Metabolomic investigation of the ethnopharmacological use of Artemisia afra with NMR Spectroscopy and Multivariate Data Analysis.

Ethnopharmacological relevance: Artemisia afra has been used as an infusion to treat malaria throughout the southern parts of Africa, in much the same way as the antimalarial plant Artemisia annua in China. The antiplasmodial activity of purified components from an apolar fraction of A. afra has been shown in the past. No data on the efficacy of the tea infusion prepared from A. afra are however available. OBJECTIVE: To investigate the antiplasmodial activity of various extracts of A. afra including an ethnopharmacological prepared sample. To identify polar metabolites in A. afra and A. annua and by using multivariate data analysis investigate the metabolic differences between these species. Materials and methods: The antiplasmodial activity of A. afra and A. annua extracts were tested for activity against Plasmodiam falciparum 3D7 (chloroquine-sensitive strain) with chloroquine, quinine and artemisinin as positive controls. Hydrophilic metabolites in A. afra and A. annua were identified directly from the crude extracts through 1D- and 2D-NMR spectra. The NMR spectra were also used to differentiate between the two species using principal component analysis (PCA) for quality control purposes. RESULTS: The apolar fractions of both A. afra and A. annua showed activity against P. falciparum while activity was only found in the tea infusion of A. annua. Metabolomic studies using 1D- and 2D-NMR spectroscopy identified 24 semi-polar components in A. afra including three new phenylpropanoids for this species: caffeic acid, chlorogenic acid and 3,5-dicaffeoyl quinic acid. PCA analysis conducted on the samples yielded good separation between the polar extracts of A. afra and A. annua. CONCLUSION: These findings shows that there are no in vitro activity in the tea infusion of A. afra and lists the identified metabolites causing the metabolic differences between A. afra and A. annua for quality control purposes.