6-Biopterin (L-Biopterin) is the oxidized form of tetrahydro-L-biopterin (BH4), a nitric oxide synthase (NOS) cofactor. L-Biopterin can be reduced to BH4 via thioredoxin reductase followed by dihydropteridine reductase or reduced glutathione. It is extremely toxic to human melanocytes in culture (IC50 = 0.2 μM after 48 hrs). L-Biopterin is rarely found under physiological conditions except in the epidermis of patients with the depigmentation disorder Vitiligo.
L-Biopterin is a pteridine widely distributed in nature; naturally occurring as the L-erythro-form. Considered as a growth factor for some insects. Fluoresces with a blue color in alkaline solution.
6-Biopterin is an enzymatic cofactor derived from pterin and involved in certain oxidation-reduction reactions. It is a biopterin in which the 1,2-dihydroxypropyl group has (1R,2S)-configuration; naturally occurring form. It is an enantiomer of a D-erythro-biopterin.
6-Biopterin is an oxidation product from the melanogenesis regulating cofactor (6R)5,6,7,8 tetrahydrobiopterin (6-BH4). In vitro, 6-Biopterin is cytotoxic to melanocytes. However, in vivo, 6-Biopterin is rapidly and sequentially reduced back to 6-GH4 via q-BH2. Recent studies suggest that 6-Biopterin among other pteridines may be a useful non-invasive biomarker for cancer.
Biopterin is synthesized by reacting 2,4,5-triamino-6-hydroxypyrimidine with 5-deoxy-L-arabinosone in aqueous solution at pH of about 7.5 to 10, acidifying and then recrystallizing by dissolving in basic solution and precipitating with acid. 5-deoxy-L-arabinosone is prepared by oxidizing S-deoxy-L-arabinose, which is prepared from L-rhamnose, using cupric acetate.
Process for the synthesis of biopterin
Moderately toxic by ingestion andintraperitoneal routes. Mutation data reported. Whenheated to decomposition it emits toxic vapors of NOx.
[1] SCHALLREUTER K.U. Cytotoxicity of 6-Biopterin to Human Melanocytes[J]. Biochemical and biophysical research communications, 1994, 204 1: Pages 43-48. DOI:
10.1006/bbrc.1994.2423[2] JEREMY MOORE Karin U S John M Wood. Evidence for Specific Complex Formation between α-Melanocyte Stimulating Hormone and 6(R)-l-Erythro-5,6,7,8-tetrahydrobiopterin using Near Infrared Fourier Transform Raman Spectroscopy[J]. Biochemistry Biochemistry, 1999, 38 46: 15317-15324. DOI:
10.1021/bi991448j
