Abstract
Higher food intake promotes obesity, a critical public health challenge with increasing prevalence worldwide. Selective modulators of appetite can be applied as therapeutic intervention. Nevertheless, currently the appetite suppressant drugs trigger severe side effects, such as anxiety and depression. For that reason, there is a priority to discover new pharmaceuticals. In this study, a library of 117 cyanobacterial fractions from marine and freshwater environments belonging to The Blue Biotechnology and Ecotoxicology Culture Collection (LEGE-CC) of CIIMAR (Interdisciplinary Centre of Marine and Environmental Research) were screened for their ability to interfere in the food intake behavior of zebrafish larvae—a whole small animal model. Two different bioassays were performed for appetite-reducing activity, using fluorescent stained liposomes (passive food intake) or Paramecia bursaria (active food intake). Three cyanobacterial fractions from the order Nostocales, Chroococcidiopsidales and Pleurocapsales expressed appetite-suppression bioactivity in the liposomes assay, while three different fractions from the order Synechococcales, Oscilatoriales and Nostocales significantly reduced the appetite in the Paramecium assay. To highlight putatively associated metabolites for the bioactivities, dereplication by metabolomics approaches (LC-MS/MS) was performed, as well as a bioactivity-guided feature-based molecular networking using GNPS, and four compounds were positively correlated to the bioactivity. No matches were found in any database for these molecules, indicating putatively new compounds. Molecular analyses are currently ongoing to discover the involved genes that regulate the passive and active food intake in zebrafish larvae, and consequently uncover the mechanisms of action.
Author Contributions
A.F., bioactivity screenings, metabolomic analysis and writing; J.S.M., bioactivity screenings; V.V., funding acquisition; M.R., supervision of metabolomic analysis; R.U., conceptualization, supervision of all work, funding acquisition. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by R&D&IATLANTIDA—Platform (reference NORTE-01-0145-FEDER-000040), the FCT (Fundação para a Ciência e Tecnologia, Portugal) scholarship grant UI/BD/150901/2021, and the project EMERTOX with funding from the European Union’s Horizon 2020 Marie Skłodowska-Curie Research and Innovation Staff Exchange, under grant agreement Nº 778069.
Institutional Review Board Statement
According to the EC Directive 86/609/EEC for animal experiments, zebrafish larvae in non-independent feeding stages of development are not considered animal experimentation. Hence, ethical review and approval were not necessary.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).