Radiolabeled Peptides and Antibodies in Medicine

Radiolabeled peptides are a relatively new, very specific radiotracer group, which is still expanding. This group is very diverse in terms of peptide size. It contains very small structures containing several amino acids and whole antibodies. Moreover, radiolabeled peptides are diverse in terms of the binding aim and therapeutic or diagnostic applications. The majority of this class of radiotracers is utilized in oncology, where the same structure can be used in therapy and diagnostic imaging by varying the radionuclide. In this study, we collected new reports of radiolabeled peptide applications in diagnosis and therapy in oncology and other fields of medicine. Radiolabeled peptides are also increasingly being used in rheumatology, cardiac imaging, or neurology. The studies collected in this review concern new therapeutic and diagnostic procedures in humans and new structures tested on animals. We also performed an analysis of clinical trials, which concerns application of radiolabeled peptides and antibodies that were reported in the clinicaltrials.gov database between 2008 and 2018.

An investigation into the pleiotropic activity of metformin. A glimpse of haemostasis

The most characteristic features of type 2 diabetes mellitus (T2DM) are hyperglycaemia and insulin resistance, however, patients with T2DM are at higher risk of cardiovascular disease (CVD) and atherosclerosis. Diabetes, frequently related to metabolic and vascular impairments, is also associated with thrombosis, increased blood coagulation and an imbalance between coagulation and fibrinolysis. Metformin is the most often used oral glucose-lowering agent; its beneficial properties include lowering insulin resistance, weight reduction and cardioprotection. Available data suggest that the advantageous properties of metformin stem from its favourable effects on endothelium, and anti-oxidative and anti-inflammatory properties. This paper reviews the favourable impact of metformin on endothelial function, with particular emphasis on the release of endogenous molecules modulating the state of the vascular endothelium and coagulation. It also summarizes the present knowledge on the influence of metformin on platelet activity and plasma haemostasis, including clot formation, stabilization and fibrinolysis. Its findings confirm that metformin should constitute first line therapy of T2DM subjects; however, more comprehensive methodical studies are required to discover the full potential of this drug.

Biocompatibility Studies of Gadolinium Complexes with Iminodiacetic Acid Derivatives

Apart from using as radiopharmaceuticals, iminodiacetic acid derivatives, after complexation with gadolinium, have been also tested as MRI CAs (magnetic resonance imaging contrast agents) since they show high affinity to hepatocytes and therefore provide high-resolution MRI of the liver. The purpose of this study was to evaluate the biocompatibility of four gadolinium complexes with iminodiacetic acid (IDA) derivatives differing in substituent in aromatic ring by estimating their influence on plasma hemostasis, integrity of erythrocyte membrane, and toxicity towards human umbilical vein endothelial cells (HUVECs). The influence of gadolinium-based CAs on plasma hemostasis was evaluated by measuring PT (prothrombin time), APTT (activated partial tromboplastin time), and TT (thrombin time). The effects of tested compounds on RBCs (Red Blood Cells) were assessed using hemolysis assay and microscopy studies. The influence of gadolinium complexes on the barrier properties of HUVECs was assessed by means of real-time method based on the measurements of the impedance changes of the cells. Gadolinium complexes did not affect significantly PT and TT. APTT measurements revealed significant prolongation in the presence of all tested gadolinium complexes at the concentration higher than 0.5 μmol/mL. Hemolysis assay showed that compounds with alkyl substituents in benzene ring without halogen atom (1-3) do not exert unfavorable effect on the integrity of erythrocyte membrane over the entire concentration range. All gadolinium complexes at 1.0 μmol/mL contribute to the decrease in HUVEC viability and integrity. To conclude, the study describes biocompatibility studies of gadolinium-based CAs, provides additional insight into their potential toxicity associated with systemic administration, and underscores the necessity for further research.

Generation 2 (G2) - Generation 4 (G4) PAMAM dendrimers disrupt key plasma coagulation parameters

The aim of the research was to evaluate the effects of G2 - G4 PAMAM dendrimers on basic plasma haemostasis parameters (Partially Activated Thrombin Time (APTT), Prothrombin Time (PT), Thrombin Time (TT)) as well as the activity of factor X, antithrombin III (AT), protein C and plasmin. Furthermore, tissue factor (TF) synthesis in endothelial cells and viability of smooth muscle cells in the presence of PAMAM dendrimers was investigated. APTT, PT and TT were performed according to the available commercial methods. The activity of factor X was conducted based on deficient plasma factor X. Protein C, AT and plasmin activity were measured spectrophotometrically using chromogenic substrates. Intracellular TF production in human umbilical vein endothelial cells (HUVECs) was measured using immunohistochemical method. Viability of Human Aortal Smooth Muscle cells (hAoSMCs) was established using WST-1 assay. PAMAM dendrimers decreased activity of factor X, and concomitantly prolonged PT and APTT. We also demonstrated shortened TT and increased fibrinogen concentrations in plasma treated with G4 PAMAM dendrimers, suggesting formation of fibrinogen aggregates. G2 - G4 PAMAM dendrimers decreased the activity of both naturally occurring anticoagulants AT and protein C. G2 and G3 PAMAM dendrimers did not affect the proteolytic reaction with plasmin. PAMAM dendrimers were found not to trigger TF production in undisturbed endothelial cells. PAMAM dendrimers, depending on the concentration and generation decreased viability of AoSMCs. The results presented within the current study suggest complex but mostly undesirable effect of G2 - G4 PAMAM dendrimers on plasma haemostasis and underscore the need for further in-depth research.

