Structurally novel HDAC inhibitors based on the trans-β-arylacryl tetrahydroisoquinoline scaffold: the design, synthesis, and anti-cancer activity / 药学学报

In this study, a series of 18 histone deacetylases inhibitors (HDACis), derived from our in-house anti-cancer trans-β-arylacryl 1,2,3,4-tetrahydroisoquinoline-based scaffold, were designed, synthesized, and antitumor evaluated. HDAC1 inhibitory activity assay showed that compounds 13d-13f and 13m-13o demonstrated attractive enzymatic activity with IC50 at single-digit nanomolar or subnanomolar level.In addition, 13o exerted superior anti-proliferative activity (A549, IC50 = 0.89 μmol·L-1; HCT116, IC50 = 0.49 μmol·L-1) to that of vorinostat (SAHA).Besides,13e, with the most potent HDAC1 enzymatic activity (IC50 = 3.8 nmol·L-1), also displayed attractive cellular activity (A549, IC50 = 1.74 μmol·L-1; HCT116, IC50 = 2.43 μmol·L-1). The Western blot analysis illustrated that 13e treatment increased the acetylation of H3 and α-tubulin in a dose-dependent manner in A549 cells. In summary, 13e and 13o deserve further functional investigation.

Dihydrofolate reductase-like protein inactivates hemiaminal pharmacophore for self-resistance in safracin biosynthesis

Dihydrofolate reductase (DHFR), a housekeeping enzyme in primary metabolism, has been extensively studied as a model of acid-base catalysis and a clinic drug target. Herein, we investigated the enzymology of a DHFR-like protein SacH in safracin (SAC) biosynthesis, which reductively inactivates hemiaminal pharmacophore-containing biosynthetic intermediates and antibiotics for self-resistance. Furthermore, based on the crystal structure of SacH-NADPH-SAC-A ternary complexes and mutagenesis, we proposed a catalytic mechanism that is distinct from the previously characterized short-chain dehydrogenases/reductases-mediated inactivation of hemiaminal pharmacophore. These findings expand the functions of DHFR family proteins, reveal that the common reaction can be catalyzed by distinct family of enzymes, and imply the possibility for the discovery of novel antibiotics with hemiaminal pharmacophore.

Mechanism of inhibiting proliferation of tumor cells by a new tetrahydroisoquinoline compound SYT-1 / 药学学报

In this study, we investigated the inhibitory effect of SYT-1, a new compound of tetrahydroisoquino-line, on tumor cell proliferation and underlying mechanisms. Cell counting kit-8 (CCK-8) method was used to detect cell proliferation; clone formation experiment was used to detect cell clone formation ability; JC-1 probe was used to detect cell mitochondrial membrane potential; 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) probe was used to detect intracellular reactive oxygen species; Annexin V-FITC/PI (fluorescein isothiocyanate/propidium) counterstaining method was used to detect apoptosis; Western blot assay was used to detect the expression level of related proteins. The experimental results show that SYT-1 has a significant inhibitory effect on the proliferation of six human-derived cancer cells. Among them, the inhibitory effect on breast cancer MCF-7 cells is the strongest, the half maximal inhibitory concentration (IC50) of SYT-1 of 48 h administration on MCF-7 cells is 5.87 μmol·L-1, which is better than that of cisplatin (8.92 μmol·L-1). Further studies have shown that SYT-1 can dose-dependently inhibit the monoclonal formation ability of MCF-7 cells, and can cause the mitochondrial membrane potential of the cells to decrease and the level of reactive oxygen species to increase. In addition, SYT-1 can significantly inhibit the activation of PI3K-Akt (phosphatidylinositol 3-kinase/protein kinase B) signaling pathway and induce apoptosis of MCF-7 cells. The above research results show that, as a new type of tetrahydroisoquinoline compound, SYT-1 has the potential to inhibit tumor cell proliferation.

Inhibition activities of levodopa derivatives against dopa decarboxylase / 中国药学杂志

OBJECTIVE: To investigate the inhibition activities of levodopa(LD) derivatives against dopa decarboxylase(DDC). METHODS: Five compounds 1-4a/4b were synthesized and identified as 1,1-dimethyl-3-carboxyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (1), 1α-methyl-3-carboxyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline(2),3-carboxyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline(3), 1α/1α-phenyl-3-carboxyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (4a/4b). Their inhibition activities against DDC were assayed, and Michael's equation of 1 were further tested. RESULTS: Compounds 1-4 could inhibit DDC activities dose dependency, while 1 showed strongest activity with its 50% inhibition concentration to be 0.387 mmol·L-1. Compound 1 showed non-competitive inhibition model with LD against DDC enzyme. CONCLUSION: Compounds 1-4 are proved to inhibit DDC activities for the first time. Therefore, compounds 1-3 of Mucuna seeds could improve LD bioavailability effectively in part through this mechanism.

