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Polyneurines A-H, iboga alkaloids from Tabernaemontana polyneura
Sin-Yee Tang1, Chun-Hoe Tan2, Kae-Shin Sim3
1Department of Chemistry, Faculty of Science, Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Abstract:
Eight undescribed iboga alkaloids, polyneurines A-H, were isolated from the bark of Tabernaemontana polyneura. The structures of these alkaloids were established by interpretation of the MS and NMR data, while the configurations were determined using GIAO NMR calculations and DP4+ probability analysis, TDDFT-ECD method, or X-ray diffraction analysis. Polyneurine A possesses a γ-lactone unit embedded within the iboga skeleton, while polyneurines D and E incorporate a formylmethyl moiety at C-3 of the iboga skeleton. Biosynthetic pathways towards the formation of polyneurines A, C, D, and E were proposed.
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