Ulcerative colitis (UC), a chronic non-specific inflammatory bowel disease (IBD) involving the colon and rectum, is characterized by attacks, remitting, and recurrent episodes (Kobayashi et al., 2020). Epidemiological surveys suggest that the incidence and prevalence of UC, which is defined as one of the most intractable diseases by the World Health Organization, have been increasing rapidly worldwide over time (Kaplan, 2015; Ng et al., 2017). UC patients are afflicted with abdominal pain, diarrhea, and other extraintestinal manifestations, which lower their life quality and aggravate economic burden (Neurath, 2019). Modern medicine shows that UC is related to genetic susceptibility, host immune system disorder, intestinal flora imbalance, but the specific etiology and pathogenesis are still unclear (Zundler et al., 2019). At present, major drugs used for UC treatment, such as amino acid salicylates, glucocorticoids and immunosuppressants, can result in poor compliance, osteoporosis, and other serious adverse reactions (Segal et al., 2021). Therefore, the development of more safe and effective drugs is urgent for UC treatment.

Currently, accumulating evidences indicate that traditional Chinese medicines (TCMs) have obvious advantages in the treatment of UC, such as fewer adverse reactions, lower recurrence rate and lower cost (Y. Liu et al., 2022; Zheng et al., 2022). Lizhong decoction (LZD), a classical herbal formula recorded by Zhang Zhongjing in Treatise on Febrile and Miscellaneous Diseases, is composed of equal amounts of Panax ginseng C.A. Mey. (Ginseng Radix Rhizoma, PG), Zingiber officinale Rosc. (Zingiberis Rhizoma, ZO), Atractylodes macrocephala Koidz. (Atractylodis Macrocephalae, AM) and Glycyrrhiza uralensis Fisch. (Glycyrrhizae Radix Et Rhizoma, GU) (Zou et al., 2020). This herbal prescription is commonly used to warm the spleen and stomach for dispelling cold, which contains saponins, gingerols, lactones, flavonoids and other active ingredients. In addition, emerging evidences have shown that LZD has a variety of pharmacological effects such as anti-inflammation, anti-oxidation, anti-infection, anti-ulcer, and immune regulation (Jiayao et al., 2022; Miao et al., 2023; Song et al., 2020; Yang et al., 2020a). In our previous study, LZD was found to significantly ameliorate dextran sulfate sodium (DSS)-induced UC in mice by regulating plasma and urine metabolic profiling as well as modulating gut microbiota and its metabolites (Zou et al., 2020; Wang et al., 2022). However, the material basis of LZD in treating UC has not been clarified.

In recent years, spectrum-effect relationship based on modern analytical techniques has been a powerful tool to elucidate the material bases of TCMs (H. Chen et al., 2022; Lv et al., 2023). The spectrum-effect relationship is a method of associating the spectra and efficacy via multiple statistical analyses to screen active ingredients, which not only reflects the intrinsic quality of TCMs, but also embodies the holistic perspective of TCMs (Zhu et al., 2016). The statistical analysis methods of spectrum-effect relationships include grey relational analysis (GRA), regression analysis, correlation analysis, cluster analysis and so on. Besides, ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) has been proved to be the most reliable analytical technique to identify components in herbal medicines due to its high sensitivity, high selectivity, and high specificity (H. Liu et al., 2022). The UPLC system provides higher separation efficiency, shorter separation time and less solvent consumption, which enables the UPLC to quickly and efficiently separate complex compositions in TCMs. Meanwhile, Q-TOF-MS/MS can enhance mass analysis accuracy and accurate mass determination capabilities with high sensitivity and resolution (Sun et al., 2012). Thus, the UPLC system combining with MS/MS analysis is an efficient tool for characterizing chemical components in TCMs.

Furthermore, network pharmacology combined with molecular docking can contribute to revealing the mechanisms of TCMs exerting the efficacy. Network pharmacology is based on systematic biological network analysis strategy, multidisciplinary theory and technologies including omics, high-throughput screening, network visualization, and network analysis to construct a multi-level and multi-angle “component-target-disease” biological network to elucidate the potential mechanisms of drugs. The integrality and systematization of network pharmacology are consistent with the TCM theory of treating diseases from a holistic perspective and the principles of multi-component, multi-target and multi-pathway synergistic effects of TCMs (Hopkins, 2007; Li et al., 2022). Network pharmacology mainly consists of three aspects: network construction, network analysis and experimental verification, which is widely applied to reveal the mechanisms of herbal medicines. Moreover, molecular docking is a computational chemistry method to predict and evaluate the interactions and binding capacities between receptors and ligands, which can profile the binding of active ingredients and key targets (Pinzi and Rastelli, 2019). Thus, molecular docking is generally used to further verify the results of network pharmacology (Liu et al., 2021). In a word, the combination of network pharmacology, molecular docking and experimental verification can provide a more comprehensive research perspective to help clarify the complex mechanisms of TCMs.

In this study, the UC mouse model induced by DSS was successfully established to assess the efficacy of different extraction parts of LZD by body weight change, disease activity index (DAI), the levels of cytokines and histopathological changes. In addition, UPLC-Q-TOF-MS/MS was used to identify the components of different extraction fractions. And GRA, bivariate correlation analysis (BCA) and partial least squares regression (PLSR) were applied to analyze spectrum-effect relationships between chromatographic peaks and drug efficacy. Furthermore, the possible targets and signaling pathways of LZD were screened and validated by network pharmacology, molecular docking and RT-qPCR. Collectively, the integration of UPLC-Q-TOF-MS/MS, spectrum-effect analyses, network pharmacology, molecular docking and experimental verification contributes to systematically and comprehensively unravelling efficacy components and potential mechanisms of TCMs.