Tetrahydroisoquinolines as novel histone deacetylase inhibitors for treatment of cancer

Histone acetylation is a critical process in the regulation of chromatin structure and gene expression. Histone deacetylases (HDACs) remove the acetyl group, leading to chromatin condensation and transcriptional repression. HDAC inhibitors are considered a new class of anticancer agents and have been shown to alter gene transcription and exert antitumor effects. This paper describes our work on the structural determination and structure-activity relationship (SAR) optimization of tetrahydroisoquinoline compounds as HDAC inhibitors. These compounds were tested for their ability to inhibit HDAC 1, 3, 6 and for their ability to inhibit the proliferation of a panel of cancer cell lines. Among these, compound 82 showed the greatest inhibitory activity toward HDAC 1, 3, 6 and strongly inhibited growth of the cancer cell lines, with results clearly superior to those of the reference compound, vorinostat (SAHA). Compound 82 increased the acetylation of histones H3, H4 and tubulin in a concentration-dependent manner, suggesting that it is a broad inhibitor of HDACs.

Chemical resolution on (±)1-(Benzamidomethyl)-1,2,3,4-tetrahydro-isoquinoline / 中国生化药物杂志

Objective To obtain two types of optical isomers from 1-(Benzamidomethyl)-1,2,3,4-tetrahydro-isoquinoline (BTIQ). Methods ( ±) BTIQ as raw materials , optically pure camphor sulfonic acid as resolution agent was used and repeated resolution in acetone , And the resolution product was detected by specific optical rotation .The product of BTIQ was hydrolyzed , and the ratio of ATIQ was compared with that of the literature .ResuIts After two repeated chemical resolutions , the specific rotations of both enantiomers are no longer changed .It was showed that the products of higher optical purity.The specific rotation of both isomers are -35.65°(CH2Cl2, C=0.5)with the yield of 27.52%,and +35.17°(CH2Cl2, C =0.5) with the yield of 31.55% respectively.The specific rotation value of chiral 1,2,3,4-tetrahydroisoquino line ( ATIQ) which was the hydrolysis product of BTIQ consistent with values reported in the literature .ConcIusion The (-) BTIQ and ( +) BTIQ enantiomers were successfully obtained by the method of resolution , and the yield and optical purity of the obtained products are higher , laying the foundation for the further development of high efficiency , low toxicity of chiral schistosomicide ( praziquantel ) and other containing tetrahydroisoquinoline structure of chiral drugs .

Identification of the related substances in HZ08 by LC-MS techniques / 中国药学杂志

OBJECTIVE: To identify the related substances in HZ08 by hyphenated techniques. METHODS: A LC-PDA-MS/MS method was developed for the related substances separation and determination. A Sapphire C18(4.6 m×250 mm, 5 μm). column was used with a mixture of methanol and ammonium acetate buffer solution as the mobile phase with gradient elution. HZ08 and the related substances resulted from acid, alkali, and light stress tests were separated under the established HPLC condition and detected with electro-spray positive ionization MS/MS method. The spectra obtained were used for the structures elucidation. RESULTS: Only one related substance was found in HZ08 with the content over 0.1%. Four decomposed substances were found in the acid stress test, one from the alkali and one from the light stress tests. Their structures were elucidated by using the spectra as well as the organic reaction mechanisms. CONCLUSION: The hyphenated LC-MS method is useful for the identification of related substances in pharmaceuticals. The related compounds found in HZ08 are valuable for the manufacturing process optimization and quality control of HZ08. Copyright 2012 by the Chinese Pharmaceutical Association.

Bioactivity diversity and functional mechanism of etrahydroisoquinoline alkaloids / 药学学报

Tetrahydroisoquinoline alkaloids distributed widely in the nature and some have a broad application in clinic. More attention has been paid in recent years on this type of alkaloid, owing to the diverse range of biological activities exhibited by these alkaloids and the discovery of new functional mechanisms and molecular targets underlying these activities. This article summarized the recent advances in the biological activities and functional mechanism of tetrahydroisoquinoline, which included the activities such as antitumor, antibiotic, antivirus, anti-inflammatory, anticoagulation, bronchodilation, and the action on central nervous system, with the purpose of providing some ideas in the study of biological activity of this type of alkaloid and in the search for lead-compound and rational drug design.

Neurotoxic Effects of Tetrahydroisoquinolines and Underlying Mechanisms

Tetrahydropapaveroline (THP), a neurotoxic tetrahydroisoquinoline alkaloid formed by condensation between dopamine and dopaldehyde, has been speculated to cause Parkinson's disease and also to contribute to alcohol dependence. Having two catechol moieties, THP may readily undergo oxidation to form an o-quinone intermediate with concomitant production of reactive oxygen species, which can cause neuronal cell death and DNA damage. This review will deal with the current knowledge of neurotoxic effects of this endogenous alkaloid and underlying biochemical mechanisms.