The Associations between Central Nervous System Diseases and Haemostatic Disorders

The aim of this review was to examine the relationship between the occurrence of central nervous system (CNS) diseases, the medicines used in their treatment and the blood coagulation process. The paper mainly focuses on the effects of antidepressant and antipsychotic drugs. Special attention has been paid to the influence of drugs on platelets, the vascular endothelium, plasma coagulation and fibrinolysis, regarding coagulation.

Synthesis and Biocompatibility Studies of New Iminodiacetic Acid Derivatives

BACKGROUND

Iminodiacetic acid (IDA) derivatives can be used as ligands to form complexes with technetium, with potential application as hepatobiliary diagnostic agents. The aim of this study was to synthesize five novel IDA derivatives and to compare their effects on plasma haemostasis with clinically approved ligands for technetium complexation.

METHODS

The influence of synthesized IDA derivatives on plasma haemostasis was evaluated spectrophotometrically by clot formation and lysis test (CL-test), coagulation assay, Prothrombin Time and Activated Partial Tromboplastin Time. The effects of the tested compounds on erythrocytes were assessed using haemolysis assays, microscopy and flow cytometry studies.

RESULTS

Despite their significant influence on the kinetic parameters of the process of clot formation and fibrinolysis, the tested ligands, at potential diagnostic concentrations, did not alter the overall potential of clot formation and lysis (CLAUC). At potential diagnostic concentrations (0.4 μmol/mL) all the tested compounds showed no adverse effects on the membranes of RBCs (Red Blood Cells).

CONCLUSION

IDA derivatives with methoxy substituents in aromatic ring, exert multidirectional effects on plasma haemostasis and should be considered safe as their significant impacts were mostly observed at 4 μmol/mL, which is about 10-fold higher than the theoretical plasma concentrations of these compounds.

Metformin - a Future Therapy for Neurodegenerative Diseases : Theme: Drug Discovery, Development and Delivery in Alzheimer's Disease Guest Editor: Davide Brambilla

Type 2 diabetes mellitus (T2DM) is a complex, chronic and progressive metabolic disease, which is characterized by relative insulin deficiency, insulin resistance, and high glucose levels in blood. Esteemed published articles and epidemiological data exhibit an increased risk of developing Alzheimer's disease (AD) in diabetic pateints. Metformin is the most frequently used oral anti-diabetic drug, which apart from hypoglycaemic activity, improves serum lipid profiles, positively influences the process of haemostasis, and possesses anti-inflammatory properties. Recently, scientists have put their efforts in establishing metformin's role in the treatment of neurodegenerative diseases, such as AD, amnestic mild cognitive impairment and Parkinson's disease. Results of several clinical studies confirm that long term use of metformin in diabetic patients contributes to better cognitive function, compared to participants using other anti-diabetic drugs. The exact mechanism of metformin's advantageous activity in AD is not fully understood, but scientists claim that activation of AMPK-dependent pathways in human neural stem cells might be responsible for the neuroprotective activity of metformin. Metformin was also found to markedly decease Beta-secretase 1 (BACE1) protein expression and activity in cell culture models and in vivo, thereby reducing BACE1 cleavage products and the production of Aβ (β-amyloid). Furthermore, there is also some evidence that metformin decreases the activity of acetylcholinesterase (AChE), which is responsible for the degradation of acetylcholine (Ach), a neurotransmitter involved in the process of learning and memory. In regard to the beneficial effects of metformin, its anti-inflammatory and anti-oxidative properties cannot be omitted. Numerous in vitro and in vivo studies have confirmed that metformin ameliorates oxidative damage.

Novel tetrahydroacridine derivatives with iodobenzoic acid moiety as multifunctional acetylcholinesterase inhibitors

New synthesized series of 9-amino-1,2,3,4-tetrahydroacridine derivatives with iodobenzoic acid moiety were studied for their inhibitory activity toward cholinesterase and against β-amyloid aggregation. All novel molecules 3a-3i interacted with both cholinesterases-acetylcholinesterase and butyrylcholinesterase-delivered nanomolar IC₅₀ values. The structure-activity relationship showed that N-butyl moiety derivatives are stronger inhibitors toward AChE and BuChE than N-ethyl and N-propyl moieties compounds. The most potent compound toward acetylcholinesterase was inhibitor 3f (IC₅₀  = 31.2 nm), and it was more active than reference drug, tacrine (IC₅₀  = 100.2 nm). Compound 3f showed strong inhibition of butyrylcholinesterase (IC₅₀  = 8.0 nm), also higher than tacrine (IC₅₀  = 16.3 nm). In the kinetic studies, compound 3f revealed mixed type of acetylcholinesterase inhibition. The computer modeling was carried out. The most active compound 3f was confirmed as peripheral anionic site inhibitor of acetylcholinesterase. Moreover, molecule 3f inhibited β-amyloid aggregation (at the concentration 10 μm-24.96% of inhibition, 25 μm-72%, 50 μm-78.44%, and 100 μm-84.92%). Therefore, among all examined, compound 3f is the most promising molecule for further, more detailed research of novel multifunctional agents in the therapy of Alzheimer's disease.

