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Caprospinol: Discovery of a Steroid Drug Candidate to Treat Alzheimer’s Disease Based on 22 R ‐Hydroxycholesterol Structure and Properties
Author(s) -
Papadopoulos V.,
Lecanu L.
Publication year - 2012
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2011.02167.x
Subject(s) - drug , steroid , drug discovery , medicine , disease , alzheimer's disease , endocrinology , drug candidate , pharmacology , bioinformatics , biology , hormone
The overall ability of the brain to synthesise neuroactive steroids led us to the identification of compounds that would reproduce aspects of neurosteroid pharmacology. The rate‐determining step in neurosteroid biosynthesis is the import of the substrate cholesterol into the mitochondria, where it is metabolised into pregnenolone via the intermediate 22 R ‐hydroxycholesterol. The levels of translocator protein 18‐kDa, mediating the import of cholesterol into mitochondria, correlated with increased pregnenolone formation and reduced levels of 22 R ‐hydroxycholesterol in biopsies from Alzheimer’s disease (AD), but not age‐matched control, brains. 22 R ‐hydroxycholesterol was shown to protect against β‐amyloid (Aβ 42 )‐induced neurotoxicity. In search of 22 R ‐hydroxycholesterol stable analogues, we identified the naturally occurring heterospirostenol, (22 R ,25 R )‐20α‐spirost‐5‐en‐3β‐yl hexanoate (caprospinol) and derivatives that protect neuronal cells against Aβ 1–42 neurotoxicity. The neuroprotective effect of caprospinol is the result of a combination of overlapping properties, including: (i) the ability to bind to Aβ 42 and reduce plaque formation in the brain in vivo ; (ii) interaction with components of the mitochondria respiratory chain resulting in an anti‐uncoupling effect; (iii) the capacity to scavenge Aβ 42 monomers present in mitochondria; and (iv) the property of being a sigma‐1 receptor ligand. In vivo , caprospinol crosses the blood–brain barrier, accumulates in the brain, and restores cognitive impairment in a pharmacological rat model of AD. Caprospinol is stable, does not bind to known steroid receptors, is devoid of mutagenic and genotoxic properties, and is devoid of acute toxicity in rodents. The pharmacokinetics and pharmacodynamics of caprospinol were studied, and long‐term toxicity studies are under investigation, aiming to develop this compound as a disease‐modifying drug for the treatment of AD.