Synthesis and multidrug resistance reversal activity of 1-akyl-2-acetyl-1,2,3, 4-tetrahydroisoquinoline derivatives / 中国药科大学学报

To study the multidrug resistance activity of 1-alkyl-2-acetyl-1, 2, 3, 4-tetrahydroisoquinoline derivatives. Methods: A series of novel tetrahydroisoquinoline derivatives bearing at C-1 position a carbon chain derived from fatty acids were prepared through the Bischler-Napieralski cyclization reaction. Their multidrug resistance (MDR) reversal cancerous multidrug resistance activities were evaluated against K562 and K562/DOX cell lines in vitro by MTT assay with verapamil as a control. Results and Conclusion: The structures of these tetrahydroisoquinolines were confirmed by extensive spectroscopic methods(1H NMR, MS, IR and elemental ana-lyses). MDR results showed that compounds 7 and 10 exhibited moderate reversal activities, and were slightly less potent than those of verapamil against K562 cell line. It is believed that compounds 7 and 10 have MDR activity.

Inhibition of Inducible Nitric Oxide Synthase Expression by YS 49, a Synthetic Isoquinoline Alkaloid, in ROS 17/2.8 Cells Activated with TNF-alpha, IFN-gamma and LPS

Nitric oxide (NO) has been suggested to act as a mediator of cytokine-induced effects of turn over of bone. Activation of the inducible nitric oxide synthase (iNOS) by inflammation has been related with apoptotic cell death in osteoblast. YS 49, a synthetic isoquinoline alkaloid, inhibits NO production in macrophages activated with cytokines. In the present study, we investigated the molecular mechanism of YS 49 to inhibit iNOS expression in ROS 17/2.8 cells, which were activated with combined treatment of inflammatory cytokines (TNF-alpha, IFN-gamma) and lipopolysaccharide (LPS). Results indicated that YS 49 concentration-dependently reduced iNOS mRNA and protein expression, as evidenced by Northern and Western blot analysis, respectively. The underlying mechanism by which YS 49 suppressed iNOS expression was not to affect iNOS mRNA stability but to inhibit activation and translocation of NF-kappaB by preventing the degradation of its inhibitory protein IkappaBalpha. As expected, YS 49 prevented NO-induced apoptotic cell death by sodium nitroprusside. Taken together, it is concluded that YS 49 inhibits iNOS expression by interfering with degradation of phosphorylated inhibitory kappaBalpha (p-IkappaBalpha). These actions may be beneficial for the treatment of inflammation of the joint, such as rheumatoid arthritis.

Effect of Tetrahydroisoquinoline Alkaloids on the alpha-adrenoceptors in Rat Aorta and Brain Homogenates

Tetrahydroisoquinoline(THI) alkaloids can be considered as cyclized derivatives of simple pthylamines and many of them, especially with 6,7-disubstitution, demonstrate relatively high affinity for catecholamines. In the present study, pharmacological action of limited series of THI has been examined using rat isolated atria and aorta. In addition, (H) prazosin displacement binding study with THI compounds using rat brain homogenates was performed to find out if these probes to have a-adrenoceptor affinity. In isolated rat atria, all THls and dobutamine increased heart rate and contractile force. In the presence of propranolol, the concentration response curves of YS 49 and YS 51 shifted to the right resulting in 8.07+0.84 and 7. 93+0.11 of pA values, respectively. The slope of each compound was not deviated from unity, indicating that these chemicals are highly competitive at the cardiac beta1-adrenoceptors. YS 49, YS 51 and higenamine showed alpha1- adrenoceptor affinity in rat brain in which the dissociation constant(K,) was 2.75, 2.81 and 1.02pM, respectively. It is concluded, therefore, that THI alkaloids have considerable affiniyt to alpha1-adrenoceptors in rat aorta and atria. while these probes show relatively high affinity for cardiac beta1-adrenoceptors. The authors speculate that it is worthy investigating whether these chemicals are useful in the management of vasospasm of aneurysmal subarachnoid hemorrhage.

