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6R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for aromatic L-amino acid hydroxylases, including tyrosine hydroxylase (TH), alkylglycerol monooxygenase, and three types of nitric oxide (NO) synthases (NOS). Sepiapterin reductase (SPR) catalyzes the third step of BH4 biosynthesis. SPR gene-disrupted (Spr

Neopterin (NP), biopterin (BP) and monapterin (MP) exist in saliva. The physiological role of salivary NP as well as the pathophysiological role of increased NP in the immune-activated state has been unclear. Saliva is a characteristic specimen different from other body fluids. In this study, we analysed salivary NP and related pterin compounds, BP and MP and revealed some of its feature. High-performance liquid chromatography (HPLC) analysis of saliva and plasma obtained from 26 volunteers revealed that salivary NP existed mostly in its fully oxidized form. The results suggested that salivary NP as well as BP would mostly originate from the oral cavity, perhaps the salivary glands, and that salivary NP levels might not reflect those in the plasma. We also found that a gender difference existed in correlations between concentrations of salivary total concentrations of NP (tNP) and BP (tBP). HPLC analysis of saliva obtained from 5 volunteers revealed that the concentrations of salivary tNP as well as tBP fluctuated in an irregular fashion in various individuals. MP, a diastereomer of NP, might have come from oral cavity NP itself or its precursor. These results indicated that the nature of salivary NP might be different from that of NP in the blood or urine.

(6 R )‐l‐ erythro ‐5,6,7,8‐Tetrahydrobiopterin (BH4) is an essential cofactor for monoamine and nitric oxide (NO) production. Sepiapterin reductase (SPR) catalyzes the final step in BH4 biosynthesis. We analyzed the cardiovascular function of adult Spr gene‐disrupted ( Spr −/− ) mice for the first time. After weaning, Spr −/− mice suffered from hypertension with fluctuation and bradycardia, while the monoamine contents in these mice were less than 10% of those in the wild‐type mice as a result of BH4 depletion. Heart rate variability analysis indicated the sympathetic dominant state in Spr −/− mice. The endothelium‐dependent vascular relaxation in response to acetylcholine was significantly impaired in Spr −/− mice after sexual maturation (above 4 months old). Protein amounts of α 1 adrenergic receptor and eNOS in the aorta were not altered. Spr −/− mice exhibited hypoglycemia and elevation of plasma renin activity. Our results suggest that the hypertension with fluctuation and bradycardia of Spr −/− mice would be caused by an imbalance of sympathetic and parasympathetic input and impaired nitric oxide production in endothelial cells. We suggest an important role of BH4 and SPR in age‐related hypertension and a possible relationship with the cardiovascular instabilities in autonomic diseases, including Parkinson9s disease and spinal cord injury.

Aims: Cilostazol, a type III phosphodiesterase inhibitor, is utilized for the treatment of intermittent claudication and is considered to have the beneficial effects against the atherogenic process. In the present study, we examined the effects of cilostazol on BH4 biosynthesis in HUVEC treated with a mixture of the pro-inflammatory cytokines IFN-γ and TNF-α.Methods: Isolated HUVECs were grown to confluence and treated with IFN-γ (300 units/mL) and TNF-α (300 units/mL) for 16 h in order to stimulate BH4 biosynthesis. The BH4 levels were mea-sured by HPLC. The mRNA expression of GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme of BH4 biosynthesis, and GTPCH feedback regulatory protein (GFRP) were quantified by real-time PCR. The GTPCH protein expression was assessed by western blot analysis.Results: Cilostazol significantly reduced the BH4 levels in cytokine-stimulated HUVEC. Cilostazol produced a concomitant increase in the cAMP levels in HUVEC. Cilostazol decreased the GTPCH activity as well as the expression of GTPCH mRNA and protein. 8-bromo-cAMP (8Br-cAMP), a cell-permeable cAMP analogue, did not reproduce the effects of cilostazol. Cilostazol did not affect the cytokine-induced inhibition of GFRP mRNA expression.Conclusions: We conclude that cilostazol inhibited cytokine-stimulated BH4 biosynthesis via a cAMP-independent mechanism in HUVEC. Our data indicate that cilostazol reduced GTPCH activity and did so by suppressing the GTPCH protein levels.

