Protective effect of Tecomastans (L.) Juss.exKunth in CFA-induced arthritic rat model

Abstract Tecoma stans (L.) Juss.exKunth (Bignoniaceae) is mainly found in tropical and subtropical regions of Africa and Asia. The leaves, flowers, roots, and bark are used to treat various aliments includes, skin infections, kidney problems, intestinal disorders, jaundice, toothaches, joint pain and repair cracked bones, antidotes for snake, scorpion, and rat bites. The aim of the study is to assess the anti-arthritic properties of T. stansleaf using Complete Freund's adjuvant (CFA)-induced rat model. The ethanol extract of T. stansleaf (ETSL) was taken for Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS) analysis for the identification of potential bioactive. The in vitro antioxidant and anti-arthritic activity was studied at concentrations of 25, 50, 100, 200, 400, and 500 μg/ml. In vivo anti-arthritic activity was carried out by administering CFA (0.1 ml) into the sub-plantar surface of the right hind paw. The experimental animals were treated with indomethacin (10 mg/kg) and ETSL (250, 500 mg/kg) once a daily for fourteen days. The arthritic parameters such as paw thickness, arthritic index, arthritic score, body weight, organ weight, and hematological and biochemical parameters were evaluated. Pro-inflammatory cytokines; tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β, anti-inflammatory cytokines; IL-4 and IL-10 and inflammatory mediator cyclooxygenase-2 (COX-2) were examined in blood serum. In vivo antioxidants parameters; superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and lipid peroxidation (LPO) was carried out in liver and joint. Radiological and histopathological analysis of joint was performed.A computational molecular docking investigation of the phytoconstituents was conducted against COX-2, IL-1β, IL-6, and TNF-α receptors by utilizing AutoDock 4.2 and BIOVIA-Discovery Studio Visualizer software. The in vitro result showed concentration dependent antioxidant activity with highest percentage of inhibition at 500 µg/ml. The in vivo result demonstrated significant restoration of arthritic parameters, hematological and biochemical indices and oxidative stress in CFA-induced rat which was further supported by radiological histological examination at ETSL 500 mg/kg. In addition, there was significant (p<0.05) reduction in pro-inflammatory cytokines, inflammatory mediators and up-regulation of anti-inflammatory cytokines was observed in the treated group. Verbascoside was found to exhibit better biding affinities -10.4, -7.4, -7 and -6.2 kcal/mol against COX-2, IL-1β, TNF-α, and IL-6 respectively, confirmed through in silico study. The observed outcome suggests that ETSL at a dosage of 500 mg/kg demonstrated notable anti-arthritic effects by suppressing pro-inflammatory cytokines and oxidative stress biomarkers. This effect could potentially be attributed to the presence of bioactive verbascoside identified in the LC-MS analysis.