Comparison of inodilator effect of higenamine, YS49, YS51, tetra-hydroisoquinoline analogs, and dobutamine in the rat

Tetrahydroisoquinoline (THI) alkaloids can be considered as cyclized derivatives of simple phenylethylamines. Many of them, especially with 6,7-disubstitution, demonstrate a relatively high affinity for catecholamines. Present study examines the pharmacological action of limited series of THI, using rats' isolated atria and aorta. In addition, a (3H) prazosin displacement binding study with THI compounds was performed, using rat brain homogenates to investigate whether these probes have a-adrenoceptor affinity. We also compared the vascular relaxation potency of these probes with dobutamine. YS 49, YS 51, higenamine and dobutamine, concentration-dependently, relaxed endothelium-denuded rat thoracic aorta precontracted with phenylephrine (PE, 0.1 micrometer) in which pEC50 were 5.56-0.32 and 5.55+/-0.21, 5.99+/- 1.16 and 5.57+/-0.34, respectively. These probes except higenamine also relaxed KCl (65.4 mM)-contracted aorta. In isolated rat atria, all THIs and dobutamine increased heart rate and contractile force. In the presence of propranolol, the concentration response curves of YS 49 and YS 51 shifted to the right and resulted in pA2 values of 8.07+/-0.84 and 7.93+/-0.11, respectively. The slope of each compound was not deviated from unity, indicating that these chemicals are highly competitive at the cardiac beta-adrenoceptors. YS 49 YS 51, and higenamine showed alpha-adrenoceptor affinity in rat brain, in which the dissociation constant (Ki) was 2.75, 2.81, and 1.02 micrometer, respectively. It is concluded, therefore, that THI alkaloids have weak affinity to alpha1-adrenoceptors in rat aorta and brain, respectively, while these probes show relatively high affinity for cardiac beta-adrenoceptors. Thus, these chemicals may be useful in the treatment of congestive heart failure.

Pharmacological characterization of synthetic tetrahydroisoquinoline alkaloids, YS 51 and YS 55, on the cardiovascular system

Tetrahydroisoquinoline (THI) alkaloids can be considered as cyclized derivatives of simple phenylethylamines, and many of them, especially with 6,7-disubstitution, demonstrate relatively high affinity for catecholamines. Two -OH groups at 6 and 7 positions are supposed to be essential to exert beta-receptor activities. However, it is not clear whether -OH at 6,7 substitution of THIs also shows alpha-adrenoceptor activities. In the present study, we investigated whether -OH or -OCH3 substitutions of 6,7 position of THIs differently affect the alpha1-adrenoceptor affinity. We synthesized two 1-naphthylmethyl THI alkaloids, 1-beta-naphthylmethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline HBr (YS 51) and 1-beta-naphthylmethyl-6, 7-dimethoxy-1,2,3,4-tetrahydroisoquinoline HCl (YS 55), and their pharmacological actions on alpha1-adrenoceptor were compared. YS 51 and YS 55, concentration-dependently relaxed endothelium-denuded rat thoracic aorta precontracted with phenylephrine (PE, 0.1 micrometer) in which pEC50 were 5.89+0.21 and 5.93+ 0.19, respectively. Propranolol (30 nM) did not affect the relaxation-response curves to YS 51 and YS 55. Concentration-response curves to PE were shifted to right by the pretreatment with YS 51 or YS 55. The pA2 values of YS 51 and YS 55 showed 6.05 + 0.24 and 5.88 + 0.16, respectively. Both probes relaxed KCl (65.4 mM)-contacted aorta and inhibited CaCl2-induced contraction of PE-stimulated endothelium-denuded rat thoracic aorta in Ca2+-free solutions. In isolated guinea pig papillary muscle, 1 and 10 micrometer YS 51 increased contractile force about 4- and 8- fold over the control, respectively, along with the concentration-dependent increment of cytosolic Ca2+ ions. While, 10 micrometer YS 55 reduced the contractile force about 50 % over the control and lowered the cytosolic Ca2+ level, in rat brain homogenates, YS 51 and YS 55 displaced (3H)prazosin binding competitively with Ki 0.15 and 0.12 micrometer, respectively. However, both probes were ineffective on (3H)nitrendipine binding. Therefore, it is concluded that two synthetic naphthylmethyl-THI alkaloids have considerable affinity to alpha1-adrenenoceptors in rat aorta and brain.

Blocking action of 1 -(? -naphthylmethyl) -2 -methyl- 6, 7 - dimethoxy- 1,2,3,4 -tetrahydroisoquinoline (86040) on ?-adrenoceptors / 中国药理学通报

The blocking action and selectivity of 1 - (? -naphthylmethyl)-2 - methyl - 6,7 - dimethoxy -1,2,3,4 -tetrahydroisoquinoline (86040) on a - a-drenoceptor have been investigated in isolated tissues. 86040 suppressed the inhibition of clonidine for the electrically stimulated twitch response of rat vas deferens ( - adre - noceptor), with pA2 value of 5. 85. 86040 could competitively inhibit anococcygeus muscle contraction (?1 -a-drenoceptor ) induced by phenylephrine with pA2 value of 7. 62. 86040 was found that the selectivity radio to block ?2 - and ?2 adrenoceptor(?1/?2)was 60. these results indicate that 86040 is a potentant relatively selective ?1 - adrenoceptor blocker.