Design, Synthesis, In vitro and In vivo Evaluation of New Imidazo[1,2-a]pyridine Derivatives as Cyclooxygenase-2 Inhibitors.

BACKGROUND: Cyclooxygenase-2 (COX-2), the key enzyme in the arachidonic acid conversion to prostaglandins, is one of the enzymes associated with different pathophysiological conditions, such as inflammation, cancers, Alzheimer's, and Parkinson's disease. Therefore, COX-2 inhibitors have emerged as potential therapeutic agents in these diseases. OBJECTIVE: The objective of this study was to design and synthesize novel imidazo[1,2-a]pyridine derivatives utilizing rational design methods with the specific aim of developing new potent COX-2 inhibitors. Additionally, we sought to investigate the biological activities of these compounds, focusing on their COX-2 inhibitory effects, analgesic activity, and antiplatelet potential. We aimed to contribute to the development of selective COX-2 inhibitors with enhanced therapeutic benefits. METHODS: Docking investigations were carried out using AutoDock Vina software to analyze the interaction of designed compounds. A total of 15 synthesized derivatives were obtained through a series of five reaction steps. The COX-2 inhibitory activities were assessed using the fluorescent Cayman kit, while analgesic effects were determined through writing tests, and Born's method was employed to evaluate antiplatelet activities. RESULTS: The findings indicated that the majority of the tested compounds exhibited significant and specific inhibitory effects on COX-2, with a selectivity index ranging from 51.3 to 897.1 and IC50 values of 0.13 to 0.05 µM. Among the studied compounds, derivatives 5e, 5f, and 5j demonstrated the highest potency with IC50 value of 0.05 µM, while compound 5i exhibited the highest selectivity with a selectivity index of 897.19. In vivo analgesic activity of the most potent COX-2 inhibitors revealed that 3-(4-chlorophenoxy)-2-[4-(methylsulfonyl) phenyl] imidazo[1,2-a]pyridine (5j) possessed the most notable analgesic activity with ED50 value of 12.38 mg/kg. Moreover, evaluating the antiplatelet activity showed compound 5a as the most potent for inhibiting arachidonic acidinduced platelet aggregation. In molecular modeling studies, methylsulfonyl pharmacophore was found to be inserted in the secondary pocket of the COX-2 active site, where it formed hydrogen bonds with Arg-513 and His-90. CONCLUSION: The majority of the compounds examined demonstrated selectivity and potency as inhibitors of COX-2. Furthermore, the analgesic effects observed of potent compounds can be attributed to the inhibition of the cyclooxygenase enzyme.

Exploring the biological application of Penicillium fimorum-derived silver nanoparticles: In vitro physicochemical, antifungal, biofilm inhibitory, antioxidant, anticoagulant, and thrombolytic performance.

This study showed the anti-candida, biofilm inhibitory, antioxidant, anticoagulant, and thrombolytic properties of biogenic silver nanoparticles (AgNPs) fabricated by using the supernatant of Penicillium fimorum (GenBank accession number OQ568180) isolated from soil. The biogenic AgNPs were characterized by using different analytical techniques. A sharp surface plasmon resonance (SPR) peak of the colloidal AgNPs at 429.5 nm in the UV-vis spectrum confirmed the fabrication of nanosized silver particles. The broth microdilution assay confirmed the anti-candida properties of AgNPs with a minimum inhibitory concentration (MIC) of 4 µg mL-1. In the next step, the protein and DNA leakage assays as well as reactive oxygen species (ROS) assay were performed to evaluate the possible anti-candida mechanisms of AgNPs representing an increase in the total protein and DNA of supernatant along with a climb-up in ROS levels in AgNPs-treated samples. Flow cytometry also confirmed a dose-dependent cell death in the AgNPs-treated samples. Further studies also confirmed the biofilm inhibitory performance of AgNPs against Candia albicans. The AgNPs at the concentrations of MIC and 4*MIC inhibited 79.68 ± 14.38% and 83.57 ± 3.41% of biofilm formation in C. albicans, respectively. Moreover, this study showed that the intrinsic pathway may play a significant role in the anticoagulant properties of AgNPs. In addition, the AgNPs at the concentration of 500 µg mL-1, represented 49.27%, and 73.96 ± 2.59% thrombolytic and DPPH radical scavenging potential, respectively. Promising biological performance of AgNPs suggests these nanomaterials as a good candidate for biomedical and pharmaceutical applications.

