Inhibition of phospholipase A₂ from Naja haje and Naja nigricollis venoms by active fraction of Moringa oleifera leaves: in vitro and in silico methods

Abstract

Phospholipases are one of the principal toxic enzymes in snake venoms inducing a wide variety of pharmacological effects after envenomation. Natural inhibitors from plants are known to inhibit the toxic enzyme activities of snake venoms. In this study, ethanol crude extract of M. oleifera leaves was partitioned using n-hexane and ethyl acetate after which fractionation was done using column and thin layer chromatography. Subsequently, the inhibitory activities of the crude extract and sub-fractions of M. oleifera were investigated against phospholipases A₂ isolated from Naja haje and Naja nigricollis venoms using in vitro and in-silico approaches while EchiTab-PLUS polyvalent antivenom was used as the standard drug. The molecular weight of isolated N. haje phospholipase A₂ (NH-PL) and N. nigricollis phospholipase A₂ (NN-PL) were 24.11 and 35.22 kDa respectively. NH-PL enzyme had a specific activity of 2.70 μM/min/mg substrate while NN-PL activity was 2.10 μM/min/mg substrate. The K_m of NH-PL was 0.330 μM with V_max of 0.085 μM/mL min while NN-PL had V_max of 0.198 μM/mL.min and K_m of 0.670 μM. M. oleifera n-hexane sub-fraction 5 (MOLH5) exhibited a total inhibition of NN-PL and NH-PL enzyme activities at all concentrations used. Molecular docking of the phytoconstituents of MOLH5 against the catalytic site of phospholipase A₂ revealed 2-Hydrazino-8-hydroxy-4-phenylquinoline as the lead compound and a potential drug candidate with a docking score of −6.789 kcal/mol. Findings indicated that MOLH5 possesses phospholipase A₂ natural inhibitors that could be explored as a therapy for snake envenoming.

Keywords:

• Snakebites
• Naja haje
• Phospholipase A₂
• Moringa oleifera
• envenoming
• Naja nigricollis

Author contributions

Conceptualization: Dr Akindele Adeyi Prof Emuebie Okonji, and Dr Damilohun Metibemu, Methodology: Dr Akindele Adeyi, Prof Emuebie Okonji, Mr Babafemi Ajisebiola and Mr Jimoh Abideen, Formal analysis and investigation: Dr Adeyi Olubisi and Mr Jimoh Abideen; Manuscript Writing - original draft and editing: Mr Babafemi Ajisebiola, Dr Akindele Adeyi and Dr Damilohun Metibemu. All authors have read and approved the final manuscript.

Ethical approval

Not applicable.

Disclosure statement

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

Data availability statement

The data sets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors