Diogo Teixeira Carvalho

Arboviruses represent an ongoing global health challenge, particularly in tropical regions where diseases caused by Chikungunya virus (CHIKV) and Mayaro virus (MAYV) continue to emerge. Given the absence of licensed antiviral therapies, the identification of effective small molecules remains critical. This study evaluated sixteen eugenol‐ and dihydroeugenol‐derived piperazine Mannich bases for antiviral activity against CHIKV, MAYV, and Zika virus (ZIKV) in Vero cells. Cytotoxicity was assessed using the MTT assay, and antiviral activity was quantified through median effective concentration (EC ₅₀ ) and selectivity index (SI) values. Time‐dependent cytopathic effect inhibition, plaque reduction assays, virucidal assays and docking were performed to characterize the mechanism of action. Three compounds ( D3 , D7 , and E7 ) exhibited selective antiviral activity. Notably, compound D7 demonstrated low‐micromolar anti‐MAYV inhibition (EC ₅₀ = 14.43 μM; SI > 16.6), surpassing ribavirin by more than thirty‐fold in relative potency. Time‐dependent assays revealed progressive viral titer reductions of up to 3 log ₁₀ PFU/mL over 48 h. Virucidal assays confirmed that D7 does not directly inactivate viral particles. These findings identify D7 as a promising antiviral lead compound and provide a foundation for further mechanistic, optimization, and in vivo studies aimed at developing anti‐alphavirus therapeutics.

Coumarins are phenolic compounds widely recognized for their diverse pharmacological activities and have attracted increasing attention as potential chemopreventive agents. In the present study, four known 3‐benzoylcoumarin derivatives [( 1 ), ( 2 ), ( 3 ), and ( 4 )] were evaluated for their cytotoxic, mutagenic, and antigenotoxic effects in Chinese hamster lung fibroblasts (V79 cells). Cytotoxicity was initially assessed using the MTT assay to establish sub‐cytotoxic concentrations for subsequent analyses. Genotoxicity and chemopreventive activity were investigated using the cytokinesis‐block micronucleus (CBMN) assay following DNA damage induced by doxorubicin (DXR) or methyl methanesulfonate (MMS). All compounds exhibited concentration‐dependent cytotoxicity, with ( 2 ) showing the greatest potency. In the CBMN assay, none of the compounds significantly altered the nuclear division index (NDI), indicating the absence of cytostatic effects. However, at higher concentrations, the derivatives increased micronucleus (MN) frequency, suggesting the induction of chromosomal damage. In the antigenotoxicity assay, differential protective effects were observed depending on the mutagen used. Cotreatment with DXR demonstrated that ( 1 ) significantly reduced MN frequency at the highest tested concentration, whereas ( 3 ) and ( 4 ) significantly decreased DXR‐induced chromosomal damage. When MMS was used as the mutagenic agent, ( 2 ) significantly reduced MN formation at lower concentrations. Taken together, these findings support a Janus‐like behavior of 3‐benzoylcoumarins and indicate dose‐dependent genotoxic and antigenotoxic properties and highlight their potential as modulators of DNA damage induced by different mutagenic mechanisms. Overall, these findings highlight the concentration‐dependent dual biological effects of 3‐benzoylcoumarins and support further investigations into their potential as chemopreventive agents.

Sixteen thiazoles, of which nine are unprecedented substances (11, 12, 15, 16, 17, 19, 20, 23, and 24), were obtained by a cyclocondensation reaction between a thioamide and an α-bromoketone, via Hantzsch synthesis. All thiazoles (11-26), along with four thiosemicarbazone derivatives (7-10) and their precursors (1-6), were evaluated for their activity against Mycobacterium species Mycobacterium abscessus, Mycobacterium massiliense, Mycobacterium fortuitum, and Mycobacterium smegmatis, as well as for their antibiofilm properties. Among them, compounds 7, 8, 14, 17, 18, 19, 20, and 21 showed promising results in minimum inhibitory concentration (MIC) assays, demonstrating bactericidal activity within 48 h. Moreover, all these compounds inhibited biofilm formation. Notably, the unprecedented thiazole 17, along with 18 (MIC = 36 μmol L^-1) and 21 (MIC = 65 μmol L^-1), exhibited the lowest MIC values against all tested species, outperforming the reference drugs. Furthermore, these compounds showed a high degree of selectivity toward mycobacterial cells, as confirmed by cytotoxicity assays using peripheral blood mononuclear cells (PBMC) and Vero cells. These findings highlight the strong antimycobacterial potential of the new thiazole derivatives, warranting further investigation.

