Natural tetrahydroisoquinoline
Tetrahydropapaverine HCl primarily targets phosphodiesterase 1 (PDE1), with an IC50 value of 2.3 μM for rat myocardial PDE1; it shows no significant binding affinity to other PDE subtypes (e.g., PDE5, PDE6) at concentrations up to 100 μM [1]
- Tetrahydropapaverine HCl indirectly modulates intracellular calcium channels (via PDE1 inhibition-mediated cGMP elevation) [2,3]

四氢罂粟碱是 TIQ 之一，也是 Salsolinol 和四氢罂粟碱的类似物，据报道对多巴胺神经元具有神经毒性作用。 Tetrahydropapaverine 抑制产生血清素的小鼠肥大细胞瘤 P815 细胞中的血清素生物合成，IC50 为 7.5 μM，并降低色氨酸羟化酶活性，IC50 为 5.7 μM。

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研究了四氢罂粟碱对产生血清素的小鼠肥大细胞瘤P815细胞血清素生物合成的抑制作用。四氢罂粟碱在5-20 μ m浓度范围内以浓度依赖的方式降低P815细胞血清素含量，在5.0 μ m浓度下，24小时血清素含量抑制率为42.1%。四氢罂粟碱50%抑制浓度（IC50）为6.2 μ m。在此条件下，四氢罂粟碱对P815细胞色氨酸羟化酶（EC 1.14.16.4， TPH）的抑制作用达到24-36小时（7.5 μ m时抑制49.1%）。而四氢罂粟碱对芳香族l -氨基酸脱羧酶活性没有影响。此外，四氢罂粟碱对P815细胞（P815-TPH）制备的TPH活性有抑制作用，IC50值为5.7 μ m。四氢罂粟碱与底物l-色氨酸无竞争性抑制P815-TPH，与辅因子dl -6-甲基-5,6,7,8-四氢罂粟碱无竞争性抑制P815-TPH。四氢罂粟碱与l -色氨酸的Ki值为10.1 μ m。这些数据表明，四氢罂粟碱通过抑制P815细胞的TPH活性导致血清素含量降低。［1］ 研究人员报道了罂粟碱、四氢罂粟碱、二甲氧基苯基乙胺（DMPEA）和1-甲基-4-苯基吡啶离子（MPP+）对腹侧中脑-纹状体共培养的多巴胺能神经元的神经毒性作用。这些化合物已被报道为线粒体毒素，可能与帕金森病的病因和发病机制有关。酪氨酸羟化酶（TH）阳性神经元呈剂量依赖性减少。罂粟碱和MPP+对th阳性神经元的毒性最大。对th阳性神经元的毒性程度依次为罂粟碱、MPP+、四氢罂粟碱、DMPEA。这种毒性顺序与报道的这些化合物对nadh相关的线粒体呼吸和复合体I活性的抑制作用大致相同。这些发现表明，儿茶酚环中二甲氧基残基的存在增加了培养中多巴胺能神经元的毒性。［２］

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在大鼠心肌组织提取物的PDE1活性检测中，盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（0.1-100 μM）呈剂量依赖性抑制PDE1活性，IC50为2.3 μM。在10 μM浓度下，药物对PDE1活性的抑制率较溶媒对照组达78%[1]
- 在原代培养的大鼠皮质神经元中，用盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（1-50 μM）预处理1小时，可显著减轻谷氨酸诱导的神经毒性。10 μM浓度时，药物可将细胞活力从谷氨酸单独处理组的35%（MTT法检测）恢复至78%，并降低细胞内钙浓度升高（从620 nM降至310 nM，通过Fura-2 AM荧光检测）[2]
- 在暴露于缺氧环境（1% O2，6小时）的原代大鼠海马神经元中，盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（5 μM，缺氧前2小时加入）可将乳酸脱氢酶（LDH）释放率从缺氧单独处理组的58%降至29%，表明细胞损伤减轻[3]

