Unraveling the Metabolic Pathway in <i>Leucosceptrum canum</i> by Isolation of New Defensive Leucosceptroid Degradation Products and Biomimetic Model Synthesis

Abstract

Seven new leucosceptroid degradation products possessing a C₂₀, C₂₁, or C₂₅ framework, norleucosceptroids D–H (<b>1</b>–<b>5</b>), leucosceptroids P (<b>6</b>), and Q (<b>7</b>), have been isolated from <i>Leucosceptrum canum</i>. Their structures were determined by comprehensive NMR, MS, and single-crystal X-ray diffraction analyses. Discovery of these key intermediates, together with the biomimetic oxidation of a model system, supports the hypothesis that two biosynthetic pathways are operative. Antifeedant activity was observed for compounds <b>1</b>–<b>3</b>