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dc.contributor.advisorMalan, E.
dc.contributor.advisorCoetzee, J. C.
dc.contributor.authorMciteka, Lulama Patrick
dc.date.accessioned2017-03-27T10:25:16Z
dc.date.available2017-03-27T10:25:16Z
dc.date.issued1999-04
dc.identifier.urihttp://hdl.handle.net/11660/6011
dc.description.abstractEnglish: The bark of Cassia petersiana afforded the known flavan-f-ols (+)-catechin, (-)- epicatechin, (+)-gallocatechin and epigallocatechin which co-occured with three new procassinidins namely cassiaflavan-( 4ß-8)-gallocatechin, cassiaflavan-( 4a.-8)- epigallocatechin and cassiaflavan-( 4a-8)-epigallocatechin as well as four novel probutinidins namely butiniflavan-( 4a.-8)-epicatechin, butiniflavan-( 4ß~8)- epicatechin, butiniflavan-( 4~8)-epigallocatechin and ent-butiniflavan-( 4J3~8)- epicatechin. A combination of solvent extraction, column (LH20) and thin layer chromatography procedures were used to isolate and purify the compounds mentioned. Structure elucidation was done using high resolution IH NMR spectroscopy which included NOE and COSY experiments in conjunction with FAB-MS. Due to a high degree of rotational isomerism structural assignments of the following compounds cassiaflavan-( 4J3~8)-epigallocatechin, cassiaflavan-( 4a.~8)-epigallocatechin, butiniflavan-( 4a.~8)-epicatechin, butiniflavan-( 4J3~8)-epicatechin, butiniflavan- (4J3~8)-epigallocatechin and ent-butiniflavan-( 4J3~8)-epicatechin were obtained by tedious NMR experiments and CD data hence recourse to synthesis was absolutely essential to confirm the proposed structures beyond any doubt. Biomimetic synthesis of the procassinidin dimers via reduction of the racerrue flavanones, (±)-4',7-di-O-methyIcassinidin to the diastereomeric flavan-e-ols and condensation with 3',4',S',S,7-penta-O-methylepigallocatechin usmg titanium tetrachloride as Lewis acid was used to confirm the structures. A similar biomimetic synthesis of probutinidins via reduction of the racemic flavanones, (±)-3',4',7-tri-O-methylbutin to the diastereomeric flavan-t-ols followed by condensation with 3',4',5,7 -tetra-O-methylepicatechin and 3',4',5',5,7 -penta-Omethylepigallocatechin using titanium tetrachloride as Lewis acid was also employed to confirm the proposed structures. The biornimetic synthesis of probutinidins yielded two other novel compounds which were not obtained from natural source viz. butiniflavan-(4a.~8)-epigallocatechin and ent- butiniflavan-( 413~8)-epigalloca techin. The isolation and identification of the three new procassinidins and four probutinidins from Cassia petersiana represent the first report of dimeric compounds in this rare class of the proanthocyanidins. This study also represents the first report of the synthesis of the new dimers butiniflavan-( 4a.~8)-epicatechin, butiniflavan-( 413~8)-epicatechin, butiniflavan- (413~8)-epigallocatechin and ent-butiniflavan-( 413~8)-epicatechin as well as butiniflavan-( 4a.~8)-epigallocatechin and ent-butiniflavan-( 413~8)-epigallocatechin.en_ZA
