The anti-diarrhoeal properties of Breonadia salicina, Syzygium cordatum and Ozoroa sphaerocarpa when used in combination in Swazi traditional medicine.

AIM OF THE STUDY: The aim of the study was to determine in vitro activity of the bark of Ozoroa sphaerocarpa R. Fern & A. Fern (Anacardiaceae), Breonadia salicina (Vahl) Hepper & J.I.R. Wood (Rubiaceae) and Syzygium cordatum Hochst ex C Krauss (Myrtaceae) against a diarrhoea-causing pathogen, Escherichia coli; as well as the pharmacological interactions present in their combination.
MATERIALS AND METHODS: In consultation with traditional healers, the plants were collected from the wild, dried and extracted with dichloromethane:methanol (1:1). Thereafter, antimicrobial activity of the individual plants and their different combinations was tested using a common diarrhoea pathogen, Escherichia coli by employing the minimum inhibitory concentration assay.
RESULTS: Ozoroa sphaerocarpa was the most potent inhibitor of antimicrobial growth (MIC value of 1.2 mg/ml), followed by Syzygium cordatum (MIC value of 1.44 mgl/ml) and lastly Breonadia salicina (MIC value of 10.89 mg/ml). The combination between Syzygium cordatum and Ozoroa sphaerocarpa gave the strongest synergistic interaction (MIC value of 0.33 mg/ml); whilst that between Syzygium cordatum and Breonadia salicina was mildly synergistic (MIC value of 1.00 mg/ml). The triple combination (1:1:1) was also very effective in inhibiting microbial growth (MIC value of 0.44 mg/ml). The combined effect of these plants on toxicity was predominantly synergistic except for the combination of Ozoroa sphaerocarpa and Syzygium cordatum which was predominantly antagonistic (ΣFIC value of 1.48 ± 0.25). The triple combination had a favourable toxicity profile with an IC(50) value of 155.76 ± 11.86 μg/ml.
CONCLUSION: This study supports the rationale by traditional healers to use the bark of Syzygium cordatum, Breonadia salicina and Ozoroa sphaerocarpa in combination for the treatment of diarrhoea.