dopan.
/ˈdəʊpə/, U.S. /ˈdoʊpə/ Chemistry and Biochemistry.
3,4-Dihydroxyphenylalanine, C9H11NO4, a crystalline amino-acid which occurs naturally (not as a constituent of proteins) and is used in the treatment of Parkinsonism; in humans it is a precursor of noradrenaline and of melanin, being formed by the oxidation of tyrosine in the nerves and adrenal medulla.
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1917 Jrnl. Chem. Soc. 112 i. 675 When a frozen section of..skin is treated with a 1‰ solution of 3:4-dihydroxyphenylalanine (termed ‘dopa’), oxidation and condensation occur with the formation of a..pigment (dopamelanin)..owing to the action of an..enzyme, dopaoxydase.
1923 Nature 3 Nov. 675/1 The presence of ‘dopa’ (3,4-dioxyphenylalanin) in the cocoons of night-butterflies and sawflies causes spontaneous formation of melanine when water is admitted.
1956 Nature 3 Mar. 430/2 The mechanism of formation of melanin pigments in insects may be as follows: Phenylalanine → tyrosine → dopa → dopaquinone..→ dopachrome, [etc.].
1962 J. H. Burn Drugs, Med. & Man xi. 115 There are..substances which can pass through the blood-brain barrier..easily. One of these is the substance out of which noradrenaline is made. It is called dihydroxyphenylalanine, and is known as dopa for short.
1968 J. W. T. Dickerson in Davison & Dobbing Appl. Neurochem. ii. 61 The conversion of tyrosine to DOPA is probably mainly a non-enzymic one.
1970 Nature 4 Apr. 21/1 During the past decade a new approach to Parkinsonism has evolved, culminating in the introduction of l-dopa.
1970 Daily Tel. 8 Sept. 3/3 General practitioners in the London postal area can now prescribe L-Dopa for patients with Parkinson's disease.
This entry has not yet been fully updated (first published 1972; most recently modified version published online March 2022).
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