Saffron (Crocus sativus) intake provides nutritional preconditioning against myocardial ischemia-reperfusion injury in Wild Type and ApoE(-/-) mice: Involvement of Nrf2 activation.

BACKGROUND AND AIMS: Saffron is an antioxidant herbal derivative; however, its efficacy as a nutritional cardioprotective agent has not been fully elucidated. We investigated the cardioprotective properties of a standardized saffron aqueous extract (SFE) against ischemia/reperfusion (I/R) injury in Wild-Type (WT) and ApoE(-/-) mice and the underlying molecular mechanisms. METHODS AND RESULTS: WT and ApoE(-/-) mice were subjected to 30 min I and 2 h R, with the following per os interventions for 4 weeks: 1) WT Control Group, receiving Water for Injection (WFI); 2) WT Crocus Group, receiving SFE at a dose of 60 mg/kg/day; 3) WT Crocus + Wort group, receiving SFE as described above and wortmannin at a dose of 60 µg/kg bolus 15 min before R; 4) ApoE(-/-) Control Group, receiving WFI; 5) ApoE(-/-) Crocus Group, receiving SFE at a dose of 60 mg/kg/day and 6) ApoE(-/-) Crocus + Wort: receiving SFE as described above and wortmannin at a dose of 60 µg/kg bolus, 15 min before R. Ischemic area/area at risk (I/R%) ratio was measured. Blood samples and ischemic myocardial tissue were collected at the 10th min of reperfusion for assessment of troponin I, malondialdehyde (MDA), nitrotyrosine (NT), p-eNOS, eNOS, p-Akt, Akt, p-p42/p-p44, p-GSK3ß, GSK3ß, IL-6, Nrf2, HO-1 and MnSOD expression. The effect of SFE on Nrf2 expression was also evaluated in vitro. SFE reduced infarct size in WT (16.15 ± 3.7% vs 41.57 ± 2.48%, ***p < 0.001) and in ApoE(-/-) mice (16.14 ± 1.47% vs 45.57 ± 1.73%, ***p < 0.001). The administration of wortmannin resulted in partial inhibition of the infarct size limitation efficacy of SFE (in both WT and Apo-E(-/-) mice). Mice receiving SFE showed increased levels of eNOS, p-Akt, p-ERK1/2, p-44/p-42 and p-GSK3ß-Ser9 and reduced expression of IL-6 and iNOS; furthermore, SFE reduced the levels of MDA and NT. SFE induced Nrf2 expression and its downstream targets, HO-1 and MnSOD in the myocardium of the treated animals, and induced Nrf2 expression in vitro in a dose-dependent manner. CONCLUSIONS: SFE limits myocardial infarction in Wild-Type and ApoE(-/-) mice in a multifaceted manner including activation of Akt/eNOS/ERK1/2/GSK3-ß and through Nrf2 pathway, bestowing antioxidant protection against I/R.

Investigating the signal transduction pathways underlying remote ischemic conditioning in the porcine heart.

