ACD/Labs Blog

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.

To understand the molecular mechanism underlying the genus-specificity of sperm chemotaxis of ascidians (a type of marine invertebrate filter feeders), Matsumori et al have investigated the structure of a novel compound Ascidia-SAAF 2 (molecular formula C₂₇H₄₄O₁₀S₂Na₂) isolated from the eggs of the ascidian Ascidia sydneiensis.