Résumé
Heat-processed Gynostemma pentaphyllum has strong biological activity, and saponins are the main components. To investigate the changes of saponins in G. pentaphyllum before and after heat processing, the present study determined and analyzed the content of nine saponins in G. pentaphyllum from Zhangzhou of Fujian and Jinxiu of Guangxi by ultra-high performance liquid chromatography with quadrupole ion-trap mass spectrometry(UPLC-Q-Trap-MS). The separation of the analytes was performed on an ACQUITY UPLC BEH C_(18) column(2.1 mm×50 mm, 1.7 μm) at 30 ℃, with acetonitrile and 0.1% formic acid in water as the mobile phase by gradient elution, and the flow rate was 0.3 mL·min~(-1). Quantitative analysis was performed using electrospray ionization source(ESI) in the multiple reaction-monitoring(MRM) mode. The results showed that the content of saponins with biological activities increased after heat processing. Specifically, gypenoside L, gypenoside LI, damulin A, damulin B, ginsenoside Rg_3(S), and ginsenoside Rg_3(R) in G. pentaphyllum produced in Zhangzhou of Fujian increased by 7.369, 8.289, 12.155, 7.587, 0.929, and 1.068 μg·g~(-1), respectively, while the content of ginsenoside Rd, gypenoside LVI, and gypenoside XLVI, which were abundant in the raw materials, decreased by 0.779, 19.37, and 9.19 μg·g~(-1), respectively. The content of gypenoside L, gypenoside LI, damulin A, damulin B, ginsenoside Rg_3(S), and ginsenoside Rg_3(R) in G. pentaphyllum produced in Jinxiu of Guangxi increased by 0.100, 0.161, 0.317, 0.228, 3.280, and 3.395 μg·g~(-1), respectively, while the content of ginsenoside Rd, gypenoside LVI, and gypenoside XLVI in the raw materials was reduced by 1.661, 0.014, and 0.010 μg·g~(-1), respectively. The results suggest that heat processing is an effective way to transform rare gypenosides. Furthermore, it is found that there are great differences in the content of gypenosides in different regions.