BACKGROUND: The mechanism underlying remote ischemic conditioning (RIC) remains unclear. We investigated whether RIC protects the heart through the activation of the adenosine receptor and the PI3K-Akt pathway at the onset of myocardial reperfusion. METHODS AND RESULTS: Domestic pigs (27-35 kg) were subjected to in situ left anterior descending coronary artery ischemia (60 min) followed by reperfusion (180 min) and randomised to the following: (1) Control- No additional intervention; (2) Remote ischemic preconditioning (RIPC)- Four-5 min cycles of lower limb ischemia/reperfusion were administered prior to myocardial ischemia; (3) RIPC + Wort or 8-SPT: Wortmannin (Wort 20 µg/kg, a PI3K inhibitor) or 8-sulfophenyltheophylline (8-SPT 10 mg/kg, an adenosine receptor inhibitor) were administered intravenously 30 s before myocardial reperfusion to RIPC-treated animals; (4) Remote ischemic perconditioning (RIPerC)--Four-5 min cycles of lower limb ischemia/reperfusion were applied 1 min before myocardial reperfusion; (5) RIPerC + Wort or 8-SPT: Wort or 8-SPT were given 30 s before myocardial reperfusion to RIPerC-treated animals. Both RIPC and RIPerC reduced myocardial infarct size (13.3 ± 2.2% with RIPC, 18.2 ± 2.0% with RIPerC versus 48.8 ± 4.2% in control:P < 0.05:N ≥ 5/group). Wortmannin abolished the infarct-limiting effects of RIPC (33.2 ± 6% with RIPC + Wort versus 13.3 ± 2.2% with RIPC:P < 0.05:N ≥ 5/group) but not RIPerC (18.0 ± 3.4% with RIPerC + Wort versus 18.2 ± 2.0% with RIPerC:P > 0.05:N ≥ 5/group). 8-SPT did not influence the infarct-limiting effects of either RIPC or RIPerC. Western blot analysis confirmed Wortmannin-sensitive PI3K and Akt activation at myocardial reperfusion in RIPC-treated hearts. CONCLUSIONS: In the porcine heart, both RIPC and RIPerC both reduce myocardial infarct size and with RIPC but not RIPerC this cardioprotective effect is associated with the activation of the PI3K-Akt pathway at reperfusion.

Alternative pharmacological interventions that limit myocardial infarction.

Despite current optimal treatment, the morbidity and mortality of coronary heart disease remain significant worldwide and open the way for the development of novel cardioprotective therapies. In the last two decades, a remarkable scientific effort has focused on the limitation of infarct size. Important input from experimental studies has led the way in this direction. However, clinical and preclinical results using various cardioprotective strategies to attenuate reperfusion injury have generally not been applicable for every day clinical practice. Protection of the ischemic myocardium is known to occur as a result of ischemic preconditioning (PC), in which repetitive brief periods of ischemia protect the heart from a subsequent prolong ischemic insult. Although PC is a powerful form of protection, it is of limited clinical application for obvious ethical and practical reasons. Another endogenous form of cardioprotection, similar to PC but applicable at the time of reperfusion, termed postconditioning (PostC), has been recently described. Short series of repetitive cycles of brief reperfusion and re-occlusion of the coronary artery applied at the onset of reperfusion, reduce the infarct size and coronary artery endothelial dysfunction. At present, pharmacological PC and PostC are possible alternative methods that may substitute pharmaceutical treatments the short ischemic insults. Adenosine, nicorandil and other agents have been already used as pharmacological mimetics of ischemic PC in multicenter trials. We summarize the recent research efforts on novel therapeutic strategies and on the design of new compounds, based on the accumulated knowledge of the ligands, receptors and intracellular signaling pathways of PC and PostC.

Effect of the portacaval shunt on reperfusion injury after 65% hepatectomy in pigs.

BACKGROUND: Portal flow diversion by portacaval shunts (PCS) has been shown to prevent primary graft nonfunction in liver transplantation using small-for-size grafts. In this study, we examine whether PCS can improve reperfusion injury after major hepatectomy in pigs. MATERIALS AND METHODS: In 14 pigs, a partial PCS was constructed following 65% hepatectomy and 1 h of inflow ischemia. During 24 h of reperfusion, the shunt was either closed (group A, n = 7) or left open (group B, n = 7). RESULTS: 24 h after reperfusion, group A had higher levels of alanine aminotransferase (70 +/- 12 IU/l vs. 51 +/- 5.9 IU/l; p < 0.05), alanine aminotransferase per gram of liver remnant (0.41 +/- 0.07 IU/l/g vs. 0.21 +/- 0.05 IU/l/g; p < 0.05), prothrombin time (24.1 +/- 2.4 s vs. 14.3 +/- 2.9 s; p < 0.05), international normalized ratio (2.11 +/- 0.15 vs. 1.29 +/- 0.28; p < 0.05), hepatocyte necrosis scores and percentages of nuclei stained for proliferating cell nuclear antigen (52.57 +/- 8.9% vs. 36.71 +/- 6%; p < 0.05) compared to group B. CONCLUSIONS: Partial portal flow diversion appears to attenuate reperfusion injury in a porcine model of major hepatectomy.