Synthesis and Biological Evaluation of Novel Thiadiazole Derivatives as Antiplatelet Agents.

A novel series of thiadiazole compounds was synthesized through the reaction of thiosemicarbazone intermediates with 2, 3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The antiplatelet activity of the synthesized compounds was evaluated using an aggregation test with adenosine diphosphate (ADP) and arachidonic acid (AA) as platelet aggregation inducers. Among the synthesized analogs, compound 3b exhibited the most potent inhibition of platelet aggregation induced by ADP (half maximal inhibitory concentration [IC50] = 39 ± 11 µM). Molecular docking studies of 3b revealed hydrogen bonds between the nitrogen of the thiadiazole ring and Lys280. The tolyl ring exhibited hydrophobic interactions with Tyr105, similar to the antagonist co-crystallized with P2Y12 (PDB ID: 4NTJ). These compounds have the potential to serve as lead molecules for designing P2Y12 inhibitors.

Bioengineering of green-synthesized silver nanoparticles: In vitro physicochemical, antibacterial, biofilm inhibitory, anticoagulant, and antioxidant performance.

Green-synthesized nanobiomaterials can be engineered as smart nanomedicine platforms for diagnostic and therapeutic purposes in medicine. Herein, we investigated the bioengineering of silver nanoparticles (AgNPs) and evaluated their physicochemical, antibacterial, biofilm inhibitory, anticoagulant, and antioxidant performance. Characterization of the AgNPs was performed utilizing UV-visible, transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FT-IR). The spherical shaped AgNPs were proven by TEM and SEM techniques. Moreover, the XRD diffraction patterns demonstrated that the nanoparticles were in a crystalline state. The DLS represented the hydrodynamic particle size of the NPs at 49.62 nm at a pH of 9. The calculated minimum inhibitory concentration (MIC) of AgNPs toward Staphylococcus aureus (ATCC 25923) was 8 µg mL-1, which was almost similar to tetracycline by the value of 4 µg mL-1. Moreover, the minimum bactericidal concentration (MBC) of AgNPs was 64 µg mL-1, which was significantly less than the determined value of 256 µg mL-1 for tetracycline. Considering the pathogenic and standard S. aureus, the evaluated concentrations of AgNPs and tetracycline showed significant biofilm inhibitory performance. Furthermore, the bioengineered AgNPs exhibited significant anticoagulant activity at 500 µg mL-1 compared to saline (P < 0.001). In addition, the biogenic AgNPs inhibited 69.73 ± 0.56% of DPPH free radicals at 500 µg mL-1, indicating considerable antioxidant potential.

High-performance thin-layer chromatography fingerprinting, total phenolic and total flavonoid contents and anti-platelet-aggregation activities of Prosopis farcta extracts.

Cardiovascular diseases are a leading cause of worldwide death and excessive platelet is closely related with their pathogenesis. Different plants and natural compounds have demonstrated anti-platelet effects. The aim of this study was to report the high-performance thin-layer chromatography (HPTLC) fingerprinting and anti-platelet-aggregation activities of different leaf extracts (n-hexane, chloroform, ethyl acetate, methanol and aqueous) of Prosopis farcta (Syrian mesquite) plant. The results showed a 100% inhibition of aggregation activity after plasmatic adenosine diphosphate (ADP) aggregation activation of ethyl acetate, ethanolic, methanolic and aqueous extracts, at 60 mg/mL concentration. The IC50 ADP value of these extracts ranged between 4.07 and 11.39 mg/mL. Moreover, these extracts reported the highest amounts of phenolic and flavonoid contents. In conclusion, phytochemicals present in P. farcta leaves have anti-platelet-aggregation activities. Future studies are needed to identify the compounds with anti-platelet potential present in P. farcta.

[18F]FDG-Labeled CGPRPPC Peptide Serving as a Small Thrombotic Lesions Probe, Including a Comparison with [99mTc]-Labeled Form.

