Erythrocyte Membrane Stabilisation, Protease Activities And Antioxidant Properties of The Stem Bark Extract of Alstonia boonei (DC)

Abstract

There is an increasing search for natural antioxidants because of the growing concern about the safety of the synthetic ones and their potency in stabilising biological membranes. Because of this, we investigated the membrane stabilizing effects, proteinase activities and antioxidant properties of extract and fractions of Alstonia boonei. The in vitro and in vivo antioxidant properties of Alstonia boonei, erythrocyte membrane stabilising and inhibitory effects of the extract and fractions of the plant on proteinase activity were assessed spectrophotometrically. Assessment of the antioxidant properties of extract and fractions of A. boonei showed that the plant exhibited significant antioxidant activities both in vitro and in vivo. In the in vitro antioxidant assessment of the extract and fractions of Alstonia boonei, the MF had the highest significant effects on nitric oxide inhibition (95.90±9.18), reducing power (1.311±0.054), and 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging (90.00±0.010). The CF had the highest effect on percentage hydroxyl radical scavenging activity (79.72±6.84), and inhibition of lipid peroxidation (96.70±12.44). In vivo, extract and fractions of Alstonia boonei significantly altered the antioxidant status of the treated animals relative to control. The n-hexane fraction stabilized the red cell membrane in a concentration dependent manner and also significantly inhibited proteinase activity in vitro. These preventive effects may be as a result of the antioxidant properties of the extract and fractions of Alstonia boonei and the various fractions may find use either as natural antioxidants or as inhibitors of protease enzymes