Medicinal Chemistry - Volume 12, Issue 8, 2016

Background: Cancer is one of the most serious illnesses of our civilization. Therefore, scientists of different disciplines try to find new treatment strategies and new chemical molecules which might be useful in a cancer treatment. Objective: The goal of this work is to perform the most significant achievements in the area of chemotherapeutic treatment, published during the last two years. Methods: We reviewed almost 80 contributions, searching for new molecules with anticancer activity and treatment strategies. Results: We have presented tens of new anticancer molecules interacting with DNA or affecting cell cycle and new findings in this area. These compounds are chemically synthesized as well as are isolated from natural sources. The discovered molecules may induce cancer cells apoptosis, improve other cancer treatments, such as radiotherapy or reduce side effects of chemotherapy. Conclusion: The review shows that the cancer battle is still in progress and the combined studies in different disciplines, devoted to this subject, are a rapidly expanding area.

Background: Green chemistry is a discipline of great interest in medicinal chemistry. It involves all fields of chemistry and it is based on the principle to conduct chemical reactions protecting the environment at the same time, through the use of chemical procedures able to avoid pollution. In this context, water as solvent is a good choice because it is abundant, nontoxic, non-caustic, and non-combustible. Even if microwave assisted organic reactions in conventional solvents have quickly progressed, in the recent years medicinal chemists have focused their attention to processes deemed not dangerous for the environment, using nanotechnology and greener solvents as water. Objective: Several reports of reaction optimizations and selectivities, demonstrating the capability of microwave to allow the obtaining of increased yields have been recently published using water as solvent. In this review, we selected the available knowledge related to microwave assisted organic synthesis in aqueous medium, furnishing examples of the newest strategies to obtain useful scaffolds and novel derivatives for medicinal chemistry purposes. Conclusion: The intention of this review is to demonstrate the exclusive ability of MAOS in water as solvent or as co-solvent. For this purpose we report here the most representative applications of MAOS using water as solvent, focusing on medicinal chemistry processes leading to interesting nitrogen containing heterocycles with potential pharmaceutical applications.

Cardiovascular diseases, such as thrombosis and stroke, represent the major cause of disability and death worldwide; and dysfunctions in platelet aggregation and blood coagulation processes are involved. The regular antithrombotic drugs have unsatisfactory results and may produce side effects. Therefore, alternative therapies have been extensively investigated. Objective: The anticoagulant and antiplatelet aggregation potential of a series of six synthetic 1,2,3-triazole derivatives were investigated through in vitro models. Methods: Coagulation tests included the prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) assays, and were performed on a multichannel coagulometer, using human plasma. The platelet aggregation assays were carried out using human platelet-rich-plasma (PRP). Aggregation was initiated by adding ADP or collagen and monitored turbidimetrically on a Whole Blood Aggregometer. Toxicity of derivatives was evaluated on platelets and red blood cells, by measuring the release of lactate dehydrogenase and hemoglobin, respectively. Moreover, theoretical toxicity of derivatives was calculated using the software Osiris® Property Explorer. Results: All the six derivatives tested inhibited, but with different potencies, the plasma coagulation assessed by the PT and TT assays, and also inhibited platelet aggregation of PRP induced by collagen or ADP. The derivatives did not interfere in the aPTT assay and did not affect the viability of platelets or red blood cells. Theoretical studies also revealed that all derivatives will likely to have low toxicity, great pharmacological and oral bioavailability profiles, and a Druglikeness and Drug score similar to some commercial anticoagulant and antiplatelet drugs. Conclusion: 1,2,3-triazoles are potential candidates for molecular modeling of new antithrombotic drugs.

Background: Toll-like receptor 4 (TLR4) has been associated with several inflammatory diseases, such as sepsis, atherosclerosis and chronic pain. Objective: The aim of the present study was to develop an efficient and straightforward synthetic approach for the preparation of small-molecule antagonists Naryl- N’-(5-(2-hydroxybenzoyl)pyrimidin-2-yl)guanidines in order to evaluate these for TLR4 antagonist activity and to obtain useful information about their structure-activity relationships. Methods: The present work have designed and optimized a three-step synthetic route for derivatives of a previously demonstrated antagonist of TLR4: 1-(4- fluorophenyl)-2-(5-(2-hydroxy-5-methoxybenzoyl)pyrimidin-2-yl)guanidine. The antagonist activities of eight novel synthesized compounds were evaluated on cells which selectively express TLR4. Results: Three guanidine derivatives showed promising antagonist activities, with IC50 values in the low micromolar range. Conclusion: Our findings represent an important starting point for further studies of small-molecule agents targeting Toll-like receptors.