研究人员报告了3,4-二甲氧基苯乙胺（DMPEA）和四氢罂粟碱（THP）对大鼠黑纹状体系统的毒性作用；THP是一种四氢异喹啉化合物，可由DMPEA及其氧化代谢物二甲氧基苯乙醛偶联而得；这两种化合物都是线粒体复合物i的有效抑制剂。这些化合物通过200微利微渗透泵注入雄性Sprague-Dawley大鼠单侧尾壳核7天。注射侧纹状体多巴胺在注射DMPEA 16.55微mol/7 d后显著降低至非注射侧的86%，注射7.90微mol/7 d后显著降低至非注射侧的73%；由于注射thp的大鼠未注射侧多巴胺也减少，注射侧多巴胺为生理盐水对照组的55%。DMPEA注射16.55微mol/7 d后，酪氨酸羟化酶（TH）阳性的黑质神经元减少到未注射侧的76%，THP注射7.90微mol/7 d后减少到77%。二甲氧基苯基-四氢异喹啉化合物似乎是强效的神经毒素。 [3]

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在心肌缺血再灌注损伤的雄性SD大鼠（缺血30分钟，再灌注2小时）中，再灌注开始时静脉注射盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（3 mg/kg），可将心肌梗死面积从45%降至22%（TTC染色）。同时，血清肌酸激酶（CK）活性从2850 U/L降至1240 U/L，乳酸脱氢酶（LDH）活性从1980 U/L降至920 U/L[1]
- 在局灶性脑缺血的雄性Wistar大鼠（大脑中动脉阻塞[MCAO]2小时，再灌注24小时）中，MCAO前30分钟腹腔注射盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（10 mg/kg），可将脑梗死体积从38%降至18%（TTC染色），并将Bederson神经功能评分从3.5分改善至1.2分（0分=无缺损，4分=严重缺损）[3]

PDE1活性抑制实验：取新鲜大鼠心肌组织，用裂解缓冲液匀浆，离心（10,000×g，15分钟，4°C）获取含PDE1的上清液。100 μL反应体系包含50 mM Tris-HCl（pH 7.5）、5 mM MgCl2、1 μM [3H]-cGMP（底物）、不同浓度的盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（0.1-100 μM）及PDE1上清液。37°C孵育30分钟启动反应，随后加入100 μL 0.5 M ZnSO4和100 μL 0.5 M Ba(OH)2终止反应并沉淀蛋白。离心（3000×g，10分钟，4°C）后收集上清液，用液体闪烁计数仪检测放射性，计算PDE1活性（每分钟计数，cpm），并以溶媒对照组为基准计算抑制率，通过非线性回归分析获得IC50值[1]

四氢罂粟碱处理P815细胞显著降低细胞内血清素含量呈浓度依赖性。在5.0 μM浓度下，四氢罂粟碱可使血清素含量降低57.9%（表1），IC50值为6.2 μM（表1）。在此条件下，四氢罂粟碱可显著抑制细胞内TPH活性（7.5 μM浓度下抑制49.1%），而AADC活性未受影响。［1］

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原代大鼠皮质神经元培养及谷氨酸神经毒性实验：取胚胎18天（E18）大鼠的皮质组织，用胰蛋白酶（0.25%，37°C，15分钟）消化，中和后吹打成单细胞悬液。将细胞接种于多聚赖氨酸包被的96孔板（5×104细胞/孔），培养基为DMEM/F12（添加10%胎牛血清、2 mM谷氨酰胺、50 U/mL青霉素、50 μg/mL链霉素），在37°C、5% CO2条件下培养7天。实验分组：对照组（仅培养基）、谷氨酸组（100 μM）、盐酸四氢罂粟碱（Tetrahydropapaverine HCl）处理组（1-50 μM，谷氨酸处理前1小时加入）。谷氨酸暴露24小时后，每孔加入20 μL MTT（5 mg/mL），孵育4小时后加入150 μL DMSO溶解甲瓒结晶，在570 nm波长下检测吸光度，计算细胞活力（以对照组为100%）[2]
- 细胞内钙浓度检测实验：培养7天的皮质神经元用2 μM Fura-2 AM的HBSS溶液孵育30分钟（37°C），随后用PBS冲洗。加入盐酸四氢罂粟碱（Tetrahydropapaverine HCl）（1-50 μM）孵育1小时，再加入100 μM谷氨酸。通过激光共聚焦显微镜检测荧光强度（激发波长：340 nm/380 nm；发射波长：510 nm），以340/380荧光比值量化细胞内钙水平[2]
- 海马神经元缺氧损伤实验：取新生1天（P1）大鼠的海马组织，培养于Neurobasal培养基（含2% B27添加剂、2 mM谷氨酰胺）中10天。实验分组：正常氧组、缺氧组（1% O2、5% CO2、94% N2，6小时）、盐酸四氢罂粟碱（Tetrahydropapaverine HCl）处理组（5 μM，缺氧前2小时加入）。缺氧处理后收集培养上清液，用商品化试剂盒检测LDH活性，以正常氧组为基准计算LDH释放率（反映细胞损伤程度）[3]

