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 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.
Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Shin-Jowl
SJ
Tan
Yun-Yee
YY
Low
Yeun-Mun
YM
Choo
Zanariah
Z
Abdullah
Tadahiro
T
Etoh
Masahiko
M
Hayashi
Kanki
K
Komiyama
Toh-Seok
TS
Kam
D031051:Alstonia / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D006801:Humans; D026121:Indole Alkaloids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D007624:KB Cells; D008296:Malaysia; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D024301:Plant Bark / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D014750:Vincristine / Q000494:pharmacology
D026121:Indole Alkaloids; C554322:alstolobine A; D014750:Vincristine