The present study was designed to assess the effects of lemon and grapefruit peel hydroethanolic extracts on arthritic indices, T helper (Th)1/Th2/Th17 cytokines, oxidative stress and antioxidant defense system in arthritic rats. Male Wistar rats, with rheumatoid arthritis induced by subcutaneous injection of 0.2 ml Freunds complete adjuvant into a footpad of the right hind leg on two consecutive days, were orally treated with lemon and grapefruit peel hydroethanolic extract at a dose level of 100 mg/kg b.w./day for 9 and 18 days. The treatments of arthritic rats with lemon and grapefruit peel hydroethanolic extracts significantly reduced the right hind paw circumference, volume and thickness. The treatments also significantly decreased the elevated total leucocyte count and serum RF, PGE2, Th1 cytokine (TNF-α) and Th17 cytokine (IL-17) levels while they increased the lowered serum Th2 anti-inflammatory cytokines (IL-10 and IL-13) levels in arthritic rats after 9 and 18 days. Furthermore, the treatments significantly decreased the elevated lipid peroxidation and nitric oxide hepatic contents while they increased the lowered glutathione content and GPx, GST and SOD activities. In conclusion, lemon or grapefruit peel hydroethanolic extracts have anti-arthritic effects which may be mediated via modulation of Th1/Th2/Th17 cytokine production and enhancement of antioxidant defense system.
Key words: Rheumatoid arthritis; lemon and grapefruit peel; hydroethanolic extract; oxidative stress; inflammation; cytokines.
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