New prodrugs of metformin do not influence the overall haemostasis potential and integrity of the erythrocyte membrane

Although metformin, an oral anti-diabetic drug, has been found to have multidirectional effects over the past decade, it is characterised by unfavourable pharmacokinetic properties. This study discusses the effects of metformin, phenformin and three prodrugs of metformin on the haemostasis and integrity of Red Blood Cells (RBCs). The influence of examined biguanide derivatives on haemostasis was evaluated spectrophotometrically by clot formation and lysis test (CL-test) at 405nm. The extrinsic and intrinsic coagulation pathway were examined by measuring the PT (Prothrombin Time) and aPTT (Activated Partial Tromboplastin Time). Haemolysis assay, microscopy and flow cytometry studies were used to assess the effect of the tested compounds on RBCs. Although none of the tested biguanide derivatives significantly influenced the overall potential of clot formation and fibrinolysis (CL_AUC constants), statistically significant changes were seen in the values of the kinetic parameters of fibrinolysis. Furthermore, only prodrug 2, with an 8-carbon alkyl chain, unfavourably affected RBCs by interaction with the erythrocyte membrane leading to significant haemolysis. Our results provide a further insight into the effects of metformin and its prodrugs on haemostasis and RBCs and underscore the necessity for further research.

Novel tetrahydroacridine and cyclopentaquinoline derivatives with fluorobenzoic acid moiety induce cell cycle arrest and apoptosis in lung cancer cells by activation of DNA damage signaling

Lung cancer is still the leading cause of cancer-related death worldwide, indicating a necessity to develop more effective therapy. Acridine derivatives are potential anticancer agents due to their ability to intercalate DNA as well as inhibit enzymes involved in replication and transcription. Recently, we have evaluated anticancer activity of 32 novel acridine-based compounds. We found that the most effective were tetrahydroacridine and cyclopentaquinoline derivatives with fluorobenzoic acid containing eight and nine carbon atoms in the aliphatic chain. The aim of this study was to determine the molecular mechanisms of compounds-induced cell cycle arrest and apoptosis in human lung adenocarcinoma cells. All compounds activated Ataxia telangiectasia mutated kinase and phosphorylated histone H2A.X at Ser139 indicating DNA damage. Treatment of cells with the compounds increased phosphorylation and accumulation of p53 that regulate cell cycle as well as apoptosis. All compounds induced G0/1 cell cycle arrest by phosphorylation of cyclin-dependent kinase 2 at Tyr15 resulting in attenuation of the kinase activity. In addition, cyclopentaquinoline derivatives induced expression of cyclin-dependent kinase 2 inhibitor, p21; however, tetrahydroacridine derivatives had no significant effect on p21. Moreover, all compounds decreased the mitochondrial membrane potential accompanied by increased expression of Bax and down-regulation of Bcl-2, suggesting activation of the mitochondrial pathway. All compounds also significantly attenuated the migration rates of lung cancer cells. Collectively, our findings suggest a central role of activation of DNA damage signaling in response to new acridine derivatives treatment to induce cell cycle arrest and apoptosis in cancer cells and provide support for their further development as potential drug candidates.

Metabolite Profiling of Eastern Teaberry (Gaultheria procumbens L.) Lipophilic Leaf Extracts with Hyaluronidase and Lipoxygenase Inhibitory Activity

The phytochemical profile and anti-inflammatory activity of Gaultheria procumbens dry lipophilic leaf extracts were evaluated. Forty compounds were identified by GC-MS, representing 86.36% and 81.97% of the petroleum ether (PE) and chloroform (CHE) extracts, respectively, with ursolic acid (28.82%), oleanolic acid (10.11%), methyl benzoate (10.03%), and methyl salicylate (6.88%) dominating in CHE, and methyl benzoate (21.59%), docosane (18.86%), and octacosane (11.72%) prevailing in PE. Three components of CHE were fully identified after flash chromatography isolation and spectroscopic studies as (6S,9R)-vomifoliol (4.35%), 8-demethyl-latifolin (1.13%), and 8-demethylsideroxylin (2.25%). Hyaluronidase and lipoxygenase inhibitory activity was tested for CHE (IC50 = 282.15 ± 10.38 μg/mL and 899.97 ± 31.17 μg/mL, respectively), PE (IC50 = 401.82 ± 16.12 μg/mL and 738.49 ± 15.92 μg/mL), and nine of the main constituents versus heparin (IC50 = 366.24 ± 14.72 μg/mL) and indomethacin (IC50 = 92.60 ± 3.71 μg/mL) as positive controls. With the best activity/concentration relationships, ursolic and oleanolic acids were recommended as analytical markers for the extracts and plant material. Seasonal variation of both markers following foliar development was investigated by UHPLC-PDA. The highest levels of ursolic (5.36-5.87 mg/g DW of the leaves) and oleanolic (1.14-1.26 mg/g DW) acids were observed between August and October, indicating the optimal season for harvesting.

Biological evaluation of the toxicity and the cell cycle interruption by some benzimidazole derivatives

In this work, the in vitro tests of biological activity of benzimidazoles were conducted. This group of benzimidazole derivatives was evaluated as potential bioreductive agents and their characteristic pro-apoptosis activity and cell cycle interruption on the human lung adenocarcinoma A549 cells were discussed. Their toxicity on the healthy human erythrocytes and their influence on the healthy human erythrocytes acetylcholinesterase enzyme (AChE) were established. Their apoptosis activity on A549 cells line was determined by Annexin V-APC test, and it was visualized by Hoechst test. In the next stage, their influence on the cell cycle interruption was determined by using the ribonuclease reagent. The AChE inhibition test was defined by the Ellman method, and the red blood cell lysis was defined by erythrotoxicity test. The results proved the pro-apoptosis properties of all tested compounds in normoxia and hypoxia. The DNA content assay showed that the benzimidazoles possess the ability to interrupt S phase of tumor cell cycle. The best activity in this action was presented by compound 1, especially in hypoxia, and it proves that the N-oxide analogs are predispositioned to the hypoxic target. In this study, the benzimidazoles were found as potentially biocompatible and their inhibition of acetylcholinesterase was lower than tirapazamine and much lower than tacrine which constitutes their desired effect of potential biological activity.

