Comparisons of the chemical profiles, cytotoxicities and anti-inflammatory effects of raw and rice wine-processed Herba Siegesbeckiae

Abstract

Ethnopharmacological relevance: Although slightly toxic, the Chinese medicinal herb Herba Siegesbeckiae (HS) has long been used as a remedy for traditional Chinese medicine symptoms that resemble inflammatory joint disorders, because it can eliminate the wind-dampness and soothe painful joints. Proper processing can reduce the toxicity and/or enhance the efficacy of raw herbs. In this study, we aim to examine if processing with rice wine reduces the cytotoxicities and/or enhances the anti-inflammatory effects of HS, and to explore the chemical basis behind the potential changes of medicinal properties caused by the processing.

Materials and methods: We used cell models to examine the cytotoxicities and anti-inflammatory effects of HS and rice wine-processed HS (WHS). The chemical profiles of HS and WHS were compared using the ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF-MS) analysis.

Results: We found that WHS was less toxic than HS in cultured cells as shown in the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Both HS and WHS had anti-inflammatory effects as demonstrated by their abilities to reduce nitric oxide (NO) production as well as protein and mRNA expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Interestingly, the anti-inflammatory effects of WHS were more potent than that of HS at the concentration of 100 μg/mL. By comparing the chemical profiles, we found that 19 peaks were lower, while 2 other peaks were higher in WHS than in HS. Four compounds including neo-darutoside, darutoside, stigmasterol and 16-O-acetyldarutoside corresponding to 4 individual changed peaks were tentatively identified by matching with empirical molecular formulae and mass fragments.

Conclusion: Our study showed that processing with rice wine significantly reduced the cytotoxicities and enhanced the anti-inflammatory effects of HS as demonstrated in cell models. We also developed a UPLC/Q-TOF-MS method to clearly differentiate HS from WHS by their different chemical profiles. Further study is warranted to establish the relationship between the alteration of chemical profiles and the changes of medicinal properties caused by processing with rice wine.

Keywords: Anti-inflammatory effect; Cytotoxicity; Herba Siegesbeckiae; Processing with rice wine; UPLC/Q-TOF-MS.