4 - Artemisia afra

Abstract

Artemisia afra Jacq. ex Willd. (Asteraceae), also known as ‘African wormwood’, is a multi-stemmed and aromatic shrub with a height of approximately 2m. The plant has a wide distribution range in South Africa. The roots, stems and leaves of A. afra are used in various forms, such as infusions, body washes, lotions, smoke and snuff, to treat colic, headaches, earache, intestinal worms, stomach pain and malaria. In vitro and in vivo biological properties of the plant including antimicrobial, anti-inflammatory, anti-oxidant and antiparasitic activities have been documented. The volatile and non-volatile fractions of the plant have been explored and several compounds isolated and characterised. A quality control protocol for A. afra based on the chromatographic profiling of the non-volatile and volatile fractions is herein documented. Using various methods such as semi-automated high-performance thin-layer chromatography (HPTLC), ultra-performance liquid chromatography coupled to mass spectrometry and photodiode array detection (UPLC-MS-PDA), and gas chromatography coupled to mass spectrometry and flame ionisation detection (GC-MS-FID), the chemical profiles of six samples of A. afra were established. The aerial parts were harvested and divided into two. The first portion was extracted with methanol to obtain the non-volatile fraction, while the second was subjected to hydrodistillation to obtain the essential oil (volatile fraction). The non-volatile fractions were analysed using HPTLC and UPLC-MS-PDA, while the essential oils were profiled using HPTLC and GC-MS-FID. The HPTLC profiles of the methanol extracts viewed under 366nm radiation after derivatisation using natural product reagent, revealed the presence of rutin, acacetin, scopoletin and scopolin in all the samples. The presence of these marker compounds was confirmed by UPLC-MS-PDA. The HPTLC plate of the essential oils viewed under white light, followed by derivatisation with anisaldehyde, revealed the presence of several compounds in the oils. Santolina alcohol, thujone and camphor were identified in the oils using GC-MS-FID analysis.