Unlocking molecular mechanisms of Saussurea costus (Falc.) Lipsch. root extract against experimentally induced hypothyroidism through integrated ultra-performance liquid chromatography-tandem mass spectrometry-based serum metabolomics and network pharmacology approaches.

Objectives: Saussurea costus (Falc.) Lipschitz is traditionally used to manage thyroid disorders; however, the components responsible for its effects on propylthiouracil (PTU)-induced hypothyroidism and their mechanisms remain unclear. This study investigated the effects of S. costus on PTU-induced hypothyroid rats using serum metabolomics, network pharmacology, and in vivo testing.

Methods: Hypothyroidism was induced in rats by oral PTU administration. The metabolites absorbed from S. costus were characterized using UPLC-MS/MS and then analysed through network pharmacology to construct a compound-target-pathway network. Biological assays assessed the anti-hypothyroid effects of S. costus through ELISA and qRT-PCR techniques.

Key findings: A total of 28 compounds (6 prototypes and 22 metabolites) were identified from the serum of S. costus extracts, including terpenes and phenolic compounds. The component-target network identified 67 nodes with 51 target genes, such as SLC26A4, SLC5A5, Dio1, Dio2, TPO, CTSB, and THR-β. Key compounds like chlorogenic acid-O-methyl and dihydroreynosin glucuronide showed the highest combined scores in the compound-target network. Top KEGG pathways related to these targets included cancer, TNF signalling, apoptosis, NF-kappa B, and cAMP signalling pathways. Gene ontology analysis revealed biological processes like thyroid hormone generation, cell migration regulation, and hormone biosynthesis as key targets. Cellular components such as collagen-containing extracellular matrix and molecular functions like glycine binding and nuclear receptor activity were also associated with hypothyroidism. Administration of S. costus root extract to hypothyroid rats upregulated genes like SLC5A5, TPO, and Dio1, enhancing T4-to-T3 conversion and restoring normal T3 levels. This treatment also significantly activated Dio2 and THR-β, suggesting enhanced T4-to-T3 conversion in the pituitary gland, promoting negative feedback inhibition of TSH production.

Conclusions: S. costus root extract may act as a safe, effective alternative or adjunct therapy to the conventional treatments for hypothyroidism.