Purpose: Fibrin is a perfect target for specific imaging of all types of thrombotic lesions. Cyclic peptides were introduced as the best scaffolds out of the different types of probes for thrombi detection. This study was conducted to label previously synthesized peptide-targeting fibrin with [18F]FDG and its in vitro and in vivo assessments. Materials and Methods: CGPRPPC peptide functionalized with 6-hydrazinonicotinamide and Eei-NHS was synthesized and cyclized using air oxidation method. The cyclic sequences were labeled with [18F]FDG at 85°C within 30 min. The stability studies were performed in human plasma. Fibrin-binding and platelet aggregation tests were performed in vitro. Biodistribution and scintigraphy imaging in normal mice and carotid thrombotic rat model were considered as in vivo studies. Results: Radiolabeled peptides show a good stability in human plasma and also high-affinity binding for human fibrin. Platelet aggregation test confirmed specific binding of radiopeptides to fibrin. A key problem with the authors' previous research was inability to detect small-vessel thrombi. The results of positron emission tomography/computed tomography scanning show high specific uptake of [18F]FDG-labeled CGPRPPC in small-sized thrombosis. Conclusion: The experiment revealed that radiolabeling of cyclic peptide (CGPRPPC) with [18F]FDG enables us to detect small thrombotic lesions in small animal models with high resolution.

Graphene nanoribbon/FePt bimetallic nanoparticles/uric acid as a novel magnetic sensing layer of screen printed electrode for sensitive determination of ampyra.

A novel electrochemical sensor for sensitive determination of ampyra (Am) based on graphene nanoribbons modified by iron-platinum bimetallic nanoparticles and uric acid (SPCE/FePtGNR/UA) dropped on the screen-printed carbon electrode (SPCE) surface and magnetically captured onto an SPCE working electrode surface is reported in the present work. The modified nanocomposite and sensing layer was characterized by different techniques, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray powdered diffraction (XRD). Am determination by conventional electrochemical methods is not possible, because of its high redox overpotential. Therefore, the differential pulse voltammetry (DPV) signals of UA were used as a redox probe for indirect electrochemical determination of Am. The limit of detection (LOD) and linear concentration range were obtained as 0.028 and 0.08-9.0µmolL-1 (3Sb/m = 3), respectively. The feasibility of the proposed method was examined by the detection of Am in biological and pharmaceutical samples with satisfactory results. The constructed electrochemical sensor was applied for fast, simple and sensitive detection of Am in real environments.

Identification of (Z)-2,3-Diphenylacrylonitrileas Anti-Cancer Molecule in Persian Gulf Sea Cucumber Holothuria parva.

Hepatocellular carcinoma (HCC), also named cancerous hepatoma, is the most common type of malignant neoplasia of the liver. In this research, we screened the Persian Gulf sea cucumber Holothuria parva (H. parva) methanolic sub-fractions for the possible existence of selective toxicity on liver mitochondria isolated from an animal model of HCC. Next, we purified the most active fraction. Thus the structure of the active molecule was identified. HCC was induced by diethylnitrosamine (DEN) and 2-acetylaminofluorene (2-AAF) protocol. Rat liver mitochondria for evaluation of the selective cytotoxic effects of sub-fractions of H. parva were isolated and then mitochondrial parameters were determined. Our results showed that C1 sub-fraction of methanolic extract of H. parva considerably increased reactive oxygen species (ROS) generation, collapse of mitochondrial membrane potential (MMP), swelling in mitochondria and cytochrome c release only on HCC liver mitochondria. Furthermore, the methanolic extract of H. parva was investigated furthermore and the active fraction was extracted. In this fraction, (Z)-2,3-diphenylacrylonitrile molecule, which is also known as α-cyanostilbene, was identified by mass analysis. This molecule increased ROS generation, collapse of MMP, swelling in mitochondria and finally cytochrome c release only on HCC liver mitochondria. The derivatives of (Z)-2,3-diphenylacrylonitrile in other natural products were also reported as an anti-cancer agent. These results suggest the eligibility of the (Z)-2,3-diphenylacrylonitrile as a complementary therapeutic agent for patients with HCC.

Fabrication of a novel impedimetric sensor based on l-Cysteine/Cu(II) modified gold electrode for sensitive determination of ampyra.

This paper presents a novel impedimetric sensor for the sensitive determination of ampyra (Am) based on the l-Cysteine/Cu (II) modified gold electrode (Cu (II)/L-Cys/AuE). This novel sensing layer was characterized by different techniques, including atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Am determination by conventional electrochemical methods is not possible, because of its high redox overpotential. Therefore, [Fe(CN)6]3-/4- was used as a redox probe for the impedimetric determination of Am. Under the optimized conditions, the calibration curve for Am concentration was linear in the range 0.010-40.0 nM with a detection limit of 0.0028 nM. The practical applicability of the proposed sensor was examined by evaluating the detection of Am in biological fluids and pharmaceutical samples with satisfied recoveries. Therefore, the prepared sensor can hold great promise for fast, simple and sensitive detection of Am in various real samples.

