Strychnan and secoangustilobine A type alkaloids from alstonia spatulata. Revision of the C-20 configuration of scholaricine
A total of 25 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia spatulata, of which five are new alkaloids of the strychnan type (alstolucines A-E, 1-5)and the other, a new alkaloid of the secoangustilobine A type(alstolobine A, 6). The structures of these alkaloids were estab...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Chemical Society and American Society of Pharmacognosy
2010
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| Subjects: | |
| Online Access: | http://eprints.um.edu.my/10400/1/Strychnan_and_Secoangustilobine_A_Type_Alkaloids_from_Alstonia_spatulata._Revision_of_the_C-20_Configuration_of_Scholaricine.pdf http://eprints.um.edu.my/10400/ |
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| Summary: | A total of 25 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia spatulata, of which five are new alkaloids of the strychnan type (alstolucines A-E, 1-5)and the other, a new alkaloid of the secoangustilobine A type(alstolobine A, 6). The structures of these alkaloids were established using NMR and MS analysis and, in the case of alstolucine B (2), also confirmed by X-ray diffraction analysis. A reinvestigation of the stereochemical assignment of scholaricine (13) by NMR and X-ray analyses indicated that the configuration at C-20 required revision. Alkaloids 1, 2, 6, 7, 9, 10, and 13 reversed multidrug resistance in vincristine-resistant KB cells. |
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