Molecules 2012, 17(9), 10774-10790; doi:10.3390/molecules170910774

Aggregating Behavior of Phenolic Compounds — A Source of False Bioassay Results?

1,2,* email and 3email
Received: 6 August 2012; in revised form: 27 August 2012 / Accepted: 4 September 2012 / Published: 7 September 2012
(This article belongs to the collection Bioactive Compounds)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Previous descriptions of quercetin, a widely studied flavonoid, as a frequently reported nonspecific screening hit due to aggregating behavior has raised questions about the reliability of in vitro bioactivity reports of phenolic compounds. Here a systematic study on 117 phenolic compounds is presented, concerning their aggregating tendency and the relevance of this phenomenon to obtaining false bioassay results. Fourteen compounds formed aggregates detectable by dynamic light scattering (DLS) when assayed at 10 µM in Tris-HCl pH 7.5. Flavonoids were more prone to aggregation than other phenolic compounds, and the aggregate formation was highly dependent on the vehicle, ionic strength and pH. The compounds were also assayed against three unrelated enzymes in the presence and absence of Triton X-100, and their bioactivity ratios were collected from PubChem database. By comparing these datasets, quercetin and rhamnetin were confirmed as promiscuous inhibitors. In general, flavonoids exhibited also higher bioactivity ratios in the PubChem database than coumarins or organic acids. To conclude, aggregate formation can be controlled with Triton X-100 and this phenomenon needs to be considered when bioassay data is interpreted, but our data indicates that it does not always lead to unspecific inhibition of biological targets.
Keywords: flavonoid; bioactivity screening; promiscuous binder; nonspecific inhibition; quercetin; rhamnetin; aggregation; dynamic light scattering
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MDPI and ACS Style

Pohjala, L.; Tammela, P. Aggregating Behavior of Phenolic Compounds — A Source of False Bioassay Results? Molecules 2012, 17, 10774-10790.

AMA Style

Pohjala L, Tammela P. Aggregating Behavior of Phenolic Compounds — A Source of False Bioassay Results? Molecules. 2012; 17(9):10774-10790.

Chicago/Turabian Style

Pohjala, Leena; Tammela, Päivi. 2012. "Aggregating Behavior of Phenolic Compounds — A Source of False Bioassay Results?" Molecules 17, no. 9: 10774-10790.

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