Rauvolfia grandiflora (Apocynaceae) extract interferes with staphylococcal density, enterotoxin production and antimicrobial activity

Staphylococci bacteria are involved in many human and animal infections and development of alternative antimicrobial drugs against pathogenic bacteria is of great interest to the pharmaceutical industry. This study investigated the in vitro effect of Rauvolfia grandiflora methanol extract (root bark fraction) (RGE) on the density of ATCC strains of Staphylococcus aureus and Staphylococcus epidermidis, and a clinical enterotoxin-producer, S. aureus bovine strain. The alkaloid, isoreserpiline, obtained from dichloromethane extract of R. grandiflora was ineffective against the strains tested. After incubation of staphylococci strains in the presence of 1.2 mg.mL-1 RGE, a significant inhibition of cell growth was observed using both spectrophotometry and ELISA assays. Twelve drugs were evaluated for their antimicrobial effects on culture RGE-treated cells using the disk diffusion method. Penicillin resistant strains became sensitive to the drug after RGE treatment. Furthermore, enterotoxin production by RGE-treated S. aureus was evaluated using a standardized ELISA method. Although staphylococcal LSA 88 bovine strain cells remained viable after exposure to the extract, enterotoxin production was precluded in 20 percent after RGE treatment. Significant interference in staphylococci cell density, drug sensitivity and enterotoxin secretion was observed after treatment. The study highlights the necessity to find new methods of disease prevention and new antibiotic therapies against staphylococcal infections.

Sub-chronic Toxicity Studies of the Aqueous Leaf Extract of Rauvolfia Vomitoria (Afzel)

The cumulative effects of the aqueous leaf extracts of Rauvolfia vomitoria on body tissues was studied. Six groups of male rats consisting of 5 rats per group were given doses of the leaf extract ranging from 0.03g kg-1-1.2g kg-1 to drink at will from their drinking bottles for 42 days. During the period of the study; weights of the animals were monitored weekly with their gross appearances. At the end of the 42nd day; the rats were killed by cervical dislocation. Post-mortem of each of the animals was performed. The liver; kidney; stomach; heart and lungs were excised. The organs from the groups given plant extract were compared with those of the controls. Body weight of both the treated and the control animals rose progressively as the period increased. The pathological features like oedema and hypertrophy noticed in the tissues are considered to be of no serious consequence as they disappeared after cessation of therapy. There abnormalities may possibly not develop with R. vomitoria used for a short period. It is therefore; considered to be non-hazardous