Chagas disease, caused by Trypanosoma cruzi, remains a major public health concern in Latin America and beyond, with limited treatment options and high morbidity in chronic stages. Currently, benznidazole remains the first-line therapy for Chagas disease but exhibits considerable limitations, including dose-dependent toxicity and poor efficacy in long-term infections. In response to the pressing need for safer and more effective therapies, this study reports the design, synthesis, and biological evaluation of 17 novel eugenol-based hybrid compounds (18–34), strategically constructed by integrating pharmacophoric features from nitroaromatic trypanosomicidal agents, azole-based CYP51 inhibitors, and the phenylpropanoid core of eugenol. The synthetic sequence included key steps such as nitration, O-alkylation, epoxidation, nucleophilic epoxide opening, and CuAAC reactions to afford 1,2,4-triazole-, imidazole-, and 1,2,3-triazole-containing hybrids. All compounds were structurally characterized by IR, HRMS, and NMR spectroscopy. Biological assays were performed against both trypomastigote and amastigote forms of T. cruzi (Y strain), revealing compound-dependent antiparasitic profiles. Hybrid 29, bearing benzyl and nitro substituents on an imidazole ring, emerged as the most active candidate (EC₅₀ = 26.5 μmol·L^–1) with a selectivity index exceeding 49. Enantioseparation by chiral HPLC enabled the isolation of (+)-29 and (−)-29 enantiomers, both of which showed comparable activity, indicating no significant stereoselectivity. Cytotoxicity assays in mammalian cell lines (Vero and H9c2) confirmed low toxicity for most hybrids (CC₅₀ > 1300 μmol·L^–1). Although the compounds were inactive against intracellular amastigotes, the observed trypomastigote-selective activityparticularly of nitrobenzylated derivatives suggests a non-CYP51-related mechanism of action. These findings highlight the value of phenylpropanoid-based molecular hybridization as a promising strategy for developing new antiparasitic agents against T. cruzi.

Carbohydrates are well known to be one of the most abundant and structurally diverse natural organic compounds, and they are of great importance as an energy source and as structural components of cell walls in different organisms. They are involved in various biological and pathological processes, including homeostasis, cell–cell interaction, cell migration, cell development, bacterial and viral infection, inflammation, immunology, and cancer metastasis. The variety of these properties is a result of the structural diversity found in carbohydrates. The chemistry of carbohydrates involved in the diagnosis and treatment of diseases has attracted increasing attention from researchers, which is why they should be one of the main focuses in new drug discovery. This study focuses on the synthesis of new glycotriazole–metronidazole compounds as antifungal agents and antifungal biofilm agents, from the glycosylation of metronidazole with various carbohydrates ( d ‐glucose, d ‐galactose, d ‐ N ‐acetylglucosamine, and d ‐lactose). Our hypothesis is that the glycosides could be taken into fungal biofilms through recognition by glycoreceptors and transporters, carrying the active residue with them. In a low‐oxygen environment, the nitro group would then undergo bioreduction leading to the formation of toxic radicals potentially resulting in the destruction or paralysis of biofilm formation—essentially functioning as a bioactive “Trojan horse.” The compounds were obtained via a click chemistry reaction using a triazole connector, and the subsequent antifungal tests showed good results for a number of compounds. In silico studies demonstrated positive data for all synthesized compounds, and, in general, they present low toxicological risks.

