Asphodelus tenuifolius extracts arrested inflammation and arthritis through modulation of TNF-α, NF-κB, ILs, and COX-2 activities in in vivo models

Asphodelus tenuifolius is traditionally used in the management of rheumatic pain and inflamed body parts. The current study validated its traditional use as an anti-arthritic and anti-inflammatory agent using a series of in vivo models. Carrageenan and histamine-induced acute oedema models were employed to study the effects of n-hexane (n-HeAT) and ethanolic (EeAT) extracts on acute inflammatory mediators and were found to inhibit oedema formation in a dose-dependent manner. Formalin and complete Freund's adjuvant (CFA) were injected into the hind paw of rats for the induction of arthritis. In the formalin model both n-HeAT and EeAT showed significantly better (p < 0.05) anti-oedema effects from day 6 onward. In CFA model rats were treated on 8th day of induction with extracts at the doses of 250, 500, and 750 mg/kg respectively. Piroxicam (10 mg/kg) and normal saline (10 mL/kg) were used as positive and negative controls respectively. Both n-HeAT and EeAT significantly (p < 0.05) decreased arthritis development in a time-dependent manner and at 28th day extent of inflammation was even less than that observed at day 8. The arthritic score was measured at day 12, 16, 20, 24, and 28 and was observed to be significantly less (p < 0.05) in animals treated with 750 mg/kg of n-HeAT and EeAT, respectively. Joint inflammation (p < 0.01), bone erosion (p < 0.001) and, pannus formation (p < 0.01) were significantly declined in A. tenuifolius treatment groups. Radiographic evaluations (X-ray) were conducted to check bone integrity and extent of inflammation and were observed to be diminished at day 28 in A. tenuifolius extracts treated groups. HPLC was performed to screen the phytochemical profile of n-HeAT and EeAT and were found to contain flavonoids and phenolic compounds. Quantitative real-time polymerase chain reaction (qPCR) was performed to detect effects of n-HeAT and EeAT treatments on inflammatory markers i.e., IL-4, IL-6, IL-10, COX-2, NF-κB, and I-κB using blood samples. ELISA assays were performed for the detection of levels of C-reactive proteins, respectively. Significant downregulation of TNF-α, IL-4, IL-6, IL-1β, COX-2, NF-κB with simultaneous upregulation of IL-10 and I-κB was observed in n-HeAT and EeAT treatment groups. ELISA assays also showed significant (p < 0.05) down-modulation in the serum levels of CRP and TNF-α. Both extracts showed relatively weak antioxidant activities as compared with ascorbic acid in in vitro assay. Based on findings of the current study it is concluded that A. tenuifolius has anti-inflammatory and anti-arthritic effects and thus has potential to be used as an adjunct to standard NSAIDs therapy.Graphic abstract.

Keywords: Arthritis; Chronic inflammation; Inflammatory biomarkers; Oxidative stress; qPCR.