Effects of Aqueous Stem Extract of Achyranthes aspera on Bitis arietans Venom Protease and Phospholipase A 2 Activity

Aqueous stem extract of Achyranthes aspera was investigated for inhibitory activity against Bitis arietans venom protease and phospholipase A 2 activity. The elemental analysis and phytochemical screening of the plant extract were carried out. The activities of protease and phospholipase A 2 (V o) of the crude Bitis arietans venom was determined and the data obtained was used to estimate K M, V max and K cat. Inhibition studies were carried out using the same procedure except that different concentrations of the extracts (5%, 10%, 15% for protease assay and 0.5%, 0.75%, 10%, 1.25% and 1.5% for phospholipase A 2 assay) were added to the reaction mixture. The result showed that the Bitis arietans venom protease had a V max of 0.062 ± 0.013 μmol/min, K M of 0.496 ± 0.095mg/ml and a K cat of 0.125 ± 0.001min -1. The result also indicates that the Bitis arietans phospholipase A 2 had a V max of 3.27 ± 0.030min -1, K M of 8.358 ± 0.050 mg/ml and K cat of 0.391 ± 0.002min -. The aqueous stem extract produced a statistically significant (P<0.05) decrease in the V max, K M and K cat of the Bitis arietans venom phospholipase A 2 in a dose dependent manner and a statistically significant (P<0.05) increase in the V max, K M and K cat of Bitis arietans protease in a dose dependent manner. The phytochemical screening revealed the presence of flavonoids, tannins, steroids, saponins and terpenoids in the extract while the elemental analysis revealed the presence of Zn, Cr, Ni, Cd, Mn, Fe and Na. The result suggests that aqueous stem extract of Achyranthes aspera inhibited the Bitis arietans venom phospholipase A 2 in an uncompetitive manner while the protease activity was stimulated by the extracts. It was observed that the use of the stem of Achyranthes aspera may be important in the treatment of snake bites.