Lycojaponicumin D Structure Elucidation

Previously Wang et al reported three trace Lycopodium alkaloids, lycojaponicumins A and B with a 5/5/5/5/6 pentacyclic ring system and lycojaponicumin C with a 6/5/5/6 tetracyclic ring system. The same group later described the discovery of structurally unique alkaloid, Lycojaponicumin D (molecular formula was established to be C₁₆H₂₃NO₃), with an unprecedented 5/7/6/6 tetracyclic skeleton formed by an unusual C3-C13 linkage.

Lee et al have investigated the chemical constituents of the extracts obtained from cultures of the marine-derived fungus Aspergillus sp. SF-5044. This study led to the isolation of new natural products, particularly, an oxepin-containing diketopiperazine-type metabolite named Protuboxepins A (molecular formula C₂₂H₂₃N₃O₃).

Marine mollusks of the genus Siphonaria, commonly known as false limpets, are shelled, air-breathing herbivores that are believed to have a marine ancestry. When disturbed, siphonariid limpets secrete a sticky white mucus rich in polypropionate secondary metabolites. Specimens were steeped in acetone, and the acetone extract was subjected to extensive chromatography to afford three new polypropionate metabolites. Spectroscopic data of Polypropionate 1 (molecular formula C₂₀H₃₂O₃) are used here to describe the structure elucidation of this compound using CASE techniques.

Sikorska et al isolated and investigated the unusual polyketide macrolides Mandelalides A-D which were isolated from a new species of Lissoclinum ascidian. Their planar structures were elucidated from sub-milligram samples by comprehensive analysis of 1D and 2D NMR data, and supported by mass spectrometry. Here we will describe the elucidation of Mandelalide A (molecular formula C₃₃H₅₂O₁₁) using ACD/Structure Elucidator Suite.

In search for bioactive compounds from the mushroom Stropharia rugosoannulata, Wu et al discovered four novel steroids named strophasterols A, B, C, and D which contained a very unique and unprecedented carbon skeleton. Here we will describe the computerized structure determination of Strophasterol A (molecular formula C₂₈H₄₄O₄).

While studying the herb Aconitum barbatum Pers. var. puberulum Ledeb., Mu et al isolated six new C18-diterpenoid alkaloids including Puberunine (molecular formula C₂₃H₃₅NO₇) that possesses an unusual rearranged 7-membered ring. This structural feature is unprecedented in the field of diterpenoid alkaloids.

Meng et al. investigated potentially biologically active substances from the chemical constituents of the stems of S. glaucescens. As a result, a novel triterpenoid possessing an unusual 6/7/9-fused tricyclic ring system was obtained, which was designated as Schiglautone A (molecular formula C₃₀H₄₆O₆).

Zhao and co-workers isolated two new Securinega alkaloids (virosaines A and B) with an unprecedented skeleton and elucidated their structures. We used the spectroscopic data presented in by the authors to establish the structure of Virosaine A (molecular formula C₁₂H₁₃NO₄) which had been confirmed by X-ray diffraction.

Wang and coworkers collected the branches and leaves of Croton laevigatus and performed an intensive chemical analysis. They isolated and elucidated structures of two diterpenoids, laevinoids A (molecular formula C₂₀H₂₂O₅) and B, which represent a new rearranged ent-clerodane scaffold with an unusual 3/5 bicyclic motif.

Fan et al isolated two PPAPs, Garcimulins A and B, including a pair of enantiomers [(+)-Garcimulin A and (-)-Garcimulin A)] with the unique caged tetracyclo[5.4.1.11,5.09,13]tridecane skeleton from the leaves and twigs of G. multiflora. The spectroscopic 1D and 2D NMR data used by the authors for structure elucidation of Garcimulin A (molecular formula C₃₈H₅₀O₆) were input into ACD/Structure Elucidator Suite.