Stereoselectivity of satropane, a novel tropane analog, on iris muscarinic receptor activation and intraocular hypotension

L-Satropane Prevents Retinal Neuron Damage by Attenuating Cell Apoptosis and Aβ Production via Activation of M1 Muscarinic Acetylcholine Receptor

Muscarinic acetylcholine receptor (mAChR) agonists have been used to treat glaucoma due to their intraocular pressure-lowering effects. Recently, it has been reported that retinal mAChRs activation can also stimulate neuroprotective pathways.

PURPOSE

In our study, we evaluated the potential neuroprotective effect of L-satropane, a novel mAChR agonist, on retinal neuronal injury induced by cobalt chloride (CoCl₂) and ischemia/reperfusion (I/R).

METHODS

CoCl₂-induced hypoxia injury in cultured cell models and I/R-induced retinal neuronal damage in rats in vivo were used to evaluate the abilities of L-satropane. In detail, we measured the occurrence of retinal pathological changes including molecular markers of neuronal apoptosis and Aβ expression.

RESULTS

Pretreatment with L-satropane protects against CoCl₂-induced neurotoxicity in PC12 and primary retinal neuron (PRN) cells in a dose-dependent manner by increasing retinal neuron survival. CoCl₂ or I/R-induced cell apoptosis by upregulating Bax expression and downregulating Bcl-2 expression, which resulted in an increased Bax/Bcl-2 ratio, and upregulating caspase-3 expression/activity was significantly reversed by L-satropane treatment. In addition, L-satropane significantly inhibited the upregulation of Aβ production in both retinal neurons and tissue. We also found that I/R-induced histopathological retinal changes including cell loss in the retinal ganglion cell layer (GCL) and increased TUNEL positive retinal ganglion cells in GCL and thinning of the inner plexiform layer (IPL) and inner nuclear layer (INL) were markedly improved by L-satropane. The effects of L-satropane were largely abolished by the nonselective mAChRs antagonist atropine and M1-selective mAChR antagonist pirenzepine.

CONCLUSION

These results demonstrated that L-satropane might be effective in preventing retinal neuron damage caused by CoCl₂ or I/R. The neuroprotective effects of L-satropane may be attributed to decreasing cell apoptosis and Aβ production through activation of M1 mAChR.

Rational design, synthesis and 2D-QSAR studies of antiproliferative tropane-based compounds

Novel tropane-based compounds were synthesized exhibiting antiproliferative properties against HepG2 and MCF7 carcinoma cell lines.

Activation of M1 mAChRs by lesatropane rescues glutamate neurotoxicity in PC12 cells via PKC-mediated phosphorylation of ERK1/2

Lesatropane, a synthesized chiral tropane (3S, 6S-isomer of satropane), is a novel muscarinic agonist, and is being under preclinical development in China for the treatment of primary glaucoma. The reports concerning that activation of muscarinic acetylcholine receptors (mAChRs) could protect cells against apoptosis prompted us to study the neuroprotective effects of lesatropane and the mechanism. We found that lesatropane could protect PC12 cells from glutamate-induced neurotoxicity and reverse the decreased ERK1/2 activation caused by glutamate. Atropine or pirenzepine, antagonist of mAChR or M1 mAChR, antagonized the protective effects of lesatropane respectively and suppressed the lesatropane's effects on ERK1/2. Furthermore, chelerythrine, a PKC inhibitor, partially suppressed ERK1/2 activation induced by lesatropane. The results indicated that the specific M1 mAChR via PKC-ERK1/2 pathway might be involved in the neuroprotective effects of lesatropane. While M1 mAChR is a therapeutic target of Alzheimer's disease (AD), the results of this paper contribute to further information concerning the activation of M1 mAChR as a therapeutic target in AD.

(1R,3S,5R,6S)-6-Hydr-oxy-3-tosyl-oxy-tropan-8-ium chloride

The title compound, C₁₅H₂₂NO₄S⁺·Cl⁻, is a hydrolysis product of lesatropane [(1R,3S,5R,6S)-6-acet­oxy-3-tosyl­oxytropane] hydro­chloride, a potential anti­glaucoma agent. As in lesatropane, the piperidine and pyrrolidine rings in the title compound adopt chair and envelope conformations, respectively. There are two mol­ecules in the unit cell with similar conformations. The crystal structure is stabilized by inter­molecular O—H⋯Cl and N—H⋯Cl hydrogen bonds.

Quantitative determination of a novel enantiomeric tropane analog, (-)-satropane, in biological fluids using liquid chromatography/tandem mass spectrometry

A sensitive, accurate and precise liquid chromatography-tandem mass spectrometry method was developed for the determination of (-)-satropane (3alpha-paramethyl-benzenesulfonyloxy-6beta-acetoxy-tropane) in rabbit aqueous humor. Since (-)-satropane may be absorbed from the aqueous humour with resultant systemic side effects, the LC-MS/MS method was also evaluated for its applicability in analyzing plasma samples containing this compound. (-)-Satropane and phentolamine (the internal standard, represented as IS) were detected by multiple reaction monitoring using the transitions m/z 354-182 and 282-212, respectively. The calibration curve was linear over the ranges 2-500 and 5-1000 ng/mL, and the values of the lower limit of quantification were 2 and 5 ng/mL for the microdialysis dialysate and rat plasma samples, respectively. The intra-day and inter-day precision and accuracy were better than 8.6 and 6.00%, respectively, in both matrices investigated. The absolute recovery of the plasma samples was more than 76.30%. The average matrix effects of (-)-satropane were 91.72 and 83.05% in the microdialysis dialysate and plasma samples, respectively. The validated method was successfully applied to analyze (-)-satropane in microdialysis dialysate and rat plasma samples, and this assay has been used to quantify (-)-satropane in the pharmacokinetic and toxicokinetic studies in our laboratory.

(1R,3S,5R,6S)-6-Acet-oxy-8-methyl-3-(p-tolyl-sulfon-yloxy)-8-azoniabicyclo-[3.2.1]octane (2R,3R)-2,3-bis-(benzo-yloxy)-3-carboxy-propanoate

The title compound, C(17)H(24)NO(5)S(+)·C(18)H(13)O(8) (-), is the key inter-mediate during the preparation of lesatropane [systematic name (1R,3S,5R,6S)-6-acetoxy-3-(4-methylphenylsulfonyloxy)tropane], a potential anti-glaucoma agent. The tertiary N atom of the tropane ring is involved in inter-molecular N-H⋯O hydrogen bonding, and the carboxylate groups are involved in inter-molecular O-H⋯O hydrogen bonding.

(1R,3S,5R,6S)-6-Acet-oxy-3-(4-methyl-phenyl-sulfon-yloxy)tropane

IN THE TITLE COMPOUND [SYSTEMATIC NAME: (1R,3S,5R,6S)-8-methyl-3-(4-methyl-phenyl-sulfon-yloxy)-8-aza-bicyclo-[3.2.1]octan-6-yl acetate], C(17)H(23)NO(5)S, the fused piperidine ring exists in a chair conformation with the N atom and one C atom displaced by 0.876 (2) and -0.460 (3) Å, respectively, on opposite sides of the mean plane defined by the other four atoms. The fused pyrrolidine ring adopts an envelope conformation with the N atom deviating by 0.644 (3) Å from the mean plane of the other four atoms.