Alkaloids from Alstonia scholaris and Ficus schwarzii
Alkaloids, which are the most studied secondary metabolites, are structurally diverse and well known for their biological activity. The aim of the present study is to perform phytochemical investigations on the alkaloidal composition of two selected plant species, namely, Ficus schwarzii (Moraceae)...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2022
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| Online Access: | https://eprints.nottingham.ac.uk/69459/ |
| _version_ | 1848800566325542912 |
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| author | Krishnan, Premanand |
| author_facet | Krishnan, Premanand |
| author_sort | Krishnan, Premanand |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Alkaloids, which are the most studied secondary metabolites, are structurally diverse and well known for their biological activity. The aim of the present study is to perform phytochemical investigations on the alkaloidal composition of two selected plant species, namely, Ficus schwarzii (Moraceae) and Alstonia scholaris (Apocynaceae). (specimen from the West Coast of Peninsular Malaysia). The previously unexplored phytochemistry of F. schwarzii and the phytochemical variation of A. scholaris due to locality have motivated research into the two species collected from Peninsular Malaysia.
Phytochemical investigation of the leaves of F. schwarzii yielded nine novel alkaloids, namely, schwarzinicines A−G (1−7), and schwarzificusines A and B (8 and 9). The schwarzinicine alkaloids represent the first examples of 1,4 diarylbutanoid−phenethylamine conjugates, while schwarzificusines A and B (8 and 9) represent a pair of new diastereomeric 1-phenyl-3-aminotetralins that are structurally related to the schwarzinicines alkaloids. The structures of alkaloids 1–9 were elucidated by detailed analysis of their HRMS and NMR data. Plausible biogenetic pathways that furnish the skeletons of the schwarzinicine and schwarzifiscusine alkaloids were proposed.
Phytochemical investigation of the leaves, bark and flowers of A. scholaris cultivated on the West Coast of Peninsular Malaysia provided a total of 17 alkaloids, of which five are new, namely, alstoscholactine (10), alstolaxepine (11), N-formylyunnanensine (12), scholaphylline (13), and alstobrogaline (19). Alstoscholactine (10), alstolaxepine (11), and alstobrogaline (19) were established to contain novel ring systems. Alstoscholactine (10) represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, while alstolaxepine (11) represents a 6,7-seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. On the other hand, alstobrogaline (19) is an unusual monoterpenoid indole alkaloid incorporating a third N atom, and possessing an aldimine as well as a nitrone function. N-Formylyunnanensine (12) is the N-formyl derivative of the known alkaloid yunnanensine, and it was isolated as a pair of unseparable E/Z-formamide rotamers. Scholaphylline (13) represents the first member of the secostemmadenine-secovallesamine-type bisindole alkaloid. The 12 known alkaloids obtained from Alstonia scholaris are 19,20-E-vallesamine (14), 19,20-Z-vallesamine (15), 19,20-E-vallesamine N-oxide (16), 6,7-secoangustilobine B (17), and 6,7-seco-19,20-epoxyangustilobine B (18), tetrahydroalstonine (20), picrinine (21), 16R-19,20-Z-isositsirikine (22), 16R-19,20-E-isositsirikine (23), scholaricine (24), N-demethylalstogustine N-oxide (25), and E/Z-vallesiachotamine (26). |
| first_indexed | 2025-11-14T20:53:36Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-69459 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T20:53:36Z |
| publishDate | 2022 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-694592024-07-23T04:30:16Z https://eprints.nottingham.ac.uk/69459/ Alkaloids from Alstonia scholaris and Ficus schwarzii Krishnan, Premanand Alkaloids, which are the most studied secondary metabolites, are structurally diverse and well known for their biological activity. The aim of the present study is to perform phytochemical investigations on the alkaloidal composition of two selected plant species, namely, Ficus schwarzii (Moraceae) and Alstonia scholaris (Apocynaceae). (specimen from the West Coast of Peninsular Malaysia). The previously unexplored phytochemistry of F. schwarzii and the phytochemical variation of A. scholaris due to locality have motivated research into the two species collected from Peninsular Malaysia. Phytochemical investigation of the leaves of F. schwarzii yielded nine novel alkaloids, namely, schwarzinicines A−G (1−7), and schwarzificusines A and B (8 and 9). The schwarzinicine alkaloids represent the first examples of 1,4 diarylbutanoid−phenethylamine conjugates, while schwarzificusines A and B (8 and 9) represent a pair of new diastereomeric 1-phenyl-3-aminotetralins that are structurally related to the schwarzinicines alkaloids. The structures of alkaloids 1–9 were elucidated by detailed analysis of their HRMS and NMR data. Plausible biogenetic pathways that furnish the skeletons of the schwarzinicine and schwarzifiscusine alkaloids were proposed. Phytochemical investigation of the leaves, bark and flowers of A. scholaris cultivated on the West Coast of Peninsular Malaysia provided a total of 17 alkaloids, of which five are new, namely, alstoscholactine (10), alstolaxepine (11), N-formylyunnanensine (12), scholaphylline (13), and alstobrogaline (19). Alstoscholactine (10), alstolaxepine (11), and alstobrogaline (19) were established to contain novel ring systems. Alstoscholactine (10) represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, while alstolaxepine (11) represents a 6,7-seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. On the other hand, alstobrogaline (19) is an unusual monoterpenoid indole alkaloid incorporating a third N atom, and possessing an aldimine as well as a nitrone function. N-Formylyunnanensine (12) is the N-formyl derivative of the known alkaloid yunnanensine, and it was isolated as a pair of unseparable E/Z-formamide rotamers. Scholaphylline (13) represents the first member of the secostemmadenine-secovallesamine-type bisindole alkaloid. The 12 known alkaloids obtained from Alstonia scholaris are 19,20-E-vallesamine (14), 19,20-Z-vallesamine (15), 19,20-E-vallesamine N-oxide (16), 6,7-secoangustilobine B (17), and 6,7-seco-19,20-epoxyangustilobine B (18), tetrahydroalstonine (20), picrinine (21), 16R-19,20-Z-isositsirikine (22), 16R-19,20-E-isositsirikine (23), scholaricine (24), N-demethylalstogustine N-oxide (25), and E/Z-vallesiachotamine (26). 2022-07-24 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by https://eprints.nottingham.ac.uk/69459/1/Thesis_Premanand%20Krishnan%20%28014227%29.pdf Krishnan, Premanand (2022) Alkaloids from Alstonia scholaris and Ficus schwarzii. PhD thesis, University of Nottingham. alkaloids phytochemical investigation Ficus schwarzii (Moraceae) Alstonia scholaris (Apocynaceae) |
| spellingShingle | alkaloids phytochemical investigation Ficus schwarzii (Moraceae) Alstonia scholaris (Apocynaceae) Krishnan, Premanand Alkaloids from Alstonia scholaris and Ficus schwarzii |
| title | Alkaloids from Alstonia scholaris and Ficus schwarzii |
| title_full | Alkaloids from Alstonia scholaris and Ficus schwarzii |
| title_fullStr | Alkaloids from Alstonia scholaris and Ficus schwarzii |
| title_full_unstemmed | Alkaloids from Alstonia scholaris and Ficus schwarzii |
| title_short | Alkaloids from Alstonia scholaris and Ficus schwarzii |
| title_sort | alkaloids from alstonia scholaris and ficus schwarzii |
| topic | alkaloids phytochemical investigation Ficus schwarzii (Moraceae) Alstonia scholaris (Apocynaceae) |
| url | https://eprints.nottingham.ac.uk/69459/ |