U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

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Showing 171 - 180 of 520 results

Status:
Other

Class (Stereo):
CHEMICAL (ABSOLUTE)

Status:
Other

Class (Stereo):
CHEMICAL (RACEMIC)

Status:
Other

Class (Stereo):
CHEMICAL (RACEMIC)

Status:
Other

Class (Stereo):
CHEMICAL (ABSOLUTE)



3-Tyrosine, in contrast to the para isomer, is readily racemized. The majority of the load was metabolized to m-hydroxyphenylacetic acid but m-hydroxymandelic acid and 3,4-dihydroxyphenylacetic acid were also detected. Low circulating levels of m-tyrosine in the plasma suggest that most of the load is held due to a first pass effect somewhere in the enterohepatic system and that this portion of the load is not in equilibrium with the plasma m-tyrosine. The metabolism of a m-tyrosine may give further insight into the deficiencies of the phenylalanine hydroxylating system found in the various phenotypes of phenylketonuria. 3-Tyrosine has been used experimentally as a substitute for L-DOPA in the treatment of Parkinsonism. 3-tyrosine mimics the action of Dopa in two experimental animal models. It was also obvious from the experiments with d,l- and l-m-tyrosine that only the l-isomer (3-Tyrosine) is active.
3-O-methyldopa (3-OMD) is a metabolite of L-3,4-dihydroxyphenylalanine (L-DOPA), a drug used for the treatment of Parkinson's disease patients. 3-OMD is formed by catechol-O-methyltransferase. 3-OMD may be responsible for the side effects of L-DOPA.
Status:
Other

Class (Stereo):
CHEMICAL (RACEMIC)

Conditions:

There is no information related to the pharmacological application of DL-thyroxine, but is known, that this is a mixture of two: L (levothyroxine) and D (dextrothyroxine) forms, and it was shown, that levothyroxine possessed greater antioxidative effect, than the DL.
Status:
Other

Class (Stereo):
CHEMICAL (ABSOLUTE)

Status:
US Previously Marketed
Source:
21 CFR 310.545(a)(20) weight control cystine
Source URL:

Class (Stereo):
CHEMICAL (ABSOLUTE)



Cystine is the oxidized dimer form of the amino acid cysteine. Cystine serves two biological functions, a site of redox reactions and a mechanical linkage that allows proteins to retain their 3-dimensional structure. It is common in many foods such as eggs, meat, dairy products, and whole grains as well as skin, horns and hair. Human hair and skin contain approximately 10–14% cystine by mass. Cysteine supplements are sometimes marketed as anti-aging products with claims of improved skin elasticity. Cysteine is more easily absorbed by the body than cystine, so most supplements contain cysteine rather than cystine. N-acetyl-cysteine (NAC) is better absorbed than other cysteine or cystine supplements.
Status:
US Previously Marketed
Source:
21 CFR 310.545(a)(20) weight control phenylalanine
Source URL:

Class (Stereo):
CHEMICAL (ABSOLUTE)



Phenylalanine is a biologically essential amino acid that acts as a precursor to tyrosine and the catecholamines (epinephrine, norepinephrine, dopamine, and tyramine), and is a constituent of many central nervous system neuropeptides. Normal dietary levels of phenylalanine are approximately 1-2 grams daily. Phenylalanine appears in two forms which are identical mirror images of each other: L-phenylalanine, a nutritional supplement, and D-phenylalanine, an effective painkiller and antidepressant due to its ability to inhibit the breakdown of enkephalins, the brain’s natural pain killers.

Showing 171 - 180 of 520 results