Syntheses of NAMDA derivatives inhibiting NO production in BV-2 cells stimulated with lipopolysaccharide

Collision-induced dissociation of phenethylamides: role of ion-neutral complexes

RATIONALE

Phenethylamides are a large group of naturally occurring molecules found both in the plant and animal kingdoms. In addition, they are used as intermediates for the synthesis of pharmaceutically important dihydro- and tetrahydroisoquinolines. To enable efficient characterization of this class of molecules, a detailed mass spectrometric fragmentation study of a broad series of analogs was carried out.

METHODS

The test compounds were synthesized using standard methods for amide bond formation. Low-energy high-resolution tandem mass spectra were acquired on a hybrid quadrupole/time-of-flight mass spectrometer using positive ion electrospray ionization.

RESULTS

A total of 26 analogs were investigated in the study. Fragmentation of phenethylamides was found to proceed via intermediate ion-neutral complexes. The complexes can break down via multiple pathways including dissociation, proton transfer, Friedel-Crafts acylation, and single electron transfer. The relative contribution of each of these pathways strongly depends on the structure of the coupling amine and acid.

CONCLUSIONS

A general scheme for the fragmentation of phenethylamides was developed. This study further extends the knowledge base of the ion-neutral complex by discovering Friedel-Crafts acylation as a novel reaction. The strong influence of minor structural modifications on the fragmentation patterns highlights the importance of testing many analogs in order to fully predict a fragmentation pattern of a particular class of molecules.

A novel compound PTIQ protects the nigral dopaminergic neurones in an animal model of Parkinson's disease induced by MPTP

BACKGROUND AND PURPOSE

In Parkinson's disease, the dopaminergic neurones in the substantia nigra undergo degeneration. While the exact mechanism for the degeneration is not completely understood, neuronal apoptosis and neuroinflammation are thought to be key contributors. We have recently established that MMP-3 plays crucial roles in dopaminergic cell death and microglial activation.

EXPERIMENTAL APPROACH

We tested the effects of 7-hydroxy-6-methoxy-2-propionyl-1,2,3,4-tetrahydroisoquinoline (PTIQ) on expression of MMP-3 and inflammatory molecules and dopaminergic cell death in vitro and in an animal model of Parkinson's disease, and Parkinson's disease-related motor deficits. The pharmacokinetic profile of PTIQ was also evaluated.

KEY RESULTS

PTIQ effectively suppressed the production of MMP-3 induced in response to cellular stress in the dopaminergic CATH.a cell line and prevented the resulting cell death. In BV-2 microglial cells activated with lipopolysaccharide, PTIQ down-regulated expression of MMP-3 along with IL-1β, TNF-α and cyclooxygenase-2 and blocked nuclear translocation of NF-κB. In the mouse model of Parkinson's disease ,induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), PTIQ attenuated the associated motor deficits, prevented neurodegeneration and suppressed microglial activation in the substantia nigra. Pharmacokinetic analysis showed it was relatively stable against liver microsomal enzymes, did not inhibit the cytochrome p450 isozymes or the hERG ion channel, exhibited no cytotoxicity on liver cells or lethality when administered at 1000 mg kg(-1) and entered the brain rather rapidly yielding a 28% brain:plasma ratio after i.p. injection.

CONCLUSIONS AND IMPLICATIONS

These results suggest PTIQ has potential as a candidate drug for disease-modifying therapy for Parkinson's disease.

Doxycycline is neuroprotective against nigral dopaminergic degeneration by a dual mechanism involving MMP-3

In Parkinson disease (PD), the dopaminergic (DAergic) neurons in the substantia nigra undergo degeneration. While the exact mechanism for the degeneration is still not completely understood, neuronal apoptosis and inflammation are thought to play roles. We have recently obtained evidence that matrix metalloproteinase (MMP)-3 plays a crucial role in the apoptotic signal in DAergic cells as well as activation of microglia. The present study tested whether doxycycline might modulate MMP-3 and provide neuroprotection of DAergic neurons. Doxycycline effectively suppressed the expression of MMP-3 induced in response to cellular stress in the DAergic CATH.a cells. This was accompanied by protection of CATH.a cells as well as primary cultured mesencephalic DAergic neurons via attenuation of apoptosis. The active form of MMP-3, released under the cell stress condition, was also decreased in the presence of doxycycline. In addition, doxycycline led to downregulation of MMP-3 in microglial BV-2 cells exposed to lipopolysaccharide (LPS). This was accompanied by suppression of production of nitric oxide and TNF-alpha, as well as gene expression of iNOS, TNF-alpha, IL-1beta, and COX-2. In vivo, doxycycline provided neuroprotection of the nigral DAergic neurons following MPTP treatment, as assessed by tyrosine hydroxylase immunocytochemistry and silver staining, and suppressed microglial activation and astrogliosis as assessed by Iba-1 and GFAP immunochemistry, respectively. Taken together, doxycycline showed neuroprotective effect on DAergic system both in vitro and in vivo and this appeared to derive from anti-apoptotic and anti-inflammatory mechanisms involving downregulation of MMP-3.