Postnatal development of dopaminergic system is closely related to the development of psychomotor function. Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the biosynthesis of dopamine and requires tetrahydrobiopterin (BH4) as a cofactor. To clarify the effect of partial BH4 deficiency on postnatal development of the dopaminergic system, we examined two lines of mutant mice lacking a BH4-biosynthesizing enzyme, including sepiapterin reductase knock-out (Spr(-/-)) mice and genetically rescued 6-pyruvoyltetrahydropterin synthase knock-out (DPS-Pts(-/-)) mice. We found that biopterin contents in the brains of these knock-out mice were moderately decreased from postnatal day 0 (P0) and remained constant up to P21. In contrast, the effects of BH4 deficiency on dopamine and TH protein levels were more manifested during the postnatal development. Both of dopamine and TH protein levels were greatly increased from P0 to P21 in wild-type mice but not in those mutant mice. Serotonin levels in those mutant mice were also severely suppressed after P7. Moreover, striatal TH immunoreactivity in Spr(-/-) mice showed a drop in the late developmental stage, when those mice exhibited hind-limb clasping behavior, a type of motor dysfunction. Our results demonstrate a critical role of biopterin in the augmentation of TH protein in the postnatal period. The developmental manifestation of psychomotor symptoms in BH4 deficiency might be attributable at least partially to high dependence of dopaminergic development on BH4 availability.

According to the synthetic route for 11,12-methylenehexadec-11-enoic acid [10-(2-butyl-1-cyclopropenyl)decanoic acid] and the amide, their related cyclopropene compounds, which possessed a propene ring at the 7,8-, 9,10-, or 13,14-position in a C16 chain and the 11,12-position in a C14 or C18 chain, were synthesized via the corresponding 1-alkyl-1,2,2-tribromocyclopropane. Their activities as biosynthetic inhibitors of bombykol [(10E,12Z)-10,12-hexadecadien-1-ol; sex pheromone of the silkworm moth Bombyx mori L.] were measured with virgin female silkworm moths in vivo. The 7,8-methylene compounds were inactive even at the dose of 10 μg/gland, but other compounds at 1 μg/gland inhibited the conversion of [16,16,16-2H3]hexadecanoic acid to bombykol to some extent. Each amide showed stronger inhibitory activity than the corresponding acid, and the 11,12-methylene amide with a C16 chain was the strongest (I50 = 0.016 μg/gland) among the tested compounds. Furthermore, experiments comparing the incorporation of...

11,12-メチレンヘキサデク-11-エノイック酸とそのアミド体を, トリブロモシクロプロパン化合物を脱ブロム化後アルキル化する方法 (Baird ら, 1992) を用いて合成した. それら化合物のフェロモン生合成に及ぼす影響をカイコガ処女雌を用いて検討したところ, フェロモン腺への処理はボンビコール含量の低下をもたらした. また, 14C標識あるいは2H標識ヘキサデカン酸を利用した実験において, 上記のシクロプロペン化合物をフェロモン腺あたり1μg前処理すると, 生合成前駆体のボンビコールおよび (Z)-11-ヘキサデセノールへの変換が完全に抑えられ, ヘキサデカノールへの変換は逆に促進された. 以上の結果より, これら11-位にシクロプロペン構造をもつ化合物は, ボンビコール生合成の不飽和化の過程 (11-位とおそらく10,12-位不飽和化反応) を阻害することが明らかになった. 一方, ニトリル誘導体はフェロモン生合成阻害活性を示さなかった.

Objective— Diabetes mellitus is associated with increased oxidative stress, which induces oxidation of tetrahydrobiopterin (BH4) in vessel wall. Without enough BH4, eNOS is uncoupled to L-arginine and produces superoxide rather than NO. We examined the role of uncoupled eNOS in vascular remodeling in diabetes. Methods and Results— Diabetes mellitus was produced by streptozotocin in C57BL/6J mice. Under stable hyperglycemia, the common carotid artery was ligated, and neointimal formation was examined 4 weeks later. In diabetic mice, the neointimal area was dramatically augmented. This augmentation was associated with increased aortic superoxide formation, reduced aortic BH4/dihydrobiopterin (BH2) ratio, and decreased plasma nitrite and nitrate (NOx) levels compared with nondiabetic mice. Chronic BH4 treatment (10 mg/kg/d) reduced the neointimal area in association with suppressed superoxide production and inflammatory changes in vessels. BH4/BH2 ratio in vessel wall was preserved, and plasma NOx levels increased. Furthermore, in the presence of diabetes, overexpression of bovine eNOS resulted in augmentation of neointimal area, accompanied by increased superoxide production in the endothelium. Conclusions— In diabetes, increased oxidative stress by uncoupled NOSs, particularly eNOS, causes augmentation of vascular remodeling. These findings indicate restoration of eNOS coupling has an atheroprotective benefit in diabetes.

