Planta Med 2019; 85(18): 1526
DOI: 10.1055/s-0039-3400027
Main Congress Poster
Poster Session 2
© Georg Thieme Verlag KG Stuttgart · New York

Discovery of GABAA receptor modulators of natural origin – validation of a FLIPR assay for screening and HPLC-based activity profiling

MT Faleschini
1   Department of Pharmaceutical Sciences, University of Basel,, Klingelbergstrasse 50, 4056 Basel, Switzerland
,
A Maier
2   Institute for Pharma Technology, School of Life Sciences, University of Applied Sciences Northwestern Switzerland,, Hofackerstrasse 30, 4132 Muttenz, Switzerland
,
S Fankhauser
2   Institute for Pharma Technology, School of Life Sciences, University of Applied Sciences Northwestern Switzerland,, Hofackerstrasse 30, 4132 Muttenz, Switzerland
,
K Thasis
2   Institute for Pharma Technology, School of Life Sciences, University of Applied Sciences Northwestern Switzerland,, Hofackerstrasse 30, 4132 Muttenz, Switzerland
,
S Hebeisen
3   B’Sys GmbH,, Benkenstrasse 254, 4108 Witterswil, Switzerland
,
V Butterweck
2   Institute for Pharma Technology, School of Life Sciences, University of Applied Sciences Northwestern Switzerland,, Hofackerstrasse 30, 4132 Muttenz, Switzerland
4   Zeller Medical AG,, Seeblickstrasse 4, 8590 Romanshorn, Switzerland
,
M Hamburger
1   Department of Pharmaceutical Sciences, University of Basel,, Klingelbergstrasse 50, 4056 Basel, Switzerland
› Author Affiliations
Further Information

Publication History

Publication Date:
20 December 2019 (online)

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    Gamma-aminobutyric acid type A (GABAA) receptor modulators are used to treat epilepsy, insomnia, anxiety, and mood disorders. However, currently used drugs lack receptor subtype selectivity and, therefore exhibit various side effects. Moreover, the scAF3400027fold diversity of synthetic drugs and experimental compounds targeting GABAA receptors is limited. Natural products such as piperine have been reported as allosteric GABAA receptor modulators interacting with a benzodiazepine-independent binding site. For screening of large extract libraries and efficient localization of active compounds via HPLC-based activity profiling we established a Fluorometric Imaging Plate Reader (FLIPR) membrane potential assay utilizing stably transfected Chinese Hamster Ovary (CHO) cells expressing GABAA receptors of α1β2γ2 subunit composition. Assay protocols for rapid screening of plant extract libraries and localization of active compounds in extracts were validated with known GABAergic natural products. An HPLC-based activity profiling protocol was developed. Extract separations (0.4 to 1.2 mg) on an analytical HPLC column were sufficient for the sensitivity of the bioassay. The protocol successfully localized the activity of magnolol in Magnolia officinalis, valerenic acid in Valeriana officinalis, and piperine in Piper nigrum extracts. EC50 values of compounds (magnolol: 4.81 ± 1.0 μM, valerenic acid: 12.56 ± 1.2 μM and piperine: 5.76 ± 0.7 μM) were found to be comparable or lower than those reported using Xenopus oocyte assays. The FLIPR assay is now used for the screening of a large extract library and identification of new GABAergic natural products via HPLC-based activity profiling.


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