Abstract
The use of ultrasound as a potential technique for improving the extraction efficiency of Artemisinin, an anti-malarial and cytotoxic drug, from Artemisia annua has been explored in this research project.This has been achieved through conducting ultrasonic extractions, in comparison to conventional steeping, and altering parameters, including: extraction time, temperature, ultrasonic frequency, Artemisia annua country of origin, extraction solvent and the age of leaf material. Samples of the resultant extracts were tested using Thin Layer Chromatography and High Performance Liquid Chromatography techniques for the quantity of extracted artemisinin. The proportion of artemisinin in extracts was also calculated to allow the concentration to be considered in relation to the presence of co-extracted impurities.
Ultrasound was most effective at enhancing the extraction of artemisinin in Ugandan A. annua, hexane extractions at the low temperature of 25°C. Extraction enhancement seemed to be dependent on the ultrasonic frequency; as with lower frequencies there were increased artemisinin concentrations; but this also seemed to lead to an increase in impurities. Therefore the extracts containing the highest proportion of artemisinin were achieved using high frequency ultrasound. Preliminary studies, using a scanning electron microscope, suggested that this was due to the low frequencies causing high destruction of leaf material; whereas the high frequencies potentially target the rupturing of trichome glands which house the artemisinin.
Due to all ultrasonic frequencies enhancing the concentration of artemisinin within low temperature hexane extractions (in comparison to steeping alone), but with differing proportions of artemisinin, their cytotoxic activity against leukaemia (HL-60) cells was tested using MTT assays. All extracts showed cytotoxic activity but the high frequency extracts were shown to be the most potent; which seems to correlate with the proportion of artemisinin.
| Date of Award | 2013 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Larysa Paniwnyk (Supervisor), Timothy Mason (Supervisor) & Mircea Vinatoru (Supervisor) |