Background: Nardostachys jatamansi DC. (Gansong), a widely utilized herb in traditional Chinese medicine, has been historically employed in the management of various neuropsychiatric disorders. Nardosinone (Nar), a sesquiterpenoid compound, has been identified as one of the principal bioactive constituents of N. jatamansi. This study investigated the effects of ethyl acetate extract (NJ-1A) from N. jatamansi and its active constituent nardosinone on neuroinflammatory mediator release, glucose metabolic reprogramming, and T cell migration using both in vitro and in vivo experimental models. Methods: Lipopolysaccharide(LPS)-induced BV-2 microglial cells and a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/probenecid (MPTP/p)-induced male C57BL/6N mouse chronic model of Parkinson’s disease were applied. Results: Both NJ-1A and Nar could significantly suppress LPS-induced production of M1 pro-inflammatory factors or markers in microglia and could inhibit the glycolytic process and promote oxidative phosphorylation via the AKT/mTOR signaling pathway. Furthermore, they exhibited the capacity to attenuate chemokine release from activated microglia, consequently reducing T cell migration. In vivo experiments revealed that NJ-1A and Nar effectively inhibited microglial activation, diminished T cell infiltration, and mitigated the loss of tyrosine hydroxylase (TH)-positive dopaminergic neurons in the substantia nigra of MPTP-induced mice. Conclusions: NJ-1A and nardosinone exert neuroprotective effects through the modulation of microglial polarization states, regulation of metabolic reprogramming, and suppression of T cell infiltration.

Nardosinone, a predominant bioactive product from Nardostachys jatamansi DC, is well-known for its promising therapeutic applications, such as being used as a drug on anti-inflammatory, antidepressant, cardioprotective, anti-neuroinflammatory, anti-arrhythmic, anti-periodontitis, etc. However, its stability under varying environmental conditions and its degradation products remain unclear. In this study, four main degradation products, including two previously undescribed compounds [2–deoxokanshone M (64.23%) and 2–deoxokanshone L (1.10%)] and two known compounds [desoxo-narchinol A (2.17%) and isonardosinone (3.44%)], were firstly afforded from the refluxed products of nardosinone in boiling water; their structures were identified using an analysis of the extensive NMR and X–ray diffraction data and the simulation and comparison of electronic circular dichroism spectra. Compared with nardosinone, 2–deoxokanshone M exhibited potent vasodilatory activity without any of the significant anti-neuroinflammatory activity that nardosinone contains. Secondly, UPLC–PDA and UHPLC–DAD/Q–TOF MS analyses on the degradation patterns of nardosinone revealed that nardosinone degraded more easily under high temperatures and in simulated gastric fluid compared with the simulated intestinal fluid. A plausible degradation pathway of nardosinone was finally proposed using nardosinonediol as the initial intermediate and involved multiple chemical reactions, including peroxy ring-opening, keto–enol tautomerization, oxidation, isopropyl cleavage, and pinacol rearrangement. Our findings may supply certain guidance and scientific evidence for the quality control and reasonable application of nardosinone-related products.