Quantitation of total biopterin and tetrahydrobiopterin in plasma

Kinetics of acid-induced degradation of tetra- and dihydrobiopterin in relation to their relevance as biomarkers of endothelial function

“…It was found that 0.1% DTT offered better protection than 0.5 and 0.25% DTT. It was also observed that centrifugation of the blood sample right after it had been collected gave a lower total biopterin level compared to waiting for 3 h before centrifugation of the blood sample, and after 3 h the level of BH 4 started to decline whereas the total biopterin level remained constant for 24 h (Fekkes & Voskuilen-Kooijman, 2007). Our results do not show a higher biopterin level if the blood sample is allowed to stand for 3 h prior to centrifugation.…”

“…DTE and the closely related dithiothreitol (DTT) are often used to stabilize BH 4 in plasma before analysis. A concentration of 0.1%, corresponding to 6.5 mM, is commonly employed at which concentration DTT has been found to be able to stabilize BH 4 in plasma for a few hours (Fekkes & Voskuilen-Kooijman, 2007). TCEP is an antioxidant used primarily for reducing disulfide bonds.…”

Pteridine determination in human serum with special emphasis on HPLC methods with fluorimetric detection

“…As the reported values of total BIO in the plasma of healthy controls show large variations (6.9-23.6 nmol L −1 ), both BH4 and total BIO in plasma have been determined by means of RP-HPLC with fluorimetric detection [12]. The authors propose a modification of the Fukushima and Nixon method using DTT as an antioxidant to prevent the oxidation of the reduced form.…”

“…Hence, the content of BH4 in the original sample is calculated by the difference between the amounts of BIO obtained by acid and alkaline oxidations. Some modifications to this method are intended to prevent the auto-oxidation of BH4 by atmospheric oxygen at room temperature by using antioxidants such as dithioerythriol (DTE) or dithiothreitol (DTT) [12,23], but the effect of these reagents in the I 2 oxidation processes is not clear.…”

“…Several protected agents have been used in the analysis of pteridines: ascorbic acid, DTE and DTT [12], the last being currently the most recommended. Special caution must be taken into account in the analysis of BH4 and BH2.…”