Moore Benjamin J R, Islam Barira, Ward Sean, Jackson Olivia, Armitage Rebecca, Blackburn Jack, Haider Shozeb, McHugh Patrick C
Centre for Biomarker Research, School of Applied Sciences, Department of Pharmacy, School of Applied Sciences, Innovative Physical Organic Solutions (IPOS), Department of Chemical and Biological Sciences, and Department of Chemical Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.
UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, U.K.
ACS Omega. 2019 Jul 10;4(7):11960-11972. doi: 10.1021/acsomega.9b01228. eCollection 2019 Jul 31.
Tetrahydrobiopterin (BH) is a cofactor in the production of various signaling molecules including nitric oxide, dopamine, adrenaline, and noradrenaline. BH levels are critical for processes associated with cardiovascular function, inflammation, mood, pain, and neurotransmission. Increasing pieces of evidence suggest that BH is upregulated in chronic pain. Sepiapterin reductase (SPR) catalyzes both the reversible reduction of sepiapterin to dihydrobiopterin (BH) and 6-pyruvoyl-tetrahydrobiopterin to BH within the BH pathway. Therefore, inhibition of SPR by small molecules can be used to control BH production and ultimately alleviate chronic pain. Here, we have used various in silico and in vitro experiments to show that tranilast, licensed for use in bronchial asthma, can inhibit sepiapterin reduction by SPR. Docking and molecular dynamics simulations suggest that tranilast can bind to human SPR (hSPR) at the same site as sepiapterin including S157, one of the catalytic triad residues of hSPR. Colorimetric assays revealed that tranilast was nearly twice as potent as the known hSPR inhibitor, -acetyl serotonin. Tranilast was able to inhibit hSPR activity both intracellularly and extracellularly in live cells. Triple quad mass spectrophotometry of cell lysates showed a proportional decrease of BH in cells treated with tranilast. Our results suggest that tranilast can act as a potent hSPR inhibitor and therefore is a valid candidate for drug repurposing in the treatment of chronic pain.
四氢生物蝶呤（BH）是多种信号分子生成过程中的一种辅助因子，这些信号分子包括一氧化氮、多巴胺、肾上腺素和去甲肾上腺素。BH水平对于与心血管功能、炎症、情绪、疼痛和神经传递相关的过程至关重要。越来越多的证据表明，慢性疼痛中BH会上调。蝶呤还原酶（SPR）在BH途径中催化蝶呤可逆还原为二氢生物蝶呤（BH）以及6-丙酮酰四氢生物蝶呤还原为BH。因此，小分子对SPR的抑制可用于控制BH的生成并最终缓解慢性疼痛。在此，我们通过各种计算机模拟和体外实验表明，已获许可用于支气管哮喘治疗的曲尼司特能够抑制SPR介导的蝶呤还原。对接和分子动力学模拟表明，曲尼司特可与蝶呤在人SPR（hSPR）的同一结合位点结合，该位点包括hSPR催化三联体残基之一的S157。比色法测定显示，曲尼司特的效力几乎是已知的hSPR抑制剂N-乙酰血清素的两倍。曲尼司特能够在活细胞的细胞内和细胞外抑制hSPR活性。对细胞裂解物进行的三重四极杆质谱分析表明，用曲尼司特处理的细胞中BH呈比例下降。我们的结果表明，曲尼司特可作为一种有效的hSPR抑制剂，因此是用于治疗慢性疼痛的药物重新利用的有效候选药物。
