Current Topics in Medicinal Chemistry - Volume 18, Issue 17, 2018

Heterocyclic rings having nitrogen atoms are the molecular fragments most used in drug design by using the tools of medicinal chemistry. The 1,2,4-triazole rings are part of an extensive family of drugs that are in use in the pharmaceutical market. More recently, 1,2,3-triazole rings have begun to arouse the great interest of scientists and therefore, many researches have been developed seeking the synthesis of new substances and their possible biological activities. A number of articles have been published by us and others highlighting the synthetic and biological aspects of 1,2,3-triazoles. The growth of new substances of this class was largely due to the simple and selective synthetic method of 1,2,3- triazole ring developed by Sharpless et al. However, some 1,2,3-triazole cannot be synthesized by this method. This review focuses on other synthetic methods that give access to other variations around the 1,2,3-triazole core. The systematic arrangement in this review explores the possibility of providing practical guidance to alternatives of this heterocycle. It has been divided into sections according to the types of starting materials and reactions.

Background: Leishmaniasis is a neglected public health problem caused by several protozoanspecies of the genus Leishmania. The therapeutic arsenal for treating leishmaniasis is quite limited, raising concerns about the occurrence of resistant strains. Furthermore, most of these drugs were developed more than 70 years ago and suffer from poor efficacy and safety and are not well adapted to the needs of patients. Therefore, research on novel natural or synthetic compounds with antiparasitic activity is urgently needed. In this paper, we evaluated the effect and the mechanism of action of naphthotriazolyl-4-oxoquinolines on promastigotes and intracellular amastigotes of Leishmania amazonensis. Materials and Methods: The naphthotriazolyl-4-oxoquinoline derivatives were obtained in good to moderate yields via the [3+2] cycloaddition reaction between 1,4-naphtoquinone and azido-4- oxoquinoline derivatives. HMPA at 100°C was established as the best solvent and temperature condition for this reaction. The structures of the compounds were confirmed by spectral analyses (infrared spectroscopy, one- and two-dimensional ¹H and ¹³C NMR spectroscopy, and high-resolution mass spectrometry). The compounds exhibited promising activities with IC50 values ranging from 0.7 to 2.0 μM against intracellular amastigotes of Leishmania amazonensis. The most selective compound was the Npentyl- substituted derivative, which showed a Selectivity Index (SI) of 8.6, making it less toxic than pentamidine (SI 4.5). Results: Our results demonstrated that all compounds, except the N-propyl-substituted derivative, induce ROS production by parasites early in the culture. As a proof of concept, we demonstrated that the most selective compound was able to interfere with sterol biosynthesis in L. amazonensis. Conclusion: The naphthotriazolyl-4-oxoquinoline derivatives were obtained in good to moderate yields. These conjugates have potent in vitro antileishmanial activity involving at least two different mechanisms of action, making them promising lead compounds for the development of new therapeutic alternatives for leishmaniasis.

Background: Breast cancer is a major cause of death among women worldwide. Treatment for breast cancer involves the surgical removal of cancer tissue, followed by chemotherapy. Although the treatment is efficient, especially when the cancer is detected early, recurrence is common and is often resistant to the previous treatment. Therefore, a constant search for efficient and novel drugs for the treatment of breast cancer is mandatory. Recently, triazole derivatives have shown promising effects against different types of cancer, revealing these molecules as putative anticancer drugs. Experimental: We have synthesized a series of naphthotriazolyl-4-oxoquinoline derivatives and tested their activity against a human breast cancer cell line. Among the compounds tested, we identified a molecule that killed the human breast cancer cell line MCF-7 with minimal effects on its noncancer counterpart, MCF10A. This effect was seen after 24 hours of treatment and persisted for additional 24 hours after treatment withdrawal. After 1 hour of treatment, the compound, here named 12c, promoted a decrease in cell glucose consumption and lactate production. Moreover, the cells treated with 12c for 1 hour showed diminished intracellular ATP levels with unaltered mitochondrial potential and increased reactive oxygen species production. Additionally, apoptosis was triggered after treatment with the drug for 1 hour. All of these effects are only observed with MCF-7 cells, and not MCF10A. These data show that 12c has selective activity against breast cancer cells and is a potential candidate for a novel anticancer drug. Results and Conclusion: The naphthotriazolyl-4-oxoquinoline derivatives were obtained in good to moderate yields, and one of them, 12c, exhibited strong and selective antitumor properties. The antitumor mechanism involves inhibition of glycolysis, diminished intracellular ATP levels, induction of ROS production and triggering of apoptosis. These effects are all selective for cancer cells, since noncancer cells are unaffected, and these effects can only be attributed to the whole molecule, as different pharmacophoric groups did not reproduce these effects.