2,4-Diamino-6-hydroxypyrimidine (DAHP) is considered a specific inhibitor of BH(4) biosynthesis and is widely used in order to elucidate the possible biological function of BH(4) in various cells. In the present study, we found that both the synthesis of tetrahydrobiopterin (BH(4)) and expression of vascular cell adhesion molecule 1 (VCAM-1) were increased in human umbilical vein endothelial cells (HUVEC) treated with proinflammatory cytokines. Thus we examined the effects of DAHP to clarify whether BH(4) might be involved in the expression of VCAM-1 in HUVEC. DAHP reduced the levels of both BH(4) and VCAM-1 induced by TNF-alpha and IFN-gamma. However, the dose-response curves of DAHP for the suppression of the VCAM-1 level and that of BH(4) level were markedly different. Supplementation with sepiapterin failed to restore the depressed VCAM-1 level, although it completely restored the BH(4) level. Furthermore, DAHP significantly reduced the VCAM-1 level under the experimental conditions using TNF-alpha alone, which failed to induce BH(4) production. Taken together, these results indicate that DAHP inhibited the expression of VCAM-1 in a BH(4)-independent manner in HUVEC. In the present study, we also found that DAHP significantly suppressed the accumulation of cytokine-induced NF-kappaB (p65) in the nucleus as well as the mRNA levels of VCAM-1 and GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme of BH(4) synthesis. The data obtained in this study suggest that DAHP reduced VCAM-1 and GTPCH protein synthesis at least partially via suppressing the NF-kappaB level in the nucleus of HUVEC.

Unique pterins were identified as a major pterin in several microorganisms. D-Monapterin was identified as major pterin in Tetrahymena pyriformis (1 ), which is a protozoa living in fresh water, and L-monapterin was identified in E. coli (2), respectively. However, their biological functions have not been revealed yet. We recently reported presence of reduced forms of those monapterins in each microorganism, and the reduced form was estimated 5,6,7,8-tetrahydro form (3, 4). In this study, we would describe structural determination of unstable natural 5,6,7,8-tetrahydromonapterins in the two microorganisms. First, the configuration of 1′,2′,3′-trihydroxypropyl side chain was determined by fluorescence detected circular dichroism (FDCD) spectra using stable aromatic derivatives, which has strong fluorescence nature, and then configurations of 6-position was determined by LC-MS analysis using stable completely acetyl derivatives.

Completely acetylated derivatives of naturally occurring tetrahydro-D-monapterin, (6R)-2-acetamido-6-[(1R,2R)-1,2,3-triacetoxypropyl]-5,8-diacetyl-5,6,7,8-tetrahydropteridin-4(3H)-one, show plus and minus CD signs at X 280 and 240 nm, respectively. Similar CD spectra are obtained on (2S)-1,4-diacetyl-1,2,3,4-tetrahydro-2-isopropylquinoxaline and (2S)-1,4-diacetyl-1,2,3,4-tetrahydro-2-isobutylquinoxaline but not on (25)-1,4-diacetyl-1,2,3,4-tetrahydro-2-methylquinoxaline nor on the 2-ethyl derivative. The similarity of their CD spectra is represented the same stereogenic structure based on the boat conformation confirmed by X-Ray crystallographic analyses.

Absolute configurations of 6-(1-hydroxyalkyl)pterin derivatives are determined by fluorescence detected circular dichroism (FDCD) spectroscopy. This method is at least 10 times more sensitive than CD analysis and specificeven existence of 10 times excess amounts of chiral sugars or nucleic acids.