Monoterpenoid Indole Alkaloids Bearing an N4-Iridoid from Gelsemium elegans

• Published in: Chemistry, an Asian journal an Asian journal, 2008-10, Vol.3 (10), p.1824-1829
• Main Authors: Yin, Sheng, He, Xiu-Feng, Wu, Yan, Yue, Jian-Min
• Format: Article
• Language: English
• Subjects: alkaloids; Circular Dichroism; Gelsemium - chemistry; Iridoids - chemistry; Iridoids - isolation & purification; Molecular Structure; natural products; Plant Leaves - chemistry; Plant Stems - chemistry; Plants, Medicinal - chemistry; Secologanin Tryptamine Alkaloids - chemistry; Secologanin Tryptamine Alkaloids - isolation & purification; structure elucidation; terpenoids; X-ray diffraction
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.200800021

Five new alkaloids, gelseganines A–D (1–4) and humantenine N4‐oxide (5), were isolated from the stems and leaves of Gelsemium elegans. Compounds 1–4 represent a rare class of monoterpenoid indole alkaloids that bear an N4‐iridoid unit. The structures of 1–5 were determined by spectroscopic analysis, single‐crystal X‐ray diffraction, and chemical correlation, and their absolute configurations were elucidated by CD analysis. A plausible biogenetic pathway for alkaloids 1–5 was also postulated. Rare gems from stems: The stems and leaves of Gelsemium elegans yield a rare class of monoterpenoid indole alkaloids bearing an N4‐iridoid unit. Spectroscopic analysis, single‐crystal X‐ray diffraction, and chemical correlation shed light on the structures of these alkaloids, and a plausible biogenetic pathway for these compounds can also be postulated.