A hit optimization protocol applied to the first nonnucleoside inhibitor of the ATPase activity of human DEAD-box RNA helicase DDX3 led to the design and synthesis of second-generation rhodanine derivatives with better inhibitory activity toward cellular DDX3 and HIV-1 replication. Additional DDX3 inhibitors were identified among triazine compounds. Biological data were rationalized in terms of structure-activity relationships and docking simulations. Antiviral activity and cytotoxicity of selected DDX3 inhibitors are reported and discussed. A thorough analysis confirmed human DDX3 as a valid anti-HIV target. The compounds described herein represent a significant advance in the pursuit of novel drugs that target HIV-1 host cofactors.

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Doxorubicin represents a valuable choice for different cancers, although the severe side effects occurring at the high effective dose limits its clinical use. In the present study, potential strategies to potentiate low-dose doxorubicin efficacy, including a metronomic schedule, characterized by a short and repeated exposure to the anticancer drug, and the combination with the natural chemosensitizing sesquiterpenes β-caryophyllene and β-caryophyllene oxide, were assessed in human hepatoma HepG2 cells. The involvement of P-glycoprotein (P-gp) in the HepG2-chemosensitization to doxorubicin was evaluated. Also, the direct interaction of caryophyllene sesquiterpenes with P-gp was characterized by molecular docking and dynamic simulation studies. A metronomic schedule allowed us to enhance the low-dose doxorubicin cytotoxicity and the combination with caryophyllane sesquiterpenes further potentiated this effect. Also, an increased intracellular accumulation of doxorubicin and rhodamine 123 induced by caryophyllane sesquiterpenes was found, thus suggesting their interference with P-gp function. A lowered expression of P-gp induced by the combinations, with respect to doxorubicin alone, was observed too. Docking studies found that the binding site of caryophyllane sesquiterpene was next to the ATP binding domain of P-gp and that β-caryophyllene possessed the stronger binding affinity and higher inhibition potential calculated by MM-PBSA. Present findings strengthen our hypothesis about the potential chemosensitizing power of caryophyllane sesquiterpenes and suggest that combining a chemosensitizer and a metronomic schedule can represent a suitable strategy to overcome drawbacks of doxorubicin chemotherapy while exploiting its powerful activity.Int. J. Mol. Sci. 2020, 21, 633 2 of 28 Int. J. Mol. Sci. 2020, 21, 633 5 of 28 oxide were selected for the combination experiments. Under our experimental conditions, both the sesquiterpenes were able to potentiate the effect of doxorubicin in different experimental conditions, although with different profiles. Particularly, after 24 h exposure, the lower chemosensitizing concentration (50 µM) of β-caryophyllene significantly enhanced the doxorubicin-cytotoxicity starting from the concentration of 10 µM, achieving almost the maximum potentiation of about 32% at concentration of 20 µM (Figure 2a).

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BackgroundThe currently available antifungal drugs suffer from toxicity, greatest potential drug interactions with other drugs, insufficient pharmacokinetics properties, and development of resistance. Thus, development of new antifungal agents with optimum pharmacokinetics and less toxicity is urgent task. In the search for new azole antifungals, we have been previously described azolylchromanone oxime ethers as rigid analogs of oxiconazole. In continuation of our work, we incorporated phenylhydrazone moiety instead of oxime ether fragment in azolylchromanone derivatives.MethodsThe 3-azolyl-4-chromanone phenylhydrazones were synthesized via ring closure of 2-azolyl-2'-hydroxyacetophenones and subsequent reaction with phenylhydrazine. The biological activity of title compounds was evaluated against different pathogenic fungi including Candida albicans, Saccharomyces cerevisiae, Aspergillus niger, and Microsporum gypseum. Docking study, in silico toxicity risks and drug-likeness predictions were used to better define of title compounds as antifungal agents.ResultsThe in vitro antifungal activity of compounds based on MIC values revealed that all compounds showed good antifungal activity against C. albicans, S. cerevisiae and M. gypseum at concentrations less than 16 μg/mL. Among the test compounds, 2-methyl-3-imidazolyl derivative 3b showed the highest values of drug-likeness and drug-score.ConclusionThe 3-azolyl-4-chromanone phenylhydrazones considered as analogs of 3-azolyl-4-chromanone oxime ethers basically designed as antifungal agents. The antifungal activity of title compounds was comparable to that of standard drug fluconazole. The drug-likeness data of synthesized compounds make them promising leads for future development of antifungal agents.

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