Protective effect of Tecoma stans (L.) Juss.ex Kunth in CFA-induced arthritic rats

Tecoma stans (L.) Juss.ex Kunth (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 objective of the study is to assess the anti-arthritic properties of T. stans leaf using Complete Freund's adjuvant (CFA)-induced rat.

The ethanol extract of T. stans leaf (ETSL) was subjected toGas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS) analysis for the identification of potential bioactive. The 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 day orally for fourteen days. The arthritic parameters and hematological and biochemical parameters were evaluated using standard kit reagents. The levels of pro-inflammatory cytokines and inflammatory mediators were measured in blood serum. Antioxidant parameters were assessed in homogenized liver and joint tissues. 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.

The ETSL at 500 mg/kg demonstrated significant (p < 0.01) restoration of arthritic parameters, hematological and biochemical indices and oxidative stress in CFA-induced rats which was further supported by radiological histological examination. In addition, there was significant (p < 0.05) reduction observed in pro-inflammatory cytokines, inflammatory mediators and up-regulation of anti-inflammatory cytokines 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.