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Walrobsins A (1) and B (2), two limonoids featuring an unprecedented 5-oxatricyclo[5.4.11,4]hendecane ring system, were isolated from the root barks of Walsura robusta. Their structures, including their absolute configurations, were determined by analyses of HR-ESIMS, 1D/2D NMR, and X-ray crystallography. Compounds 1 and 2 possessed a stable hemiketal structure formed between the OH-11 and 3-carbonyl group in the hexatomic oxoheterocyclic ring. Compound 1 showed significant anti-inflammatory activity with an IC50 value of 7.8 μM and inhibited the expression of iNOS and IL-1β in a dose-dependent manner. [ABSTRACT FROM AUTHOR]

Two novel sesterterpenoids, leucosceptroids C (1) and D (2), possessing unusual antipodal cyclopentenones while maintaining the stereochemistry and functionality of the tricyclic cores, were discovered from the leaves of Leucosceptrum canum(Labiatae). Their structures including absolute stereochemistries were determined by comprehensive NMR, MS, and single-crystal X-ray diffraction analyses. The potent antifeedant activity of 1against the generalist plant-feeding insect Helicoverpa armigera(EC50= 0.017 μmol/cm2) suggested them to be new defensive sesterterpenoids of L. canum. [ABSTRACT FROM AUTHOR]

Cipadonoid A ( 1), a novel limonoid with an unprecedented skeleton, was isolated from the leaves of Cipadessa cinerasecns. Its structure and relative configuration were determined by spectroscopic analysis and computer modeling. 1represents a new type of limonoid, characterized by a rearranged tetrahydropyranyl ring B incorporating usually exocyclic C-30. A possible biosynthetic pathway of 1was also proposed. [ABSTRACT FROM AUTHOR]