Lippia javanica is an erect, small woody shrub that grows up to two metres in height, popularly known as “fever tea” or “koorsbossie”. It is distributed throughout southern Africa covering almost the entire country of Swaziland and large parts of South Africa. Its uses range from that of caffeine free tea with fever and pain-relieving activities to treatment of microbial infections such as coughs, colds and other bronchial ailments as well as the basic symptoms of HIV and AIDS. Topical uses also include disinfection and treatment of skin disorders such as dermatitis and dry skin, and even for the treatment of lice and scabies. Furthermore, it is used in combination with Artemisia afra as a remedy against malaria and as a prophylactic against dysentery and diarrhoea. In view of the traditional medicinal importance of L. javanica, it was surprising that not much is known on the polar fraction of this plant. This work was done to explore the presence of the polar compounds of L. javanica which may contribute to the plants’ medicinal properties. The chemical screening was conducted using both the non-polar and polar extracts of the aerial parts of L. javanica collected from various localities in South Africa and Swaziland. The screening involved extraction of the aerial parts of the plant in solvents of different polarities after which TLC showed the presence of essential oils, phenolic glycosides, amino acids, diterpenoids, triterpenoids and other phenolic compounds which may include flavonoids. The chemical variation was further investigated by means of chromatographic techniques such as HPLC and GC/MS. The essential oils of L. javanica demonstrated a dramatic variation both in quality and in quantity within and between natural plant populations. The variation was found to be random and it was not correlated to the geographical distribution of this plant. The polar extracts also showed variation in the chemical compounds, v with clear differences observed between Swaziland and South African populations. Even among the amino acids a considerable variation was observed on a geographical level. Although only the aerial parts of the plants were used in each case, the observed variation could be due to the different developmental stages of the plants and the different harvesting times. We have also established that there are different compounds present in L. rehmannii (toxic Lippia species) and L. javanica which are similar to each other in appearance and they grow in the same regions and similar environments. The results demonstrated the importance of performing chemical variation studies before using these plants and for quality control purposes for marketed products. The extracts of L. javanica were subjected to the isolation of compounds and structural elucidation. Two phenylethanoid glycosides, verbascoside β-[(3,4- dihydroxyphenyl)-ethyl]-(3′-O-α-L-rhamnopyranosyl)-(4′-O-caffeoyl)-β-Dglucopyranoside and isoverbascoside β-[(3,4-dihydroxyphenyl)-ethyl]-(3′-O-α-Lrhamnopyranosyl)-( 6′-O-caffeoyl)-β-D-glucopyranoside, previously unknown in L. javanica were isolated. The structures were established by extensive spectroscopic investigation (IR, UV, FAB-MS, 1D- and 2D-NMR). The discovery of these compounds gave the most important new insight in this study and they are known to possess antioxidant activities1. This activity is still to be investigated in L. javanica. / Mrs. D. K. Olivier Dr. R. W. M. Krause
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:2191 |
| Date | 23 May 2008 |
| Creators | Dlamini, Thobile Prudence |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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