ENT-A010, a Novel Steroid Derivative, Displays Neuroprotective Functions and Modulates Microglial Responses

Abstract

Tackling neurodegeneration and neuroinflammation is particularly challenging due to the complexity of central nervous system (CNS) disorders, as well as the limited drug accessibility to the brain. The activation of tropomyosin-related kinase A (TRKA) receptor signaling by the nerve growth factor (NGF) or the neurosteroid dehydroepiandrosterone (DHEA) may combat neurodegeneration and regulate microglial function. In the present study, we synthesized a C-17-spiro-cyclopropyl DHEA derivative (ENT-A010), which was capable of activating TRKA. ENT-A010 protected PC12 cells against serum starvation-induced cell death, dorsal root ganglia (DRG) neurons against NGF deprivation-induced apoptosis and hippocampal neurons against Aβ-induced apoptosis. In addition, ENT-A010 pretreatment partially restored homeostatic features of microglia in the hippocampus of lipopolysaccharide (LPS)-treated mice, enhanced Aβ phagocytosis, and increased Ngf expression in microglia in vitro. In conclusion, the small molecule ENT-A010 elicited neuroprotective effects and modulated microglial function, thereby emerging as an interesting compound, which merits further study in the treatment of CNS disorders.

Microneurotrophin BNN27 Reduces Astrogliosis and Increases Density of Neurons and Implanted Neural Stem Cell-Derived Cells after Spinal Cord Injury

“…Considering a wider perspective, our study suggests that MNTs can contribute to combinatorial treatments for CNS injuries by simultaneously enhancing cell therapies and modulating the loss of neuronal tissue. MNT contribution in such treatments could be further enhanced by optimizing MNT dosing, exploiting novel MNT designs that target specific neurotrophin receptors [ 67 , 68 ] or utilizing targeted methods to control their spatiotemporal delivery within CNS lesions.…”

A quest for the stereo-electronic requirements for selective agonism for the neurotrophin receptors TrkA and TrkB in 17-spirocyclic-dehydroepiandrosterone derivatives

“…Based on our previous results (Yilmaz et al, 2022 ) that we identified compound ENT-A010 bearing a cyclopropyl group conjugated to an α,β-unsaturated ester as a dual agonist of TrkA and TrkB receptors, we set out to prepare a small series of cyclobutyl derivatives to clarify the optimum size of the C17-spirocyclic moiety. Thus, the C17-cyclobutanone analog ( ENT-A076 ), the α,β-unsaturated cyano ( ENT-A077 ), α,β-unsaturated ethyl ester ( ENT-A079 ), α,β-unsaturated methyl ester ( ENT-A087 ), and α,β-unsaturated acid ( ENT-A080 ) derivatives were prepared.…”

“…Incubation conditions were optimized to ensure linear metabolite formation with respect to protein concentration and reaction time. All test compounds were assessed at 1 μM based on our ADMET standard operating procedures and protocols, also published previously (1 μM was selected based on our ADMET standard operating procedures and protocols also published previously) (Rogdakis et al, 2022 ; Yilmaz et al, 2022 ). Approximately 1 mM of NADPH served as a cofactor.…”

“…Test compounds were assessed at 1 μM for their effects on CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. Approximately 1 μM was selected based on our ADMET standard operating procedures and protocols also published previously (Rogdakis et al, 2022 ; Yilmaz et al, 2022 ). CYP450-enzymatic activity was determined based on the kinetic model for each CYP450 isoform (Cohen et al, 2003 ; Veith et al, 2009 ).…”

“…However, it was shown that BNN27 undergoes rapid hydroxylation and subsequent excretion during hepatic catabolism, resulting in an elimination constant (K el ) of 0.465 h −1 and a mean residence time (MRT) of 2.154 h in murine models (Bennett et al, 2016 ; Tsika et al, 2021 ). To address the metabolic stability issue of BNN27 while maintaining potency and enhancing selectivity toward TrkA or TrkB receptors, our initial research efforts sought to replace the C-17 spiro epoxide moiety with the more stable cyclopropyl group with promising results (Rogdakis et al, 2022 ; Yilmaz et al, 2022 ).…”