Synthesis and biological evaluation of N-cyanoalkyl-, N-aminoalkyl-, and N-guanidinoalkyl-substituted 4-aminoquinoline derivatives as potent, selective, brain permeable antitrypanosomal agents

Hybrid-Compounds Against Trypanosomiases

Neglected tropical diseases (NTDs) are a global public health problem associated with approximately 20 conditions. Among these, Chagas disease (CD), caused by Trypanosoma cruzi, and human African trypanosomiasis (HAT), caused by T. brucei gambiense or T. brucei rhodesiense, affect mainly the populations of the countries from the American continent and sub- Saharan Africa. Pharmacological therapies used for such illnesses are not yet fully effective. In this context, the search for new therapeutic alternatives against these diseases becomes necessary. A drug design tool, recently recognized for its effectiveness in obtaining ligands capable of modulating multiple targets for complex diseases, concerns molecular hybridization. Therefore, this review aims to demonstrate the importance of applying molecular hybridization in facing the challenges of developing prototypes as candidates for the treatment of parasitic diseases. Therefore, studies involving different chemical classes that investigated and used hybrid compounds in recent years were compiled in this work, such as thiazolidinones, naphthoquinones, quinolines, and others. Finally, this review covers several applications of the exploration of molecular hybridization as a potent strategy in the development of molecules potentially active against trypanosomiases, in order to provide information that can help in designing new drugs with trypanocidal activity.

Late-Stage Modification of Medicine: Pd-Catalyzed Direct Synthesis and Biological Evaluation of N-Aryltacrine Derivatives

A new series of N-aryltacrine derivatives were designed and synthesized as cholinesterase inhibitors by the late-stage modification of tacrine, using the palladium-catalyzed Buchwald-Hartwig cross-coupling reaction. In vitro inhibition assay against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) demonstrated that most of the synthesized compounds had potent AChE inhibitory activity with negative inhibition of BuChE. Among them, N-(4-(trifluoromethyl)phenyl)-tacrine (3g) and N-(4-methoxypyridin-2-yl)-tacrine (3o) showed the most potent activity against AChE (IC₅₀ values of 1.77 and 1.48 μM, respectively). The anti-AChE activity of 3g and 3o was 3.5 times more than that of tacrine (IC₅₀ value of 5.16 μM). Compound 3o also displayed anti-BuChE activity with an IC₅₀ value of 19.00 μM. Cell-based assays against HepG2 and SH-SY5Y cell lines revealed that 3o had significantly lower hepatotoxicity compared to tacrine, with additional neuroprotective activity against H₂O₂-induced damage in SH-SY5Y cells. The advantages including synthetic accessibility, high potency, low toxicity, and adjunctive neuroprotective activity make compound 3o a new promising multifunctional candidate for the treatment of Alzheimer's disease.

Synthesis and Biological Activity of Hydrazones and Derivatives: A Review

Hydrazones and their derivatives are very important compounds in medicinal chemistry due to their reported biological activity for the treatment of several diseases, like Alzheimer's, cancer, inflammation, and leishmaniasis. However, most of the investigations on hydrazones available in literature today are directed to the synthesis of these molecules with little discussion available on their biological activities. With the purpose of bringing lights into this issue, we performed a revision of the literature and wrote this review based on some of the most current research reports of hydrazones and derivatives, making it clear that the synthesis of these molecules can lead to new drug prototypes. Our goal is to encourage more studies focused on the synthesis and evaluation of new hydrazones, as a contribution to the development of potential new drugs for the treatment of various diseases.

Centrally Active Multitarget Anti-Alzheimer Agents Derived from the Antioxidant Lead CR-6

Oxidative stress is a major pathogenic factor in Alzheimer's disease, but it should not be tackled alone rather together with other key targets to derive effective treatments. The combination of the scaffold of the polar antioxidant lead 7-methoxy-2,2-dimethylchroman-6-ol (CR-6) with that of the lipophilic cholinesterase inhibitor 6-chlorotacrine results in compounds with favorable brain permeability and multiple activities in vitro (acetylcholinesterase, butyrylcholinesterase, β-site amyloid precursor protein (APP) cleaving enzyme-1 (BACE-1), and Aβ42 and tau aggregation inhibition). In in vivo studies on wild-type and APP/presenilin 1 (PS1) mice, two selected compounds were well tolerated and led to positive trends, albeit statistically nonsignificant in some cases, on memory performance, amyloid pathology (reduced amyloid burden and potentiated non-amyloidogenic APP processing), and oxidative stress (reduced cortical oxidized proteins and increased antioxidant enzymes superoxide dismutase 2 (SOD2), catalase, glutathione peroxidase 1 (GPX1), and heme oxygenase 1 (Hmox1) and transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2)). These compounds emerge as interesting brain-permeable multitarget compounds, with a potential as anti-Alzheimer agents beyond that of the original lead CR-6.

Novel symmetric bis-benzimidazoles: Synthesis, DNA/RNA binding and antitrypanosomal activity

The novel benzimidazol-2-yl-fur-5-yl-(1,2,3)-triazolyl dimeric series with aliphatic and aromatic central linkers was successfully prepared with the aim of assessing binding affinity to DNA/RNA and antitrypanosomal activity. UV-Visible spectroscopy, thermal denaturation showed interaction of heterocyclic bis-amidines with ctDNA. Circular dichroism studies indicated uniform orientation of heterocyclic bis-amidines along the chiral double helix axis, revealing minor groove binding as the dominant binding mode. The amidino fragment and 1,4-bis(oxymethylene)phenyl spacer were the main determinants of activity against Trypanosoma brucei. The bis-benzimidazole imidazoline 15c, which had antitrypanosomal potency in the submicromolar range and DNA interacting properties, emerged as a candidate for further structural optimization to obtain more effective agents to combat trypanosome infections.

Synthesis, anti-bacterial and anti-protozoal activities of amidinobenzimidazole derivatives and their interactions with DNA and RNA

Amidinobenzimidazole derivatives connected to 1-aryl-substituted 1,2,3-triazole through phenoxymethylene linkers 7a-7e, 8a-8e, and 9a-9e were designed and synthesised with the aim of evaluating their anti-bacterial and anti-trypanosomal activities and DNA/RNA binding affinity. Results from anti-bacterial evaluations of antibiotic-resistant pathogenic bacteria revealed that both o-chlorophenyl-1,2,3-triazole and N-isopropylamidine moieties in 8c led to strong inhibitory activity against resistant Gram-positive bacteria, particularly the MRSA strain. Furthermore, the non-substituted amidine and phenyl ring in 7a induced a marked anti-bacterial effect, with potency against ESBL-producing Gram-negative E. coli better than those of the antibiotics ceftazidime and ciprofloxacin. UV-Vis and CD spectroscopy, as well as thermal denaturation assays, indicated that compounds 7a and 8c showed also binding affinities towards ctDNA. Anti-trypanosomal evaluations showed that the p-methoxyphenyl-1,2,3-triazole moiety in 7b and 9b enhanced inhibitory activity against T. brucei, with 8b being more potent than nifurtimox, and having minimal toxicity towards mammalian cells.