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<p>Four unprecedented polycyclic alkaloids, designated pandazepines A–D (<b>1</b>–<b>4</b>), featuring rare diazepine-containing frameworks, were isolated from the leaves of <i>Pandanus yvanii</i>. Their structures were elucidated through comprehensive spectroscopic analyses. Pandazepines A and B (<b>1</b> and <b>2</b>) represent the first examples of tetracyclic pyrrolidinoindoline-1,3-diazepine alkaloids, with their absolute configurations established by comparison of experimental and TDDFT-calculated ECD spectra. Pandazepines C and D (<b>3</b> and <b>4</b>) possess unprecedented pentacyclic fused-ring systems comprising linearly fused 1,3-diazepine, γ-lactam, and indolizidine units. The relative configurations of <b>3</b> and <b>4</b> were determined through GIAO NMR chemical shift calculations in combination with DP4+ probability analysis. A putative biosynthetic pathway for <b>1</b>–<b>4</b>, originating from putrescine is proposed. Collectively, these findings expand the structural diversity of diazepine-containing natural products and provide new insights into the biosynthetic capabilities of the <i>Pandanus</i> genus.</p> Graphical Abstract <p></p>

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Isolation and structural characterization of polycyclic diazepine alkaloids from Pandanus yvanii

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月13日

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  • Jin-Ning Chu,
  • Premanand Krishnan,
  • Kien-Thai Yong,
  • Yun-Yee Low,
  • Kuan-Hon Lim

摘要

Four unprecedented polycyclic alkaloids, designated pandazepines A–D (1–4), featuring rare diazepine-containing frameworks, were isolated from the leaves of Pandanus yvanii. Their structures were elucidated through comprehensive spectroscopic analyses. Pandazepines A and B (1 and 2) represent the first examples of tetracyclic pyrrolidinoindoline-1,3-diazepine alkaloids, with their absolute configurations established by comparison of experimental and TDDFT-calculated ECD spectra. Pandazepines C and D (3 and 4) possess unprecedented pentacyclic fused-ring systems comprising linearly fused 1,3-diazepine, γ-lactam, and indolizidine units. The relative configurations of 3 and 4 were determined through GIAO NMR chemical shift calculations in combination with DP4+ probability analysis. A putative biosynthetic pathway for 1–4, originating from putrescine is proposed. Collectively, these findings expand the structural diversity of diazepine-containing natural products and provide new insights into the biosynthetic capabilities of the Pandanus genus.

Graphical Abstract