Hydrocortisone cardioprotection in ischaemia/reperfusion injury involves antioxidant mechanisms.

BACKGROUND: Glucocorticoid (GR) and mineralocorticoid (MR) receptors are highly expressed in cardiac tissue, and both can be activated by corticosteroids. MR activation, in acute myocardial infarction (AMI), worsens cardiac function, and increase NHE activity contributing to the deleterious process. In contrast, effects of GR activation are not fully understood, probably because of the controversial scenario generated by using different doses or potencies of corticosteroids. AIMS: We tested the hypothesis that an acute dose of hydrocortisone (HC), a low-potency glucocorticoid, in a murine model of AMI could be cardioprotective by regulating NHE1 activity, leading to a decrease in oxidative stress. MATERIALS AND METHODS: Isolated hearts from Wistar rats were subjected to regional ischemic protocol. HC (10 nmol/L) was added to the perfusate during early reperfusion. Infarct size and oxidative stress were determined. Isolated papillary muscles from non-infarcted hearts were used to evaluate HC effect on sodium-proton exchanger 1 (NHE1) by analysing intracellular pH recovery from acute transient acidosis. RESULTS: HC treatment decreased infarct size, improved cardiac mechanics, reduced oxidative stress after AMI, while restoring the decreased level of the pro-fusion mitochondrial protein MFN-2. Co-treatment with the GR-blocker Mifepristone avoided these effects. HC reduced NHE1 activity by increasing the NHE1 pro-inhibiting Ser648 phosphorylation site and its upstream kinase AKT. HC restored the decreased AKT phosphorylation and anti-apoptotic BCL-2 protein expression detected after AMI. CONCLUSIONS: Our results provide the first evidence that acute HC treatment during early reperfusion induces cardioprotection against AMI, associated with a non-genomic HC-triggered NHE1 inhibition by AKT and antioxidant action that might involves mitochondrial dynamics improvement.

Antioxidant, anticancer activities and mechanistic studies of the flavone glycoside diosmin and its oxidovanadium(IV) complex. Interactions with bovine serum albumin.

The natural antioxidant flavonoid diosmin, found in citric fruits, showed low antioxidant properties among other flavonoids due to its structural characteristics and low cytotoxicity against lung (A549) and breast (T47D, SKBR3 and MDAMB231) cancer cell lines. The anticancer behavior has been improved by the metal complex generated with the flavonoid and the oxidovanadium(IV) ion. This new complex, [VO(dios)(OH)3]Na5·6H2O (VOdios), has been synthesized and characterized both in solid and solution states. The interaction of the metal ion through the sugar moiety of diosmin precluded the improvement of the antioxidant effects. However, the cell-killing effects tested in human lung A549 and breast T47D, SKBR3 and MDAMB231 cancer cell lines, were enhanced by complexation. The anti-proliferative effects on the human lung cancer cell line were accompanied by cellular ROS generation and an increase in cytoplasm condensation. The breast cancer cell lines did not produce caspase3/7 activation, mitochondrial potential reduction and ROS generation. Therefore, a non-apoptotic form of cell death in a caspase- and oxidative stress-independent manner has been proposed. The protein binding ability has been monitored by the quenching of tryptophan emission in the presence of the compounds using bovine serum albumin (BSA) as a model protein. Both compounds could be distributed and transported in vivo and the complex displayed stronger binding affinity and higher contributions to the hydrogen bond and van der Waals forces.

Complexation of the Antihypertensive Drug Olmesartan with Zn: In Vivo Antihypertensive and Cardiac Effects.

