The European Journal of Medicinal Chemistry has published a curious retraction notice for a paper in its February 2012 issue from a group of Indian scientists.
The abstract of the article,”Proton-pumping-ATPase-targeted antifungal activity of cinnamaldehyde based sulfonyl tetrazoles,” is still available on Medline:
Here’s what the abstract of the paper said about the study:
Azoles are generally fungistatic, and resistance to fluconazole is emerging in several fungal pathogens. We designed a series of cinnamaldehyde based sulfonyl tetrazole derivatives. To further explore the antifungal activity, in vitro studies were conducted against 60 clinical isolates and 6 standard laboratory strains of Candida. The rapid irreversible action of these compounds on fungal cells suggested a membrane-located target for their action. Results obtained indicate plasma membrane H(+)-ATPase as site of action of the synthesized compounds. Inhibition of H(+)-ATPase leads to intracellular acidification and cell death. Presence of chloro and nitro groups on the sulfonyl pendant has been demonstrated to be a key structural element of antifungal potency. SEM micrographs of treated Candida cells showed severe cell breakage and alterations in morphology.
But the analysis seems to have suffered a fatal flaw or two, although the precise nature of those glitches isn’t clear from the retraction statement:
This article has been retracted at the request of the Authors.
The authors have retracted this article because of errors relating to molecule characterization reported in the text. The authors express their sincere apologies for this oversight.
We’re guessing that faulty “molecular characterization” rises above, say, that involved in slipping on black ice or adding a tablespoon of salt in a recipe that calls instead for sugar. But is it fair to assume that what the authors are trying to say is that their “series of cinnamaldehyde based sulfonyl tetrazole derivatives” was not, in fact, those substances? If so, that would seem like a pretty monumental mischaracterization, yes?
We’ve contacted the corresponding author of the paper, and will update with anything we find out.
Trying to be reasonable, I would guess that some of the compounds were misidentified- basically since they are synthesizing the compounds, they need to perform the syntheses and then validate the products. If they misidentify some of the products, or for example their cinnamaldehyde stock was not what they thought it was, that could be the issue. Remember the retraction that was because of a mislabeled chemical stock? Some sort of metal based catalyst for some reaction- they attributed it to a metal that had not been previously known to perform the reaction but their stock of a chemical- a legacy stock from another lab or something- was mislabeled. I think I read about this at “In the Pipeline”.
You may be recalling this post: http://www.retractionwatch.com/2011/02/07/biologist-realizes-hes-been-studying-cadbury-egg-mislabeled-bottle-leads-to-phys-rev-b-retraction/ In the Pipeline may have covered a similar case.
When I use the term “molecular characterization” in my work, I normally mean the identification of strains or species by sequencing, e.g. of their rDNA or ITS sequences. So, my guess is that the Candida strains and isolates were not correctly identified or mixed up.
This is actually very odd. The main finding of this study was that some compounds exhibit antifungal activity. Even if the compounds turned out to have different structures than originally thought, it should have no bearing on their antifungal activity. Why not just correct the structures and let the paper live?
BTW: Assigning a wrong structure to a compound is not uncommon. Every organic chemist dreads this because when it does happen all of the sudden many other organic chemists claim that the mistake was avoidable. Typical Monday morning quarterbacking.
Maybe the real molecules were known antifungals, so the experiment wouldn’t show anything new.
Agree with what’s been said re: ease of misidentification. Even research supply vendors are not immune to this. Another possibility is a previously missed contaminant unrelated to their compounds that was responsible for activity – certainly wouldn’t be first time. I do wonder if rather cryptic nature of notice is on part of authors or journal.
There’s a difference between “molecule characterization” and “molecular characterization”… isn’t there? That is, the original statement appears to say they mischaracterized a molecule. Maybe the compound causing instant cell destruction wasn’t a cinnamaldehyde at all, but a cyanide.
It`s important that the authors expressed their sincere apologies for this oversight. Everyone can make mistakes, but it`s fundamental to know when and where did they happen so they won`t occur again.