Miyase Gözde Gündüz

Synthesis and evaluation of 1,4-dihydropyridine derivatives with calcium channel blocking activity.

Abstract1,4-Dihydropyridines (DHPs) are an important class of L-type calcium channel blockers that are used to treat conditions such as hypertension and angina. Their primary target in the cardiovascular system is the Cav1.2 L-type calcium channel isoform, however, a number of DHPs also block low-voltage-activated T-type calcium channels. Here, we describe the synthesis of a series of novel DHP derivatives that have a condensed 1,4-DHP ring system (hexahydroquinoline) and report on their abilities to block both L- and T-type calcium channels. Within this series of compounds, modification of a key ester moiety not only regulates the blocking affinity for both L- and T-type channels, but also allows for the development of DHPs with 30-fold selectivity for T-type channels over the L-type. Our data suggest that a condensed dihydropyridine-based scaffold may serve as a pharmacophore for a new class of T-type selective inhibitors.

Analgesic effect of a broad-spectrum dihydropyridine inhibitor of voltage-gated calcium channels

Voltage-activated calcium channels are important facilitators of nociceptive transmission in the primary afferent pathway. Consequently, molecules that block these channels are of potential use as pain therapeutics. Our group has recently reported on the identification of a novel class of dihydropyridines (DHPs) that included compounds with preferential selectivity for T-type over L-type channels. Among those compounds, M4 was found to be an equipotent inhibitor of both Cav1.2 L- and Cav3.2 T-type calcium channels. Here, we have further characterized the effects of this compound on other types of calcium channels and examined its analgesic effect when delivered either spinally (i.t.) or systemically (i.p.) to mice. Both delivery routes resulted in antinociception in a model of acute pain. Furthermore, M4 was able to reverse mechanical hyperalgesia produced by nerve injury when delivered intrathecally. M4 retained partial activity when delivered to Cav3.2 null mice, indicating that this compound acts on multiple targets. Additional whole-cell patch clamp experiments in transfected tsA-201 cells revealed that M4 also effectively blocks Cav3.3 (T-type) and Cav2.2 (N-type) currents. Altogether, our data indicate that broad-spectrum inhibition of multiple calcium channel subtypes can lead to potent analgesia in rodents.

Substituted 9-aryl-1,8-acridinedione derivatives and their effects on potassium channels

In this study, 12 new 3,6-dimethyl-9-aryl-3,4,6,7-tetrahydroacridine-1,8(2H,5H,9H,10H)-diones derivatives were synthesized. Synthesis of the compounds was realized by the reaction of 5-methyl-1,3-cyclohexanedione, the appropriate aromatic aldehyde, and ammonium acetate in methanol. The structure of the compounds was elucidated by infrared (IR), 1H-nuclear magnetic resonance (NMR), 13C-NMR, mass spectroscopy, and elemental analysis. Functional effects of the compounds on vascular potassium channels and mechanism of phenylephrine-induced contractile responses were investigated in isolated rat aorta rings. Pinacidil was used as a standard potassium channel opener.

Synthesis and Myorelaxant Activity of Fused 1,4‐Dihydropyridines on Isolated Rabbit Gastric Fundus

Strategy, Management and Health Policy Preclinical Research

Microwave-assisted synthesis and myorelaxant activity of 9-indolyl- 1,8-acridinedione derivatives

In this study a microwave-assisted method was applied for the synthesis of novel 9-(substituted indolyl)-3,4,6,7-tetrahydroacridine-1,8-(2H,5H,9H,10H)-dione derivatives. The structures of the compounds were confirmed by spectral methods including X-ray studies and elemental analysis. The Emax and pD2 values of the compounds and pinacidil were determined on noradrenaline precontracted tissues of isolated strips of rabbit gastric fundus smooth muscle. The obtained results indicated that some compounds and pinacidil produced concentration-dependent relaxation on the strips. The efficacy of compound 9 was higher than pinacidil. Docking studies were carried out to understand the interactions of the compounds with the active site of potassium channel. Methyl substituents on the acridine backbone and bromine atom on the indole ring led to more active compounds.

Cocrystals of diastereoisomers of 1,4-dihydropyridine derivatives.

A mixture of the RR/SS and RS/SR diastereoisomeric pairs of methyl 4-(2,4-dichlorophenyl)-2,7-dimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C 19 H 19 Cl 2 NO 3 , forms cocrystals in which there is one unique molecule in the asymmetric unit, but the molecule displays disorder in the region of the 7-position of the quinoline ring system as a result of the random occurrence of the diastereoisomers at the same crystallographic site. A similar arrangement exists in the monohydrate cocrystals that form from a mixture of the RRI SS and RS/SR diastereoisomeric pairs of methyl 4-(2,4-dichlorophenyl)-2-methyl-7-phenyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate monohydrate, C 24 H 21 Cl 2 NO 3 ·-H 2 O. These compounds belong to a class of 1,4-dihydropyridines whose members have calcium modulatory properties. The 1,4-dihydropyridine rings have the usual shallow boat conformation. In each structure, the 2,4-dichlorophenyl ring is oriented such that the 2-chloro substituent is in a synperiplanar orientation with respect to the 1,4-dihydropyridine ring plane. In each crystal structure, the molecules are linked into chains by N-H···O hydrogen-bonding interactions.