Stability of erythrocyte membrane and overall hemostasis potential - A biocompatibility study of mebrofenin and other iminodiacetic acid derivatives

BACKGROUND

Intravenous injection seems to be the most convenient way of administering drugs and contrast agents, which makes components of the blood the first and usually unwanted target of their action. Binding of intravenously administered compounds to erythrocytes, blood platelets and vascular wall may have serious clinical implications. The aim of this study was to examine the influence of four iminodiacetic acid derivatives, potential ligands for gadolinium complexation, on the process of coagulation and fibrinolysis, activity of thrombin and hemolysis.

METHODS

Kinetic parameters of coagulation and fibrinolysis process were determined during an optical CL-test based on measurement of transmittance alterations. Thrombin (0.5 IU/mL) and t-PA (240 ng/mL) were used to obtain a clotting and lysis curve. The activity of thrombin was determined with a chromogenic substrate S-2238. Hemolysis was examined spectrophotometrically and expressed as a percentage of released hemoglobin.

RESULTS

Exposure to iminodiacetic acid derivatives resulted in a significant increase in the overall potential of clotting and lysis (CLAUC), as well as with the significant changes in the key parameters of these processes (thrombin time, initial plasma clotting velocity, clot stabilization time). Furthermore, iminodiacetic acid derivatives caused a significant decrease in the amidolytic activity of thrombin and enhanced hemolysis in a concentration-dependent manner.

CONCLUSION

Despite their influence on the process of coagulation and fibrinolysis, amidolytic activity of thrombin and hemolysis, iminodiacetic acid derivatives should be generally considered safe as the significant effects were observed mostly at 4 μmol/mL, which is about 10-fold higher than the theoretical plasma concentration of these compounds.

Some characteristics of activity of potential chemotherapeutics--benzimidazole derivatives

In this work, the biological activity of some benzimidazoles and benzimidazole-4,7-diones was compared. These two groups of compounds were evaluated as potential chemotherapeutics and their characteristic relationship structure to biological activity was discussed. The authors compared their effect into the cytotoxic, apoptosis and DNA destruction approach. Their cytotoxic effect on the human lung adenocarcinoma A549 cells line was determined by WST-1 test. Next the cytotoxic way of tumor cells death was determined by caspase 3/7 test. The last point referred to the DNA destruction of A549 cells and test in situ DNA Assay Kit was applied. Two of the examined compounds (B2 and D2) show a very good correlation of the cytotoxic effect normoxia to hypoxia and they have been found as the potential agents of the DNA damage. The most cytotoxic feature possesses N-oxide benzimidazole derivatives (D and B groups). The screening test of the DNA damage established that N-oxide benzimidazole derivatives (D and B groups) can be more potent as the hypoxia-selective agents for tumor cells than benzimidazole derivatives (A and C groups). Additionally, the test of the caspase-dependent apoptosis proved that the exposure of benzimidazole-4,7-diones against A549 cells, especially in hypoxia, promotes apoptotic cell death.

Novel tetrahydroacridine derivatives inhibit human lung adenocarcinoma cell growth by inducing G1 phase cell cycle arrest and apoptosis

Lung cancer is not only the most commonly diagnosed cancers worldwide but it is still the leading cause of cancer-related death. Acridine derivatives are a class of anticancer agents with the ability to intercalate DNA and inhibit topoisomerases. The aim of this study was to evaluate the effect of sixteen new tetrahydroacridine derivatives on the viability and growth of human lung adenocarcinoma cells. We compared anticancer activity of a series of eight compounds with 4-fluorobenzoic acid and eight compounds with 6-hydrazinonicotnic acid differed from each other in length of the aliphatic chain containing from 2 to 9 carbon atoms. Interestingly, tetrahydroacridine with 4-fluorobenzoic acid (compounds 9-16) showed higher anticancer activity than derivatives with 6-hydrazinonicotnic acid (compounds 1-8) and their efficacy was correlated with increasing number of carbon atoms in the aliphatic chain. The results showed that inhibition of cancer cell growth by the most effective compounds 15 and 16 was associated with induction of G1 phase cell cycle arrest followed by caspase-3 dependent apoptosis. Our findings suggest that tetrahydroacridine with 4-fluorobenzoic acid containing 8 and 9 carbon atoms may be potential candidate for treatment of lung cancer.

Studies towards biocompatibility of PAMAM dendrimers--overall hemostasis potential and integrity of the human aortic endothelial barrier

The last decade has brought many examples of utilization of dendrimers as drug delivery systems; however, their possible application is limited because of inherent toxicity associated with them. This study discusses the influence of G1-G4 PAMAM-NH2 dendrimers on the process of hemostasis and integrity of endothelial monolayer. The global assay of coagulation and fibrinolysis was investigated spectrophotometrically by means of CL-test at 405 nm. Thrombin (0.5 I U/mL) and t-PA (240 ng/mL) were used to obtain clotting and lysis curve. The activity of thrombin was determined by means of chromogenic substrate S-2238. The influence of PAMAM dendrimers on the barrier properties of human primary aortal endothelium was assessed by means of method based on the measurements of the impedance changes of the cells. Observed multidirectional impact of dendrimers, without affecting the thrombin activity, on clot formation, its stabilization and fibrinolysis could be regarded as important when trying to use them clinically. It is crucial that examined PAMAM dendrimers did not lead to spontaneous aggregation of fibrinogen. Importantly, examined polymers have concentration- and generation-dependent adverse effect towards the endothelial monolayer.

