chrysin and Pain

Our recent reports have revealed that inhibiting NLRP3 activation reduces synovial inflammation and fibrosis in knee osteoarthritis (KOA). Synovial inflammation is involved the entire process of KOA and promotes the progression of KOA. Natural flavonoid Chrysin from Scutellariae Radix, a traditional Chinese medicine, exhibits multifarious biological activities and potentially has protective activity against osteoarthritis. However, the mechanism of Chrysin in the treatment of synovial inflammation remains elusive. The purpose of our research was to explore the anti-inflammatory effects of Chrysin on KOA, which was induced by monoiodoacetic acid (MIA) in rats by targeting the NLRP3 inflammasome in the hopes of identifying an effective drug to treat KOA.. The MIA-induced KOA model was used to evaluate the cold pain threshold and paw withdrawal threshold (PWT) of joints after MIA (40 mg/mL) injection into the knee joints. Microscopically, we used LPS (5 ug/mL) and ATP (4 mmol/L) to stimulate fibroblast-like synovial cells (FLSs) to explore the underlying mechanisms and effects of Chrysin. Two staining methods, H&E and Sirius Red, were applied to assess histopathological changes in synovial membranes. Cellular signal transduction was determined by qRT-PCR and WB. Cytokine expression (inflammatory cytokines and pain-related cytokines) was detected by ELISA. The degree of chronic inflammatory pain was evaluated by c-Fos immunofluorescence.. The results showed that Chrysin not only attenuated synovial inflammation but also reduced the secretion of pain-related factors and increased the PWT and cold pain threshold in rats. Chrysin also inhibited NLRP3 inflammasome activation and increased IL-1β levels to alleviate the synovitis.. Chrysin can relieve knee synovial inflammation and improve pain behavior in KOA rats, which may be related to the ability of Chrysin to inhibit NLRP3 inflammasome activation. Therefore, Chrysin may be developed as a new drug for the treatment of KOA.

Topics: Animals; Anti-Inflammatory Agents; Drugs, Chinese Herbal; Flavonoids; Inflammasomes; Iodoacetic Acid; Male; Medicine, Chinese Traditional; NLR Family, Pyrin Domain-Containing 3 Protein; Osteoarthritis, Knee; Pain; Plant Extracts; Rats; Rats, Sprague-Dawley; Scutellaria baicalensis; Synovitis

Flavonoids are the most abundant natural polyphenols widely distributed in plants. Among them, chrysin has recently attracted the attention for its anti-tumor and anti-oxidant activities and also for its protective effects on allergic inflammation. Therefore, in this study, we set out to investigate and characterize the effects of chrysin in classical models of inflammation reasoning that this would expand our knowledge on the pharmacological properties of this flavone. To this aim we have firstly isolated chrysin from Potentilla evestita Th. Wolf. and successively evaluated its anti-inflammatory and analgesic potential on writhing and formalin test and also on carrageenan-induced paw oedema. Finally, the present study was planned to investigate, by the aim of docking analysis, the molecular interaction of this compound on the binding site of COX-1 and COX-2 enzymes. On writhing test, we observed a significant inhibition of writhings after the administration of chrysin at 5.0 and 10.0 mg/kg i.p. (25.00±9.22% and 55.67±7.62% respectively). On formalin test, the flavone at dose of 10.0 mg/kg i.p. displayed its maximum analgesic and anti-inflammatory effect on both early (35.67±7.88%) and late phase (50.57±5.36%) and similarly displayed at 4h a significant anti-inflammatory effect in carrageenan-induced paw oedema. Moreover, in silico analysis of receptor ligand complex shows that chrysin interacts weakly with COX-1 binding site whereas displayed a remarkable interaction with COX-2. These findings suggest that the flavone chrysin isolated from P. evestita Th. Wolf. possesses in vivo anti-inflammatory and anti-nociceptive potential, which are supported in silico by an interaction with COX-2 binding site.

Topics: Analgesics; Animals; Anti-Inflammatory Agents; Binding Sites; Cyclooxygenase Inhibitors; Flavonoids; Inflammation; Male; Mice, Inbred BALB C; Models, Molecular; Pain; Potentilla