Analgesic C20-diterpenoid alkaloids from the lateral roots of Aconitum carmichaelii Debeaux: Natural inhibitors of NLRP3 activation

Bioorg Chem. 2025 May:158:108321. doi: 10.1016/j.bioorg.2025.108321. Epub 2025 Mar 5.

Abstract

Five new C20-diterpenoid alkaloids carmaloidlines A-E (1-5) and a known C20-diterpenoid alkaloid (6) were isolated from the lateral roots of Aconitum carmichaelii Debeaux. Their structures were determined through spectrometric analysis and quantum chemical calculations. Meanwhile, the plausible biosynthetic pathways of 1-6 were also discussed. Western blot results indicated that 2, 4, and 6 significantly inhibited caspase-1 maturation and IL-1β production on the NLRP3 signaling pathway at a concentration of 10 μM, among which 2 exhibited the greatest impact on NLRP3 inflammasome activation in a dose-dependent manner (5, 10 and 20 μM). Notably, the hot plate test in mice demonstrated that the analgesic efficacy of 2 was equivalent to that of morphine at the same dose (0.3 mg/kg), while also providing a longer pain latency period compared to morphine. Additionally, compound 2 effectively mitigated both mechanical allodynia and thermal hyperalgesia induced by the NLRP3 agonist nigericin at a dose of 0.03 mg/kg, exhibiting effects comparable to those of the NLRP3 inhibitor MCC950 (10 mg/kg). Molecular docking revealed that 2 could bind to the active site of MCC950 in NLRP3 protein, and 2 had the lower interaction energy. Cellular thermal shift assay (CETSA) further validated the binding of 2 to NLRP3. This could provide a scientific basis for developing NLRP3 activation inhibitors as novel analgesics.

Keywords: Aconitum carmichaelii Debeaux; Analgesic effect; Diterpenoid alkaloids; NLRP3 activation inhibitor.

MeSH terms

  • Aconitum* / chemistry
  • Alkaloids* / chemistry
  • Alkaloids* / isolation & purification
  • Alkaloids* / pharmacology
  • Analgesics* / chemistry
  • Analgesics* / isolation & purification
  • Analgesics* / pharmacology
  • Animals
  • Diterpenes* / chemistry
  • Diterpenes* / isolation & purification
  • Diterpenes* / pharmacology
  • Dose-Response Relationship, Drug*
  • Humans
  • Male
  • Mice
  • Molecular Docking Simulation
  • Molecular Structure
  • NLR Family, Pyrin Domain-Containing 3 Protein* / antagonists & inhibitors
  • NLR Family, Pyrin Domain-Containing 3 Protein* / metabolism
  • Plant Roots* / chemistry
  • Structure-Activity Relationship

Substances

  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Analgesics
  • Alkaloids
  • Diterpenes
  • Nlrp3 protein, mouse