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Title: Cytotoxicity of ethanolic extracts of Artemisia annua to Molt-4 human leukemia cells

Author
item SINGH, NARENDRA - University Of Washington
item Ferreira, Jorge
item PARK, JI SUN - University Of Washington
item LAI, HENRY - University Of Washington

Submitted to: Planta Medica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2011
Publication Date: 6/6/2011
Citation: Singh, N.P., Ferreira, J.F., Park, J., Lai, H. 2011. Cytotoxicity of ethanolic extracts of Artemisia annua to Molt-4 human leukemia cells. Planta Medica. 77:1788-1793.

Interpretive Summary: Cancer is the second cause of death in the United States, and current treatment is expensive and kills also healthy cells. Affordable alternatives that kill only cancer cells are needed. Artemisinin, a compound extracted from the annual wormwood plant has shown to be a potential anticancer compound, but plant extracts containing artemisinin and other potential anticancer compounds have never been evaluated. This work showed that hydro-alcoholic extracts made from a Brazilian and a Chinese annual wormwood cultivar contained artemisinin in high concentrations and also had high antioxidant activity as assayed from the leaves of each plant. The Chinese extract was more concentrated in artemisinin than the Brazilian extract, but the latter had a higher antioxidant and anticancer activity than the Chinese extract. The Brazilian annual wormwood extract had a higher anticancer activity against human leukemia cells than dihydroartemisinin, a semi-natural pharmaceutical drug made from artemisinin and previous used in anticancer tests. The Brazilian extract also had a much higher toxicity towards human leukemia cells than against human healthy cells. These results suggest that artemisinin is not the only anticancer compound produced by the annual wormwood plant and that the high antioxidant capacity of the plant, accounted for by compounds called flavonoids – among others, might play an important role in potentiating the anticancer activity of artemisinin. Flavonoids, by themselves, have been previously linked to antioxidant, anticancer and anti-parasitic activity. The present work suggests that flavonoids can be used simultaneously with artemisinin against cancer and that a simple, and more affordable, hydro-alcoholic extract can be as, or more, effective than the purified semi-natural drug dihydroartemisinin. The low toxicity of artemisinin and flavonoids present in the annual wormwood traditional Chinese tea – consumed for hundreds of years to treat malaria - and the encouraging results obtained against leukemia cells strongly suggest that the ethanolic extracts of annual wormwood should undergo animal testing to verify their anticancer activity and low toxicity to normal cells.

Technical Abstract: Cancer is the second cause of death in the United States, and current treatment is expensive and kills also healthy cells. Affordable alternatives that kill only cancer cells are needed. Artemisinin, extracted from the Artemisia annua, has potent anticancer activity and low toxicity to normal cells. This work evaluated the citoxicity of ethanolic extracts of A. annua leaves from Brazilian and Chinese origins to Molt-4 human leukemia cells and compared their activities to dihydroartemisinin (DHA). Cytotoxicity of DHA and of the extracts was assessed in Molt-4 cells and in normal human leukocytes after 24, 48 and 72 hr of incubation. Results show that the Brazilian A. annua ethanolic extract was significantly more toxic toward Molt-4 cells than both DHA and the Chinese A. annua ethanolic extract at all time points. Both Brazilian and Chinese A. annua extracts were somewhat toxic to leukocytes. However, the Brazilian A. annua ethanolic extract was significantly more effective in killing cancer cells than normal cells, in comparison with DHA. Brazilian and Chinese A. annua leaf extracts, analyzed by HPLC-UV, contained 1.6 % and 2.7 % (g/100 g) artemisinin, respectively. However, the antioxidant activity of the Brazilian A. annua extract surpassed that of the Chinese A. annua extract (2,535 vs. 1,960 µmole trolox equivalents/g) indicating a higher content of antioxidant flavonoids. The higher anti-cancer cell and antioxidant activities of the Brazilian A. annua ethanolic extract suggest that flavonoids increase the in vitro anti-cancer activity of the extracts. This possible synergistic effect of A. annua flavonoids and artemisinin would be a major asset to the fight against cancer supporting the idea that these extracts should be tested in vivo.