This study is based on the premise that the application of chemical synthesis strategies to structurally modify commercial drugs by complexation with biometals is a valid procedure to improve their biological effects. Our purpose is to synthesize a compound with greater efficacy than the original drug, able to enhance its antihypertensive and cardiac pharmacological activity. Herein, the structure of the coordination compound of Zn(II) and the antihypertensive drug olmesartan, [Zn(Olme)(H2O)2] (ZnOlme), is presented. After 8 weeks of treatment in SHR male rats, ZnOlme displayed a better blood pressure-lowering activity compared with olmesartan, with a noticeable effect even in the first weeks of treatment, while ZnCl2 showed similar results than the control. ZnOlme also reduced left ventricle (LV) weight and left ventricle/tibia length ratio (LV/TL), posterior wall thickness (PWT), and intraventricular septum in diastole (IVSd) suggesting its potential to prevent LV hypertrophy. Besides, ZnOlme reduced interstitial fibrosis (contents of collagen types I and III, responsible for giving rigidity and promoting vascular elasticity, respectively). The recovery of heart function was also evidenced by fractional shortening (diastolic left ventricular/systolic left ventricular) diameter determinations. Furthermore, ZnOlme increased the antioxidant capacity and prevented cardiac oxidative stress: it enhanced the reduction of reactive oxygen species generation, exerted a significant decrease in lipid peroxidation and enhanced glutathione contents in heart tissues compared to the control, Zn, and olmesartan treatments. Our results demonstrate that continuous oral administration of ZnOlme causes a better antihypertensive effect and grants enhancement of cardioprotection through antioxidant activity, in combination with hemodynamic improvement.

Improvement of the cardiovascular effect of methyldopa by complexation with Zn(II): Synthesis, characterization and mechanism of action.

BACKGROUND: the antihypertensive drug α-methyldopa (MD) stands as one of the extensively used medications for managing hypertension during pregnancy. Zinc deprivation has been associated with many diseases. In this context, the synthesis of a Zn coordination complex [Zn(MD)(OH)(H2O)2]·H2O (ZnMD) provide a promising alternative pathway to improve the biological properties of MD. METHODS: ZnMD was synthesized and physicochemically characterized. Fluorescence spectral studies were conducted to examine the binding of both, the ligand and the metal with bovine serum albumin (BSA). MD, ZnMD, and ZnCl2 were administered to spontaneous hypertensive rats (SHR) rats during 8 weeks and blood pressure and echocardiographic parameters were determined. Ex vivo assays were conducted to evaluate levels of reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), and nitric oxide (NO). Cross-sectional area (CSA) and collagen levels of left ventricular cardiomyocytes were also assessed. Furthermore, the expression of NAD(P)H oxidase subunits (gp91phox and p47phox) and Superoxide Dismutase 1 (SOD1) was quantified through western blot analysis. RESULTS: The complex exhibited a moderate affinity for binding with BSA showing a spontaneous interaction (indicated by negative ΔG values) and moderate affinity (determined by affinity constant values). The binding process involved the formation of Van der Waals forces and hydrogen bonds. Upon treatment with MD and ZnMD, a reduction in the systolic blood pressure in SHR was observed, being ZnMD more effective than MD (122 ± 8.1 mmHg and 145 ± 5.6 mmHg, at 8th week of treatment, respectively). The ZnMD treatment prevented myocardial hypertrophy, improved the heart function and reduced the cardiac fibrosis, as evidenced by parameters such as left ventricular mass, fractional shortening, and histological studies. In contrast, MD did not show noticeable differences in these parameters. ZnMD regulates negatively the oxidative damage by reducing levels of ROS and lipid peroxidation, as well as the cardiac NAD(P)H oxidase, and increasing SOD1 expression, while MD did not show significant effect. Moreover, cardiac nitric oxide levels were greater in the ZnMD therapy compared to MD treatment. CONCLUSION: Both MD and ZnMD have the potential to be transported by albumin. Our findings provide important evidence suggesting that this complex could be a potential therapeutic drug for the treatment of hypertension and cardiac hypertrophy and dysfunction.

Effect of the structural modification of Candesartan with Zinc on hypertension and left ventricular hypertrophy.

Hypertension is the most common cause of left ventricular hypertrophy, contributing to heart failure progression. Candesartan (Cand) is an angiotensin receptor antagonist widely used for hypertension treatment. Structural modifications were previously performed by our group using Zinc (ZnCand) as a strategy for improving its pharmacological properties. The measurements showed that ZnCand exerts a stronger interaction with the angiotensin II receptor, type 1 (AT1 receptor), reducing oxidative stress and intracellular calcium flux, a mechanism implied in cell contraction. These results were accompanied by the reduction of the contractile capacity of mesangial cells. In vivo experiments showed that the complex causes a significant decrease in systolic blood pressure after 8 weeks of treatment in spontaneously hypertensive rats (SHR). The reduction of heart hypertrophy was evidenced by echocardiography, the histologic cross-sectional area of cardiomyocytes, collagen content, the B-type natriuretic peptide (BNP) marker and connective tissue growth factor (CTGF) and the matrix metalloproteinase 2 (MMP-2) expression. Besides, the complex restored the redox status. In this study, we demonstrated that the complexation with Zn(II) improves the antihypertensive and cardiac effects of the parental drug.