Relationship between iNOS expression and aortic cell proliferation and apoptosis in an elastase-induced model of aorta aneurysm and the effect of 1400 W administration.

BACKGROUND: In the present study, we employed an elastase infusion-dependent abdominal aortic aneurysm (AAA) model to examine inducible nitric oxide synthase (iNOS) expression in relation to cellular proliferation and apoptosis in this pathologic condition. Furthermore, we employed N-(3-(aminomethyl)benzyl)acetamidine (1400 W), a previously shown selective iNOS inhibitor, to further explore this relationship. METHODS: Adult male Wistar rats were randomized into separate groups. Group A served as a control and received an intra-aortic saline infusion, while groups B, C, and D received an intra-aortic elastase infusion according to standard protocols. The animals in group C were administered postoperatively the highly selective iNOS inhibitor, 1400 W, while rats in group D received regularly the same compound preoperatively and postoperatively. The animals were killed at postoperative days 7 and 14. Aorta diameter and nitric oxide (NO), nitrite/nitrate, and MDA levels were measured. iNOS expression was assessed by immunohistochemistry and Western blot analysis, while Ki-67 immunohistochemistry and TUNEL assay were used to evaluate cellular proliferation and apoptosis, respectively. RESULTS: Increased iNOS and NO levels accompanied aneurysm development in groups B, C, and D, but these levels were significantly lower in groups C and D, compared with group B. Interestingly, very low but detectable levels of iNOS were found in the control group, indicating a basal constitutive level. Cell growth parameters were augmented in group B compared with group A. In contrast, groups C and D exhibited a significant decrease of the cellular growth parameters but did not attain normal values. CONCLUSIONS: iNOS-derived NO is associated with the cellular growth parameters of the vessel cells, predominantly smooth muscle cells. Selective iNOS blockage ameliorates the cellular remodeling in AAAs.

Synthesis of novel Se-substituted selenocysteine derivatives as potential kidney selective prodrugs of biologically active selenol compounds: evaluation of kinetics of beta-elimination reactions in rat renal cytosol.

Eighteen Se-substituted selenocysteine derivatives were synthesized as potential kidney selective prodrugs which can be activated by renal cysteine conjugate beta-lyase to selenium-containing chemoprotectants or antitumor agents. Selenocysteine derivatives with aliphatic and benzylic Se-substituents were synthesized by reducing selenocystine to selenocysteine followed by a reaction with the corresponding alkyl and benzyl halogenides. Selenocysteine derivatives with aromatic Se-substitutes were synthesized by reaction of beta-chloroalanine with substituted phenylselenol compounds, which were formed by reducing substituted diphenyl diselenides by NaBH4. The enzyme kinetic parameters (apparent Km and Vmax) of the beta-elimination reaction of the selenocysteine conjugates were studied in rat renal cytosol. The results suggest that Se-substituted L-selenocysteine conjugates are extremely good substrates for renal cysteine conjugate beta-lyases as indicated by low apparent Km and high Vmax values. The benzyl-substituted Se-conjugates appeared to be better substrates than the phenyl- and alkyl-substituted Se-conjugates. Corresponding L-cysteine S-conjugates were too poor substrates to obtain proper enzyme kinetics. Recently, local activation of cysteine S-conjugates by renal cysteine conjugate beta-lyases was proposed as a new strategy to target antitumor agents to the kidney. The present results show that Se-substituted selenocysteine conjugates may be more promising prodrugs because these compounds are much better substrates for beta-lyase.

