Methods for treating multiple sclerosis employing desmethylselegiline

#The present invention pertains to methods and pharmaceutical compositions for using the selegiline metabolite R(−)desmethylselegiline (also referred to simply as “desmethylselegiline” or “R(−)DMS”) either alone or in combination with its enantiomer, entdesmethylselegiline (also referred to as “S(+)desmethylselegiline” or “S(+)DMS”). In particular, the present invention provides compositions and methods for using these agents in the treatment of selegiline-responsive diseases and conditions, particularly diseases or conditions involving neuronal degeneration or neuronal rescue).

#Two distinct monoamine oxidase enzymes are known in the art: monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). The cDNAs encoding these enzymes show different promoter regions and distinct exon portions, indicating they are encoded independently at different gene positions. In addition, analysis of the two proteins has shown differences in their respective amino acid sequences.

#The first compound found to selectively inhibit MAO-B was R-(−)-N-methyl-N-(prop-2-ynyl)-2-aminophenylpropane, also known as L-(−)-deprenyl, R-(−)-deprenyl, or selegiline. Selegiline has the following structural formula: 1

#FIG. 1: HPLC Chromatogram of Purified R(−)DMS (Microsorb MV Cyano Column). The purity of a preparation of R(−)DMS was determined by HPLC on a Microsorb MV Cyano column and results are shown in FIG. 1. The column had dimensions of 4.6 mm×15 cm and was developed at a flow rate of 1.0 ml/min using a mobile phase containing 90% 0.01 M H3PO4(pH 3.5) and 10% acetonitrile. The column was run at a temperature of 40° C. and effluent was monitored at a wavelength of 215 nm. The chromatogram shows one major peak appearing at a time of 6.08 minutes and having 99.5% of the total light-absorbing material eluted from the column. No other peak had greater than 0.24%.

#FIG. 2: HPLC Elution Profile of R(−)DMS (Zorbax Mac-Mod C18 Column). The same preparation that was analyzed in the experiments discussed in FIG. 1 was also analyzed for purity by HPLC on a Zorbax Mac-Mod SB-C18 column (4.6 mm×75 mm). Effluent was monitored at 215 nm and results can be seen in FIG. 2. Greater than 99.6% of the light-absorbing material appeared in the single large peak eluting at a time of between 2 and 3 minutes.

#FIG. 3: Mass Spectrum of R(−)DMS. A mass spectrum was obtained for purified R(−)DMS and results are shown in FIG. 3. The spectrum is consistent with a molecule having a molecular weight of 209.72 and a molecular formula of C12H15N.HCl.

#The surprising utility of desmethylselegiline and ent-desmethylselegiline in treating selegiline-responsive diseases or conditions is attributable in part to their powerful action in preventing loss of dopaminergic neurons by promoting repair and recovery. Because desmethylselegiline prevents loss and facilitates recovery of nerve cell function, it is of value in a wide variety of neurodegenerative and neuromuscular diseases. In this regard, desmethylselegiline is at least as potent as selegiline, and in one model of neuroprotection, appeared to be substantially more potent. This is described more empirically in Examples 4 to 9 below.

#A. Desmethylselegiline

#Desmethylselegiline (designated below as “R(−)DMS”) is prepared by methods known in the art. For example, desmethylselegiline is a known chemical intermediate for the preparation of selegiline as described in U.S. Pat. No. 4,925,878. Desmethylselegiline can be prepared by treating a solution of R(−)-2-aminophenylpropane (levoamphetamine): 3