Background: An alarming increment in pathogenic resistance to existing anti-microbial agents is a serious problem and the treatment of these bacterial infections is becoming increasingly challenging. Therefore, there is an urgent need to develop novel antimicrobial agents. Objective: As a part of our ongoing studies toward the development of novel antibacterial agents, the synthesis and antibacterial activity of a series of (Z)-5-((3-phenyl-1H-pyrazol-4-yl)methylene)-2-thioxothiazolidin-4-one derivatives will be discussed in this study. Method: (Z)-5-((3-phenyl-1H-pyrazol-4-yl)methylene)-2-thioxothiazolidin-4-one derivatives were designed, synthesized and evaluated for antibacterial activity. The structures were confirmed by IR, 1H NMR, 13C NMR and mass spectrometry. All of the synthesized compounds were evaluated in vitro using a 96-well microtiter plate and a serial dilution method to obtain their minimum inhibitory concentration (MIC) values against a variety of different strains, including multidrug-resistant clinical isolates. Results: The antibacterial test in-vitro showed that most compounds in series 7 and 9 exhibited significant inhibitory activities against anaerobic bacteria (Streptococcus mutans) strains with a MIC value of 1 μg/mL. Compounds 7c and 9c showed the most potent activity against MRSA (3167 and 3506) with a minimum inhibitory concentration (MIC) value of 1 μg/mL, which is equivalent to moxifloxacin and greater than gatifloxacin, oxacillin and norfloxacin. Additionally, compound 9c showed potent antibacterial activity against Bacillus subtilis (aerobic bacteria) with a MIC value of 2 μg/mL. Conclusion: The work suggests that these type of rhodanine compounds had a better potent activity against MRSA compared with other perviously reported rhodanine derivatives, which might provide a valuable information for the development of new antibacterial agents against multidrug-resistant clinical isolates MRSA.

Background: The present study was carried out to evaluate the antimicrobial activity of a synthesized 2-methylthio-benzo[g][1,2,4]triazolo[1,5- a]quinazoline series. The compounds (1-21) were tested against a variety of Gram-positive bacterial species including Bacillus subtilis (RCMB 01001 69-3), Enterococcus faecalis (RCMB 0100154-2), Staphylococcus aureus (RCMB 0100183-9), Staphylococcus epidermidis (RCMB 0100183-9) and Streptococcus pyogenes (RCMB 0100172-5). In addition, Gram-negative bacteria were also tested including Pseudomonas aeruginosa (RCMB 0100243-5), Escherichia coli (RCMB 010052-6), Proteus mirabilis (RCMB 01002 54-2), Klebsiella oxytoca (RCMB 01002 83-4) and Enterobacter cloacae (RCMB 01002 64-5). Furthermore, their activities were screened against ten types of fungi i.e. Aspergillus fumigatus (RCMB 02568), Syncephalastrum racemosum (RCMB 05922), Geotricum candidum (RCMB 05097), Candida albicans (RCMB 05036), Aspergillus niger (RCMB 02724), Cryptococcus neoformans (RCMB 05642), Candida tropicalis (RCMBA 05239), Penicillium expansum (RCMB 01924), Microsporum canis (RCMB 0834) and Trichophyton mentagrophytes (RCMB 0925). Methods: Evaluation of antimicrobial activity was performed using agar well diffusion method in comparison with ampicillin and gentamycin as antibacterial reference drugs, and amphotericin B as antifungal reference drug. The minimum inhibitory concentration (MIC) was determined using the broth double dilution technique. Results: The MIC values of the tested compounds were reported in μg/mL in which ampicillin, gentamicin and amphotericin B were used as standard reference drugs. The obtained results revealed that compounds 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20 and 21 showed significant antimicrobial activity against six bacterial and six fungal strains. Conclusion: The promising compounds could be employed as useful scaffolds for building of new derivatives with more potent antimicrobial effects.

A novel, green, and atom-economical boric acid catalyzed direct amidation without the use of any coupling agents for the preparation of suberoylanilide hydroxamic acid (SAHA) and SAHA-based inhibitors targeting anti-proliferation of cancer cells is provided. The new SAHA-based inhibitor B123, when used alone, exhibited higher anti-proliferative activities than SAHA or Cisplatin against a number of human cancer cells. We have examined the effect of combination of these SAHA-based inhibitors with Cisplatin. We found synergistic effects of the combination of SAHA-based inhibitors with Cisplatin over a wide range of concentrations against human liver cancer cells HepG2 and two human lung cancer cell lines H1299 and H460. This synergism leads up to 8-fold of dose reduction for Cisplatin in the combination with our synthesized inhibitor B123 against H1299.

