Antifibromyalgic Activity of Phytomolecule Niranthin

Fibromyalgia (FM) is characterized by chronic pain and heightened sensitivity to painful stimuli. This study investigated the potential of Niranthin (NR), a natural compound derived from Phyllanthus species, in a rat model of FM. We employed a multifaceted approach to comprehensively assess the potential benefits of NR as a treatment for FM, including in-vivo analysis, molecular docking studies, and molecular dynamics (MD) simulations, and Density Functional Theory (DFT) calculations. Three doses of NR (5 mg/kg, 10 mg/kg and 20 mg/kg) significantly reduced mechanical allodynia induced by acidic saline injections. In an acute study, NR dosing increased the mechanical threshold in both ipsilateral and contralateral paws. In a four-day study, twice-daily NR treatment further elevated the mechanical threshold. Temporary treatment interruption led to a re-establishment of allodynia, but subsequent reinitiation of NR treatment remained effective, ruling out tolerance development. MD simulations were conducted to investigate the stability and dynamics of NR-target complexes, revealing stable binding interactions and conformational changes associated with NR binding. Docking calculations indicated that the NR molecule had a similar binding affinity to the drug Amiloride towards Acid-sensing ion channels (ASICs). NR showed interactions with amino acid residues, including LYS 373, ARG 370, GLU 374 and GLN 277. DFT calculations provided insights into the electronic and structural properties of NR and its interactions with FM-related molecular target ASICs. We propose that NR may modulate ASICs, leading to decreased pain sensitivity in FM rats. However, further research is required to fully understand the mechanism of action and explore NRs therapeutic potential for the treatment of FM.