Influence of ondansetron on thiopental hypnotic requirements.

Ondansetron, a selective 5-HT3 antagonist has been proved to be an effective antiemetic agent for prophylaxis of nausea and vomiting after surgery. This study was conducted to determine whether ondansetron changes thiopental requirements for induction of anesthesia in patients unpremedicated and premedicated with diazepam. One hundred sixty eight adult female patients classified as American Society of Anesthesiologists (ASA) physical status I (normal healthy patient) or II (patient with mild systemic disease) participated in this prospective, double blinded, randomized study. Patients were assigned to receive either 0.07 mg/Kg diazepam orally or no premedication. They then received saline and ondansetron 0.1 mg/Kg or 0.2 mg/Kg intravenously 5 minutes before thiopental induction. Thiopental was administered at a rate of 25 mg/min until the patient lost the ability to open eyes on command. Thiopental requirements were not significantly different among groups. The results indicate that ondansetron in clinically used doses does not influence the hypnotic requirements of thiopental.

Metabolic modulation and optimization of energy consumption in heart failure.

Chronic heart failure (CHF) is a common and disabling syndrome with a poor prognosis. It is a major and increasing public health problem. Angiotensin-converting enzyme inhibitors, diuretics, and digitalis are the standards treatments for CHF. Other drugs, such as beta-blockers, spironolactone, calcium antagonists, vasodilators, and antiarrhythmic agents are used to counteract the progression of the syndrome or to improve the hemodynamic profile. Despite optimum treatment with neurohumoral antagonists, prognosis of CHF remains poor; the patients complain of persistent reductions in their exercise capacity and quality of life. Fatigue and shortness of breath, two common and disabling symptoms in patient with CHF, are relatively independent from hemodynamic and neuroendocrine changes, although they seem to be related to the impairment of peripheral muscle metabolism and energetic phosphate production. Therefore, CHF is a complex metabolic syndrome in which the metabolism of cardiac and peripheral muscles is impaired and novel therapeutic strategies have been aimed at positive modulation with compounds such as carnitine, trimetazidine, and ranolazine.

Effect of novel anti-inflammatory ethanolamine derivatives with antioxidant properties on drug metabolising enzymes.

The influence of four ethanolamine derivatives with anti-inflammatory and antioxidant activity on the in vitro aminopyrine N-demethylation was studied. It was found that these compounds inhibit the N-demethylation of aminopyrine. 1-Cyclohexyl-5-(2-hydroxy-ethylamino)-pentan-2-one (compound 4), possessing the highest inhibitory activity and found earlier to be a potent anti-inflammatory agent, is further tested in vivo on zoxazolamine-induced paralysis, after a single administration to rats, and on aminopyrine N-demethylation, rat hepatic total cytochrome P450 and protein (postmitochondrial and microsomal) content, after a prolonged treatment. It was found that the examined compound had no significant influence on the above biotransformations, however, it could decrease the catalytically active hepatic cytochrome P450 content. These results, considered together with some structural and physicochemical properties of the compound, indicate that this compound may act as a CYP2D6 substrate.

Association of soluble apoptotic markers with impaired left ventricular deformation in patients with rheumatoid arthritis. Effects of inhibition of interleukin-1 activity by anakinra.

