ACD/Labs Blog

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.

To understand the molecular mechanism underlying the genus-specificity of ascidians' sperm chemotaxis, Matsumori et al investigated the structure of a novel compound Ascidia-SAAF 2 (molecular formula C₂₇H₄₄O₁₀S₂Na₂), which was isolated from the eggs of the ascidian Ascidia sydneiensis. Utilizing Structure Elucidator Suite allowed the correct structure of unknown, and its configuration upon a double bond to be determined.

Kim et al isolated and identified two unprecedented phosphorus-containing iodinated polyacetylenes, Phosphoiodyn A and B, from a Korean marine sponge Placospongia sp. Here we will describe the structural elucidation of Phosphoiodyn A (molecular formula C₁₆H₂₄O₄PI).

Aquatolide is a humulane-derived sesquiterpenoid lactone isolated from Asteriscus aquaticus. The structure originally proposed on the basis of 1D and 2D NMR analysis contains an exceedingly rare ladderane substructure. As a result of the quantum-chemical (QM) calculations of the 13C and 1H chemical shifts and associated coupling constants for a series of possible structures, it was shown that the proposed structure was incorrect. We applied a well-established Computer Assisted Structure Elucidation (CASE) method to the problem, in order to compare results with the QM method.

Wang and co-workers isolated Jatrophalactam (molecular formula C₂₀H₂₉NO₃), a novel diterpenoid lactam possessing an unprecedented skeleton from the roots of Jatropha curcas.