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

Seven new leucosceptroid degradation products possessing a C₂₀, C₂₁, or C₂₅ framework, norleucosceptroids D–H (1–5), leucosceptroids P (6), and Q (7), have been isolated from Leucosceptrum canum. 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 1–3.