Myocardial function is impaired in rheumatoid arthritis (RA). Inhibition of interleukin (IL)-1 activity reduces experimental myocardial infarction by limiting apoptosis. We investigated whether a) soluble apoptotic markers are related with impaired left ventricular (LV) performance and b) treatment with anakinra, an IL-1 receptor antagonist, reduces apoptotic markers leading to improved LV performance in RA. We studied 46 RA patients. In an acute, double-blind cross-over trial, 23 patients were randomised to a single injection of anakinra or placebo and after 48 hours (h) to the alternative treatment. In a chronic trial, 23 patients who received anakinra for 30 days were compared with 23 patients who received prednisolone. At baseline, 3 h and 30 days after treatment, we measured circulating IL-1ß, tumour necrosis factor (TNF)-α, Fas, Fas-ligand and caspase-9 to assess apoptosis. At baseline and 30 days after treatment, we assessed LV longitudinal strain, strain rate and E/Em ratio using 2D-speckle tracking and tissue Doppler echocardiography. At baseline, increased apoptotic markers were related with reduced LongSRS and increased E/Em (p<0.05). After 3 h and 30 days of anakinra, there was a reduction in Fas (median 481 vs. 364 vs. 301 pg/ml), Fas-ligand (median 289 vs. 221 vs. 190 pg/ml), caspase-9 (median 1.90 vs. 1.40 vs. 1.07 ng/ml), TNF-α and IL-1ß (p<0.05 for all comparisons). E/Em, LongS and LongSRS were improved after anakinra (p<0.01) and their percent changes were related with the corresponding changes of Fas and caspase-9 (p<0.05). No changes of the examined parameters were observed after prednisolone. In conclusion, inhibition of IL-1 activity by anakinra reduces apoptotic markers leading to improved LV performance in RA.

Lowering interleukin-1 activity with anakinra improves myocardial deformation in rheumatoid arthritis.

OBJECTIVE: Inhibition of interleukin-1 activity improves nitro-oxidative stress, endothelial and coronary function. The authors investigated (a) the association of nitro-oxidative stress and endothelial function with myocardial deformation, (b) the effects of anakinra, an interleukin-1a receptor antagonist on myocardial deformation in patients with rheumatoid arthritis (RA). METHODS: The authors compared 46 RA patients to 23 normal controls. 23 patients received anakinra (150 mg subcutaneously once daily) and 23 patients a 5-mg increase of prednisolone dose for 30 days. At baseline and post-treatment this study assessed (a) the left ventricular (LV) longitudinal, circumferential and radial strain and strain rate, using speckle tracking echocardiography, (b) the coronary flow reserve (CFR), (c) the flow-mediated endothelial-dependent dilation of the brachial artery (FMD) and (d) nitrotyrosine (NT) and malondialdehyde blood levels. RESULTS: Patients had impaired baseline myocardial deformation indices compared to controls (p<0.05). CFR and NT levels were related to longitudinal strain, systolic and diastolic strain rate, circumferential strain and systolic strain rate (p<0.05). FMD was related to longitudinal and circumferential diastolic strain rate (p<0.01). Compared to baseline, anakinra-treated patients increased the longitudinal strain (-17.8% (3.7%) vs -22.1% (3.5%)), systolic (-1.02 (0.23) l/s vs -1.25 (0.23) l/s) and diastolic (0.96 (0.37) l/s vs 1.20 (0.39) l/s) longitudinal strain rate, circumferential strain and strain rate (p<0.05 for all comparisons). No significant changes were observed among prednisolone-treated patients CONCLUSIONS: Myocardial deformation is impaired in RA patients and is related to nitro-oxidative stress and endothelial dysfunction. Chronic inhibition of IL-1 improves LV deformation in parallel with endothelial function and nitro-oxidative stress.

Plasma levels of osteopontin before and 24 h after percutaneous coronary intervention.

OBJECTIVE: Previous studies demonstrated that osteopontin (OPN) was increased after vascular injury, such as atherosclerosis and restenosis following angioplasty. We sought to determine the effects of percutaneous coronary intervention (PCI) on plasma OPN levels compared with coronary arteriography (CA). METHODS: Plasma OPN levels were determined in 103 patients who underwent CA or PCI with stent implantation, at baseline and 24 h after the procedure. Patients were divided into three groups; group I: patients without significant coronary artery stenosis, group II: patients with coronary artery disease in whom only CA was performed, group III: patients with coronary artery disease who had PCI and stent implantation. RESULTS: Plasma OPN levels before the procedure were similar in all three groups. OPN levels 24 h after the procedure were significantly higher only in group III compared with baseline. Among three groups, the OPN levels observed in 24 h were significantly higher in group III compared with group I. Patients in group III had significantly higher OPN values after the procedure, depending on the number of stents implanted (p = 0.03). CONCLUSION: The increase in OPN levels after PCI suggests that vascular injury due to PCI is responsible for this phenomenon.