Neglected tropical diseases (NTDs) and malaria remain significant public health challenges, particularly in resource‐limited regions. The search for novel therapeutic agents to combat these diseases is imperative due to emerging drug resistance and limited treatment options. Mannich bases, a class of organic compounds synthesised via the Mannich reaction, exhibit diverse pharmacological properties, including antimicrobial, antimalarial, antiviral, antimycobacterial, antiparasitic (leishmanicidal, trypanocidal, anthelmintic) and even anti‐diabetic. Their structural versatility allows for modifications to enhance bioavailability, potency and selectivity against specific pathogens. Moreover, Mannich bases can target multiple biological pathways involved in the pathogenesis of NTDs and malaria, thereby offering a multifaceted approach to treatment. This review explores the pharmacological potential of Mannich bases in addressing NTDs and malaria.

Leishmaniasis is a neglected tropical disease with limited therapeutic options characterized by high toxicity, adverse side effects, and growing resistance to existing treatments. In this study, machine learning (ML) methods were employed to design and evaluate benzophenone and xanthone derivatives as potential antileishmanial agents. A dataset of 73 compounds was curated, and Quantitative Structure-Activity Relationship (QSAR) models were developed using artificial neural networks (ANN), Random Forest (RF), and J48 decision tree classifiers. The ANN model achieved the highest accuracy (86.2%) in predicting antileishmanial activity, validated through in vitro assays. Among 14 newly synthesized benzophenones, compounds 5 and 7 demonstrated significant biological activity with inhibitory concentration 50 (IC50) values of 10.19 and 14.35 μM, respectively, and favorable selectivity indices compared to reference drugs pentamidine and amphotericin B. Structural analysis highlighted the importance of thiosemicarbazone and 4-methyl groups, alongside electronegative substituents at position 11, in enhancing activity. This study underscores the potential of computational tools to streamline the discovery of novel, effective, and selective antileishmanial agents.

Eugenol, a natural compound found in essential oils such as clove oil, has been extensively studied for its diverse biological activities including the therapeutic potential against microbial and parasitic infections. This review provides an overview of the synthetic strategies (shown in Supplementary Material) employed to develop bioactive derivatives and analogues derived from eugenol and related compounds (e.g., dihydroeugenol and isoeugenol), focusing on biological activity of more than 100 bioactive eugenol derivatives against bacterial, fungal, viral and protozoal pathogens. Through a comprehensive survey of literature, this paper shows the impact of structural modifications of these phenylpropanoids on antimicrobial and antiparasitic activity. Key findings highlight promising candidates for further development in antimicrobial drug discovery, suggesting directions for future research in the pursuit of effective therapeutic agents.

The presence of impurities in active pharmaceutical ingredients (APIs) and drug products represents a risk to patients' health. Such substances are related to diverse side effects and may have mutagenic potential. That's why it is necessary to establish acceptable limits for these by-products, to minimize the risk associated with medicinal therapy. This work focused on presenting a critical review of relevant points related to the presence of impurities in pharmaceuticals. The main legislation and guidelines from the FDA, EMA, ICH, and Pharmacopeias about the subject were evaluated, and recent articles related to the topic were searched in Scopus, ScienceDirect, PubMed, and Web of Science from 2013 to 2023. Additionally, the analytical techniques used for quantifying impurities were discussed, along with relevant tests for assessing the toxicological and mutagenic risks of these by-products. Recent legislation, including ICH Q3A (R2), ICH Q3B (R2), ICH M7 (R2), ICH Q3D (R2), ICH Q3C (R9), ICH Q3E, ICH Q6A, ICH M3 (R2), as well as FDA and EMA guidelines, highlights a comprehensive and effective framework for controlling impurities in pharmaceuticals. Despite this, there remains a lack of harmonization and standardized procedures across different regions. From the review of scientific literature, we observed that advancements in analytical techniques have significantly improved the sensitivity and selectivity in detecting impurities and degradation products. This underscores the ongoing commitment of health agencies and the pharmaceutical industry to ensure the safety and efficacy of medicinal products.