Candesartan, losartan and valsartan Zn(II) complexes interactions with bovine serum albumin.

Background: The pharmacological response and the therapeutic efficacy of a drug depends on the interactions with plasma proteins. Methodology: The interaction of bovine serum albumin (BSA) with the metal complexes of antihypertensive drugs, Zn(II)/sartan complexes (candesartan, valsartan and losartan), was investigated using fluorescence quenching determinations at different temperatures. Results: The binding studies of the compounds with BSA showed static quenching and moderate binding with calculated constants in the range of 104-106 M-1, indicating potent serum distribution via albumins. In all cases, negative values of free energy are indicative of spontaneous processes and the stabilization of BSA/compound complexes through hydrogen bonding and van der Waals forces. The results for the sartans agree with the reported pharmacokinetics studies. Conclusion: It has been determined that the three sartans and the Zn complexes could be transported and distributed by albumin.

Antimetastatic effects of VOflavonoid complexes on A549 cell line.

BACKGROUND: Non-small-cell lung cancer (NSCLC) is the most frequent type of lung cancer and more than 90 % of mortality is due to metastasis-related deaths. Flavonoids are considered nutraceuticals due to the variety of pharmacological properties. In this paper, we studied the effects of baicalin, silibinin, apigenin, luteolin, and its oxidovanadium(IV) cation complexes on the viability, adhesion to fibronectin, invasion, and migration on human lung cancer cell line A549. In addition, in order to complete the study of the interaction of VOflavonoids and bovine serum albumin (BSA), the binding ability of silibinin and VOsil to the protein was evaluated. METHOD: To establish the non-cytotoxic concentration range of the tested compounds, the cancer cell viability was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Cell migration and invasion assays were performed using Boyden chambers and adhesion assay using MTT method. The interaction of compounds with BSA were investigated in physiological buffer (pH = 7.4) by fluorescence spectroscopy. RESULTS: All complexes inhibited the metastatic cascade steps to a greater extent than their respective ligands. Likewise, based on binding constant values (Kb) for BSA-silibinin and BSA-VOsil, we can suggest that both compounds can interact with the protein. CONCLUSION: Although all the complexes suppressed cell adhesion, invasion and migration, VOlut can be considered as a good candidate to continue the trials because it presented encouraging results as a potential antitumor and antimetastatic agent, and can be transported by BSA.

Zinc complexation improves angiotensin II receptor type 1 blockade and in vivo antihypertensive activity of telmisartan.

Background: Angiotensin II receptor blockers were designed as therapeutic agents to block the binding site of the angiotensin II receptor type 1 (AT1R). Methodology: The structure of telmisartan was modified by coordination to the biometal Zn(II), resulting in the compound ZnTelm. Its antihypertensive activity and cellular mechanisms in comparison to telmisartan were studied. Results: Compared with telmisartan, ZnTelm displayed stronger binding to AT1R (binding studies on AT1R-transfected human embryonic kidney cells) and a greater reduction of reactive oxygen species and cytosolic calcium concentration induced by angiotensin II. The antihypertensive activity of the complex (assessed in an N(G)-Nitro-L-arginine methyl ester-induced hypertension model) was significantly higher. ZnTelm also reduced hypertrophy in aortic artery rings and tubular collagen deposition. Conclusion: ZnTelm enhances the AT1R blockade and consequently its antihypertensive effect.

Improvement of the Anticancer Activities of Telmisartan by Zn(II) Complexation and Mechanisms of Action.

