ABSTRACT
Rauwolfia vomitoria is a medicinal plant that has served through the ages as the mainstay in the treatment of variety of diseases such as malaria, hypertension, and cancer. Several reports of the use of this plant in both traditional and modern medicine has emerged, however little is known about its immunomodulatory effects hence, this study was carried out to determine its potential immunomodulatory and toxicological effects on Wistar rats.
The plant materials Rauvolfia vomitoria were collected from the forest in Egba community, Ikpoba Okha Local Government Area, Edo State, Nigeria. The leaf, bark and root sample were identified and authenticated in the Department of Plant Biology and Biotechnology, University of Benin. Preliminary phytochemical analysis was carried out on the different parts of the plant using aqueous and ethanol solvents. The antimicrobial activity of the various parts of Rauvolfia vomitoria were investigated by evaluating the effects of the plant extracts against the microbial isolates from Neonatal sepsis. Immunomodulatory activity of the ethanolic root extract was screened using the Delayed Type hypersensitivity and CD4 cell count in wistar rats. The possible effects associated with the administration of ethanolic root extract on the haematological parameters and toxicological effects on the liver and kidney were also studied in Wistar rats.
The phytochemical results showed that the aqueous and ethanol extracts of R. vomitoria contain alkaloids, carbohydrates, reducing sugar, tannins, steroids and phenols in all the extracts. The ethanolic root extract however gave the most activity with a zone of inhibition range of 10.50 to 20.50 mm. The cellular immunity response indicated that there was a dose dependent significant increase when compared with the control from 7.93 ± 1.08 to 11.68 ± 0.87 and 11.40 ± 0.65 at 50 mg/kg and 300 mg/kg respectively for the experimental groups. Among the hematological parameters examined, the lymphocytes count had a reduction from 89.88 ± 5.36 for control to 80.58 ± 7.15 and 75.83 ± 13.04 at 50 mg/kg and 300 mg/kg respectively. The toxicological analysis and histology showed a mild to moderate reaction of the liver and kidney of the experimental groups relative to the control. The results suggest that Rauvolfia vomitoria can be useful in treating various pathogenic diseases but however they are not potential plant immunodulators and consumption of the plant should be minimal and limited to management of a diseased condition.