Background: The development of antiangiogenic agents arises as a more effective and selective therapeutic approach for the treatment of cancer. In addition to reduced acute toxicity, the efficacy of chemotherapy could be improved when administered in combination specific antiangiogenic with cytotoxic agents. The conjugation or hybridization of bifunctional molecules is one of the alternative rational design strategies for co-administration of anticancer drugs. Objective and Methods: The goal of this work is to prepare the conjugates of an antiangiogenic triterpene, 3-oxo oleanolic acid, and structurally related triterpenoids with a cytotoxic semibenzoquinone, jacaranone. The cytotoxic, antiproliferative and antiangiogenic activities of segments and conjugates were determined. The possible targets of conjugates 6a-6h were predicted using Similarity Ensemble Approach (SEA). Results: The results showed that these conjugates are more potent in both cytotoxic and antiangiogenic assays than their corresponding parent molecules, and are also selectively more active against melanoma cells B16 and metastatic B16BL6 than the two other cancer cell lines (A549 and MCF-7) tested. The predicted antiangiogenesis related targets could involve glycogen phosphorylase, neuraminidase, interferon gamma, and tubulin beta chain. Conclusion: The bifunctional conjugates could be useful as dual acting antitumor/antigiogenic agents.

Background: To discover a novel antidepressant-like effect and anticonvulsant compound, seventeen new 2-oxo-3-phenyliminoindolin-1-Nphenylacetamide compounds were synthesized and screened for the antidepressant activity and anticonvulsant effects. Method: 2-oxo-3-phenyliminoindolin-1-N-phenylacetamide derivatives were synthesized with indoline-2, 3-dione as the starting material, through a nucleophilic substitution reaction and a nucleophilic addition-elimination reaction. The target derivatives 2a-2q were evaluated the antidepressant-like activity using the FST, TST, and evaluated anticonvulsant effect by MES test. The main monoamine neurotransmitters and their metabolites in mouse brain regions were also simultaneously determined by HPLC-ECD. Results: It was observed that 13 compounds showed significant reductions in the immobility time in the FST at a concentration of 50 mg/kg. Compound 2b was found to have the most potent antidepressant activity in the FST and the TST for 30 min after treatment. Compound 2b significantly increased the concentrations of the main neurotransmitters 5-HT, NE and the metabolite (5-HIAA, suggesting that the effects of compound 2b may be mediated through these neurotransmitters. As assessed using maximal electroshock, 13 compounds showed the anticonvulsant effects administered at the concentration levels of 100 or 300 mg/kg. Compound 2b showed anticonvulsant effect. Compound 2b could potentially be used as adjuncts of the antidepressants to treat depression in patients with epilepsy. Conclusion: In conclusion, compound 2b produced significant antidepressant-like activity and the mechanism of action may be due to increased 5-HT and NE in the mouse. Compound 2b showed more anticonvulsant effect. Compound 2b could potentially be used as adjuncts of the antidepressants to treat depression in patients with epilepsy.

Background: Fungi are an emerging threat in medicine and agriculture and current therapeutics have proved to be insufficient and toxic. This has led to an increased interest in peptide-based therapeutics, especially antifungal peptides (AFPs), being safer and more effective drug candidates against fungal threats. However, screening for peptides with antifungal activity is costly and timeconsuming. However, by using computational techniques, we can overcome these restricting factors. The aim of the present study is to compare different machine learning algorithms in combination with Chou’s pseudo amino acid composition in classifying and predicting AFPs to represent a precise model for AFP prediction. Methods: Five different machine learning algorithms frequently used for classification of biological data were used and their performance was evaluated and compared based on their accuracy, sensitivity, specificity and Matthew’s correlation coefficient. The two algorithms with the best performance were then further verified with an independent test dataset. Results: SVM and Bagged-C4.5 classifiers had the highest performance results among the five algorithms. Further validations showed that the model generated using SVM can be employed for precise classification and prediction of antifungal peptides. All the performance values of this model were above 80%, making the classifier highly accurate and trustable. Conclusion: Using computational approaches, especially data mining techniques, we can develop a precise prediction model for antifungal peptides. The model developed in this study using SVM can be considered a powerful tool for the prediction of antifungal peptides, which can be the first step in synthesis and discovery of novel fungi targeting agents.