Methylspinazarin is a naphthoquinone bacterial metabolite that has been found in Streptomyces and is an inhibitor of catechol O-methyltransferase (COMT; IC50 = 0.8 μg ml).1 It is selective for COMT over tyrosinehydroxylase, DOPA decarboxylase, and dopamine-β-hydroxylase at 100 μg ml. Methylspinazarin decreases blood pressure in spontaneously hypertensive rats when administered at a dose of 50 mg kg. |1. Chimura, H., Sawa, T., Takita, T., et al. Methylspinazarin and dihydromethylspinazarin, gatechol-O-methyl transerfase inhibitors produced by Streptomyces. J. Antibiot. 26(2), 112-114 (1973).
L-Tyrosine-13C9,15N is intended for use as an internal standard for the quantification of L-tyrosine by GC- or LC-MS. L-Tyrosine is a non-essential amino acid.1It is produced by hydroxylation of phenylalanine by phenylalanine hydroxylase but can also be obtained from dietary sources or degradation of endogenous proteins, resulting in L-tyrosine release.1,2L-Tyrosine is a precursor in the biosynthesis of catecholamine neurotransmitters, melanins, and thyroid hormones.3Plasma, skeletal muscle, and erythrocyte levels of L-tyrosine are decreased in patients with chronic kidney disease.1 1.Kopple, J.D.Phenylalanine and tyrosine metabolism in chronic kidney failureJ. Nutr.137(6 Suppl 1)1586S-1590S(2007) 2.Webster, D., and Wildgoose, J.Tyrosine supplementation for phenylketonuriaCochrane DB Syst. Rev.2013(6)CD001507(2013) 3.Slominski, A., and Paus, R.Towards defining receptors for L-tyrosine and L-DOPAMol. Cell Endocrinol.99(2)C7-C11(1994)
Catalpalactone exhibits high antitermitic, and cytotoxic activities, it exhibits potent inhibitory effects on lipopolysaccharide-induced NO synthesis in RAW 264.7 cells , with IC50 values of 9.80 microM. Catalpalactone can inhibit dopamine biosynthesis by