RESULT

of described studies provide additional insight into PAMAM dendrimers toxicity associated with systemic administration and underscore the necessity for further research.

New cyclopentaquinoline derivatives with fluorobenzoic acid induce G1 arrest and apoptosis in human lung adenocarcinoma cells

Non-small cell lung cancer accounts for 80-85% of all lung cancer cases and is the leading cause of cancer death indicating inefficient current treatment. Acridine derivatives interact with DNA and inhibit topoisomerase leading to cell growth arrest or cell death. The aim of this study was to evaluate the effects of new synthesized sixteen 2,3-dihydro-1H-cyclopenta[b]quinoline derivatives (cyclopentaquinoline), a member of acridine-based compounds, on the survival and growth of human lung adenocarcinoma, A549 cells. Anticancer activity of eight new cyclopentaquinoline derivatives with hydrazinonicotinic acid (compounds 1-8) and eight with fluorobenzoic acid (compounds 9-16) were screened using WST-1 assay. Interestingly, cyclopentaquinoline derivatives with fluorobenzoic moiety were found to have a higher anticancer activity than derivatives with hydrazinonicotinic acid. Four out of eight tested compounds with fluorobenzoic acid inhibited 50% cancer cell growth at concentration below 20μM. Moreover, the efficacy of cyclopentaquinoline derivatives containing fluorobenzoic acid correlated with increasing number of carbon atoms in the aliphatic chain. The most effective compounds (6, 15, 16) were selected to determine molecular mechanisms of their anticancer action. The results indicated that inhibition of A549 cell growth by compounds 15 and 16 was associated with a cell cycle arrest at G0/1 phase and with induction of caspase 3-dependent apoptosis. Compound 6 also caused A549 cells death due to apoptosis, however, it had no significant effect on a cell cycle progression. These findings suggest that cyclopentaquinoline derivatives containing fluorobenzoic acid with 8 and 9 carbon atoms in aliphatic chain may be promising candidate for treatment of lung cancer.

Biological approach of anticancer activity of new benzimidazole derivatives

BACKGROUND

A series of new benzimidazole derivatives, earlier synthesized, was tested in vitro as new bioreductive prodrugs with the potential anticancer activity. Their effect on the DNA destruction and growth inhibition into selected tumor cell lines at normoxia and hypoxia conditions was determined.

METHODS

The human lung adenocarcinoma A549 cell line was used to determine the anticancer activity of the analyzed compounds by using WST-1 assay. The apoptosis test (caspase 3/7 assay) was used to define the cytotoxic way of tumor cells death. Additionally test In situ DNA Damage Assay Kit was applied to recognize the DNA destruction.

RESULTS

Four of the examined compounds (1, 3, 7, 9) show a very good antiproliferative effect and three of them are specific for hypoxia conditions (2, 4, 8).

CONCLUSION

Compound 8 is the most cytotoxic against human lung adenocarcinoma A549 cells at hypoxic conditions. Hypoxia/normoxia cytotoxic coefficient of compound 8 (4.75) is close to hypoxia/normoxia cytotoxic coefficient of tirapazamine (5.59) - reference substance in our experiments and this parameter locates it between mitomycin C and 2-nitroimidazole (misonidazole). The screening test of the caspase-dependent apoptosis proved that the exposure of compounds 1-2 and 7-8 against A549 cells for a 48 h promote apoptotic cell death. Additionally, the test of the DNA damage established that compounds 1, 2, 7, 8 are specific agents for the hypoxia-selective cytotoxicity of nitrobenzimidazoles [6,26].

Extract of Aronia melanocarpa-modified hemostasis: in vitro studies

Purpose

Aronia melanocarpa has an extremely high content of procyanidins and anthocyanins. The multidirectional benefits of consumption of these berries are widely reported. Although numerous studies confirmed the influence of polyphenols on various stages of hemostasis, the exact mechanism of this phenomenon is not understood. The aim of our study was to evaluate the in vitro effect of A. melanocarpa extract on various parameters of hemostasis.

Methods

Adenosine 5′-diphosphate (ADP)-induced aggregation was measured with turbidimetric method. Spontaneous and ADP-activated platelet adhesion were investigated using a colorimetric method. The global assay of coagulation and fibrinolysis was performed with the use of optical clotting and lysis (CL) test. Thrombin (0.5 IU/mL) and tissue plasminogen activator (60 ng/mL) were used to obtain a CL curve. The activity of thrombin and plasmin was determined by means of chromogenic substrate (S-2238, S-2251)

Results

The aronia extract contributed to the reduction in spontaneous and ADP-activated platelet adhesion. A significant increase in overall potential of CL as well as significant changes in key parameters of these processes (T_t—thrombin time, F_vo—initial plasma clotting velocity, and L_max—maximum lysis) was reported. Chokeberry extract significantly inhibited the amidolytic activity of thrombin and plasmin.

Conclusion

Our in vitro findings indicate a complex mechanism of influence of chokeberry polyphenols on platelet activity and the overall potential of CL. We confirmed that chokeberry inhibits the amidolytic activity of thrombin. It was demonstrated for the first time that chokeberry polyphenols inhibit the amidolytic activity of another serine protease, i.e., plasmin, which is the main fibrinolytic enzyme. Furthermore, our research points out a significant contribution of other plasma components and fibrinogen in the modulation of hemostasis by polyphenols.