Background: A series of symmetrical 1,4-disubstituted bis-1,2,3-triazoles was prepared by double copper catalyzed Azide-alkyne Cycloaddition (CuAAC) from aliphatic bis-azides and a tetraethylene glycol bis-azide derivative. The eighteen novel compounds were evaluated in vitro for their cytotoxic activity against two human tumor cell lines: Human breast adenocarcinoma (MDA-MB 231) and ovarian adenocarcinoma (TOV-21G). Results and Conclusion: The results of colorimetric MTT assays showed that compounds 4j and 4q exhibited a better selectivity index and cell viability comparable with the standard drug doxorubicin. These compounds induced apoptosis in both tested cell lines, as assessed by BrdU assay. The results suggest that these structurally simple compounds may be promising prototypes for antitumoral agents.

Background: Cancer is a major cause of death worldwide, despite many different drugs available to treat the disease. This high mortality rate is largely due to the complexity of the disease, which results from several genetic and epigenetic changes. Therefore, researchers are constantly searching for novel drugs that can target different and multiple aspects of cancer. Experimental: After a screening, we selected one novel molecule, out of ninety-four triazole derivatives, that strongly affects the viability and proliferation of the human breast cancer cell line MCF-7, with minimal effects on non-cancer cells. The drug, named DAN94, induced a dose-dependent decrease in MCF-7 cells viability, with an IC50 of 3.2 ± 0.2 μM. Additionally, DAN94 interfered with mitochondria metabolism promoting reactive oxygen species production, triggering apoptosis and arresting the cancer cells on G1/G0 phase of cell cycle, inhibiting cell proliferation. These effects are not observed when the drug was tested in the non-cancer cell line MCF10A. Using a mouse model with xenograft tumor implants, the drug preventing tumor growth presented no toxicity for the animal and without altering biochemical markers of hepatic function. Results and Conclusion: The novel drug DAN94 is selective for cancer cells, targeting the mitochondrial metabolism, which culminates in the cancer cell death. In the end, DAN94 has been shown to be a promising drug for controlling breast cancer with minimal undesirable effects.

Background: According to the World Health Organization (WHO), the fight against Acquired Immunodeficiency Syndrome (AIDS) is still one of the most significant challenges facing humanity. Worldwide, it is estimated that 36.7 million people are infected by the Human Immunodeficiency Virus (HIV). Despite the variety of available drugs, the search for new enzymatic inhibitors of HIV is still important due to the presence of adverse effects and the development of resistant strains. Therefore, the present study aimed to design, synthesize, and biologically evaluate novel inhibitors of HIV Reverse Transcriptase (RT). Materials and Methods: These compounds were obtained in two series, and compounds in both series contain a 1,2,3-triazole ring in their structures. The compounds in the first series are Efavirenz (EFV) analogues with the N-1 position substituted by another important fragment as described in the medicinal chemistry literature on anti-HIV drugs. The second series has a phosphonate chain similar to that in the structure of Tenofovir Disoproxil Fumarate (TDF). Results and Conclusion: The results of the biological evaluation showed that all compounds presented high RT inhibition values and lower or comparable inhibitory concentrations (the concentration needed to reduce the enzymatic activity by 50%, IC50 values, 0.8-1.9 μM). Among the compounds in the first series, the three with the lowest IC50 values had values between 0.8-0.9 μM, and of those in the second series, the most potent had an IC50 value of 1.1 μM; compounds in both series were equipotent to TDF (1.2 μM). Thus, the new compounds could be considered lead compounds for the development of new antiretroviral compounds.

Background: Oxazolones and 1,2,3-triazoles are among the extensively studied heterocycles in medicinal chemistry. Both of these moieties are reported to possess a broad spectrum of biological activity including antimicrobial. Objective: The objective of the current work is to design, synthesize and antimicrobial evaluation of some new oxazolone-1,2,3-triazole hybrids. Methods: The designed oxazolone-1,2,3-triazole hybrids were synthesized using copper(I)-catalyzed azide-alkyne cycloaddition. The antimicrobial evaluation was carried out using serial dilution method. Results: Most of the synthesized hybrids showed significant antimicrobial properties. Some of the compounds were found to be possessing better or comparable activity to that of the standards used. The docking simulations results are also in agreement with the antimicrobial activity data. Conclusion: Sixteen new hybrids were synthesized and tested in vitro for their antimicrobial activity. Some of the tested compounds exhibited promising antimicrobial activity and could be utilized for the development of the lead compounds for new and more potent antimicrobial drugs.