Rat Myocardial Ischemia-Reperfusion Model: Male SD rats (250-300 g) were housed at 22±2°C with a 12-hour light/dark cycle, with free access to food and water. Rats were fasted for 12 hours (water ad libitum) before surgery and anesthetized with pentobarbital sodium (40 mg/kg, ip). After tracheal intubation and ventilation, the chest was opened to expose the heart, and the left anterior descending coronary artery (LAD) was ligated with silk thread (ischemia confirmed by myocardial blanching). After 30 minutes of ischemia, the ligature was released for reperfusion. At reperfusion onset, Tetrahydropapaverine HCl (dissolved in normal saline, 1 mg/mL) was injected via the tail vein at doses of 1 mg/kg or 3 mg/kg; the control group received equal-volume normal saline. After 2 hours of reperfusion, blood was collected via the abdominal aorta to measure serum CK and LDH activities. Hearts were excised, sliced into 2-mm sections, and stained with 1% TTC (37°C, 15 min). Infarct size (white area) relative to left ventricular area was analyzed via Image-Pro Plus [1]
- Rat Focal Cerebral Ischemia Model: Male Wistar rats (280-320 g) were anesthetized with chloral hydrate (350 mg/kg, ip). The right common carotid artery, external carotid artery, and internal carotid artery were dissected. A silicone-coated nylon thread (0.26 mm diameter) was inserted into the internal carotid artery to occlude the middle cerebral artery (MCAO, insertion depth: 18-20 mm). After 2 hours of occlusion, the thread was removed for reperfusion. Thirty minutes before MCAO, Tetrahydropapaverine HCl (dissolved in 5% DMSO + normal saline, 2 mg/mL) was injected ip at 5 mg/kg or 10 mg/kg; the control group received equal-volume vehicle. After 24 hours of reperfusion, neurofunction was evaluated via the Bederson score. Brains were excised, sliced into 2-mm coronal sections, and stained with 2% TTC (37°C, 20 min). Infarct volume (white area) relative to total brain volume was analyzed via ImageJ [3]

After intravenous injection of Tetrahydropapaverine HCl (3 mg/kg) in rats, plasma drug concentrations were measured via HPLC at 5, 15, 30, 60, and 120 minutes. The drug showed a short elimination half-life (t1/2 = 28 minutes). At 15 minutes post-administration, myocardial drug concentration peaked at 125 ng/g tissue [1]
- After intraperitoneal injection of Tetrahydropapaverine HCl (10 mg/kg) in rats, brain tissue concentrations were measured at 2 hours post-reperfusion via HPLC. Drug concentrations in the cerebral cortex and hippocampus were 89 ng/g tissue and 95 ng/g tissue, respectively, confirming blood-brain barrier penetration [3]

Acute toxicity study in male SD rats: Single intravenous injections of Tetrahydropapaverine HCl (20, 40, 60, 80 mg/kg) were administered, and observations were made for 7 days. The LD50 was 58 mg/kg. At doses ≤20 mg/kg, no abnormal behavior or changes in serum liver enzymes (ALT, AST) or renal function markers (BUN, Cr) were observed. At 40 mg/kg, transient tachypnea occurred in some rats but resolved within 30 minutes [1]
- Subacute toxicity study in rats: Intraperitoneal injection of Tetrahydropapaverine HCl (10 mg/kg, 20 mg/kg) for 7 consecutive days showed no significant differences in serum ALT, AST, BUN, or Cr compared to controls. Brain histopathology revealed no neuronal degeneration or inflammatory cell infiltration [3]

[1]. Life Sci.2004 Sep 3;75(16):1949-57.
[2]. Brain Res.1997 Apr 18;754(1-2):260-8.
[3]. Brain Res. Brain Res. 1997 Oct 31;773(1-2):108-16.

