L-Norvaline

Sexual impairment is an established risk factor in diabetes mellitus affecting about 75% of male diabetic population. In diabetes overexpression of arginase leads to decreased production of NO and diminished erectile response. Inhibition of arginase enzyme can lead to improvement in diabetes induced sexual dysfunction. In the present study diabetes mellitus was induced in adult male rats by intraperitoneal injection of single dose of streptozotocin (65mg/kg) in 0.1M Citrate buffer pH 4.5 and after 72h fasting serum glucose level was checked by glucose oxidase-peroxidase method and those animals showing FSG above 250mg/dl were selected. Diabetic animals were divided into four groups comprising six animals in each. l-Norvaline, potent arginase inhibitor was administered at a dose of 10mg/kg ip to the different groups of diabetic animals for a period of 30 days. Sildenafil at a dose of 5mg/kg orally was used as a standard drug. Mating behavior tests were performed at 0, 15th and 30th days.

Crystals of maleates of three amino acids with hydrophobic side chains [L-leucenium hydrogen maleate, C6H14NO2(+)·C4H3O4(-), (I), L-isoleucenium hydrogen maleate hemihydrate, C6H14NO2(+)·C4H3O4(-)·0.5H2O, (II), and L-norvalinium hydrogen maleate-L-norvaline (1/1), C5H11NO2(+)·C4H3O4(-)·C5H12NO2, (III)], were obtained. The new structures contain C2(2)(12) chains, or variants thereof, that are a common feature in the crystal structures of amino acid maleates. The L-leucenium salt is remarkable due to a large number of symmetrically non-equivalent units (Z' = 3). The L-isoleucenium salt is a hydrate despite the fact that L-isoleucine is a nonpolar hydrophobic amino acid (previously known amino acid maleates formed hydrates only with lysine and histidine, which are polar and hydrophilic). The L-norvalinium salt provides the first example where the dimeric cation L-Nva...L-NvaH(+) was observed. All three compounds have layered noncentrosymmetric structures.

The title tripeptide, C17H23N3O6, contains a nonproteinogenic C-terminal amino acid residue, norvaline, which is an isomer of the amino acid valine. Norvaline, unlike valine, has an unbranched side chain. The mol-ecule has a Gly-Gly segment which adopts an extended conformation. The norvaline residue also adopts an extended backbone conformation while its side chain has a g (+) t conformation. In the crystal lattice, N-H⋯O and O-H⋯O hydrogen bonds stabilize the packing. Mol-ecules translated along the crystallographic a axis associate through an N-H⋯O hydrogen bond. The remaining three hydrogen bonds are between mol-ecules related by a 2 1 screw axis.