The Identification of Naturally Occurring Neoruscogenin as a Bioavailable, Potent, and High-Affinity Agonist of the Nuclear Receptor RORα (NR1F1)

Abstract

Plants represent a tremendous structural diversity of natural compounds that bind to many different human disease targets and are potentially useful as starting points for medicinal chemistry programs. This resource is, however, still underexploited due to technical difficulties with the identification of minute quantities of active ingredients in complex mixtures of structurally diverse compounds upon raw phytomass extraction. In this work, we describe the successful identification of a novel class of potent RAR-related orphan receptor alpha (RORα or nuclear receptor NR1F1) agonists from a library of 12,000 plant extract fractions by using an optimized, robust high-throughput cell-free screening method, as well as an innovative hit compound identification procedure through further extract deconvolution and subsequent structural elucidation of the active natural compound(s). In particular, we demonstrate that neoruscogenin, a member of the steroidal sapogenin family, is a potent and high-affinity RORα agonist, as shown by its activity in RORα reporter assays and from its effect on RORα target gene expression in vitro and in vivo. Neoruscogenin represents a universal pharmacological tool for RORα research due to its specific selectivity profile versus other nuclear receptors, its excellent microsomal stability, good bioavailability, and significant peripheral exposure in mouse.

Potent in vitro antiviral activity of Cistus incanus extract against HIV and Filoviruses targets viral envelope proteins

“…To gauge the complexity of compounds displaying anti-HIV activity in Ci extract, Ci extract was subjected to bioassay-guided fractionation. Ci extract was separated by a multi-step procedure validated for deconvolution of complex plant extracts 35 . First, a set of 96 fractions were prepared from Ci extract.…”

REV-ERB and ROR nuclear receptors as drug targets

“…Interestingly, a recent study that screened a commercially available plant extract library for ROR ligands identified a natural product plant sterol called neoruscogenin as a RORα agonist 99 . In a biochemical assay measuring the recruitment of the cofactor SRC2 to RORα, neoruscogenin had an EC 50 (effector concentration for half-maximum response) value of 0.11 μM.…”

“…In a biochemical assay measuring the recruitment of the cofactor SRC2 to RORα, neoruscogenin had an EC 50 (effector concentration for half-maximum response) value of 0.11 μM. In cell-based assays, neoruscogenin induced transcription driven by a chimeric receptor, Gal4–RORα, and also increased the transcription of RORα target genes in HepG2 cells 99 . Although neoruscogenin had activity against the pregnane X receptor, it was selective versus other nuclear receptors and it also induced the expression of hepatic RORα target genes when it was orally administered to mice 99 .…”

Natural products as modulators of retinoic acid receptor-related orphan receptors (RORs)

“…Neoruscogenin, a steroidal sapogenin, which can be found in Ruscus aculeatus (Asparagaceae), was identied as an agonist of RORa. 121 A novel HTS method utilizing a variant of a pull-down assay, in which the liganddependent recruitment of a co-activator peptide to RORa LBD is quantied using luminescence, was able to identify RORa ligands within fractionated plant extracts. Using this method combined with subsequent isolation and chromatographic purication steps led to the identication of 25S-ruscogenin (from Dalbergia cambodiana, Fabaceae) as a potent RORa agonist.…”