Studies on the Antivenom Activities of the Aqueous Extracts of Paullinia Pinnata and Detarium Microcarpum Against Echis Carinatus (Carpet Viper) Venom

Abstract

In rural savannah areas of Nigeria, Echics ocellatus (Carpet viper) is responsible for high incidence of snakebite morbidity and mortality. The snakebites are commonly treated with plant extracts in form of traditional medicine. The antivenom activity of Paullinia pinnata Linn and Detarium microcarpum Guill and Perr, popular herbs used in the treatment of Echis ocellatus bites are of great interest and were investigated in vivo and in vitro against the venom (2mg/kg) of Echis carniatus. The extracts were prepared by cold and hot extraction in water. The LD50 and minimum lethal dose (MLD) of the venom were first determined in mice to be 1.5mg/kg and 2mg/kg, respectively. The acute toxicity (LD50) testing of the extracts indicated LD50 to be 600 mg/kg (i.p) and 1200 mg/kg (p.o) for Paullinia pinnata, while 800 mg/kg (i.p) and 1400 mg/kg (p.o) for Detarium microcarpum. The extract of Detarium microcarpum (600mg/kg) reduced mortality significantly (p < 0.05) in mice, whereas the extract of Paullinia pinnata (400mg/kg) presented a weak antivenom activity. The effective dose (ED50) of the extracts was estimated as 300mg/kg (i.p) and above 400mg/kg (p.o) for Paullinia pinnata and 50mg/kg (i.p) and 200mg/kg (p.o) for Detarium microcarpum in venom pretreated mice. In animals treated with 60min pre-incubated mixtures of extracts/venom, ED50 of 100mg/kg and less than 50mg/kg was established for Paullinia pinnata and Detarium microcarpum, respectively. The ED50 of Paullinia pinnata in extract pretreated mice was more than 400mg/kg (i.p) and 400mg/kg (i.p), while Detarium microcarpum indicated 100mg/kg (i.p) and 400mg/kg (p.o) as ED50. The extracts of Paullinia pinnata and Detarium microcarpum inhibited all test bacteria (Staphylococcus aureus, Pseudomonas aeruginosa and Proteus mirabilis) at various concentrations, with the extract of Paullinia pinnata found more active having lower MIC and MBC, and broader spectrum of activity. It also significantly (p <0.05) restored blood clotting time and bleeding time in rats. The same extract reversed the venom-induced increase in capillary permeability in rabbits. The extract also restored the venom-induced abnormal WBC, PCV, and platelet values to normal. The extract of Detarium microcarpum, however, produced significant (p < 0.05) inhibition of acetic acid-induced abdominal constrictions in mice, yeast-induced rectal temperature in mice, and albumin-induced inflammation in rats. The extracts of Paullinia pinnata produced an anti-histamine activity on guinea pig ileum, relaxation of the rabbit jejunum, and an increase in contraction of rat phrenic nerve hemi-diaphragm, while the extract of Detarium microcarpum caused relaxation on rabbit jejunum and increase in contraction on rat phrenic nerve hemi-diaphragm muscle. Preliminary phytochemical analysis of the extracts indicates the presence of carbohydrates, saponins, steroids and tannins in Paullinia pinnata root bark, while Detarium microcarpum leaf contains anthraquinones, flavonoids, saponins, steroids, and tannins. The trace metal analysis of the extracts also indicates the presence of Zn, Ca and Fe in Detarium microcarpum, while Paullinia pinnata contains Zn, Ca, Fe and Pb. These results therefore suggest that Paullinia pinnata root bark and Detarium microcarpum leaves contain biologically active principles, which have potentials for the treatment of carpet viper bite poisoning. Since the extracts could protect animals from death and other deleterious effects of the venom, the study has supported the use of the medicinal plants by traditional healers in the treatment of snakebite.