Investigation of myorelaxant activity of 9-aryl-3,4,6,7-tetrahydroacridine-1,8-(2H,5H,9H,10H)-diones in isolated rabbit gastric fundus

In this study, twelve compounds having 9-aryl-3,4,6,7-tetrahydroacridine-1,8-(2H,5H,9H,10H)-dione structure were synthesized by reaction of 5-methyl-1,3-cyclohexanedione, the appropriate aromatic aldehydes, and ammonium acetate in methanol. The structures of the compounds were elucidated by infrared, 1H- and 13C-nuclear magnetic resonance spectroscopy (-NMR), mass spectroscopy, and elemental analysis. The maximum relaxant effects (Emax) and pD2 values of the compounds 3a–l and pinacidil were tested on isolated strips of rabbit gastric fundus smooth muscle.

Ethyl 4-(5-bromo-1H-indol-3-yl)-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carboxyl­ate

The title compound, C23H25BrN2O3, crystallizes with two independent molecules in the asymmetric unit (Z′ = 2) which differ in the twist of the 5-bromo-1H-indole ring with respect to the plane of the 4-methyl-1,4,5,6,7,8-hexahydroquinoline ring [dihedral angles of 78.55 (9) and 89.70 (8)° in molecules A and B, respectively]. The indole ring is planar in both molecules [maximum deviations = 0.021 (3) and −0.020 (3) Å for the N atom] while the cyclohexene ring has adopts a sofa conformation. In the crystal, molecules are linked by pairs of N—H⋯O hydrogen bonds, forming dimers with R 1 2(6) ring motifs. These dimers are connected by N—H⋯O hydrogen bonds, generating chains along [110]. A C—H⋯O contact occurs between the independent molecules.

Two 1,4-dihydropyridine derivatives with potential calcium-channel antagonist activity

The title compounds, benzyl 4-(3-chloro-2-fluorophenyl)-2-methyl-5-oxo-4,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-3-carboxylate, C(23)H(19)ClFNO(3), (I), and 3-pyridylmethyl 4-[2-fluoro-3-(trifluoromethyl)phenyl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C(26)H(24)F(4)N(2)O(3), (II), belong to a class of 1,4-dihydropyridines whose members sometimes display calcium modulatory properties. The 1,4-dihydropyridine ring in each structure has a shallower than usual shallow-boat conformation and is nearly planar in (I). In each structure, the halogen-substituted benzene ring is oriented such that the halogen substituents are in a synperiplanar orientation with respect to the 1,4-dihydropyridine ring plane. The oxocyclopentene ring in (I) is planar, while the oxocyclohexene ring in (II) has a half-chair conformation, which is less commonly observed than the envelope conformation usually found in related compounds. In (I), the frequently observed intermolecular N-H···O hydrogen bond between the amine group and the carbonyl O atom of the oxocyclopentene ring of a neighbouring molecule links the molecules into extended chains; there are no other significant intermolecular interactions. By contrast, the amine group in (II) forms an N-H···N hydrogen bond with the pyridine ring N atom of a neighbouring molecule. Additional C-H···O interactions complete a two-dimensional hydrogen-bonded network. The halogen-substituted benzene ring has a weak intramolecular π-π interaction with the pyridine ring. A stronger π-π interaction occurs between the 1,4-dihydropyridine rings of centrosymmetrically related molecules.

Photodegradation studies of 1,4-dihydropyridine compounds by MCR analysis on UV spectral data

BACKGROUND 1,4-Dihydropyridines (DHPs) are well-known light-sensitive compounds. Photostability studies are necessary to ensure safety in therapy. MATERIALS & METHODS Photodegradation experiments on 15 condensed DHP derivatives were made according to the International Conference on Harmonization rules. Degradation profiles were monitored by spectrophotometry and the data were processed by multivariate curve resolution analysis. RESULTS The analysis of the spectral data showed the formation of a single photoproduct from two DHPs, due to the aromatization of the pyridine ring. Traces of a second photoproduct were revealed in 12 DHPs and a third photoproduct was verified only in one case. CONCLUSION DHPs showed high stability when fluorine was in the position R1 of the phenyl ring or simultaneously present in R1 and R2 positions. In contrast, the presence of chlorine in R1 or R2 strongly increased the degradation.