Relationship between plasma osteopontin and oxidative stress in patients with coronary artery disease.

BACKGROUND: It is known that oxidative stress plays an important role in the pathogenesis of atherosclerosis and that an association exists between osteopontin (OPN) and atherosclerosis. OBJECTIVES: It was proposed that malondialdehyde (MDA), a biomarker of lipid peroxidation and oxidative stress, would be related to plasma OPN levels in patients with coronary artery disease (CAD). METHODS/RESULTS: Plasma OPN and MDA levels were measured in 71 patients (60 males and 11 females; mean age 61.7 +/- 10 years). Fifty-eight patients had significant CAD (group I) and 13 patients were free of CAD as defined angiographically (group II). Plasma OPN was measured by enzyme-linked immunosorbent assay (ELISA), while MDA was determined spectrophotometrically. Multivariate regression analysis revealed that ln-transformed OPN levels were independently associated with MDA after adjustment for age, hypertension and diabetes mellitus (R(2) = 0.278, p = 0.0004 and beta regression coefficient = 0.252 [standard error = 0.0958], p = 0.011). OPN and MDA levels were higher in patients with diabetes (73.6 +/- 36.2 ng/ml versus 56.1 +/- 30.9 ng/ml, p = 0.02 and 2.5 +/- 0.5 microM versus 2.0 +/- 0.5 microM, p = 0.002, respectively). CONCLUSIONS: The association between OPN and MDA levels in patients with CAD suggests an interaction between OPN and oxidative stress. This interaction may play a role in the pathogenesis of atherosclerosis.

The effect of acutely induced hepatic failure on remifentanil and fentanyl blood levels in a pig model.

BACKGROUND AND OBJECTIVE: Opioids and especially fentanyl are widely used during the intensive care unit management of intracranial pressure in fulminant hepatic failure patients as well as during and after liver transplantation. The newer synthetic opioid remifentanil is also increasingly being used in critical care patients. Due to a lack of data relating to the influence of acute hepatic failure on remifentanil and fentanyl pharmacokinetics, this study was designed in order to determine the impact of this condition on the blood levels of these opioids using a pig model. METHODS: Twenty pigs were randomly assigned to one of two groups: A group with surgically induced acute hepatic failure by hepatic devascularization (acute hepatic failure, n=10) and a control group (SHAM, n=10), subjected to a SHAM operation. Postoperatively, five animals in each group were administered remifentanil (1 microg kg-1 min-1) or fentanyl (0.2 microg kg-1 min-1) by continuous intravenous infusion. Blood samples for determination of drug concentrations were withdrawn at 0 h and 0.5, 1, 5, 7, 9 h after initiation of dosing. RESULTS: Significantly higher blood concentrations were found in animals with acute hepatic failure compared to SHAM-operated animals receiving remifentanil at 5 h (P=0.003), 7 h (P=0.007) and 9 h (P=0.004) and fentanyl at 7 h (P<0.0005) and 9 h (P=0.05). The small number and the great variability in drug concentrations did not allow a detailed kinetic analysis to be performed. Approximate clearance values were found to be greater for the SHAM compared with the acute hepatic failure animals for both fentanyl and remifentanil. CONCLUSIONS: Hepatic devascularization in our porcine acute hepatic failure model, appears to have significantly altered the disposition of fentanyl and unexpectedly remifentanil. These changes were thought to be brought about by severe disruption of blood flow and biotransformation in the liver, as well as by haemodynamic changes in the acute hepatic failure animals.

