Phytochemical studies on certain South African species of the rutaceous genera Agathosma Willd. and Zanthoxylum L
- Authors: Finkelstein, Nathan
- Date: 1979
- Subjects: Zanthoxylum Rutaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3725 , http://hdl.handle.net/10962/d1001460
- Description: Selected species of two South African rutaceous genera, Agathosma Willd. and Zanthoxylum L., were phytochemically studied. Two species of the former genus, A. puberula (Steud.) Fourc . and A. elavisepala R. A. Dyer, yielded a novel O-prenylcoumarin, puberul in, the structure of which was fully elucidated as 6,8- dimethoxy-7-prenyloxycoumarin. This represents the first report of a coumarin from that endemic genus. In another study the alkaloids in three species of Zanthoxylum, Z. davyi (Verdoorn) Waterm., Z. thorneroftii (Verdoorn) Waterm. and Z. humile (E .A. Bruce) Waterm . , were investigated. Chelerythrine, nitidine, (-) -α-N-methylcanadine, (+)-laurifoline and (+)-magnoflorine were isolated and characterized in the stem and root bark of Z. davyi, while the root bark of Z. thorneroftii contained skimmianine and decarine in addition to the alkaloids present in Z. davyi. Skimmianine, decarine, N-norchelerythrine, chelerythrine, (-)-α-N-methylcanadinc, candicine and tembetarine were identified in the root bark of Z. humile. The chemotaxonomic significance of these alkaloids occurring in the South African taxa in relation to other African Zanthoxylum taxa, is discussed. Several non-alkaloids (lupeol, β-sitosterol and (-)-sesamin) were also isolated and characterized in Z. davyi and Z. humile. Horizontal cellulose column chromatography and low pressure liquid chromatography have been applied to the separation of quaternary alkaloids
- Full Text:
- Date Issued: 1979
- Authors: Finkelstein, Nathan
- Date: 1979
- Subjects: Zanthoxylum Rutaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3725 , http://hdl.handle.net/10962/d1001460
- Description: Selected species of two South African rutaceous genera, Agathosma Willd. and Zanthoxylum L., were phytochemically studied. Two species of the former genus, A. puberula (Steud.) Fourc . and A. elavisepala R. A. Dyer, yielded a novel O-prenylcoumarin, puberul in, the structure of which was fully elucidated as 6,8- dimethoxy-7-prenyloxycoumarin. This represents the first report of a coumarin from that endemic genus. In another study the alkaloids in three species of Zanthoxylum, Z. davyi (Verdoorn) Waterm., Z. thorneroftii (Verdoorn) Waterm. and Z. humile (E .A. Bruce) Waterm . , were investigated. Chelerythrine, nitidine, (-) -α-N-methylcanadine, (+)-laurifoline and (+)-magnoflorine were isolated and characterized in the stem and root bark of Z. davyi, while the root bark of Z. thorneroftii contained skimmianine and decarine in addition to the alkaloids present in Z. davyi. Skimmianine, decarine, N-norchelerythrine, chelerythrine, (-)-α-N-methylcanadinc, candicine and tembetarine were identified in the root bark of Z. humile. The chemotaxonomic significance of these alkaloids occurring in the South African taxa in relation to other African Zanthoxylum taxa, is discussed. Several non-alkaloids (lupeol, β-sitosterol and (-)-sesamin) were also isolated and characterized in Z. davyi and Z. humile. Horizontal cellulose column chromatography and low pressure liquid chromatography have been applied to the separation of quaternary alkaloids
- Full Text:
- Date Issued: 1979
Extractives of Leonotis and Euryops species
- Authors: Eagle, G A
- Date: 1971
- Subjects: Stereochemistry Leonotis -- Analysis Euryops -- Analysis Botanical chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4465 , http://hdl.handle.net/10962/d1011610
- Description: The isolation and structure determination of dubiin and leonitin, two new diterpenoid acetates from Leonotis dubia and Leonotis leonitis respectively, are discussed. The compounds are diterpenoids of the labdane type and are closely related to marrubiin. The proposed structures are based on chemical and spectral evidence. Dubiin, C₂₂H₃₀0₆̕ contains a tertiary hydroxy- group, a furan ring and a ó-lactone while leonitin, C₂₂H₃₀0₇̕ is a γ - dilactone. at C-20. Both compounds are unusual in being oxygenated The extraction of three Euryops species and the isolation of euryopsol, C₂₂H₃₀0₄̕̕ are also described. A furanoeremophilane structure containing three hydroxy- groups, one of which is at a bridgehead position, is proposed. Euryopsol is the first furanoeremophilanoid with a substituent attached at C-IO
- Full Text:
- Date Issued: 1971
- Authors: Eagle, G A
- Date: 1971
- Subjects: Stereochemistry Leonotis -- Analysis Euryops -- Analysis Botanical chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4465 , http://hdl.handle.net/10962/d1011610
- Description: The isolation and structure determination of dubiin and leonitin, two new diterpenoid acetates from Leonotis dubia and Leonotis leonitis respectively, are discussed. The compounds are diterpenoids of the labdane type and are closely related to marrubiin. The proposed structures are based on chemical and spectral evidence. Dubiin, C₂₂H₃₀0₆̕ contains a tertiary hydroxy- group, a furan ring and a ó-lactone while leonitin, C₂₂H₃₀0₇̕ is a γ - dilactone. at C-20. Both compounds are unusual in being oxygenated The extraction of three Euryops species and the isolation of euryopsol, C₂₂H₃₀0₄̕̕ are also described. A furanoeremophilane structure containing three hydroxy- groups, one of which is at a bridgehead position, is proposed. Euryopsol is the first furanoeremophilanoid with a substituent attached at C-IO
