Africa is blessed with abundance of natural resources including both fauna and flora. Nigeria has a lot of medicinal plants that are not yet exploited and some are traditionally known to be used in the prevention and or treatment of snake bites. Screening some of these plants scientifically will prove the traditional claims by the snake charmers and herbalists may lead to the production of single polyvalent antidote for the prevention and treatment of snake bites. The objectives of the study were to: Select, collect and identify plants with potential antivenom properties and five species of poisonous snakes; Determine the phytochemical constituents of the three plants; Carry out acute toxicological studies of the selected plant extracts; Determine the LD50 of venoms of different snake species and the plant extracts; Determine the antivenom potentials of the different fractions of the plant extracts; Carry out interactive studies with various plant extract fractions on the venom in vivo; Determine the protective effects of three plant extracts against the haemorrhagic effect of snake venoms in rats; Carry out studies on the effects of various plant extracts in neutralizing snake venoms on 1kb plasmid DNA migration on agarose gel electrophoresis. Results of the phytochemical analysis of the crude extracts of the three plants (Olax manni, Urginea altissima and Xeromphis nilotica) showed the presence of carbohydrates, glycosides, steroids/triterpens, cardiac glycosides, saponins, glycosides and alkaloids. In addition, Extract of Urginea altissima contained free anthracenes. However, the ferric chloride test failed to detect glycosides in all the extracts, while Bontrager‘s test and modified Bontrager‘s test did not detect free anthracenes and combined anthracenes respectively in the extracts of Olax manni and Xeromphis nilotica. Similarly, Mayer‘s, Dragendoff‘s and Wagner‘s tests failed to detect alkaloids in Olax manni, and Xeromphis nilotica. The in vivo studies revealed that the aqueous fractions of the 3 plants (A4, B4 and C4) have the highest activity against the snake venoms when administered 30 minutes before, after and when venom and extracts were administered, which showed that the three plants have both curative, prophylactic and neutralization effects against snake venom. Plant B (Urginea altissima) had the highest (100 %) activity with all the rats treated with its aqueous extract surviving envenomation. The prophylactic method of inoculation was found to be the most effective. Toxicity studies showed that the LD50 of the venom of N. haje, N. katiensis, N. nigricollis, E. ocellatus and B. arietans in Wistar rats were found to be 0.22, 0.55, 0.87, 1.24 and 1.80 mg/kg, respectively. Bitis arietans has the highest LD50 followed by Echis ocellatus while Naja haje was having the lowest LD50 follwed by Naja katiensis, found to have the lowest LD50 Toxicity. Anticoagulant activity of the snake venom was measured by the time taken for blood to clot. The clotting time for Naja nigricollis, Naja haje and Naja katiensis were found to be 132, 128 and 115 minutes, respectively. However, the venoms of Bitis arietans and Echis ocellatus did not clot during the period of the experiment. Studies on haemorrhagic effect of venoms in rats indicated that aqueous fraction of Urginia altissima showed antivenom activity against the venoms of Naja nigricollis, Naja haje, Naja Katiensis, Bitis arietans and Echis ocellatus there were no patches observed. The aqueous extract fraction of Olax manni showed protective effect against venoms of Naja nigricollis, Naja haje, Naja katiensis, Bitis arietans and Echis ocellatus while aqueous fraction of Xeromphis nilotica also had protective effect against the venom of Naja nigricollis, Naja haje, Naja katiensis and Bitis arietans. However, there were some patches of blood in the skin of rats inoculated with venom of Echis ocellatus. The results established the aqueous fraction of the three plants the neutralization effects of venom. The interactive study of the aqueous fraction of Urgines altissima, venom and the plasmid DNA measured by migration on agarose gelelectrophoresis showed that aqueous fractions had high antivenom activity against the venoms of Naja nigricollis, Naja haje, Naja katiensis, Bitis arietans and Echis ocellatus.1 kb DNA ladder and the plasmid DNA migrated very well on agarose gel electrophoresis. The mixture of plasmid DNA with separate venom of the snakes, showed no migration of the DNA on agarose gel electrophoresis. The plasmid DNA incubated with the aqueous fraction of plant B showed clear migration of the DNA on agarose gel electrophoresis. In conclusion the extract of three plants demonstrated curative, prophylactic and detoxifying effects against the venoms of the five venomous species of snakes.
EVALUATION OF THE EFFICACY OF THREE PLANT EXTRACTS AGAINST VENOMS OF FIVE SNAKE SPECIES IN NORTHERN NIGERIA