Chemical composition and biological potential of the volatile and non-volatile constituents of tarchonanthus camphoratus and tarchonanthus trilobus var galpinni of KwaZulu–Natal province.
| dc.contributor.advisor | Oyedeji, O.A. | |
| dc.contributor.advisor | Opoku, A.R. | |
| dc.contributor.advisor | Lewu, F.B. | |
| dc.contributor.author | Nanyonga, Sarah Kiwanuka | |
| dc.date.accessioned | 2014-08-13T13:17:48Z | |
| dc.date.available | 2014-08-13T13:17:48Z | |
| dc.date.issued | 2013 | |
| dc.description | A thesis submitted to the Department of Chemistry, in the Faculty of Science and Agriculture in fulfilment of the requirements for the degree of Doctor of Philosophy, at the University of Zululand, South Africa, 2013. | en_US |
| dc.description.abstract | The chemical composition and the biological activities of the volatile extracts (essential oils) and non-volatile (solvent extracts) of the aerial parts Tarchonanthus camphoratus and Tarchonanthus trilobus var galpinni collected from Sangoyana and Ubombo respectively, in the Kwa-Zulu Natal province were investigated in this study. The essential oils were separately extracted from the fresh leaves, dry leaves and dry stem by hydro-distillation and their chemical constituents determined by Gas chromatography/mass spectrometry (GC/MS). The essential oils investigated were of the dry leaf of T. camphoratus harvested in 2009 and of the fresh leaf, dry leaf and dry stem of both T. camphoratus leaf and T. trilobus var galpinni harvested in 2010 and 2011. The compounds present in all the essential oils were categorised as monoterpene hydrocarbons, sesquiterpene hydrocarbons, oxygenated monoterpenes, oxygenated sesquiterpenes and others but they differed in the type and percentage composition. Sesquiterpene hydrocarbons dominated all the essential oils with β–caryophyllene and allo-aromadendrene present in all the essential oils either as minor or major compounds. The oxygenated monoterpene 1,8-cineole, which is suspected to be responsible for the camphor smell of T. camphoratus, was present in all the essential oils of the leaves and stem of T. camphoratus. δ-Cadinene, a sesquiterpene hydrocarbon, featured in all the essential oils except of the fresh and dry leaf of T. camphoratus harvested in 2011. The chemical constituents in the non volatile extracts were determined by Pyrolysis-Gas chromatography/mass spectrometry (Py-GC/MS). A variety of compounds categorised as hydrocarbons, tetraterpenes, triterpenoids, phenols, fatty acids, fatty alcohols, steroids and sterols among others were identified in the extracts. Phenols were identified in the aqueous, methanol, dichloromethane leaf extracts and the methanol bark extract of T. camphoratus and in the dichloromethane leaf and ethyl acetate leaf extracts of T. trilobus var galpinni. Steroids were identified in the bark extracts of T. camphoratus and in the methanol leaf extract of T. trilobus var galpinni. Hydrocarbons were identified in all the solvent/non volatile extracts but were more dominant in the dichloromethane bark extracts of both T. camphoratus and T. trilobus var galpinni. Triterpenoids were identified in the dichloromethane leaf extracts, ethyl acetate bark extracts of both species, in the methanol leaf of T. trilobus var galpinni and in the methanol bark extract of T. camphoratus. The preliminary phytochemical screening of the extracts also revealed the presence of phenols, flavonoids, saponins and tannins in some of the extracts. The volatile and non volatile extracts were screened for their antibacterial activity, antioxidant activity and cytotoxic activities and the volatile extracts were further screened for their insecticidal activities. The extracts were screened for antibacterial activity against 4 Gram positive and 5 Gram negative bacteria. The zones of inhibition of the fresh leaves, dry leaves and dry stem essential oils of T. camphoratus ranged from 7.3 – 14.0, 7.3 – 16.7 and 13.5 – 20.4 mm respectively and the zones of inhibition of the fresh leaf oil of T. trilobus var galpinni ranged from 8.2 – 21.8 mm. The volatile extracts exhibited higher percent inhibition than the non volatile extracts and the dry stem essential oil of T. camphoratus showed the highest antibacterial activity of all the extracts. The non volatile extracts exhibited significant antioxidant potential when tested by DPPH and ABTS•+ radical scavenging assays plus reducing power assay but showed poor nitric oxide inhibition and iron chelating ability. The volatile extracts generally showed poor antioxidant activity in all the antioxidant assays. The essential oils of both the dry leaf of T. camphoratus and fresh leaf of T. trilobus var galpinni showed the highest larval mortality of 100% which was observed at a concentration of 300 ppm after 24h whereas the lowest mortality after 24h was 20% at 25 ppm for T. camphoratus and 20% at 50 ppm for T. trilobus var galpinni. Insecticidal activity of the volatile extracts against stored product pests, S. zeamais and S. oryzae revealed a lack of contact and fumigation toxicity by essential oils of both plant species. The essential oil of the dry leaf of T. camphoratus, however, showed repellent activity of over 50% after 24h at all the concentrations used on both S. zeamais and S. oryzae. Cytotoxic investigation of the volatile and non volatile extracts revealed that the extracts generally had low toxicity. This study is the first to provide the chemical profiles and biological activities of the volatile and non volatile extracts of T. camphoratus and T. trilobus var galpinni from Kwa-Zulu Natal. The volatile extracts could be considered as potential alternatives, whether alone or in combination, to synthetic antibiotics, larvicides and repellents. The non volatile extracts on the other hand, could be potential sources of antioxidants that could have great importance as therapeutic agents. | en_US |
| dc.identifier.uri | https://hdl.handle.net/10530/1355 | |
| dc.language.iso | en | en_US |
| dc.publisher | University of Zululand | en_US |
| dc.subject | Essential oils | en_US |
| dc.title | Chemical composition and biological potential of the volatile and non-volatile constituents of tarchonanthus camphoratus and tarchonanthus trilobus var galpinni of KwaZulu–Natal province. | en_US |
| dc.type | Thesis | en_US |