Enantiomeric separation of selective 5-HT₇ receptor ligands.

Alexus Morgan, Barbara Bricker, Chandrashekhar Voshavar, Seth Y. Ablordeppey

Basic Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Institute of Public Health, Florida A&M University, Tallahassee, FL 32307, USA

The 5-HT₇R is a promising target for drug discovery for the treatment of pathological pain, sleep, neuropsychiatric, and circadian rhythm disorders. Accumulating evidence now suggests that 5-HT₇R ligands activate not only G protein but also β-arrestin signaling pathways. Currently, no β-arrestin-biased ligands selectively interacting with 5-HT₇R has been disclosed other than compound 1g reported in 2018. In a recent PNAS paper, Serodolin was shown to decrease hyperalgesia and pain sensation in response to inflammatory, thermal, and mechanical stimulation and its antinociceptive effect could not be observed in 5-HT₇R knockout (KO) mice and was blocked by administration of SB269-970, a specific 5-HT₇R antagonist. Thus, it is of interest to seek new selective, high affinity, more potent and efficacious β-arrestin biased ligands that could provide an understanding of the relationship between physiological effects and G protein/β-arrestin biased signaling pathways of 5-HT₇R.

Our lab has previously reported two racemic compounds that have high selectivity for 5-HT₇ receptors, leading to the design and discovery of SYA59173 and SYA0486, as novel 5-HT₇R selective ligands. Using isocratic elution with various mobile phases we were able to improve the separation of enantiomers utilizing high performance liquid chromatography (HPLC) with an analytical scale Chiralpak AD-H. Samples were then scaled up for semi-prep separations using Chiralpak AD-H and reanalyzed for enantiomeric purity on the analytical scale.

This work was financially supported by an NIH/NIGMS R16 grant number 1R16GM145581-01 and an NIGMS Endowment grant in support of an Eminent Scholar Chair in Biomedical Sciences to SYA. The research was also partly supported with funding from the U.S. Department of Education, Title III Part B, Strengthening Historically Black Graduate Institutions Programs (HBGI), awarded to Florida A&M University" and an RCMI grant # NIMHD U54 MD 007582.