Ameliorating effects of Astragalus maximus methanolic extract on inflammation and oxidative stress in streptozotocin-induced diabetic rats

Introduction: Recent studies have reported that Astragalus spp. can display various biological effects, e.g., anticancer, antioxidant, antimicrobial, neuroprotective, and hepatoprotective activities. Here we decided to assess the ameliorating effects of Astragalus maximus methanolic extract (AMME) on inflammation and oxidative stress in streptozotocin-induced diabetic rats. Methods: The dried aerial parts were extracted by maceration technique with 70% methanol. Diabetes was induced in rats via intraperitoneal injection of streptozotocin at 65 mg/kg. Diabetic rats orally received AMME at 75-30 mg/kg for 28 days. The serum levels of glucose, insulin, liver enzymes, bilirubin, creatinine (Cr), urea (Ur), triglyceride, and cholesterol, as well as the tissue levels of oxidant/antioxidant enzymes and pro-inflammatory cytokines were evaluated by the diagnostic kits. The level of α-amylase inhibition by AMME was also determined. Results: AMME (150 and 300 mg/kg) treatment significantly reduced (P<0.001) the serum levels of glucose, cholesterol, triglyceride, Cr, Ur, liver enzymes, and oxidative enzymes in diabetic rats. The tissue levels of antioxidant enzymes in diabetic rats treated with AMME (150 and 300 mg/kg) were significantly increased (P<0.01). Treatment of diabetic rats with either 150 or 300 mg/kg AMME for 28 days significantly reduced interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels in the pancreas. AMME inhibited α-amylase in a dose-dependent manner with an IC50 value of 18.1 μg/mL. Conclusion: This study showed that the oral administration of AMME in diabetic rats displayed a potent anti-diabetic activity through increasing insulin release and ameliorating effects on inflammation and oxidative stress; however, more investigations are desired to determine the action mechanism of the extract.