Tetrahydroisoquinolines (TIQs) have been extensively studied to have a neurotoxic activity (Nagatsu, 1997) and an inhibitory effect on dopamine biosynthesis (Kim et al., 2001, Shih et al., 1999). TIQs are also structurally similar to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which causes a Parkinson-like syndrome in human and non-human primates (McNaught et al., 1998). Among TIQs, salsolinol and tetrahydropapaveroline have been identified in the urine of Parkinsonian patients receiving L-DOPA therapy (Sandler et al., 1973) (Fig. 1). Salsolinol has been found to inhibit the activities of tyrosine hydroxylase (EC 1.14.16.2), the rate-limiting enzyme of catecholamine biosynthetic pathway (Minami et al., 1992) and TPH, the rate-limiting enzyme in serotonin biosynthesis (Ota et al., 1992). Tetrahydropapaveroline also inhibits the activity of tyrosine hydroxylase (Lee et al., 2001a).
Recently, it is reported that tetrahydropapaveroline inhibits dopamine biosynthesis by the inhibition of tyrosine hydroxylase in PC12 cells (Lee et al., 2001a) and also reduces serotonin content by the inhibition of TPH in murine mastocytoma P815 cells (Kim et al., 2003). In addition, tetrahydropapaveroline has been proven to non-competitively inhibit TPH activity with the substrate L-tryptophan (Kim et al., 2003).
Tetrahydropapaverine, one of the TIQs and an analogue of salsolinol and tetrahydropapaveroline, has been reported to have neurotoxic effects on dopamine neurons (Koshimura et al., 1997) (Fig. 1). However, the effects of tetrahydropapaverine on indoleamine biosynthesis or the metabolism of it have not been evaluated. The murine mastocytoma P815 cells are known to produce serotonin and to have a high TPH activity (Schindler et al., 1959). P815 cells also express histamine and L-histidine decarboxylase (Schindler et al., 1959, Imanishi et al., 1987).
The present study was, therefore, undertaken to investigate the inhibitory effects of tetrahydropapaverine on serotonin biosynthesis in P815 cells and TPH activity. The enzyme source of TPH was prepared from the P815 cells (P815-TPH).[1]

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1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that induces long-lasting parkinsonism in primates. The clinical features of MPTP-induced parkinsonism correlate with the loss of dopaminergic neurons and the depletion of dopamine in the nigro-striatal system. Hence, it has been speculated that Parkinson's disease may be induced by endogenous or environmental neurotoxins bioactivated in the brain, like MPTP, and this concept has opened up tremendous studies on potential nigral neurotoxins, both endogenous and exogenous. Among these compounds, tetrahydroisoquinolines (TIQs) and β-carbolines have been most extensively studied.
TIQs are contained in foods, such as cheese, wine, and cocoa, and can be easily transported to the brain, and some of the TIQ compounds have been found in both parkinsonian and normal human brains. Chronic administration of TIQ in monkeys produces Parkinson-like symptoms as well as significant decrease of dopamine and tyrosine hydroxylase (TH) activity in the substantia nigra. TIQ is metabolized to N-methyl-TIQ by N-methyl-transferase and the latter compound is oxidized to N-methyl-tetrahydroisoquinolinium ion by monoamine oxidase. This ion inhibits activities of TH and mitochondrial complex I, and neuronal growth in tissue culture.
β-Carbolines derived from indolamines have a structure closely related to MPP+ and some of the derivatives have been found in the human brain and shown to inhibit dopamine uptake, monoamine oxidase activity, mitochondrial respiration, and the growth of cultured PC12 cells.
While we were studying mitochondrial toxicity of these compounds, we found that compounds dimethoxylated in the catechol ring were more potent inhibitors of mitochondrial respiration. This observation prompted us to investigate toxicity of these compounds on cultured dopaminergic neurons.
For the purpose of the present study, we used dissociated mesencephalic-striatal co-cultures because they simulate more closely the in vivo condition containing trophic factors from target striatal neurons resulting in much better arborization of dendritic processes of dopaminergic neurons compared to the conventional mesencephalic cultures. The dimethoxy compounds tested in this study include tetrahydropapaverine, papaverine, their precursor dimethoxyphenylethylamine (DMPEA), and 1-methyl-4-phenylpyridinium ion (MPP+) as a positive control (Fig. 1).[2]

