Pentahydroxy flavonoid isolated from Madhuca indica ameliorated adjuvant-induced arthritis via modulation of inflammatory pathways

Rheumatoid arthritis (RA) is an autoimmune disease associated with advanced joint dysfunction. Madhuca indica J. F. Gmel, from the family Sapotaceae, is an Indian medicinal plant reported to have an array of pharmacological properties. The aim of present investigation was to determine the anti-arthritic potential of an isolated phytoconstituent from methanolic leaf extract of Madhuca indica (MI-ALC) against FCA-induced experimental arthritis. Polyarthritis was induced in female rats (strain: Wistar) via an intradermal injection of FCA (0.1 mL) into the tail. Polyarthritis developed after 32 days of FCA administration. Then rats were treated orally with an isolated phytoconstituent from MI-ALC at doses of 5, 10, and 20 mg/kg. Findings suggested that High-Performance Thin-Layer Chromatography, Fourier-Transform Infrared Spectroscopy, and Liquid Chromatography-Mass Spectrometry spectral analyses of the phytoconstituent isolated from MI-ALC confirmed the structure as 3,5,7,3′,4′-Pentahydroxy flavone (i.e., QTN). Treatment with QTN (10 and 20 mg/kg) showed significant (p < 0.05) inhibition of increased joint diameter, paw volume, paw withdrawal threshold, and latency. The elevated synovial oxidative stress (Superoxide dismutase, reduced glutathione, and malondialdehyde) and protein levels of Tumor necrosis factor-α (TNF-α) and Interleukin (ILs) were markedly (p < 0.05) reduced by QTN. It also effectively (p < 0.05) ameliorated cyclooxygenase-2 (COX-2), Nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-kβ) and its inhibitor-α (Ikβα), and ATP-activated P2 purinergic receptors (P2X7) protein expressions as determined by western blot analysis. In conclusion, QTN ameliorates FCA-induced hyperalgesia through modulation of elevated inflammatory release (NF-kβ, Ikβα, P2X7, and COX-2), oxido-nitrosative stress, and pro-inflammatory cytokines (ILs and TNF-α) in experimental rats.