To improve the anticancer activity of telmisartan, its structure has been modified by Zn(II) complexation giving [Zn(Telm)2(H2O)2]·2H2O (ZnTelm). The cytotoxic effect was measured on the human lung cancer cells (A549) and on the lung fibroblast cells (MRC-5). The complex markedly improved anticancer activity (IC50 75 µM) of telmisartan (IC50 125 µM) or ZnSO4 (IC50 225 µM) and did not show toxicity on non-cancer cells, inducing oxidative stress with cellular ROS generation and GSH/GSSG decrease. Apoptosis was the dominant form of cell death for the complex. The Bax/Bcl-XL ratio was significantly increased as well as caspase-3 activation. Both the complex and the ligand bind to bovine serum albumin (BSA) and can be stored and transported by the protein but the interaction with the complex is greater. Telmisartan binds BSA by hydrophobic interactions while the interaction of ZnTelm occurs through van der Waals forces and hydrogen bonding. Therefore, it can be shown that the coordination complex ZnTelm improved the anticancer activity of the antihypertensive drug telmisartan (IC50 75 µM and 125 µM, respectively) and the interaction with BSA. Graphical Abstract Improvement of the anticancer activities of telmisartan by Zn(II) complexation and mechanisms of action. Intrinsic apoptotic pathway: induction ofoxidative stress and regulation of proteins related to apoptosis. The complex interacted with bovine serum albumin (BSA) and can be stored and transported by the protein.

Azilsartan and its Zn(II) complex. Synthesis, anticancer mechanisms of action and binding to bovine serum albumin.

Azilsartan is the eighth approved member of angiotensin II receptor blockers for hypertension treatment. Considering that some drugs have additional effects when administered, we studied its effects and mechanisms of action on a human lung cancer cell line A549. We have also modified the structure of the drug by complexation with Zn(II) cation and assayed the anticancer effect. The crystal structure of the new binuclear Zn(II) complex, for short [Zn2(azil)2(H2O)4]·2H2O (ZnAzil), was determined by X-ray diffraction methods. The zinc ions are bridged by azilsartan ligands through their carboxylate oxygen and oxadiazol nitrogen atoms. The compounds were examined for their cytotoxic effects against human lung fibroblast (MRC5) and human lung cancer (A549) cell lines. Azilsartan displayed low cytotoxic effects at 150 µM concentrations in A549 human lung cancer cells but the higher effect measured for the Zn complex suggested that this compound may act as an anticancer agent. An apoptotic oxidative stress mechanism of action via the mitochondrial-dependent intrinsic pathway has been determined. Besides, the compounds exerted weak cytotoxic effects in the normal lung related cell line MRC5. Binding constants of the complex formed between each compound and bovine serum albumin (BSA) are in the intermediate range, hence suggesting that azilsartan and ZnAzil could be bonded and transported by BSA.

Interaction of Zn with Losartan. Activation of Intrinsic Apoptotic Signaling Pathway in Lung Cancer Cells and Effects on Alkaline and Acid Phosphatases.

A new losartan [2-butyl-5-chloro-3-[[4-[2-(2H-tetrazol-5-yl)phenyl]phenyl]methyl]imidazol-4-yl]methanol zinc(II) complex [Zn(Los)Cl], was synthesized and characterized. The crystal structure was determined by x-ray diffraction methods. When aqueous solutions of the ligand and the metal were mixed, the known and more soluble powder [Zn(Los)2].3H2O (ZnLos) complex has been obtained. The interactions with phosphatases showed a concerted mechanism displayed by the Zn ions and ZnLos up to 500 µM concentration: a decrease of the acid phosphatase (AcP) associated with an increase in the alkaline phosphatase (ALP) activities. The complex and ZnSO4 showed a cytotoxic behavior on human lung A549 cancer cell line at concentrations higher than 75 µM with reactive oxygen species (ROS) generation and GSH (and GSH/GSSG ratio) depletion. Apoptotic cells were observed using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) method, a mechanism accompanied by upregulation of BAX protein, downregulation of Bcl-XL and release of caspase-3. The BAX/Bcl-XL ratio was found to be significantly higher in cells exposure to ZnLos than cells treated with ZnSO4, in agreement with the higher apoptotic percentage of cells found for the complex. Cell death was found to be produced by apoptosis and no necrosis has been observed. On the contrary, losartan exerted low effects on phosphatases, produced some reduction of cancer cell viability (concentrations > 250 µM, number of apoptotic cells similar to the basal) with low ROS depletion, without alteration of the GSH/GSSG and low BAX/Bcl-XL ratios. In the MRC-5, normal lung fibroblasts cell line only ZnSO4 at concentrations higher than 200 µM displays cytotoxic effects. Graphical abstract Interaction of Zn with losartan. Activation of intrinsic apoptotic signaling pathway in lung cancer cells and effects on alkaline and acid phosphatases.