Background/Objectives: Heracleum millefolium Diels (HMD) is a traditional Tibetan medicinal herb that has been reported to possess analgesic, anti-edematous, and anti-inflammatory activities. However, its chemical composition and anti-inflammatory mechanisms remain unclear. Methods: In this study, ultra-performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS), combined with database searching and “seed”-based molecular networking, was used to systematically characterize the chemical constituents of HMD. Furthermore, an integrated strategy combining network pharmacology, molecular docking, and cellular validation was applied to explore potential anti-inflammatory mechanisms associated with HMD. Results: A total of 472 compounds were identified or tentatively identified from HMD. Network pharmacology analysis predicted five key targets, namely TNF, IL-6, IL-1β, GAPDH, and AKT1, together with four potential bioactive constituents, including velutin, artemitin, kaempferol, and naringenin. Pathway enrichment analysis indicated that the potential anti-inflammatory effects of HMD were mainly associated with lipid and atherosclerosis and the AGE-RAGE signaling pathway. Molecular docking suggested potential favorable interactions between the selected constituents and key targets. Moreover, cellular experiments demonstrated that the four compounds significantly inhibited inflammatory responses in LPS-stimulated RAW264.7 macrophages. Conclusions: This study systematically characterized the chemical profile of HMD and preliminarily explored its potential anti-inflammatory mechanisms, providing a scientific basis for further investigation of its bioactive constituents and pharmacological properties.

Background: Idiopathic inflammatory myopathies (IIMs), characterized by muscle weakness and chronic inflammation, currently lack highly effective therapies. This study investigated the therapeutic potential and underlying mechanism of (5R)-5-hydroxytriptolide (LLDT-8), a triptolide derivative with reduced toxicity, using an experimental autoimmune myositis (EAM) mouse model and in vitro assays. Methods: Forty female BALB/c mice were randomly assigned to five groups: normal, vehicle, methylprednisolone (MP), LLDT-8 (0.0625 mg/kg), and LLDT-8 (0.125 mg/kg). EAM mice were treated with LLDT-8 (0.0625 or 0.125 mg/kg) or methylprednisolone as a positive control. Cellular experiments and molecular docking were performed to investigate potential mechanisms of LLDT-8. Results: LLDT-8 significantly attenuated clinicopathological features, including muscle weakness and pain sensitivity, while reducing serum levels of aspartate aminotransferase and lactate dehydrogenase. Histological analysis revealed that LLDT-8 reduced inflammatory cell infiltration and the presence of CD4⁺ and CD8⁺ T cells in muscle tissues. Mechanistically, LLDT-8 inhibited the expression of nucleotide-binding oligomerization domain receptor caspase recruitment domain 5 (NLRC5), a key transcriptional regulator of major histocompatibility complex-I (MHC-I). This suppression extended to downstream antigen presentation-related molecules, including the transporter associated with antigen processing and proteasome 20S subunit beta. Molecular docking further confirmed the high binding affinity of LLDT-8 to both NLRC5 and MHC-I. Conclusions: LLDT-8 alleviates inflammatory muscle injury by targeting the NLRC5/MHC-I signaling axis, suggesting it may be a promising therapeutic candidate for IIMs.