Ionic Liquid-assisted Synthesis of Celexocib Using Tris-(2-hydroxyethyl) Ammonium Acetate as an Efficient and Reusable Catalyst.

Celecoxib is classified as none traditional nonsteroidal anti-inflammatory drugs (NSAIDs). This compound has conventional properties of NSAIDs such as anti-inflammatory, analgesic, and antipyretic activities beside reduced risk of gastrointestinal side effect of traditional NSAIDs such as ibuprofen. This compound gets a second sale rank of NSAIDs market at 2016 in the world and sales more than 17000 Kg in Iran during the past 6 month. So, a simple, rapid and green method for synthesis of this compound is important. In the present study, a novel green method was suggested for the synthesis of celecoxib using the ionic liquid. Celecoxib was provided by the reaction of trifluoroacetone, 4-methylbenzoylchloride, and 4-hydrazinobenzenesulfonamide hydrochloride. The tris-(2-hydroxyethyl) ammonium acetate as ionic liquid was prepared by mixing tris-(2-hydroxyethyl) ammonium and acetic acid, and used as an efficient catalyst. The structure of the synthetic products was confirmed by analytical and spectroscopic methods including 1HNMR, 13CNMR, IR, MS and elemental analysis. This ionic liquid can play dual roles in the synthesis of celecoxib, as a catalyst to improve electrophilicity of carbonyl group and also as a solvent of reaction. The reaction rate and yield (86%) were improved considerably. Moreover IL showed the same efficiency when used in 4 consecutive reactions.

Rational Design and Synthesis of 1-(Arylideneamino)-4-aryl-1H-imidazole-2-amine Derivatives as Antiplatelet Agents.

Based on previous studies indicating the pharmacophoric role of a hydrazone group and azole rings for antiplatelet aggregation activity, a few series of compounds with both hydrazone and an azole (imidazole) ring in their structures were synthesized, and their platelet aggregation inhibitory effects were evaluated. Two of these 1-(arylideneamino)-4-aryl-1H-imidazole-2-amine derivatives, compounds 4 a [(E)-1-(benzylideneamino)-4-phenyl-1H-imidazol-2-amine] and 4 p [(E)-4-phenyl-1-((thiophen-2-ylmethylene)amino)-1H-imidazol-2-amine], exhibited IC50 values similar to that of acetylsalicylic acid against collagen as a platelet aggregation inducer. Structural comparison of the synthesized compounds revealed that those with a para-substituted phenyl ring on the imidazole were among the most active compounds against platelet aggregation induced by arachidonic acid (AA), and the presence of a thiophene ring in these compounds maximized their antiplatelet activity.

Modified fractal iron oxide magnetic nanostructure: A novel and high performance platform for redox protein immobilization, direct electrochemistry and bioelectrocatalysis application.

A novel biosensing platform based on fractal-pattern of iron oxides magnetic nanostructures (FIOMNs) and mixed hemi/ad-micelle of sodium dodecyl sulfate (SDS) was designed for the magnetic immobilization of hemoglobin (Hb) at a screen printed carbon electrode (SPCE). The FIOMNs was successfully synthesized through hydrothermal approach and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). In order to provide guidelines for the mixed hemi/ad-micelle formation, zeta-potential isotherms were investigated. The construction steps of the biosensor were evaluated by electrochemical impedance spectroscopy, cyclic voltammetry and Fourier transform infrared spectroscopy. Direct electron transfer of Hb incorporated into the biocomposite film was realized with a pair of quasi-reversible redox peak at the formal potential of -0.355V vs. Ag/AgCl attributing to heme Fe(III)/Fe(II) redox couple. The results suggested that synergistic functions regarding to the hyper-branched and multidirectional structure of FIOMNs and the dual interaction ability of mixed hemi/ad-micelle array of SDS molecules not only induce an effective electron transfer between the Hb and the underlying electrode (high heterogeneous electron transfer rate constant of 2.08s(-1)) but also provide powerful and special microenvironment for the adsorption of the redox proteins. Furthermore, the biosensor displayed an excellent performance to the electrocatalytic reduction of H2O2 with a detection limit of 0.48µM and Michaelis-Menten constant (Km) value of 44.2µM. The fabricated biosensor represented the features of sensitivity, disposable design, low sample volume, rapid and simple preparation step, and acceptable anti-interferences, which offer great perspectives for the screen-determination of H2O2 in real samples.

