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ACD/Labs Blog

Studies aimed at the discovery of trace alkaloids in S. nux-vomica led Fu and co-workers to the isolation of Strynuxlines A and B, two novel alkaloids possessing an unprecedented skeleton with a 6/5/9/6/7/6 hexacyclic ring system. Here we will describe how Strynuxlines A (molecular formula C23H24N2O5) could be identified with the assistance of a CASE-based approach 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).

Here we describe a total synthesis of a hypothetical alternative structure and its spectroscopic confirmation, representing a huge amount of work done by the authors to disprove the original structure. We used their example to ask what solution would be obtained if the authors used ACD/Structure Elucidator Suite for processing the spectroscopic data of the unknown.

Tang et al carried out a phytochemical investigation on the stems of T. flavidus collected in China. They reported the identification of five degraded diterpenoids, including the tetranorditerpenoid dimers trigoflavidols A and B. Spectroscopic data acquired for Trigoflavidol A (molecular formula C35H32O10), possessing a rearrangement skeleton with a spiroketal core moiety, was used for challenging ACD/Structure Elucidator Suite.

In searching for novel antibiotics, Thongbai et al have focused on tropical basidiomycetes from Asia. The research led to the isolation of unprecedented antimicrobial metabolite Gymnopalynes A (molecular formula C12H7O2Cl). Though the molecule is small and relatively simple, elucidation of its structure is not straightforward. With this in mind we used this problem to illustrate some nuances associated with utilization of ACD/Structure Elucidation.

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.

This example clearly shows how an improper axiom assumption by a researcher can lead to an incorrect structure. Employing an unbiased analysis of spectral data using Structure Elucidator Suite would allow the authors to infer the correct structure (Viridol, molecular formula C20H18O6) unambiguously in several seconds.

Lorente and co-workers isolated two known compounds, pretomaymycin and oxotomaymycin, plus the previously unknown compound barmumycin from the culture broth of the marine actinomycete Streptomyces sp. BOSC-022A. Barmumycin (molecular formula C15H19NO4)and its diacetate show antitumor activity at micromolar concentrations.

A reinvestigation of the NMR and IR results for natural schizocommunin led the researchers to propose a revised structure, quinazolinone. We suggested that if a CASE approach were used elucidate the structure when this compound was firstly isolated, the structure revision would be not necessary: for final structure confirmation X-ray crystallographic analysis would be sufficient.

This month we re-visit the example of structure revision of Epohelmin A with structure revision utilizing ACD/Structure Elucidator Suite, which demonstrates how the software allows a researcher to avoid complex multi-stage synthesis to refute a wrong proposed structure and prove the revised one.