Genotoxic and genoprotective effects of 1,4-dihydropyridine derivatives: a brief review.

This review summarises current knowledge about the genotoxic and genoprotective effects of 1,4-dihydropyridines (DHP) with the main focus on the water-soluble 1,4-DHPs. Most of these water-soluble compounds manifest very low calcium channel blocking activity, which is considered "unusual" for 1,4-DHPs. Glutapyrone, diludine, and AV-153 decrease spontaneous mutagenesis and frequency of mutations induced by chemical mutagens. AV-153, glutapyrone, and carbatones protect DNA against the damage produced by hydrogen peroxide, radiation, and peroxynitrite. The ability of these molecules to bind to the DNA may not be the only mechanism of DNA protection, as other mechanisms such as radical scavenging or binding to other genotoxic compounds may take place and enhance DNA repair. These uncertainties and reports of high 1,4-DHP concentrations damaging the DNA call for further in vitro and in vivo preclinical research, pharmacokinetic in particular, as it can help pinpoint the exact mechanism(s) of the genotoxic and/or genoprotective action of 1,4-DHPs.

The Specificity and Broad Multitarget Properties of Ligands for the Free Fatty Acid Receptors FFA3/GPR41 and FFA2/GPR43 and the Related Hydroxycarboxylic Acid Receptor HCA2/GPR109A.

The paradigm of ligand-receptor interactions postulated as "one compound-one target" has been evolving; a multi-target, pleiotropic approach is now considered to be realistic. Novel series of 1,4,5,6,7,8-hexahydro-5-oxoquinolines, pyranopyrimidines and S-alkyl derivatives of pyranopyrimidines have been synthesized in order to characterise their pleiotropic, multitarget activity on the FFA3/GPR41, FFA2/GPR43, and HCA2/GPR109A receptors. Hexahydroquinoline derivatives have been known to exhibit characteristic activity as FFA3/GPR41 ligands, but during this study we observed their impact on FFA2/GPR43 and HCA2/GPR109A receptors as well as their electron-donating activity. Oxopyranopyrimidine and thioxopyranopyrimidine type compounds have been studied as ligands of the HCA2/GPR109A receptor; nevertheless, they exhibited equal or higher activity towards FFA3/GPR41 and FFA2/GPR43 receptors. S-Alkyl derivatives of pyranopyrimidines that have not yet been studied as ligands of GPCRs were more active towards HCA2/GPR109A and FFA3/GPR41 receptors than towards FFA2/GPR43. Representative compounds from each synthesized series were able to decrease the lipopolysaccharide-induced gene expression and secretion of proinflammatory cytokines (IL-6, TNF-α) and of a chemokine (MCP-1) in THP-1 macrophages, resembling the effect of HCA2/GPR109A ligand niacin and the endogenous ligand propionate. This study revealed groups of compounds possessing multitarget activity towards several receptors. The obtained data could be useful for further development of multitarget ligands.

4-Pyridinio-1,4-Dihydropyridines as Calcium Ion Transport Modulators: Antagonist, Agonist, and Dual Action.

A set of six new 4-pyridinio-1,4-dihydropyridine (1,4-DHP) compounds has been synthesized. The calcium channel modulating activity of these compounds was evaluated in an aorta vascular smooth muscle cell line (A7R5), in an isolated rat aortic ring model, and in human neuroblastoma cell lines (SH-SY5Y). The antagonistic effect of these 1,4-DHP was tested by modulating the impact of carbachol-dependent mobilization of intracellular Ca2+ in SH-SY5Y cells. The intracellular free Ca2+ concentration was measured in confluent monolayers of SH-SY5Y cells and A7R5 cells with the Ca2+-sensitive fluorescent indicator Fluo-4 NW. Only four compounds showed calcium channel blocking activity in SH-SY5Y and A7R5 cells as well as in the aortic ring model. Among them, compound 3 was the most active calcium channel antagonist, which had 3 times higher activity on carbachol-activated SH-SY5Y cells than amlodipine. Two of the compounds were inactive. Compound 4 had 9 times higher calcium agonist activity than the classic DHP calcium agonist Bay K8644. The intracellular mechanism for the action of compound 4 using inhibitor analysis was elucidated. Nicotinic as well as muscarinic receptors were not involved. Sarcoplasmic reticulum (ER) Ca2+ (SERCA) stores were not affected. Ryanodine receptors (RyRs), another class of intracellular Ca2+ releasing channels, participated in the agonist response evoked by compound 4. The electrooxidation data suggest that the studied compounds could serve as antioxidants in OS.