Effects of dopexamine on lipid peroxidation during aortic surgery in pigs: comparison with dopamine.

OBJECTIVE: We investigated the dose-related effect of dopexamine and dopamine on free radical production and lipid peroxidation estimated by MDA measurements in an ischaemia-reperfusion model of supraceliac aortic repair. DESIGN: Prospective, randomized, blinded experimental study. MATERIALS: Twenty-five healthy pigs. METHODS: All experiments were performed under general endotracheal anaesthesia. Supraceliac aortic cross clamping was performed in all pigs. The pigs were randomly assigned into five groups (n=5 in each group) and received a continuous intravenous infusion of normal saline (CTL), dopamine 2 microg kg(-1)min(-1) (dopa 2), dopamine 8 microg kg(-1)min(-1) (dopa 8), dopexamine 2 microg kg(-1)min(-1) (dopex 2), dopexamine 8 microg kg(-1)min(-1) (dopex 8). Cardiac output, mean arterial pressure, arterial blood gas analysis and blood sampling for plasma MDA measurements (to reveal lipid peroxidation) were recorded after induction of anaesthesia (baseline), 60 and 120 min after cross-clamping of aorta (ischaemia phase), and 60 and 120 min after restoration of flow (reperfusion phase). RESULTS: Dopexamine and dopamine at 8 microgkg(-1)min(-1) reduced MDA at 60 and 120 min after reperfusion. CONCLUSION: Dopexamine seems superior to dopamine in reducing oxygen free radicals and subsequent lipid peroxidation during reperfusion after supraceliac aortic cross clamping in pigs.

Effect of some novel ethylenediamine and ethanolamine derivatives on carrageenan-induced inflammation. Correlation with antioxidant activity and structural characteristics.

The effect of eight ethylenediamine and ethanolamine derivatives on inflammation was investigated in the carrageenan-induced rat paw edema model. The ability of these compounds to inhibit superoxide anion radical (O2-.) formation in vitro was also examined using the xanthine-xanthine oxidase system. Almost all of these substances were found to possess anti-inflammatory activity. This action can be well correlated with their reported capacity to inhibit microsomal membrane lipid peroxidation, while they demonstrated negligible effect on O2.- generation. The above actions appear to depend on some structural characteristics, particularly in the aromatic series of compounds.

Synthesis, antioxidant and anti-inflammatory activity of novel substituted ethylenediamines and ethanolamines. A preliminary quantitative structure-activity relationship study.

Six substituted oxo- or hydroxy-aminoethanols and ethylenediamines were synthesized and tested as anti-inflammatory agents. 1-Substituted 4-(2-aminoethylamino)-1-butanones and 1-substituted 4-(2-hydroxy-ethylamino)-1-butanones were prepared by reacting the appropriate 4-chloro-1-butanone with the corresponding aminoalcohol or ethylenediamine. 1-Substituted 4-(2-aminoethylamino)-1-butanols were prepared by the reduction of the ketones with NaBH4 or NaBH3CN. The RM values of the synthesized compounds were determined as an expression of their lipophilicity. The effect of these compounds on in vitro non-enzymatic lipid peroxidation, their hydroxyl radical scavenging activity and their ability to interact with 1,1-diphenyl-2-picrylhydrazyl stable free radical (DPPH) were studied. The effect of the synthesized compounds on inflammation, using the carrageenan induced rat paw edema model was studied. Both anti-inflammatory and antioxidant activities depended on some structural characteristics of the synthesized compounds. It was also attempted to correlate the above mentioned activities with some physicochemical parameters using a quantitative structure-activity relationship approach. The primary amino group appeared to be of importance for antioxidant activity in this series of compounds.

Evaluation of the kinetics of beta-elimination reactions of selenocysteine Se-conjugates in human renal cytosol: possible implications for the use as kidney selective prodrugs.

