leaves samples were divided into two groups according to the two different processing methods; ten chemical compositions with significant differences were screened according to mass spectrum information combined with partial least-squares discriminant analysis(PLS-DA). The result showed that most parent nucleus of the gypenosides contained three to four glycosides in drum-dried samples， and one to two glycosides in the shade-dried samples. It was inferred from further MS analysis that desugarization of gypenosides was present to produce secondary glycosides with the effect of glucosidase in the shade-drying， thus resulting in difference in compositions. This study provided data support for harvesting， processing and quality control of Gynostemma pentaphyllum leaves.

Keywords: Gynostemma pentaphyllum; different processing methods; mass spectrometry identification; saponins.