Antioxidative 1,4-Dihydropyridine Derivatives Modulate Oxidative Stress and Growth of Human Osteoblast-Like Cells In Vitro.

Oxidative stress has been implicated in pathophysiology of different human stress- and age-associated disorders, including osteoporosis for which antioxidants could be considered as therapeutic remedies as was suggested recently. The 1,4-dihydropyridine (DHP) derivatives are known for their pleiotropic activity, with some also acting as antioxidants. To find compounds with potential antioxidative activity, a group of 27 structurally diverse DHPs, as well as one pyridine compound, were studied. A group of 11 DHPs with 10-fold higher antioxidative potential than of uric acid, were further tested in cell model of human osteoblast-like cells. Short-term combined effects of DHPs and 50 µM H2O2 (1-h each), revealed better antioxidative potential of DHPs if administered before a stressor. Indirect 24-h effect of DHPs was evaluated in cells further exposed to mild oxidative stress conditions induced either by H2O2 or tert-butyl hydroperoxide (both 50 µM). Cell growth (viability and proliferation), generation of ROS and intracellular glutathione concentration were evaluated. The promotion of cell growth was highly dependent on the concentrations of DHPs used, type of stressor applied and treatment set-up. Thiocarbatone III-1, E2-134-1 III-4, Carbatone II-1, AV-153 IV-1, and Diethone I could be considered as therapeutic agents for osteoporosis although further research is needed to elucidate their bioactivity mechanisms, in particular in respect to signaling pathways involving 4-hydroxynoneal and related second messengers of free radicals.

Dihydropyridine Derivatives as Cell Growth Modulators In Vitro.

The effects of eleven 1,4-dihydropyridine derivatives (DHPs) used alone or together with prooxidant anticancer drug doxorubicin were examined on two cancer (HOS, HeLa) and two nonmalignant cell lines (HMEC, L929). Their effects on the cell growth (3H-thymidine incorporation) were compared with their antiradical activities (DPPH assay), using well-known DHP antioxidant diludine as a reference. Thus, tested DHPs belong to three groups: (1) antioxidant diludine; (2) derivatives with pyridinium moieties at position 4 of the 1,4-DHP ring; (3) DHPs containing cationic methylene onium (pyridinium, trialkylammonium) moieties at positions 2 and 6 of the 1,4-DHP ring. Diludine and DHPs of group 3 exerted antiradical activities, unlike compounds of group 2. However, novel DHPs had cell type and concentration dependent effects on 3H-thymidine incorporation, while diludine did not. Hence, IB-32 (group 2) suppressed the growth of HOS and HeLa, enhancing growth of L929 cells, while K-2-11 (group 3) enhanced growth of every cell line tested, even in the presence of doxorubicin. Therefore, growth regulating and antiradical activity principles of novel DHPs should be further studied to find if DHPs of group 2 could selectively suppress cancer growth and if those of group 3 promote wound healing.

1,4-Dihydropyridine Derivatives: Dihydronicotinamide Analogues-Model Compounds Targeting Oxidative Stress.

Many 1,4-dihydropyridines (DHPs) possess redox properties. In this review DHPs are surveyed as protectors against oxidative stress (OS) and related disorders, considering the DHPs as specific group of potential antioxidants with bioprotective capacities. They have several peculiarities related to antioxidant activity (AOA). Several commercially available calcium antagonist, 1,4-DHP drugs, their metabolites, and calcium agonists were shown to express AOA. Synthesis, hydrogen donor properties, AOA, and methods and approaches used to reveal biological activities of various groups of 1,4-DHPs are presented. Examples of DHPs antioxidant activities and protective effects of DHPs against OS induced damage in low density lipoproteins (LDL), mitochondria, microsomes, isolated cells, and cell cultures are highlighted. Comparison of the AOA of different DHPs and other antioxidants is also given. According to the data presented, the DHPs might be considered as bellwether among synthetic compounds targeting OS and potential pharmacological model compounds targeting oxidative stress important for medicinal chemistry.

