Ethnopharmacology in overdrive: the remarkable anti-HIV activity of Artemisia annua

Abstract

Ethnopharmacological relevance: Artemisia annua contains the well-known antimalarial compound artemisinin, which forms the backbone of the global malaria treatment regime. In African countries a tea infusion prepared from Artemisia annua has been used for the treatment of malaria only for the past 10-20 years. Several informal claims in Africa exist that the Artemisia annua tea infusions are also able to inhibit HIV. Since HIV is a relatively newly emerged disease, the claims, if substantiated, could provide a very good example of "ethnopharmacology in overdrive". The objective of this study was to provide quantitative scientific evidence that the Artemisia annua tea infusion exhibits anti-HIV activity through in vitro studies. A second objective was to determine if artemisinin plays a direct or indirect (synergistic) role in any observed activity. This was done by the inclusion of a chemically closely related species, Artemisia afra, known not to contain any artemisinin in our studies.

Materials and methods: Validated cellular systems were used to test Artemisia annua tea samples for anti-HIV activity. Two independent tests with different formats (an infection format and a co-cultivation format) were used. Samples were also tested for cellular toxicity against the human cells used in the assays.

Results: The Artemisia annua tea infusion was found to be highly active with IC(50) values as low as 2.0 μg/mL. Moreover we found that artemisinin was inactive at 25 μg/mL and that a chemically related species Artemisia afra (not containing artemisinin) showed a similar level of activity. This indicates that the role of artemisinin, directly or indirectly (synergism), in the observed activity is rather limited. Additionally, no cellular toxicity was seen for the tea infusion at the highest concentrations tested.

Conclusion: This study provides the first in vitro evidence of anti-HIV activity of the Artemisia annua tea infusion. We also report for the first time on the anti-HIV activity of Artemisia afra although this was not an objective of this study. These results open the way to identify new active pharmaceutical ingredients in Artemisia annua and thereby potentially reduce the cost for the production of the important antimalarial compound artemisinin.