Treatment of erectile dysfunction using isoquinoline compound melanocortin receptor ligands

A method for treating erectile dysfunction in a subject, comprising administering to the subject an effective amount of a melanocortin receptor ligand comprising the isoquinoline formula

• wherein:
• R1 is selected from the group consisting of C1 to C9 alkylene, C1 to C9 substituted alkylene, C2 to C9 alkenylene, C2 to C9 substituted alkenylene, C2 to C9 alkynylene, C2 to C9 substituted alkynylene, C7 to C12 phenylalkylene, C7 to C12 substituted phenylalkylene and —(CH2)u—CH(NHR8)—;
• wherein u is selected from a number 1 to 8;
• and
• R8 is selected from the group consisting of a hydrogen atom, C1 to C9 alkyl, C1 to C9 substituted alkyl, C7 to C12 phenylalkyl and C7 to C12 substituted phenylalkyl;
• R2 is selected from the group consisting of phenyl, substituted phenyl, naphthyl, substituted naphthyl, C7 to C12 phenylalkyl, C7 to C12 substituted phenylalkyl, a heterocyclic ring and a substituted heterocyclic ring;
• R3, R4, R5 and R6 are independently a hydrogen atom, halo, hydroxyl, protected hydroxyl, cyano, nitro, C1 to C6 alkyl, C2 to C7 alkenyl, C2 to C7 alkynyl, C1 to C6 substituted alkyl, C2 to C7 substituted alkenyl, C2 to C7 substituted alkynyl, C1 to C7 alkoxy, C1 to C7 acyloxy, C1 to C7 acyl, C3 to C7 cycloalkyl, C3 to C7 substituted cycloalkyl, C5 to C7 cycloalkenyl, C5 to C7 substituted cycloalkenyl, a heterocyclic ring, C7 to C12 phenylalkyl, C7 to C12 substituted phenylalkyl, phenyl, substituted phenyl, naphthyl, substituted naphthyl, cyclic C2 to C7 alkylene, substituted cyclic C2 to C7 alkylene, cyclic C2 to C7 heteroalkylene, substituted cyclic C2 to C7 heteroalkylene, carboxyl, protected carboxyl, hydroxylmethyl, protected hydroxylmethyl, amino, protected amino, (monosubstituted)amino, protected (monosubstituted)amino, (disubstituted)amino, carboxamide, protected carboxamide, C1 to C4 alkylthio, C1 to C4 alkylsulfonyl, C1 to C4 alkylsulfoxide, phenylthio, substituted phenylthio, phenylsulfoxide, substituted phenylsulfoxide, phenylsulfonyl and substituted phenylsulfonyl;
• X is selected from the group consisting of hydroxyl, amino, protected amino, (monosubstituted)amino, (disubstituted)amino, an amino acid, aniline, substituted aniline, a heterocyclic ring, an aminosubstituted heterocyclic ring, and a heterocyclic ring substituted with a secondary or tertiary amine;
• and
• Y is selected from the group consisting of CH2NHR7 and C(O)NHR7,
• wherein R7 is selected from the group consisting of a hydrogen atom, C1 to C6 alkyl and C1 to C6 substituted alkyl.