1. Neuroactive Type-A γ-Aminobutyric Acid Receptor Allosteric Modulator Steroids from the Hypobranchial Gland of Marine Mollusk, Conus geographus
- Author
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Shrinivasan Raghuraman, Joshua P. Torres, Baldomero M. Olivera, Ronald W. Hughen, Manju Karthikeyan, Chang-Shan Niu, Kevin Chase, Zhenjian Lin, Alan R. Light, Marco Bortolato, Jie Zhang, Lee S. Leavitt, Lili Sun, Noemi D. Paguigan, Roberto Cadeddu, Eric W. Schmidt, and Christopher A. Reilly
- Subjects
0303 health sciences ,Allosteric modulator ,Neuroactive steroid ,Hypobranchial gland ,Conus geographus ,biology ,Chemistry ,Protein subunit ,Pharmacology ,biology.organism_classification ,01 natural sciences ,Aminobutyric acid ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,03 medical and health sciences ,medicine.anatomical_structure ,Dorsal root ganglion ,Drug Discovery ,medicine ,Molecular Medicine ,Receptor ,030304 developmental biology - Abstract
In a program to identify pain treatments with low addiction potential, we isolated five steroids, conosteroids A-E (1-5), from the hypobranchial gland of the mollusk Conus geographus. Compounds 1-5 were active in a mouse dorsal root ganglion (DRG) assay that suggested that they might be analgesic. A synthetic analogue 6 was used for a detailed pharmacological study. Compound 6 significantly increased the pain threshold in mice in the hot-plate test at 2 and 50 mg/kg. Compound 6 at 500 nM antagonizes type-A γ-aminobutyric acid receptors (GABAARs). In a patch-clamp experiment, out of the six subunit combinations tested, 6 exhibited subtype selectivity, most strongly antagonizing α1β1γ2 and α4β3γ2 receptors (IC50 1.5 and 1.0 μM, respectively). Although the structures of 1-6 differ from those of known neuroactive steroids, they are cell-type-selective modulators of GABAARs, expanding the known chemical space of neuroactive steroids.
- Published
- 2021
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