An extract of the medicinal plant Artemisia annua modulates production of inflammatory markers in activated neutrophils

Abstract

Purpose

To investigate the ability of a commercial extract from the medicinal plant Artemisia annua to modulate production of the cytokine, tumor necrosis factor-alpha (TNF-α), and the cyclooxygenase (COX) inflammatory marker, prostaglandin E₂ (PGE₂) in activated neutrophils.

Methods

Neutrophils were harvested from rat whole blood and cultured in the presence of plant extract or control samples. Neutrophils, except unactivated control cells, were activated with 10 μg/mL lipopolysaccharide (LPS). The cells were cultured with a range of different concentrations of the A. annua extracts (400–1 μg/mL) and artemisinin (200 and 100 μg/mL) and the supernatants were then tested by enzyme-linked immunosorbent assay (ELISA) for the concentrations of TNF-α and PGE₂. Each sample was assayed in triplicate. Positive controls with an inhibitor were assayed in triplicate: chloroquine 2.58 and 5.16 μg/mL for TNF-α, and ibuprofen 400 μg/mL for PGE₂. An unsupplemented group was also assessed in triplicate as a baseline control.

Results

Neutrophils were stimulated to an inflammatory state by the addition of LPS. A. annua extract significantly inhibited TNF-α production by activated neutrophils in a dose-dependent manner. There was complete inhibition by the A. annua extract at 200, 100, and 50 μg/mL (all P≤0.0003). At A. annua extract concentrations of 25, 10, and 5 μg/mL, TNF-α production was inhibited by 89% (P<0.0001), 54% (P=0.0002), and 38% (P=0.0014), respectively. A. annua 1 μg/mL did not significantly inhibit TNF-α production (8.8%; P>0.05). Concentrations of 400, 200, and 100 μg/mL A. annua extract significantly inhibited PGE₂ production by 87% (P=0.0128), 91% (P=0.0017), and 93% (P=0.0114), respectively.

Conclusion

An extract of A. annua was shown to be a potent inhibitor of TNF-α and a strong inhibitor of PGE₂ production in activated neutrophils at the concentrations tested. Further studies are warranted with this promising plant extract.

Keywords:

• in vitro
• TNF-α
• COX-2
• PGE₂
• artemisinin
• Arthrem

Acknowledgments

The authors gratefully acknowledge the financial support of a Callaghan Innovation R&D Project Grant.

Disclosure

This study was funded by Promisia Integrative Ltd. Sheena Hunt is an employee of Promisia Integrative Ltd. The other authors report no conflicts of interest in this work.

Author contributions

Sheena Hunt designed the study and drafted the manuscript. Mayumi Yoshida and Catherine EJ Davis conducted the experiments and analyzed the data. Nicholas S Greenhill supervised the study and analyzed the data. Paul F Davis designed the study, analyzed the data, and helped draft the manuscript. All authors revised the manuscript for important intellectual content and read and approved the final manuscript.