- Full Text:
- Date Issued: 1971
An examination of the extractives of Leonotis species
- Authors: Kaplan, Errol R
- Date: 1966
- Subjects: Leonotis -- Analysis Botanical chemistry Chemistry, Analytic Chemistry, Organic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4481 , http://hdl.handle.net/10962/d1012628
- Description: Marrubiin and the other two diterpenoids, compounds X and Y, which had previously been isolated from Leonotus leonurus have been reinvestigated. Although the structure for marrubiin is well known its stereochemistry has been the subject of protracted discussion and is by no means secure except at C₅ and C₁₀ . N.M.R. spectral evidence showed that the lactone ring was cis-fused and β-orientated. Dehydration experiments carried out by previous workers were repeated, in order to resolve the residual uncertainty regarding the stereochemistry at C₉, an attempt was made to prepare iodoacetyl marrubic acid for X-ray crystallographic studies. Compound Y, C₂₀H₂₈0₃, a triply-unsaturated compound was shown by spectral studies to contain a furan ring and an α,β- unsaturated keto-group. It possesses a hydroxyl group incapable of acetylation, but readily removed by alkali and dehydrating agents to yield a tetraunsaturated compound, anhydro~Y; the hydroxyl is thus tertiary, Isolation of 1:2:5-trimethylnaphthalene on dehydrogenation indicated a relationship with the labdane diterpene group and supported the C₂₀ formula, The position of the α,β-unsaturated keto-group was resolved by interpretation of the ultraviolet spectra of degradation products and also by isolation of 1:2:3:5- trimethylnaphthalene on dehydrogenation of a suitable grignard product, The presence of a β-substituted furan was further indicated by colour reactions and confirmed by mass and n.m.r. spectra. The skeleton of compound Y is correlated with marrubiin via "iso-ambreinolide " and its stereochemistry is discussed. Further stereochemical assignments are postulated from the study of the n.m.r. spectra. Compound X, C₂₀H₂₈0₅, was shown by spectral and chemical evidence to be a diterpenoid dilactone containing an ether bridge between C₉ and C₁₃ Isolation of 1:2:5 trimethylnaphthal ene on dehydrogenation showed it to be closely related to marrubiin, This was supported by n.m.r. spectral results. A structure for compound X is proposed and the stereochemistry discussed. The aerial portions of Leonotis leonitis were also extracted and shown to contain a new compound, compound R. Preliminary investigation showed that it was a dilactone containing a furan ring, The n.m.r. spectrum of the compound is discussed.
- Full Text:
- Date Issued: 1966
- Authors: Kaplan, Errol R
- Date: 1966
- Subjects: Leonotis -- Analysis Botanical chemistry Chemistry, Analytic Chemistry, Organic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4481 , http://hdl.handle.net/10962/d1012628
- Description: Marrubiin and the other two diterpenoids, compounds X and Y, which had previously been isolated from Leonotus leonurus have been reinvestigated. Although the structure for marrubiin is well known its stereochemistry has been the subject of protracted discussion and is by no means secure except at C₅ and C₁₀ . N.M.R. spectral evidence showed that the lactone ring was cis-fused and β-orientated. Dehydration experiments carried out by previous workers were repeated, in order to resolve the residual uncertainty regarding the stereochemistry at C₉, an attempt was made to prepare iodoacetyl marrubic acid for X-ray crystallographic studies. Compound Y, C₂₀H₂₈0₃, a triply-unsaturated compound was shown by spectral studies to contain a furan ring and an α,β- unsaturated keto-group. It possesses a hydroxyl group incapable of acetylation, but readily removed by alkali and dehydrating agents to yield a tetraunsaturated compound, anhydro~Y; the hydroxyl is thus tertiary, Isolation of 1:2:5-trimethylnaphthalene on dehydrogenation indicated a relationship with the labdane diterpene group and supported the C₂₀ formula, The position of the α,β-unsaturated keto-group was resolved by interpretation of the ultraviolet spectra of degradation products and also by isolation of 1:2:3:5- trimethylnaphthalene on dehydrogenation of a suitable grignard product, The presence of a β-substituted furan was further indicated by colour reactions and confirmed by mass and n.m.r. spectra. The skeleton of compound Y is correlated with marrubiin via "iso-ambreinolide " and its stereochemistry is discussed. Further stereochemical assignments are postulated from the study of the n.m.r. spectra. Compound X, C₂₀H₂₈0₅, was shown by spectral and chemical evidence to be a diterpenoid dilactone containing an ether bridge between C₉ and C₁₃ Isolation of 1:2:5 trimethylnaphthal ene on dehydrogenation showed it to be closely related to marrubiin, This was supported by n.m.r. spectral results. A structure for compound X is proposed and the stereochemistry discussed. The aerial portions of Leonotis leonitis were also extracted and shown to contain a new compound, compound R. Preliminary investigation showed that it was a dilactone containing a furan ring, The n.m.r. spectrum of the compound is discussed.
- Full Text:
- Date Issued: 1966
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