Background: Dodonaea angustifolia is used in Ethiopian traditional medicine to treat malaria.
The objective of this work was to conduct bioassay guided fractionation of the leaves of D. angustifolia
using Plasmodium berghei infected mice.
Method: The antiplasmodial activity of the extracts and pure compounds was evaluated using the standard
Peter’s four-day suppressive method. The structures of isolated compounds were elucidated using
chemical and spectroscopic methods.
Results: In this study, the ethyl acetate soluble portion of the 80% aqueous MeOH extract of the leaves
significantly suppressed parasitaemia in Plasmodium berghei infected mice (80.28% at 150 mg/kg).
Three active compounds which exhibited significant percent suppression of parasitaemia by 81% at 40
mg/kg, 80% at 50 mg/kg and 70% at 40 mg/kg, respectively were identified. These are the flavanone
pinocembrin (1), the flavanol santin (2) and the clerodane diterpene 2-hydroxy-15,16-epoxyceloda-
3,13(16),14-trien-18-oic acid (3). Under similar conditions, chloroquine suppressed parasitaemia by
100% at 25 mg/kg. Chemical study of the ethanol extract of the leaves yielded 5,7,4'-trihydroxy-3,6-
dimethoxyflavone (4), ent-16-hydroxy-labdan-3,8-dihydroxy,13(14)-en-15,16-olide (5) and 5,6,7-
trihydroxy-3,4'-dimethoxyflavone (6). Compound 6 has not been reported before as a natural product.
Conclusion: From the leaves of D. angustifolia, three compounds with significant antiplasmodial activities
were isolated and characterized, with pinocembrin as the most active compound.