Cerebrocrast promotes the cotransport of H+ and Cl- in rat liver mitochondria.

Considering that cerebrocrast stimulates oligomycin-inhibited state 3 respiration simultaneously with mitochondrial transmembrane potential (Deltapsi) dissipation, the mechanism underlying the uncoupler activity of cerebrocrast was assessed by its ability to permeabilize the mitochondrial inner membrane to H(+) or to K(+) or to cotransport anions with H(+). The partition coefficient of cerebrocrast in mitochondrial membrane and its ability to act as a membrane-active compound disturbing membrane lipid organization were also investigated. Cerebrocrast induced no permeabilization of mitochondrial inner membrane to H(+) or K(+), but it was able to transport H(+) in association with Cl(-). Cerebrocrast showed a strong incorporation into the mitochondrial membrane, with a partition coefficient (Kp(m/w)) of 2.7(+/-0.1)x10(5). Cerebrocrast also reduced, in a concentration dependent manner, the phase transition temperature, the cooperative unit size, and the enthalpy associated with the phase transition temperature of DMPC membrane bilayers. It was concluded that the uncoupler activity of cerebrocrast is due to its ability to promote the cotransport of H(+) with Cl(-) through the rat liver mitochondrial inner membrane, and that this cerebrocrast mechanism of action may be potentiated by alterations of membrane lipid organization and membrane lateral heterogeneity.

Effects of 1,4-dihydropyridine derivatives (cerebrocrast, gammapyrone, glutapyrone, and diethone) on mitochondrial bioenergetics and oxidative stress: a comparative study.

The potential protective action of 1,4-dihydropyridine derivatives (cerebrocrast, gammapyrone, glutapyrone, and diethone) against oxidative stress was assessed on mitochondrial bioenergetics, inner membrane anion channel (IMAC), Ca2+-induced opening of the permeability transition pore (PTP), and oxidative damage induced by the oxidant pair adenosine diphosphate (ADP)/Fe2+ (lipid peroxidation) of mitochondria isolated from rat liver. By using succinate as the respiratory substrate, respiratory control ratio (RCR), ADP to oxygen ratio (ADP/O), state 3, state 4, and uncoupled respiration rates were not significantly affected by gammapyrone, glutapyrone, and diethone concentrations up to 100 microM. Cerebrocrast at concentrations higher than 25 microM depressed RCR, ADP/O, state 3, and uncoupled respiration rates, but increased three times state 4 respiration rate. The transmembrane potential (deltapsi) and the phosphate carrier rate were also decreased. At concentrations lower than 25 microM, cerebrocrast inhibited the mitochondrial IMAC and partially prevented Ca2+-induced opening of the mitochondrial PTP, whereas gammapyrone, glutapyrone, and diethone were without effect. Cerebrocrast, gammapyrone, and glutapyrone concentrations up to 100 microM did not affect ADP/Fe2+-induced lipid peroxidation of rat liver mitochondria, while very low diethone concentrations (up to 5 microM) inhibited it in a dose-dependent manner, as measured by oxygen consumption and thiobarbituric acid reactive substances formation. Diethone also prevented deltapsi dissipation due to lipid peroxidation initiated by ADP/Fe2+. It can be concluded that: none of the compounds interfere with mitochondrial bioenergetics at concentrations lower than 25 microM; cerebrocrast was the only compound that affected mitochondrial bioenergetics, but only for concentrations higher than 25 microM; at concentrations that did not affect mitochondrial bioenergetics (< or = 25 microM), only cerebrocrast inhibited the IMAC and partially prevented Ca2+-induced opening of the PTP; diethone was the only compound that expressed antioxidant activity at very low concentrations (< or = 5 microM). Cerebrocrast acting as an inhibitor of the IMAC and diethone acting as an antioxidant could provide effective protective roles in preventing mitochondria from oxidative damage, favoring their therapeutic interest in the treatment of several pathological situations known to be associated with cellular oxidative stress.