Oral Glucose Tolerance and Protective Effect of Aqueous Extract of Xylopia Aethiopica Seed on 2,2-Azobis(2-Amidinopropane) Dihydrochloride (AAPH) Induced Oxidative Stress

Abstract

In Nigeria, Xylopia aethiopica (Annonaceae) is locally used in tea and beverages, and in treating constipation. This study evaluated the oral glucose tolerance and protective effect of X. aethiopica seed extract on 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress in red blood cells (RBCs). Twelve experimental mice were randomly distributed into four groups of three mice administered orally with distilled water, metformin, and X. aethopica aqueous seed extract. Glucose was administered orally to 12 hour fasted mice, and plasma glucose was evaluated after 0-4 hours. Antioxidant activity was evaluated using prepared RBCs from mice after pre-treatment with AAPH. Significant increase (p < 0.05) was observed in glucose level of all treated mice after 30 minutes, which gradually decreased to 11.41%, 16.52%, and 14.19% for aqueous extract of X. aethiopica seed (250 and 500 mg/kg b. wt) and metformin (14.5 mg/kg b.wt) respectively. The antioxidant activity indicated that the extract possessed higher hydroxyl radical scavenging activity compared with vitamin C. More so, aqueous extract of X. aethiopica seed protected cells against AAPH-induced oxidative stress in cells by decreasing the activity of catalase generated and malondialdehyde concentration after 40 minutes of incubation at 2.5 mg/mL compared with vitamin C. No significant difference (p > 0.05) was observed in superoxide dismutase activity in vitro. The total tannin and phenolic contents of X. aethiopica seed were 509.16±192.13 mgQE/g and 1.59±0.63 mgGAE/g, respectively. The study concludes that aqueous extract of X. aethiopica seed possesses glucose-lowering and antioxidant detoxifying properties against 2,2-azobis(2-amidinopropane) dihydrochloride-induced oxidative stress in vitro.