Antiproliferative activity of new benzimidazole derivatives

A series of new benzimidazole derivatives were synthesized and tested in vitro for possible anticancer activity. Their effect of proliferation into selected tumor cell lines at normoxia and hypoxia conditions was determined by WST-1 test. Additionally, apoptosis test (caspase 3/7 assay) was used to check the mode caused by the agents of cell death. Four of the examined compounds (7, 8, 13, 11) showed a very good antiproliferative effect and three of them were specific for hypoxia conditions (8, 14, 11). Compound 8 was the most cytotoxic against human lung adenocarcinoma A549 cells at hypoxic conditions. Hypoxia/ normoxia cytotoxic coefficient of compound 14 (4.75) is close to hypoxia/normoxia cytotoxic coefficient of tirapazamine (5.59) - a reference compound in our experiments and this parameter locates it between mitomycin C and 2-nitroimidazole (misonidazole). Screening test of caspase-dependent apoptosis proved that exposure to A549 cells of compounds 7-8 and 13-14 for 48 h promote apoptotic cell death. These results supplement our earlier study of the activity of new potentialy cytotoxic heterocyclic compounds against selected tumor cells.

Antiproliferative activity of new benzimidazole derivatives

A series of new benzimidazole derivatives were synthesized and tested in vitro for possible anticancer activity. Their effect of proliferation into selected tumor cell lines at normoxia and hypoxia conditions was determined by WST-1 test. Additionally, apoptosis test (caspase 3/7 assay) was used to check the mode caused by the agents of cell death. Four of the examined compounds (7, 8, 13, 11) showed a very good antiproliferative effect and three of them were specific for hypoxia conditions (8, 14, 11). Compound 8 was the most cytotoxic against human lung adenocarcinoma A549 cells at hypoxic conditions. Hypoxia/ normoxia cytotoxic coefficient of compound 14 (4.75) is close to hypoxia/normoxia cytotoxic coefficient of tirapazamine (5.59) - a reference compound in our experiments and this parameter locates it between mitomycin C and 2-nitroimidazole (misonidazole). Screening test of caspase-dependent apoptosis proved that exposure to A549 cells of compounds 7-8 and 13-14 for 48 h promote apoptotic cell death. These results supplement our earlier study of the activity of new potentialy cytotoxic heterocyclic compounds against selected tumor cells.

Synthesis and biological activity of new donepezil-hydrazinonicotinamide hybrids

Currently available treatment used in Alzheimer's disease is based on acetylcholinesterase inhibitors, e. g. donepezil, tacrine, galantamine, and rivastigmine. In the present study some derivatives of donepezil were synthesized, and their potential anticholinesterase properties were investigated using the colorimetric Ellman's method. These compounds were synthesized by condensation between indanone derivatives and the hydrazine nicotinated moiety (Hynic). For received derivatives, the selectivity and the IC50 values for acetylcholinesterase and butyrylcholinesterase were calculated. All the tested compounds exhibited lower affinity for AChE than donepezil and higher affinity for BChE than donepezil. Compound 33 showed the most selectivity for AChE among the obtained indanone derivatives.

Development of copper based drugs, radiopharmaceuticals and medical materials

Copper is one of the most interesting elements for various biomedical applications. Copper compounds show vast array of biological actions, including anti-inflammatory, anti-proliferative, biocidal and other. It also offers a selection of radioisotopes, suitable for nuclear imaging and radiotherapy. Quick progress in nanotechnology opened new possibilities for design of copper based drugs and medical materials. To date, copper has not found many uses in medicine, but number of ongoing research, as well as preclinical and clinical studies, will most likely lead to many novel applications of copper in the near future.

2,3-dihydro-1H-cyclopenta[b]quinoline derivatives as acetylcholinesterase inhibitors-synthesis, radiolabeling and biodistribution

In the present study we describe the synthesis and biological assessment of new tacrine analogs in the course of inhibition of acetylcholinesterase. The obtained molecules were synthesized in a condensation reaction between activated 6-BOC-hydrazinopyridine-3-carboxylic acid and 8-aminoalkyl derivatives of 2,3-dihydro-1H-cyclopenta[b]quinoline. Activities of the newly synthesized compounds were estimated by means of Ellman’s method. Compound 6h (IC₅₀ = 3.65 nM) was found to be most active. All obtained novel compounds present comparable activity to that of tacrine towards acetylcholinesterase (AChE) and, simultaneously, lower activity towards butyrylcholinesterase (BChE). Apart from 6a, all synthesized compounds are characterized by a higher affinity for AChE and a lower affinity for BChE in comparison with tacrine. Among all obtained molecules, compound 6h presented the highest selectivity towards inhibition of acetylcholinesterase. Molecular modeling showed that all compounds demonstrated a similar binding mode with AChE and interacted with catalytic and peripheral sites of AChE. Also, a biodistribution study of compound 6a radiolabeled with ^99mTc was performed.

