Soy Protein, Genistein, and Daidzein Improve Serum Paraoxonase Activity and Lipid Profiles in Rheumatoid Arthritis in Rats

In this study, we investigated the effects of genistein, daidzein, and soy protein on paraoxonase and arylesterase activity, malondialdehyde (MDA) levels, and lipid profiles of arthritic rats in vivo and the results were compared with that of dexamethasone. Seventy-two female Sprague-Dawley rats were divided into six groups: healthy control, animals with collagen-induced arthritis (CIA), CIA-soy protein (7 g/kg)-treated rats, CIA-genistein (20 mg/kg)-treated animals, CIA-daidzein (20 mg/kg)-treated rats, and CIA-dexamethasone (1 mg/kg)-treated rats. Rheumatoid arthritis was induced using collagen type II and the treatments were carried out by daily gavages feedings for 50 days. The paraoxonase activity in serum was measured spectrophotometrically using paraoxon and phenylacetate as substrates. Serum MDA and lipids levels were determined using enzymatic colorimetric methods. Arthritis-induced decreases in paraoxonase and arylesterase activity was restored after treatment with soy protein and isoflavones (P < .05). MDA concentrations were lower after treatment with all tested compounds. However, only soy protein could partially improve the lipid profile.