Thiosemicarbazone of lapachol acts on cell membrane in Paracoccidioides brasiliensis

Lapachol inhibits the growth of lung cancer by reversing M2-like macrophage polarization via activating NF-κB signaling pathway

Resetting tumor-associated macrophages (TAMs) is a promising strategy to ameliorate the immunosuppressive tumor microenvironment (TME) and improve innate and adaptive antitumor immunity. Lapachol, a naturally occurring 1,4-naphthoquinone, exhibits various pharmacological activities including antitumor, anti-leishmanial, antimalarial and antiseptic. In this study, we investigated the relevance of macrophage polarization and the antitumor effect of lapachol in Lewis lung cancer (LLC) both in vitro and in vivo. This study demonstrated that lapachol significantly reversed the polarization of M2-like macrophages thus that were endowed with the ability to kill LLC cells by activating NF-κB signaling pathway. Furthermore, lapachol effectively suppressed tumor growth in C57BL/6 mice bearing lung tumors by reducing the proportion of M2-like macrophages. Overall, our findings clearly illustrated that lapachol could reverse the polarization of M2-like macrophages to improve the immunosuppressive tumor microenvironment, and had the potential to be developed as an immunomodulatory antitumor agent.

Curcumin inhibits Aspergillus flavus infection and aflatoxin production possibly by inducing ROS burst

Aspergillus flavus contamination is common in various food and feed ingredients, and it poses to serious threats to human and animal health. Curcumin is a plant-derived polyphenol that exhibits antifungal activity. In this study, the antifungal effect of curcumin on A. flavus was evaluated, and the underlying mechanism was investigated. Curcumin effectively decreased aflatoxin B1 synthesis and suppressed A. flavus infection in peanut. Curcumin inhibited the mycelial growth and sporulation of A. flavus. Ergosterol biosynthesis in A. flavus was suppressed, and cell membrane permeability was enhanced. The pathogenicity of A. flavus was also reduced by curcumin treatment. Curcumin induced ROS burst in the hyphae of A. flavus, and those damages could be reversed by exogenous superoxide dismutase, suggesting that curcumin inhibited A. flavus possibly via inducing oxidative stress. These results indicate that curcumin has the potential to be used as a preservative to control A. flavus contamination in food and feedstuff.

In silico evaluation of lapachol derivatives binding to the Nsp9 of SARS-CoV-2

SARS-CoV-2 is the etiological agent of COVID-19, which represents a global health emergency that was rapidly declared a pandemic by the World Health Organization. Currently, there is a dearth of effective targeted therapies against viruses. Natural products isolated from traditional herbal plants have had a huge impact on drug development aimed at various diseases. Lapachol is a 1,4- naphthoquinone compound that has been demonstrated to have therapeutic effects against several diseases. SARS-CoV-2 non-structural proteins (nsps) play an important role in the viral replication cycle. Nsp9 seems to play a key role in transcription of the RNA genome of SARS-CoV-2. Virtual screening by docking and molecular dynamics suggests that lapachol derivatives can interact with Nsp9 from SARS-CoV-2. Complexes of lapachol derivatives V, VI, VIII, IX, and XI with the Nsp9 RNA binding site were subjected to molecular dynamics assays, to assess the stability of the complexes via RMSD. All complexes were stable over the course of 100 ns dynamics assays. Analyses of the hydrogen bonds in the complexes showed that lapachol derivatives VI and IX demonstrated strongest binding, with a stable or increasing number of hydrogen bonds over time. Our results demonstrate that Nsp9 from SARS-CoV-2 could be an important target in prospecting for ligands with antiviral potential. In addition, we showed that lapachol derivatives are potential ligands for SARS-CoV-2 Nsp9.

Communicated by Ramaswamy H. Sarma

Overview of Antifungal Drugs against Paracoccidioidomycosis: How Do We Start, Where Are We, and Where Are We Going?

Paracoccidioidomycosis is a neglected disease that causes economic and social impacts, mainly affecting people of certain social segments, such as rural workers. The limitations of antifungals, such as toxicity, drug interactions, restricted routes of administration, and the reduced bioavailability in target tissues, have become evident in clinical settings. These factors, added to the fact that Paracoccidioidomycosis (PCM) therapy is a long process, lasting from months to years, emphasize the need for the research and development of new molecules. Researchers have concentrated efforts on the identification of new compounds using numerous tools and targeting important proteins from Paracoccidioides, with the emphasis on enzymatic pathways absent in humans. This review aims to discuss the aspects related to the identification of compounds, methodologies, and perspectives when proposing new antifungal agents against PCM.

Antifungal Drug Repurposing

Control of fungal pathogens is increasingly problematic due to the limited number of effective drugs available for antifungal therapy. Conventional antifungal drugs could also trigger human cytotoxicity associated with the kidneys and liver, including the generation of reactive oxygen species. Moreover, increased incidences of fungal resistance to the classes of azoles, such as fluconazole, itraconazole, voriconazole, or posaconazole, or echinocandins, including caspofungin, anidulafungin, or micafungin, have been documented. Of note, certain azole fungicides such as propiconazole or tebuconazole that are applied to agricultural fields have the same mechanism of antifungal action as clinical azole drugs. Such long-term application of azole fungicides to crop fields provides environmental selection pressure for the emergence of pan-azole-resistant fungal strains such as Aspergillus fumigatus having TR34/L98H mutations, specifically, a 34 bp insertion into the cytochrome P450 51A (CYP51A) gene promoter region and a leucine-to-histidine substitution at codon 98 of CYP51A. Altogether, the emerging resistance of pathogens to currently available antifungal drugs and insufficiency in the discovery of new therapeutics engender the urgent need for the development of new antifungals and/or alternative therapies for effective control of fungal pathogens. We discuss the current needs for the discovery of new clinical antifungal drugs and the recent drug repurposing endeavors as alternative methods for fungal pathogen control.

Antifungal activity of two oxadiazole compounds for the paracoccidioidomycosis treatment

Paracoccidioidomycosis (PCM) is a neglected disease present in Latin America with difficulty in treatment and occurrence of serious sequelae. Thus, the development of alternative therapies is imperative. In the current work, two oxadiazole compounds (LMM5 and LMM11) presented fungicidal activity against Paracoccidioides spp. The minimum inhibitory and fungicidal concentration values ranged from 1 to 32 μg/mL, and a synergic effect was observed for both compounds when combined with Amphotericin B. LMM5 and LMM11 were able to reduce CFU counts (≥2 log10) on the 5th and 7th days of time-kill curve, respectively. The fungicide effect was confirmed by fluorescence microscopy (FUN-1/FUN-2). The hippocratic screening and biochemical analysis were performed in Balb/c male mice that received a high dose of each compound, and the compounds showed no in vivo toxicity. The treatment of experimental PCM with the new oxadiazoles led to significant reduction in CFU (≥1 log10). Histopathological analysis of the groups treated exhibited control of inflammation, as well as preserved lung areas. These findings suggest that LMM5 and LMM11 are promising hits structures, opening the door for implementing new PCM therapies.