Dynamic changes of volatile components in Forsythia suspensa at different harvest periods based on GC-MS and chemometrics analysis

Abstract

Forsythiae Fructus is the dried fruit of Forsythia suspensa and the volatile compounds are its main bioactive components. According to the different harvest periods, F. suspensa can be divided into Qingqiao(mature F. suspensa) and Laoqiao(ripe F. suspensa). To investigate dynamic changes of volatile components in Qingqiao and Laoqiao samples collected at different periods, the present study extracted and analyzed the total volatile oils in Qingqiao and Laoqiao samples(four harvest periods for Qingqiao and two for Laoqiao) by steam distillation method. The results indicated that the content of volatile oils in F. suspensa samples at different harvest periods was significantly different. The content of volatile oils in Qingqiao samples(except those harvested in the first period) was higher than that of Laoqiao, and the content of volatile oils in both Qingqiao and Laoqiao increased with the harvest period. Furthermore, volatile compounds in F. suspensa were qualitatively analyzed by the gas chromatography-mass spectrometry(GC-MS), and 28 volatile compounds were identified. Chemometrics analyses including principal component analysis(PCA) and partial least squares discriminant analysis(PLS-DA) were further applied to explore differential markers and dynamic changes of volatile components in Qingqiao and Laoqiao samples at different harvest periods. Finally, four volatile compounds, including α-pinene, sabinene, β-pinene, and 4-terpenol were selected as potential differential markers. The relative content of α-pinene and 4-terpenol was consistent with that of total volatile oils in the changing trend.