Comprehensive analysis of the chemical constituents in sulfur-fumigated Lonicerae Japonicae Flos using UHPLC-LTQ-Orbitrap mass spectrometry

Lonicerae Japonicae Flos (LJF), a kind of traditional Chinese medicines (TCMs), has functions of detoxifying and evacuating heat. In the study, a method based on ultra-high performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry (UHPLC-LTQ-Orbitrap MS) was developed for the chemical constituent analysis of organic acids, flavonoids, iridoids and new-generated compounds in sulfur-fumigated LJF (SF-LJF). Based on the accurate mass measurement (< ± 5 ppm), chromatographic behavior and diagnostic product ions (DPIs), 113 constituents were unambiguously or tentatively characterized from SF-LJF extract, including 46 chlorogenic acids, 19 flavonoids, 29 iridoid glycosides and 19 newly-generated compounds (including 17 sulfur-containing derivatives). In addition, 5-CQA (5-caffeoylquinic acid, chlorogenic acid) was chosen to be sulfur-fumigated for the result validation. It was found that the most significant change of LJF after sulfur fumigation was the occurrence of sulfate or sulfite esterification reactions, which resulted in the emergence of many new sulfur-containing components. Our results demonstrated that the established method was a useful and efficient analytical tool to comprehensively characterize the material basis of SF-LJF, and also an excellent guidance of quality control about LJF.