New benzimidazole derivatives with potential cytotoxic activity--study of their stability by RP-HPLC

Obtained benzimidazole derivatives, our next synthesized heterocyclic compounds, belong to a new group of chemical bondings with potential anticancer properties (Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2006, J Liguid Chrom Rel Tech 29: 2367-2385; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2008, Wiad Chem 62: 11-12, in Polish; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2011, J Liguid Chrom Rel Tech 34: 1901-1912). We used HPLC analysis to determine stability of these compounds in 0.2% DMSO (dimethyl sulfoxide). Optimisation of the chromatographic system and validation of the established analytical method were performed. Reversed phases (RP-18) and a 1:1 mixture of acetate buffer (pH 4.5) and acetonitrile as a mobile phase were used for all the analysed compounds at a flow rate 1.0 mL/min. The eluted compounds were monitored using a UV detector, the wavelength was specific for compounds 6 and 9 and compounds 7 and 10. The retention time was specific for all four compounds. The used method was found to have linearity in the concentration range of (0.1 mg/mL-0.1 μg/mL) with a correlation coefficient not less than r(2)=0.9995. Statistical validation of the method proved it to be a simple, highly precise and accurate way to determine the stability of benzimidazole derivatives in 0.2% DMSO. The recoveries of all four compounds examined were in the range 99.24-100.00%. The developed HPLC analysis revealed that the compounds studied remain homogeneous in 0.2% DMSO for up to 96 h and that the analysed N-oxide benzimidazole derivatives do not disintegrate into their analogues - benzimidazole derivatives. Compounds 8, 6 and 9 exhibit the best cytotoxic properties under normoxic conditions when tested against cells of human malignant melanoma WM 115.

New benzimidazole derivatives with potential cytotoxic activity--study of their stability by RP-HPLC

Obtained benzimidazole derivatives, our next synthesized heterocyclic compounds, belong to a new group of chemical bondings with potential anticancer properties (Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2006, J Liguid Chrom Rel Tech 29: 2367-2385; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2008, Wiad Chem 62: 11-12, in Polish; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2011, J Liguid Chrom Rel Tech 34: 1901-1912). We used HPLC analysis to determine stability of these compounds in 0.2% DMSO (dimethyl sulfoxide). Optimisation of the chromatographic system and validation of the established analytical method were performed. Reversed phases (RP-18) and a 1:1 mixture of acetate buffer (pH 4.5) and acetonitrile as a mobile phase were used for all the analysed compounds at a flow rate 1.0 mL/min. The eluted compounds were monitored using a UV detector, the wavelength was specific for compounds 6 and 9 and compounds 7 and 10. The retention time was specific for all four compounds. The used method was found to have linearity in the concentration range of (0.1 mg/mL-0.1 μg/mL) with a correlation coefficient not less than r(2)=0.9995. Statistical validation of the method proved it to be a simple, highly precise and accurate way to determine the stability of benzimidazole derivatives in 0.2% DMSO. The recoveries of all four compounds examined were in the range 99.24-100.00%. The developed HPLC analysis revealed that the compounds studied remain homogeneous in 0.2% DMSO for up to 96 h and that the analysed N-oxide benzimidazole derivatives do not disintegrate into their analogues - benzimidazole derivatives. Compounds 8, 6 and 9 exhibit the best cytotoxic properties under normoxic conditions when tested against cells of human malignant melanoma WM 115.

Design, synthesis and biological evaluation of new 2-benzoxazolinone derivatives as potential cholinesterase inhibitors for therapy of alzheimer's disease

Currently acetylcholinesterase inhibitor (AChEI) therapy is one of the most frequently used methods in the treatment of Alzheimer's disease; tacrine, donepezil, rivastygmine and galantamine are applied in different stages of AD. In the present study, we propose a new series of 2-benzoxazolinone derivatives as potential cholinesterase inhibitors. These compounds were synthesized by condensation of 6-chloro acetyl-2-benzoxa zolinone with the corresponding amine and evaluated as acetylcholinesterase inhibitors using the colorimetric Ellman's method. Selectivity and the IC50 values were determined for the received derivatives. All tested compounds exhibited the inhibitory activity towards acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Compound 3e showed stronger activity than the standard tacrine, and compound 3a showed activity similar to that of tacrine for AChE. Compounds 3a, 3b, 3c, and 3e showed stronger activity than the standard donepezil towards the inhibition of BChE, and the compound 3e showed stronger activity than donepezil towards AChE.

Synthesis and biological activity of derivatives of tetrahydroacridine as acetylcholinesterase inhibitors

Current state of medical sciences does not allow to treatment neurodegenerative diseases such as Alzheimer's disease (AD). At present treatment of AD is severely restricted. The main class of medicines which are applied in AD is acetylcholinesterase inhibitors (AChEIs) like tacrine, donepezil, galantamine and rivastigmine that do not contribute to significant and long-term improvement in cognitive and behavioural functions. In this work, we report synthesis and biological evaluation of new hybrids of tacrine-6-hydrazinonicotinamide. The synthesis was based on the condensation reaction between tacrine derivatives and the hydrazine nicotinate moiety (HYNIC). All obtained compounds present affinity for both cholinesterases and are characterized by high selectivity in relation to butyrylcholinesterase (BChE).

Neuroimaging diagnosis in neurodegenerative diseases

Dementia affects about 8% of people age 65 years and older. Identification of dementia is particularly difficult in its early phases when family members and physicians often incorrectly attribute the patient's symptoms to normal aging. The most frequently occurring ailments that are connected with neurodegeneration are: Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. A variety of powerful techniques that have allowed visualization of organ structure and function with exact detail have been introduced in the last twenty-five years. One such neuroimaging technique is positron emission tomography (PET), which measures in detail the functioning of distinct areas of the human brain and as a result plays a critical role in clinical and research applications. Radiotracer-based functional imaging provides a sensitive means of recognizing and characterizing the regional changes in brain metabolism and receptor binding associated with cognitive disorders. The next functional imaging technique widely used in the diagnosis of cognitive disorders is single photon emission computed tomography (SPECT). New radiotracers are being developed and promise to expand further the list of indications for PET. Prospects for developing new tracers for imaging other organ diseases also appear to be very promising. In this review, we present current opportunities of neuroimaging techniques in the diagnosis and differentiation of neurodegenerative disorders.