dc.description.abstractAfrikaans: Tydens die huidige studie is die asetoonekstrak van"die bas van Cassia petersiana ondersoek. Die bas van Cassia petersiana het die bekende flavan-f-ole (+)-katesjien, (-)-epi katesjien, (+)-gallokatesjien en epigallokatesjien gelewer wat saam met drie nuwe procassinidiene voorkom, naamlik cassiaflavan-( 4f3~8)-gallokatesj ien, cassiaflavan- (4f3~8)-epigallokatesjien and cassiaflavan-(4a~8)-epigallokatesjien en ook vier on bekende probutinidiene, naamlik butiniflavan-( 4a~8)-epikatesj ien, butiniflavan- (4B~8)-epikatesjien, butiniflavan-( 4B~8)-epigallokatesj ien en ent-butiniflavan- (4B~8)-epikatesj ien. 'n Kombinasie van oplosrniddelekstrahering, kolom (LH20) en dun laag chromatografie metodes is gebruik om die gemelde verbindings te isoleer en te suiwer. Struktuuropklarings is gedoen met hoë resolusie IH KMR spektroskopie wat NOE en COSYeksperimente ingesluit het te same met FAB-MS. Te wyte aan die hoë mate van rotasieisomerie is die struktuuropklaring van die volgende verbindings, nl.cassiaflavan- (4f3~8)-epigallokatesjien, cassiaflavan-( 4a~8)-epigallokatesjien, butiniflavan- (4a~8)-epikatesjien, butiniflavan-( 4f3~~)-epikatesjien, butiniflavan-( 4f3~8)- epigallokatesjien en ent-butiniflavan-(4f3~8)-epikatesjien baie bemoeilik en nieteenstaande uitgebreide KMR eksperimente en SD data moes toevlug geneem word tot sintese om die voorgestelde strukture sonder enige twyfel te bevestig. Biornimetiese sintese van die procassinidien dimere via reduksie van die raserruese flavanoon, (±)-{ 7-di-O-metielcassinidien na die diastereomeriese flavan-ë-ole en kondensasie met 3',{5',5,7-penta-O-metielepigallokatesjien is met titaniumtetrachloried as Lewis suur gedoen om die strukture te bevestig. Soortgelyke biomimetiese sintese van probutinidiene via reduksie van die rasemiese flavanoon, (±)-3',{ 7-tri-O-metielbutin na die diastereomeriese flavan-d-ole en kondensasie met 3',{5,7-tetra-O-metielepikatesjien en 3',{5',5,7-penta-Ometielepigallokatesjien is ook met titaniumtetrachloried as Lewis suur gedoen om weereens die voorgestelde strukture te bevestig. Die biomimetiese sintese van probutinidiene het twee ander onbekende verbindings gelewer wat nie in die huidige natuurbron voorkom nie, naamlik, butiniflavan- (4a.~8)-epigallokatesjien en ent-butiniflavan-( 4f3~8)-epigallokatesj ien. Die isolasie en identifikasie. van die drie nuwe procassinidiene en vier probutinidiene vanuit Cassia petersiana is die eerste van die dimeriese verbindings in hierdie skaars klas van proanthocyanidiene. Hierdie studie behels ook die eerste verslag van die sintese van die nuwe dimere cassiaflavan-( 4f3~8)-epigallokatesj ien, cassiaflavan-( 4a.~8)-epigallokatesj ien, butiniflavan-( 4a.~8)-epikatesjien, butiniflavan-( 4f3~8)-epikatesjien, butiniflavan-( 4f3~8)-epigallokatesjien en ent-butiniflavan-( 4f3~8)-epikatesjien asook van butiniflavan-( 4a.~8)-epigallokatesjien en ent-butiniflavan-( 4f3~8)-epigallokatesjien.en_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectCassia petersianaen_ZA
dc.subjectLeguminosaeen_ZA
dc.subjectFlavanoidsen_ZA
dc.subjectLeucoanthocyanidinsen_ZA
dc.subjectFlavanonesen_ZA
dc.subjectProanthocyanidinsen_ZA
dc.subjectProcassinidinsen_ZA
dc.subjectProbutinidinsen_ZA
dc.subjectBiomimetic synthesisen_ZA
dc.subjectFlavan-flavan-3-ol dimersen_ZA
dc.subjectFlavonoidsen_ZA
dc.subjectAnthocyanidinsen_ZA
dc.subjectPlant pigmentsen_ZA
dc.subjectDissertation (M.Sc. (Chemistry))--University of the Free State, 1999en_ZA
dc.titleStructure and synthesis of flavan oligomers from Cassia petersianaen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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