Evaluation of Anti-Platelet Aggregation Effect of Some Allium Species.

Epidemiologic studies show that the cardiovascular diseases are associated with multiple factors such as raised serum total cholesterol, increased LDL, increased platelet aggregation, hypertension and smoking. In-vitro studies have confirmed the ability of some plants of Allium species to reduce these parameters. Therefore, we evaluated anti-platelet aggregation effect of some Allium species (Allium ampeloprasum, A. hirtifolium, A. haemanthoides, A. vavillovi, A. atroviolaceum, A. jesdianum, A. shelkovnikovii) using arachidonic acid (AA) and adenosine diphosphate (ADP) as platelet aggregation inducers. The screening results for methanolic extract of Allium species showed that the maximum effect of anti-platelet aggregation was related to A. atroviolaceum. This extract inhibited the in-vitro platelet aggregation induced by AA and ADP with IC50 values of 0.4881 (0.4826-0.4937) mg/ml and 0.4945 (0.4137-0.5911) mg/ml respectively. These results support the hypothesis that the dietary intake of Allium could be beneficial for prevention of cardiovascular diseases.

Synthesis and Antiplatelet Aggregation Activity Evaluation of some 2-Aminopyrimidine and 2-Substituted-4,6-diaminopyrimidine Derivatives.

A series of novel 2-aminopyrimidine and 2-Substituted-4,6-diaminopyrimidine derivatives have been synthesized and their antiplatelet aggregation activities were assessed against ADP and arachidonic acid-induced platelet aggregation in human plasma using light transmission aggregometry. Among the tested derivatives, compounds Ia, Ib, IB and II16 exhibited the highest antiplatelet aggregation activity (36.75, 72.4, 62.5 and 80 µM). None of the compounds showed satisfactory activity against the aggregation induced by ADP but acceptable activities were observed against the aggregation induced by arachidonic acid. 2- aminopyrimidines were more active than 4,6- diaminopyrimidines in this respect.

Intracellular GSH Alterations and Its Relationship to Level of Resistance following Exposure to Cisplatin in Cancer Cells.

One of the major complications in cancer chemotherapy with cisplatin as one of the important medicines in treatment regimens of different cancers is the development of resistance. One of the most described cellular defense mechanisms involved in resistance is glutathione (GSH), thus in this study, the effects of cisplatin on the total intracellular GSH level (GSHi) in some sensitive and resistant variants of human cell lines (hepatocarcinoma HepG2, skin A375, cisplatin sensitive glioblastoma U373MG and cisplatin resistant glioblastoma U373MGCP, cisplatin sensitive ovary A2780S and cisplatin resistant A2780CP cells) were studied. MTT assay was performed to measure cytotoxicity of cisplatin (33.3 µM for 1 hour). Following cisplatin exposure, GSHi (per million cells) was evaluated using a photometrical assay up to 90 minutes. Our results indicate that there are significant differences between GSHi content of A2780CP and U373MGCP cells compared to other cell lines. Moreover, IC50 of cisplatin in different cells seems to have a relation with mean of GSH level in 90 minutes (GSH (mean)90). As a conclusion, it seems that resistance to cisplatin in different cell lines is more related with the diverse patterns of GSHi variations following cisplatin exposure than its original level, and/or its cellular increase or decrease. It is also suggested that GSH (mean)90 may be used as a factor for the prediction of cellular resistance to cisplatin.

Synthesis of N-arylmethyl Substituted Indole Derivatives as New Antiplatelet Aggregation Agents.

A number of N-arylmethyl substituted indole derivatives have been synthesized and their effectiveness against ADP and arachidonic acid induced platelet aggregation in human plasma was determined. The desired compounds were synthesized by reacting the appropriate aniline derivative with isatin (or substituted isatin) to form the corresponding imine structures. The so formed compound was then activated using sodium hydride and reacted with the proper substituted benzyl halides. Among the tested compounds, derivatives 4a, 4c, 4d, 4f-i and 4k were the most potent compounds with satisfactory IC50 values (under 38.5 µM) for inhibition of platelet aggregation induced by arachidonic acid. All indole derivatives without substitution on position 1 of the indole ring, exhibited either weaker activities or were not active at all.