HPLC method for determination of the purity of a mebrofenin-ligand for 99mTc-complexes

A reversed-phase HPLC method has been developed for the estimation of purity and quantitative determination of mebrofenin UV detection at 205 nm was used. The stability of mebrofenin alone and in the presence of stannous chloride at 25 degrees C was studied. No decomposition product was found and there was no influence of SnCl2 on the stability of mebrofenin.

New tacrine-hydrazinonicotinamide hybrids as acetylcholinesterase inhibitors of potential interest for the early diagnostics of Alzheimer's disease

The syntheses and the preliminary results of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition by an affinity series of tacrine-hydrazinonicotinamide hybrids are described. These molecules were prepared by condensation of tacrine analogues with the hydrazine nicotinate moiety (HYNIC). Derivatives 6a and 6b showed lower activity than the model tacrine, while compounds 6c and 6d showed the strongest affinity to AChE. All the tested compounds exhibited lower affinity for BChE than tacrine. Alzheimer disease (AD) is characterised by a deficit of acetylcholinesterase, and these new compounds, as ligands for 99mTc complexes, are potential radiopharmaceuticals for an early diagnosis of Alzheimer's disease.

New derivatives of 2-(N-arylmethylideneamine) benzophenone oxime as potential radiopharmaceuticals for brain imaging

BACKGROUND

The aim of this work was the development of a sufficient method for synthesis and radiolabelling with technetium- 99m a new class of compounds as potential ligands for brain imaging.

METHODS

The synthesis of new ligands with the structure of 2-(N-arylmethylideneamine) benzophenone oxime (6-10) based on the cyclocondensation of appropriate 2-aminobenzophenone oxime 1-2 with respective aldehydes 3-4 or ketone 5 in acidic conditions. During our experiments in dependencies from the reaction conditions, compounds with the structure of Schiff's bases (6-10) or 3N-oxides 1,2-dihrydroquinazoline derivatives were obtained. Labelling of compounds 6 or 7 with technetium- 99m was done by stannous chloride reduction according to two methods (in ethyl alcohol or in chloroform) following the radiolabelling method of HM-PAO. The complex (99m)Tc-HM-PAO was the leading compound in our computational calculations with geometrical optimisation of a molecule. Using molecular modelling (semi-empirical method ZINDO) we have determined the electrostatic potential for the obtained ligands. Additionally we have calculated total energy,binding energy, heat of formation and several 3D-QSAR parameters for theoretically possible complexes of (99m)Tc with the obtained ligands.

RESULTS

As a result of our experiments a method of a synthesis of new compounds 6 and 7 has been developed. Computational calculations were performed using the HyperChem 4.5 program. These calculations confirmed our hypothesis that only ligand 7 is able to form a complex with (99m)Tc and this complex possesses lipophilic properties.

CONCLUSIONS

Complex (99m)Tc-7, due to its lipophilic properties, is a potential radiopharmaceutical for the brain imaging.

New analogues of ACPD with selective activity for group II metabotropic glutamate receptors

In this study we have determined the pharmacology of a series of 1-aminocyclopentane-1,3-dicarboxylic acid (1,3-ACPD) analogues at cloned metabotropic glutamic acid (mGlu) receptors. The new analogues comprise the four possible stereoisomers of 1-amino-1-carboxycyclopentane-3-acetic acid (1,3-homo-ACPD) and the racemic mixture of (1RS,2RS)-1-amino-1-carboxycyclopentane-2-acetic acid (1RS,2RS-homo-ACPD), (1RS,2RS)-Homo-ACPD was shown to be a competitive mGlu2 receptor antagonist with a KB of 391 microM. (1S,3R)-Homo-ACPD and (1R,3R)-homo-ACPD were both shown to be mGlu2 receptor agonists with EC50 values of 122 and 105 microM, respectively. Compared to (S)-Glu both compounds displayed partial agonism with intrinsic activities of 79% and 47%, respectively. (1S,3S)-Homo-ACPD was also found to be a partial mGlu2 receptor agonist with an intrinsic activity of 27% compared to (S)-Glu. None of the compounds tested showed any activity at mGlu1a or mGlu4a receptors. These homo-ACPD's show a higher degree of subtype selectivity than the parent compound (1SR,3RS)-ACPD. In addition none of the compounds demonstrated any activity at ionotropic Glu receptors.

Comparison in rabbits of chole-scintigraphic properties of several 99mTc-IDA derivatives

Pathways and kinetics of excretion were compared to four 99mTc-IDA derivatives in healthy rabbits of both sexes. Assessment of differences between the compounds was based upon: plasma clearance, characteristics of time-activity curves measured scintigraphically over the liver (time of the peak Tmax; time for decline of activity to half the peak value-T50%), and hepatocytic mean transit time (MTT) as derived after deconvolution of the hepatic time-activity curve. Hepatocyte transit time was short and similar to 99mTc-complexes of Mebrofenin, 2,4-diethyl IDA (HEPIDA) and 3-iodo-2,6-diethylphenylcarbamoylmethyliminodiacetic acid (JODIDA); it was evidently longer for 99mTc-p-butyl-IDA (BIDA). 99mTc-HEPIDA displayed significant urinary elimination; the remaining three compounds were excreted practically completely via the biliary route. It is concluded that optimal parameters were displayed by 99mTc-Mebrofenin and 99mTc-JODIDA.

New derivatives of hexahydroazepine, hexahydro(1,4,5)oxadiazepine and hexahydro(1,4,5)oxadiazocine with expected pharmacological activity

New derivatives with the expected pharmacological activity of heterocyclic systems mentioned above having ether (1-6) and ester (7-10) groups were obtained.