Use of whole plant Artemisia annua L. as an antimalarial therapy

Anti-malarial drugs are primary weapons for reducing Plasmodium transmission in human populations. Successful drugs have been highly efficacious and inexpensive to synthetically manufacture. Emergence of resistant parasites reduces the lifespan of each drug that is developed and deployed. Currently, the most effective anti-malarial is artemisinin (AN), which is extracted from the leaves of Artemisia annua. Because of its poor pharmacokinetic properties and prudent efforts to curtail emergence of resistance, AN is prescribed only in combination with other anti-malarials composing an Artemisinin Combination Therapy (ACT). Low yield in the plant and the added cost of secondary anti-malarials in the ACT, make AN in the developing world a costly treatment. Here we show that dried leaves of A. annua administered orally are more effective at killing malaria parasites than a comparable dose of purified drug in a rodent malaria model (P. chabaudi). A single dose of whole plant (WP) A. annua containing 24 mg/kg AN clears 99% of parasites, where a comparable dose of pure drug has half that effect. This is consistent with findings that blood levels of AN are 40 times greater in mice receiving WP versus those given pure drug. We hypothesize that in addition to increasing bioavailability of AN, administration of WP alone may constitute a combination therapy because it contains other anti-malarial compounds that have been shown to synergize with AN. Inexpensive, efficacious, and resilient treatment for malaria based upon WP A. annua that can be grown and processed locally would be an effective addition to the global effort to reduce malaria morbidity and mortality

In vitro analyses of Artemisia extracts on Plasmodium falciparum suggest a complex antimalarial effect.

Dried-leaf Artemisia annua L. (DLA) antimalarial therapy was shown effective in prior animal and human studies, but little is known about its mechanism of action. Here IC50s and ring-stage assays (RSAs) were used to compare extracts of A. annua (DLAe) to artemisinin (ART) and its derivatives in their ability to inhibit and kill Plasmodium falciparum strains 3D7, MRA1252, MRA1240, Cam3.11 and Cam3.11rev in vitro. Strains were sorbitol and Percoll synchronized to enrich for ring-stage parasites that were treated with hot water, methanol and dichloromethane extracts of DLA, artemisinin, CoArtem™, and dihydroartemisinin. Extracts of A. afra SEN were also tested. There was a correlation between ART concentration and inhibition of parasite growth. Although at 6 hr drug incubation, the RSAs for Cam3.11rev showed DLA and ART were less effective than high dose CoArtem™, 8 and 24 hr incubations yielded equivalent antiparasitic results. For Cam3.11, drug incubation time had no effect. DLAe was more effective on resistant MRA-1240 than on the sensitive MRA-1252 strain. Because results were not as robust as observed in animal and human studies, a host interaction was suspected, so sera collected from adult and pediatric Kenyan malaria patients was used in RSA inhibition experiments and compared to sera from adults naïve to the disease. The sera from both age groups of malaria patients inhibited parasite growth ≥ 70% after treatment with DLAe and compared to malaria naïve subjects suggesting some host interaction with DLA. The discrepancy between these data and in-vivo reports suggested that DLA's effects require an interaction with the host to unlock their potential as an antimalarial therapy. Although we showed there are serum-based host effects that can kill up to 95% of parasites in vitro, it remains unclear how or if they play a role in vivo. These results further our understanding of how DLAe works against the malaria parasite in vitro

Biomass Production of Hairy Roots of Artemisia annua and Arachis hypogaea in a Scaled-Up Mist Bioreactor

Hairy roots have the potential to produce a variety of valuable small and large molecules The mist reactor is a gas phase bioreactor that has shown promise for low-cost culture of hairy roots Using a newer disposable culture bag mist reactor performance was studied with two species Artemisia annua L and Arachts hypogaea (peanut), at scales from 1 to 20 L Both species of hairy roots when grown at 1 L in the mist reactor showed growth rates that surpassed that in shake flasks From the information gleaned at 1 L, Arachzs was scaled further to 4 and then 20 L Misting duty cycle, culture medium flow rate, and timing of when flow rate was increased were varied In a mist reactor increasing the misting cycle or increasing the medium flow rate are the two alternatives for increased delivery of liquid nutrients to the root bed Longer misting cycles beyond 2 3 min were generally deemed detrimental to growth On the other hand, increasing the medium flow rate to the sonic nozzle especially during the exponential phase of root growth (weeks 2-3) was the most important factor for increasing growth rates and biomass yields in the 20 L reactors A hypogaea growth in 1 L reactors was mu = 0 173 day(-1) with biomass yield of 12 75 g DW L(-1) This exceeded that in shake flasks at mu=0 166 day(-1) and 11 10 g DW L-1 Best growth rate and biomass yield at 20L was mu=0 147 and 7 77 g DW L(-1), which was mainly achieved when medium flow rate delivery was increased The mist deposition model was further evaluated using this newer reactor design and when the apparent thickness of roots (+hairs) was taken into account, the empirical data correlated with model predictions Together these results establish the most important conditions to explore for future optimization of the mist bioreactor for culture of hairy roots Biotechnol Bioeng 2010 107 802-813 (C) 2010 Wiley Periodicals, In