<unk> <unk>  is a metabolite of the neurotransmitter<unk> ine.<unk> ine can be metabolized into one of three substances. One such substance is<unk> . Another is<unk> -methoxytyramine <unk> -MT). Both of these substances are degraded to form homovanillic<unk>  (HVA). Both degradations involve the enzymes monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT), albeit in reverse order: MAO catalyzes<unk> ine to<unk> , and COMT catalyzes<unk>  to HVA; whereas COMT catalyzes<unk> ine to<unk> -MT and MAO catalyzes<unk> -MT to HVA. The third metabolic end-product of<unk> ine is norepinephrine (noradrenaline).<unk>  can be oxidized by hydrogen peroxide, leading to the formation of toxic metabolites which destroy<unk> ine storage vesicles in the substantia nigra. This may contribute to the failure of levodopa treatment of Parkinson's disease. A MAO-B inhibitor such as selegiline or rasagiline can prevent this from happening. Biodegradation of<unk> ine It can also be found in the bark of Eucalyptus globulus. This product has been synthesized (52% yield) from<unk> -hydroxyphenylacetic<unk>  via aerobic biotransformation using whole cell cultures of Arthrobacter protophormiae.
3,4-Dihydroxyphenylacetic acid
Beta-Hydroxy beta-methylbutyric acid
Phenylacetic acid
Asymmetric dimethylarginine
Gamma-Amino-beta-hydroxybutyric acid
Gamma-Hydroxybutyric acid
Estradiol propoxyphenylpropionate
Doisynolic acid