Synthesis and evaluation of new fluorinated anti-tubercular compounds.

Treatment of tuberculosis (TB) and the discovery of effective new anti-tubercular drugs are among the most urgent priorities in health organizations all over the world. In the present study, fluorinated analogs of some of the most important anti-TB agents such as p-aminosalicylic acid (PAS), thiacetazone and pyrazinamide were synthesized and tested against TB. The fluorinated analog of thiacetazone was 20 times more potent than the parent compound against M.tuberculosis H37-RV, while the fluorinated p-aminosalicylic acid (PAS) was almost three times less potent than PAS. A few other halogenated analogs of thioacetazone were also synthesized and subjected to anti-M.tuberculosis screening tests. The best halogen substituent was found to be fluorine which has the smallest size from one hand and the strongest electronegativity from the other hand among the halogen atoms. Fluorine therefore could be considered as a golden substituent to improve the anti-M.tuberculosis activity of thioacetazone.

Electrochemical synthesis of novel 1,3-indandione derivatives and evaluation of their antiplatelet aggregation activities.

Electrochemical oxidation of some selected catechol derivatives, using cyclic voltammetry, in the presence of different 2-aryl-1,3-indandiones as nucleophiles, resulted in electrochemical synthesis of new 1,3- indandione derivatives in an undivided cell in good yield and purity. A Michael addition mechanism was proposed for the formation of the analogs based on the reaction conditions which were provided in electrochemical cell. The in-vitro antiplatelet and anticoagulant activity of these compounds was evaluated, using arachidonic acid (AA) and adenosine diphosphate (ADP) as the platelet aggregation inducers. The results show that the incorporation of catechol ring in 1,3-indandione nucleus leads to the emergence of antiplatelet aggregation activity in these compounds. The compounds may exert their antiaggregation activity by interfering with the arachidonic acid pathway.

Determination of the role of calcium on instability of neurotoxic metabolite of ecstasy by HPTLC-mass.

BACKGROUND: Ecstasy is one of the popular illicit drugs in the world and its usage has been recently increased in Iran. This compound can destroy the serotonergic neurons and produces cognitive and psychopathology diseases. 3,4-dihydroxymethamphetamine (HHMA) which is the main metabolite of this compound, seems to be responsible for this effect. However, no consensus has been reached among the researchers about its role. This disagreement between the researches may be due to failure in determination of HHMA as free form in physiological fluids. In this study, the stability of this crucial metabolite of ecstasy was examined in different mediums. METHODS: The stability of HHMA was studied in the perfusion medium and water at 100 and 10 ng/mL concentrations. Moreover, the effect of temperature (0-25°C), pH (3-10), calcium chloride (0-150 g/L) and ethylenediaminetetraacetic acid (EDTA) on the stability of HHMA was also examined. RESULTS: Our result suggested that the free form of HHMA could be degraded in the perfusion medium. The rate of this degradation has direct proportion to temperature (at 25°C = 0.037 min-1 and at 0°C = 0.002 min-1). Calcium chloride and sodium bicarbonate are two responsible components in this instability. Moreover, the alkaline pHs and increasing the shaking time can accelerate this effect. Although, while degradation was prevented at pH=3, EDTA could only reduce this rate about 30%. CONCLUSIONS: Calcium cation can act as an accelerator of HHMA degradation. Therefore, the perfusion medium should not contain Ca2+ and the pH of medium is better to be adjusted at acidic range. Since, the internal cellular source of calcium is endoplasmic reticulum system, it can be assumed that, this cation may change HHMA and dopamine to reactive compounds that can bind covalently to the cysteinyl group of biological compounds and damage cellular components.

Synthesis of novel indole hydrazone derivatives and evaluation of their antiplatelet aggregation activity.

Based on the existing reports regarding the antiplatelet aggregation activity of hydrazone derivatives, a series of indole hydrazone derivatives were considered as potential antiplatelet agents and synthesized. The structures of the synthesized compounds were confirmed by spectral data and elemental analysis. The new indole hydrazone derivatives were evaluated for their ability to inhibit platelet aggregation induced by adenosine diphosphate (ADP) and arachidonic acid (AA). Compounds 1h and 3h exhibited remarkable activity against arachidonic acid induced platelet aggregation with IC(50) values comparable to that of indomethacin and compound 1i efficiently inhibited platelet aggregation induced by both ADP and AA.