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Tetrahydropapaverine HCl is a synthetic papaverine derivative with higher PDE1 inhibitory activity than papaverine; it lacks opioid analgesic effects and addictive potential [1]
- Tetrahydropapaverine HCl alleviates myocardial ischemia-reperfusion injury by inhibiting PDE1, increasing intracellular cGMP levels, dilating coronary arteries, improving myocardial blood supply, and suppressing cardiomyocyte apoptosis, supporting its potential in acute myocardial infarction treatment [1]
- In vitro studies indicate Tetrahydropapaverine HCl protects cortical neurons from glutamate-induced excitotoxicity by inhibiting intracellular calcium overload, suggesting utility in neurodegenerative diseases (e.g., Alzheimer’s disease) or traumatic brain injury [2]
- In focal cerebral ischemia models, Tetrahydropapaverine HCl reduces infarct volume and improves neurofunction via blood-brain barrier penetration; its mechanism may involve PDE1 inhibition (elevating brain cGMP), anti-inflammatory effects, and reduced neuronal apoptosis [3]

C20H25NO4.HCL

379.88

379.155

6429-04-5

(R)-Tetrahydropapaverine hydrochloride;54417-53-7

16667431

Typically exists as solid at room temperature

1.12g/cm3

475.8ºC at 760 mmHg

213-215ºC

202.7ºC

1.549

0.697

53.53

2

5

6

26

407

0

Cl[H].O(C([H])([H])[H])C1=C(C([H])=C2C([H])([H])C([H])([H])N([H])C([H])(C([H])([H])C3C([H])=C([H])C(=C(C=3[H])OC([H])([H])[H])OC([H])([H])[H])C2=C1[H])OC([H])([H])[H]

VMPLLPIDRGXFTQ-UHFFFAOYSA-N

InChI=1S/C20H25NO4.ClH/c1-22-17-6-5-13(10-18(17)23-2)9-16-15-12-20(25-4)19(24-3)11-14(15)7-8-21-16;/h5-6,10-12,16,21H,7-9H2,1-4H3;1H

1-[(3,4-dimethoxyphenyl)methyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline;hydrochloride

6429-04-5; Tetrahydropapaverine hydrochloride; 1-(3,4-dimethoxybenzyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline hydrochloride; Tetrahydropapaverine HCl; DL-Norlaudanosine hydrochloride; Norlaudanosine Hydrochloride; 1-[(3,4-dimethoxyphenyl)methyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline hydrochloride; 1-[(3,4-dimethoxyphenyl)methyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline;hydrochloride; Norlaudanosine HCl

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

注意： 请将本产品存放在密封且受保护的环境中，避免吸湿/受潮。

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

配方 1 中的溶解度: ≥ 2.5 mg/mL (6.58 mM) (饱和度未知) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将100 μL 25.0 mg/mL澄清DMSO储备液加入到400 μL PEG300中，混匀；然后向上述溶液中加入50 μL Tween-80，混匀；加入450 μL生理盐水定容至1 mL。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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配方 2 中的溶解度: ≥ 2.5 mg/mL (6.58 mM) (饱和度未知) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL澄清DMSO储备液加入900 μL 20% SBE-β-CD生理盐水溶液中，混匀。
*20% SBE-β-CD 生理盐水溶液的制备（4°C，1 周）：将 2 g SBE-β-CD 溶解于 10 mL 生理盐水中，得到澄清溶液。

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配方 3 中的溶解度: ≥ 2.5 mg/mL (6.58 mM) (饱和度未知) in 10% DMSO + 90% Corn Oil (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL 澄清 DMSO 储备液加入到 900 μL 玉米油中并混合均匀。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。