This study was performed to evaluate whether selenocysteine Se-conjugates are substrates for human cysteine conjugate beta-lyase enzymes. By testing kidney cytosols of three different humans, we studied interindividual differences in beta-lyase enzymes in humans. A series of 22 selenocysteine Se-conjugates were tested in rat and human kidney cytosols to compare their ability to form selenol compounds by beta-elimination. All compounds appeared to be good substrates for rat and human cysteine conjugate beta-lyase enzymes. The beta-lyase activity toward the selenocysteine Se-conjugates was comparable with those of the known nephrotoxic cysteine S-conjugate S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine in rats and humans. In rat kidney cytosol, between 22- and 877-fold higher beta-elimination rates were observed compared with human kidney cytosol. Significant correlations (P <.0001) between three human kidney cytosols in beta-lyase activities were found within the tested series of 22 compounds. Specific beta-lyase activities and intrinsic clearances of beta-elimination reactions ranged up to 3-fold, indicating that there are quantitative rather than qualitative interindividual differences in beta-eliminating enzymes in humans. Furthermore, Se-alkyl selenocysteine conjugates showed a sterically dependent bioactivation to selenol compounds in humans but not in rats. The present study supports the hypothesis that selenocysteine Se-conjugates may be useful as prodrugs to target pharmacologically active selenol compounds (e.g., antitumor or chemoprotective) to the kidney in humans.

Comparative cytotoxicity of 14 novel selenocysteine se-conjugates in rat renal proximal tubular cells.

Recently, Se-substituted selenocysteine conjugates were proposed as potential prodrugs to target biologically active selenol compounds to tissues containing high activities of cysteine conjugate beta-lyases, such as the kidneys. However, several selenium compounds are known to be relatively toxic compounds. In the present study, the cytotoxicity of 14 selenocysteine Se-conjugates was determined in freshly isolated rat renal proximal tubular cells (RPTC). The results of this study show that four selenocysteine Se-conjugates with alkyl substituents (methyl, ethyl, n-propyl, and n-butyl) did not cause significant cytotoxicity to RPTC up to concentrations of 500 microM after 90 min of incubation. Also, no effect was observed on mitochondrial functioning as indicated by the unaffected mitochondrial membrane potential (delta psi). Se-(i-Propyl)-selenocysteine, however, appeared to be a cytotoxic compound, causing time- and dose-dependent cytotoxicity, and caused a decrease of delta psi in remaining viable cells. Aminooxyacetic acid (AOAA) provided significant protection against cell death of Se-(i-propyl)-selenocysteine, pointing to involvement of cysteine conjugate beta-lyase. AOAA, however, did not prevent the decrease of delta psi. Differentially substituted Se-(phenyl)-L-selenocysteine and Se-(benzyl)-L-selenocysteine conjugates appeared to be cytotoxic to RPTC at a concentration of 200 microM, as indicated by increased cell death and a decreased delta psi in remaining viable cells. Within the Se-benzyl-series, Se-(4-methoxybenzyl)-L-selenocysteine was the most toxic conjugate, whereas Se-(4-chlorophenyl)-L-selenocysteine was the most toxic conjugate of the Se-phenyl compounds. The selenocysteine Se-conjugates with nonsubstituted phenyl and benzyl substituents were nontoxic at 200 microM, but caused significant cell death at a concentration of 500 microM. Preincubation with AOAA, an inhibitor of cysteine conjugate beta-lyase, provided only partial protection against the cytotoxicity of Se-(phenyl)-L-selenocysteine (500 microM) and Se-(4-methoxybenzyl)-L-selenocysteine (200 microM). AOAA did not protect against cytotoxicity of the other conjugates, suggesting direct effects of these compounds or involvement of alternative routes of bioactivation. This study demonstrates that cytotoxicity of selenocysteine Se-conjugates is strongly dependent on the nature of the Se-bound substituent. The nontoxic Se-(alkyl)-Se-conjugates may be promising candidates for further evaluation for chemopreventive activities.