ISHS Acta Horticulturae 576: International Conference on Medicinal and Aromatic Plants. Possibilities and Limitations of Medicinal and Aromatic Plant Production in the 21st Century
POST-HARVEST DRYING TREATMENT EFFECTS ON AMTIMALARIAL CONSTITUENTS OF ARTEMIASIA ANNUA L. |
| Author: | J.C. Laughlin |
| Keywords: | qinghao, annual wormwood, malaria, artemisinin (qinghaosu), artemisinic (qinghao) acid, essential oil, sun drying, shade drying, dark drying. |
| Abstract:
Two field experiments were carried out in cool temperate maritime latitudes in NW Tasmania (41ēS) 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 (35ēC) 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 sun-, shade- 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 35ēC, 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. | |
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