- Title
- Isolation, characterisation and biological evaluation of Tithonia diversifolia and Tephrosia vogelii as sources of Anti-oxidant and Pesticide
- Creator
- Kerebba, Nasifu https://orcid.org/0000-0003-3700-3937
- Subject
- Tephrosia vogelii
- Subject
- Tephrosia
- Subject
- Pesticides
- Date Issued
- 2022-08
- Date
- 2022-08
- Type
- Doctoral theses
- Type
- text
- Identifier
- http://hdl.handle.net/10353/27821
- Identifier
- vital:69943
- Description
- This study aimed at evaluating chemically the pesticidal and antioxidant activities of Tithonia diversifolia Hemsland Tephrosia vogelii Hook f. In the study, the composition of essential oils and non-volatile substances was evaluated by modern analytical tools. The essential oils were characterised using Gas chromatography GC mass spectrometry mass spectrometry GC MS MS, GC and multivariate techniques. While phenolic compounds of T. diversifolia were comprehensively characterised using Ultra high performance liquid-phase chromatography coupled to a tandem mass spectrometer with electrospray ionisation UHPLC ESI MS MS. Both the essential oils and non-volatile components of the plant materials were evaluated for repellency, fumigant toxicity, contact toxicity and antifeedant potential in either a choice or no choice experiments. The non-volatile substances were evaluated for antioxidant properties. Using activity-guided isolation, three known compounds, a one pimarane diterpene type compound; sandaracopimaradiene-1α,9α-diol, a sesquiterpene lactone; deacetylviguiestenin and a caffeic acid derivative; 3 4 O caffeoyloxy methyl 2-methyloxirane-2-carboxylic acid were obtained from T. diversifolia. The compounds were characterised by spectral methods; 1D and 2D nuclear magnetic resonance NMR, Fourier transform Infra-red spectroscopy FTIR and mass spectrometry MS. Characterisation of essential oils revealed three chemotypes that were found to grow at different places of eastern Uganda. Based on the profiles of the compounds of the farnesene family, results showed that farnesol was a major constituent in the oil of chemotype 1 while springene compounds β-springene and α-springene and the β-farnesene were widely expressed in chemotype 2. The third chemotype was a mixed hybrid of both farnesol and the springene chemotypes. In all the chemotypes, alkylbenzenes; o-xylene, m-xylene and ethylbenzene were in huge amounts as other significant components in the oil. 1,4- dihydroxy-p-menth-2-ene, 5,9-undecadien-2-one, 6,10-dimethyl, and 3-cyclohexen-1- carboxaldehyde,3,4-dimethyl were other most significant chemical constituents of the three chemotypes. The presence of chemical variation in the components of T. vogelii essential oil showed that the fumigant and repellency efficacy of this plant against Sitophilus zeamais Motschulsky were undermined. However, all the chemotypes of T. vogelii essential oil could show repellence and fumigant toxicity against S. zeamais. The comparison between insecticidal and repellent effects of the essential oils of chemotype 3 of T. vogelii with that of T. diversifolia was done. Results indicated that the former could be promoted more for contact toxicity effect while T. diversifolia better suits fumigation effects against S. zeamais. Investigation of the feeding deterrence of both volatile and non-volatile substances of T. diversifolia leaves revealed that its essential oil did not show significant antifeedant activity at a dose of 0.29 μL mg of flour disks. The crude extract, some fractions and the isolated compounds demonstrated feeding deterrence activity against S. zeamais. The feeding deterrence index of sandarac copimaradiene- 1α,9α-diol was 81.19 5.94 percent at 0.1percent w w 1 mg g food compared to 97.45 0.43 percentage for Neemazal extract 10 percent azadirachtin positive control at 10w w 100 mgg food. The EC50 of deacetylviguiestin, 3 4 O caffeoyloxy methyl 2 methyloxirane 2 carboxylic acid and azadirachtin commercial antifeedant against S. zeamais were 22140.23 9103.29, 3654.28 2715.09 and 14.59 5.59 ppm respectively. Although these compounds showed less activity against S. zeamais than azadirachtin, their antifeedant activities were very significant and can be valuable alternatives. UHPLC DAD ESI-MS MS characterisation of fractions of T. diversifolia led to the identification of 7 novel hydroxycinnamates; 4-O 1 O caffeoylglucosyl quinic acid, 4 O caffeoyl 2 hydroxy 3 methylbutanoic acid, 4-O-caffeoyl-2-hydroxybutanoic acid, 3,4 dihydroxyphenyl-4-O-caffeoyl-2-hydroxybutanoate, 4-vinylphenyl 4 O caffeoyl 2-hydroxy 3 methylbutanoate, 4 O caffeoyl-caffeoyloxymethyl 2 hydroxy 3 methylbutanoate, 4 O-caffeoyl 2 2 3,4 dihydroxyphenyl acetoyloxy 3-methylbutanoic acid from T. diversifolia leaves that had not been previously reported in nature. Their structures have been assigned based on the unique MS MS fragmentation patterns for each of the compounds in a switching negative or positive ionisation mode and deduction from 1D 1H and 13C NMR of similar compound. In total, 55 phenolic compounds from aqueous fractions of T. diversifolia have been identified including 4 hydroxybenzoic acids, 19 hydroxycinnamic acids, 22 flavonoids, 1 saponin triterpenoid and 9 coumarins and furocoumarins. The present study further showed that the DPPH radical scavenging effect and reducing power antioxidant activity of tested samples of T. diversifolia showed a moderate correlation with the phenolic content present in these samples. This implied that the antioxidant potential was just partly attributed to its phenolic content.
- Description
- Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (xix, 184 leaves)
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
- Rights
- All Rights Reserved
- Rights
- Open Access
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UFH Department of Chemistry
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Final thesis.pdf Nasifu Kerreba.pdf | 4 MB | Adobe Acrobat PDF | View Details Download |