Post-Harvest Drying Treatment Effects on Amtimalarial Constituents of Artemiasia Annua L.

Abstract

Two field experiments were carried out in cool temperate maritime latitudes in NW Tasmania (41ºS) to assess whether wilting and drying Artemisia annua plants in the field after harvest had any detrimental effects on artemisinin (the source of important antimalarial drugs) or its precursor artemisinic acid. A third field experiment studied the effect of steam distillation of A. annua for its essential oil, prior to oven drying, on artemisinin and artemisinic acid. In the first two experiments whole plants were cut off at the base and left in situ for 1, 3 and 7 days (Experiment 1) and for 7, 14 and 21 days (Experiment 2). Experiment 2 included two additional treatments: (i) shade drying whole plants under ambient conditions in the field for 21 days and (ii) drying leaves, detached at harvest, for 21 days under ambient conditions inside in the dark. The effects of all of these treatments were compared with oven drying (35ºC) leaves which had been detached immediately after harvest. Field drying for 1, 3 or 7 days had no adverse effect on either artemisinin or artemisinic acid in Experiment 1 and all leaf concentrations were similar to oven drying. Field drying for 7 days in Experiment 2 also gave artemisinin and artemisinic acid levels similar to oven drying. However there was a trend for sunshade de-and dark drying for 21 days to give higher artemisinin than oven drying although artemisinic acid was unaffected. Distillation of A. annua plants for oil extraction, prior to oven drying at 35ºC, resulted in nil to negligible leaf concentration of artemisinin but artemisinic acid was unaffected. Field drying may be a way of reducing the cost of antimalarial drugs and the dual production of oil and artemisinic acid is a possibility.

Cultivation and genetics ofArtemisia annuaL. for increased production of the antimalarial artemisinin

“…In a similar field study in Tasmania, Australia, whole plants of a Chinese strain of A. annua were dried under full sun for 21 days. Leaf artemisinin concentration in this low-level strain (ca 0.1%) was increased by ca 100% (Laughlin, 2002). It may be important to assess to what extent these results from continental and temperate environments would apply to sub-Saharan Africa and other tropical regions where potential leaf loss and fungal diseases may be more likely due to the hot and humid weather.…”

“…Essential oils are extracted by steam distillation at temperatures which destroy most of the artemisinin in the tissue, as reported by Magalhães (1996) and Laughlin (2002). It is important to note that if artemisinin is extracted in water below the boiling point, up to 75% of the artemisinin will be present in the aqueous extract (J. F. S. Ferreira, unpublished data).…”

Stimulation of crop productivity, photosynthesis and artemisinin production inArtemisia annuaL. by triacontanol and gibberellic acid application

“…It has been introduced into experimental cultivation in India (Singh et al 1986), Thailand, Brazil, Australia, Madagascar and in Europe into The Netherlands, Switzerland and France as far north as Finland (Laughlin 2002). Being the world's most severe parasitic infection, malaria causes more than 1 million deaths and 500 million cases annually.…”

An ecological implication of glandular trichome-sequestered artemisinin: as a sink of biotic/abiotic stress-triggered singlet oxygen

“…In view of artemisinin production, post-harvest drying of A. annua under sun, shade or dark with ambient temperature increases artemisinin yield (Laughlin 2002). Lead acetate and NaCl promote artemisinin accumulation (Quareshi et al 2005).…”

“…It was also found that an oligosaccharide elicitor derived from Colletotrichum sp. triggers the signal transduction involving rapid Ca 2+ accumulation, plasma membrane NAD(P)H oxidase activation, and ROS release (Wang et al 2001;2002).…”