Effects of Ficus sycomorus Phenolic Extracts on the Activity of Hyaluronidase and Phospholipase A2 Enzymes of Echis ocellatus Venom

Abstract

Envenomation by snake is one of the most neglected public health problems in Nigeria, causing around 100,000 human deaths annually. It however remains a serious medical, economic and social problem. This research is aimed at evaluating the effects of F. sycomorus extract fractions against Hyaluronidase and Phospholipase A2 (PLA2) enzymes of E. ocellatus snake venom. The plant leaf and stem bark were extracted using chloroform and fractionated using tin Layer and column Chromatography, where flavonoids and tannins were partially purified. Phytochemical analysis of the extracts revealed the presence of tannins, saponin, alkaloids, flavonoids, amino acids, phenols, triterpenoids, terpenoids, steroids and phlobatanins. Gas Chromatography – Mass Spectrometry (GC-MS) analysis done indicates the presence of some basic phenolic compounds, such as; Cyclohexane-1-3,5-trione and 2-phenyl-1,4-benzopyrone. Isolation of the E. ocellatus snake venom enzymes is done using two step processes which include gel filtration on Sephadex G-75 and active fractions were applied to ion–exchange chromatography on Diethylaminoethyl (DEAE) cellulose. The active fractions were then subjected to Soduin Dodecyl Sulphate–Polycrylamide (SDS-PAGE) for molecular weight determination. The partially purified Hyaluronidase and PLA2 gave a total enzyme activity of 1.126904 Tru/Mg and 3.692308 µmol/min and an estimated extrapolated molecular weight of 18 and 14 KDa respectively. IC50 determination of the partially purified plant parts flavonoids and tannins against PLA2 and hyaluronidase from E. ocellatus venom shows the leaf flavonoid extract has the lowest IC50 (Which signifies a higher inhibitory potency) concentration of 0.85 mg/ml and 1.7 mg/ml for hyaluronidase and PLA2 respectively, than all the other fractions tested against both enzymes, while the leaf tannin extract has the highest IC50 (Which signifies a lower inhibitory potency) concentration of 1.65 mg/ml and 2.00 mg/ml. Enzyme inhibition assay carried out reveals the various kinetics parameters for the enzymes in the presence and absence of the inhibitors. Only two of the eight inhibitions, carried out on the partially purified phenolics against the E. ocellatus hyaluronidase and PLA2 enzymes shows a non-competitive kind of inhibition, which is a more promising kind of inhibition and due often turns to an irreversible reaction. F. sycomorus phenolic extracts could provide an alternative natural remedy for the management and treatment of snakebite.