Inhibition of Echis ocellatus venom metalloprotease by flavonoid-rich ethyl acetate sub-fraction of Moringa oleifera (Lam.) leaves: in vitro and in silico approaches

Abstract

Envenoming by Echis ocellatus is potentially life-threatening due to severe hemorrhage, renal failure and capillary leakage. These effects are attributed to snake venom metalloproteinases (SVMPs). Due to drawbacks in the use of antivenin, natural inhibitors from plants are of interest in studies of new antivenin treatment. Antagonizing effects of bioactive compounds of Moringa oleifera is yet to be tested against SVMPs of E. ocellatus (SVMP-EO). Ethanol crude extract of M. oleifera was partitioned using n-hexane and ethyl acetate. Each partitions was fractionated using column chromatography and tested against SVMP-EO purified through ion exchange chromatography with EchiTab-PLUS polyvalent antivenin as control. Phytoconstituents of ethyl acetate fraction was screened against catalytic site of crystal of BaP1-SVMP while drug-likeness and ADMET toxicity of compound was equally determined. The molecular weight of isolated SVMP-EO was 43.28 kDa, with specific activity of 245 U/ml, percentage yield of 62.83 % and purification fold of 0.920. The V_max and K_m values are 2 mg/ml and 38.095 μmol/ml/min, respectively while the optimal pH and temperature are 6.0 and 40 °C, respectively. Polyvalent antivenin, crude extract and ethyl acetate fraction of M. oleifera exhibited complete inhibitory effect against SVMP-EO activity. Inhibitions of P-1 and P-II metalloprotease's enzymes by ethyl acetate fraction are largely due to methanol, 6, 8, 9-trimethyl-4-(2-phenylethyl)-3-oxabicyclo[3.3.1]non-6-en-1-yl)- and paroxypropione, respectively. Both compounds are potential drug candidates with little or no concern of toxicity as revealed from in-silico predictions. The inhibitory effects suggest that this compound might be therapeutic candidate for further exploration for treatment of Ocellatus' envenoming.

Keywords:

• Echis ocellatus
• Moringa oleifera
• antivenin
• metalloproteases
• snakebite
• molecular docking

Disclosure statement

No potential conflict of interest was reported by the author(s).