Biopterin isolation

A number of nitrogen heterocyclic, aromatic compounds, riboflavin 26, folic acid 27a and biopterin 27b, isolated from natural sources, are related in structure to natural redox enzyme cofactors. The electrochemistry of these and related compounds has been studied extensively. 

Among the simple pterins isolated from the eyes of Drosophila3 0 is sepiapterin (Fig. 15-17), in which the pyrazine ring has been reduced in the 7,8 position and a short side chain is present at position 6. Reduction of the carbonyl group of sepiapterin with NaBH4 followed by air oxidation produces biopterin, the most widely distributed of the pterin compounds. 

First isolated from human urine, biopterin (Fig. 15-17) is present in liver and other tissues where it functions in a reduced form as a hydroxylation coenzyme (see Chapter 18).338 It is also present in nitric oxide synthase (Chapter 18).341/342 Other functions in oxidative reactions, in regulation of electron transport, and in photosynthesis have been proposed.343 Neopterin, found in honeybee larvae, resembles biopterin but has a D-erythro configuration in the side chain. The red eye pigments of Drosophila, called drosopterins, are complex dimeric pterins containing fused 7-membered rings (Fig. 15-17).344 345... 

Both biopterin (30) and neopterin (31) belong to the family of naturally occurring 6-hydroxypropylpterin and are isolated as major pterins from almost all higher animals. Due to the existence of 2 chiral centers on the propyl side chain, 4 diastereomers are possible in biopterin and neopterin, and isomers 32-37 are found and considered to be minor or exceptional pterins. The absolute configurations of biopterin and neopterin are R,2 S and l S,2 R, respectively, and expedient notations of L-erytho, for biopterin, and d-erythro, for neopterin, have frequently been used. Following these notations, the di-... 

Methylbiopterin and 2 -deoxybiopterin are two naturally occurring pterin-6-yl acyclo C-nucleosides related to biopterin. The former was isolated from methanol extracts of the marine anthozoan Asteroides calycularis Pallas and found to inhibit growth of mouse and chick fibroblasts in culture (87E950), whereas the latter was isolated from urine of patients with malignant lymphoma (95MI2). 

Both 625 and 646 were isolated from urine of patients with a transient type of hyperphenylalaninemia that is related to a biopterin synthetase deficiency [88BBR( 153)715,88MI4,88MI5 90HCA1064], Anapterin (646) was also found in saliva of healthy human adults (89MI1). 

The term C-nucleoside was only coined after isolation and characterization of the first member of this class pseudouridine, in 1975 [97ACH(ip)]. Before that, alditolyl derivatives of some heterocycles (acyclo C-nucleo-sides) were known both as natural products (alditolyl pteridines or biopterins) as well as products of syntheses (e.g., alditolyl derivatives of imidazoles, benzimidazoles, thiazoles, benzothiazoles, 1,2,3-triazoles, quinoxalines, and flavazoles) and were classified as carbohydrate derivatives of heterocyclic compounds. After isolation of pseudouridine, other naturally occurring members were successively isolated, characterized, and synthesized. It is worth mentioning that synthesis preceded isolation in two cases 9-dea-zaadenosine and pyrrolosine. Comparison with the synthetic compounds facilitated structure elucidation in one case (9-deazaadenosine) and structure reassignment in the other (pyrrolosine). 

Biopterin (1) is one of the potent natural pteridines isolated from human urine as the growth factor of Crithidia fasciculata It has attracted much attention as a precursor of (67 )-tetrahydrobiopterin, which was known as a coenzyme of aromatic amino acid monooxygenase. ... 

Biopterin (890), a pterin isolated from human urine, is an important precursor of tetra-hydrobiopterin, which is useful in the treatment of Parkinson s disease. The anti-d o arrangement in the side chain is accessible via organometallic addition to a lactaldehyde (Scheme 118). 

Noguchi, Y., Ishii, A., Matsushima, A., Haishi, D., Yasumuro, K.-i., Moriguchi, T., Wada, T., Kodera, Y., Hiroto, M., Nishimura, H., Sekine, M., and Inada, Y. (1999). Isolation of biopterin-a-glucoside from Syirulina (Arthrospira) ylatensis and its physiologic function. 

Found in human blood and urine. First isol. from the pupae of bees. Precursor in biosynth. of Biopterin. [a]o +45 (c, 0.3 in O.IM HCl). 

A closely related substance is decenolic acid, which has been isolated from Royal Jelly . Biopterin has also been found in Royal Jelly, but its biological function for the bee has not yet been determined. 

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