New insights in the mechanism of the SARS-CoV-2 Mpro inhibition by benzisoselenazolones and diselenides.

Although global vaccination campaigns alleviated the SARS-CoV-2 pandemic in terms of morbidity and mortality, the ability of the virus to originate mutants may reduce the efficacy of vaccines, posing a serious risk of a renewed pandemic. There is therefore a need to develop small molecules capable of targeting conserved viral targets, such as the main protease (Mpro). Here, a series of benzisoselenazolones and diselenides were tested for their ability to inhibit Mpro; then the most potent compounds were measured for antiviral activity in vitro, and the mechanism of action was investigated. Density functional theory calculations, molecular docking and molecular dynamics simulations were also used to elucidate the protein/drug interaction. Finally, a bio-organic model was established to study the reaction between selenorganic compounds and biologically relevant thiols to unveil possible metabolic pathways of such compounds. The overall results contribute to the identification of a series of novel Se-containing molecules active against SARS-CoV-2 and to the clarification of some important aspects in the mechanisms of action of such inhibitors targeting SARS-CoV-2 Mpro.

Synthesis of a New Class of ß-Carbonyl Selenides Functionalized with Ester Groups with Antioxidant and Anticancer Properties-Part II.

A series of phenyl ß-carbonyl selenides with o-ester functionality substituted on the oxygen atom with chiral and achiral alkyl groups was synthesized. All compounds are the first examples of this type of organoselenium derivatives with an ester substituent in the ortho position. The obtained derivatives were tested as antioxidants and anticancer agents to see the influence of an ester functionality on the bioactivity of ß-carbonyl selenides by replacing the o-amide group with an o-ester group. The best results as an antioxidant agent were observed for O-((1R,2S,5R)-(-)-2-isopropyl-5-methylcyclohexyl)-2-((2-oxopropyl)selanyl)benzoate. The most cytotoxic derivative against breast cancer MCF-7 cell lines was O-(methyl)-2-((2-oxopropyl)selanyl)benzoate and against human promyelocytic leukemia HL-60 was O-(2-pentyl)-2-((2-oxopropyl)selanyl)benzoate.

N-3-Methylbutyl-benzisoselenazol-3(2H)-one Exerts Antifungal Activity In Vitro and in a Mouse Model of Vulvovaginal Candidiasis.

In the present work, we evaluated the antifungal activities of two novel ebselen analogs, N-allyl-benzisoselenazol-3(2H)-one (N-allyl-bs) and N-3-methylbutylbenzisoselenazol-3(2H)-one (N-3mb-bs). Colorimetric and turbidity assays were performed to determine the minimum inhibitory concentration (MIC) of these compounds in S1 (fluconazole-sensitive) and S2 (fluconazole-resistant) strains of C. albicans. N-3mb-bs was more active than the N-allyl-bs compound. It is noteworthy that the concentration of N-3mb-bs observed to inhibit fungal growth by 50% (18.2 µM) was similar to the concentration observed to inhibit the activity of the yeast plasma membrane H+-ATPase (Pma1p) by 50% (19.6 µM). We next implemented a mouse model of vulvovaginal candidiasis (VVC) using the S1 strain and examined the mouse and yeast proteins present in the vaginal lavage fluid using proteomics. The yeast proteins detected were predominately glycolytic enzymes or virulence factors associated with C. albicans while the mouse proteins present in the lavage fluid included eosinophil peroxidase, desmocollin-1, and gasdermin-A. We then utilized the N-3mb-bs compound (12.5 mg/kg) in the mouse VVC model and observed that it significantly reduced the vaginal fungal burden, histopathological changes in vagina tissue, and expression of myeloperoxidase (MPO). All in all, the present work has identified a potentially promising drug candidate for VVC treatment.

Synthesis of New Chiral ß-Carbonyl Selenides with Antioxidant and Anticancer Activity Evaluation-Part I.

A series of unsymmetrical phenyl ß-carbonyl selenides with o-amido function substituted on the nitrogen atom with chiral alkyl groups was obtained. The compounds form a series of enantiomeric and diastereomeric pairs and present the first examples of this type of chiral Se derivatives. All obtained selenides were further evaluated as antioxidants and anticancer agents to define the influence of the particular stereochemistry of the attached functional groups on the bioactivity of the molecules. The highest H2O2 reduction potential was observed for N-(cis-2-hydroxy-1-indanyl)-2-((2-oxopropyl)selanyl)benzamide, and the best radical scavenging properties for N-(-1-hydroxy-2-butanyl)-2-((2-oxopropyl)selanyl)benzamide. Also, both enantiomers of the N-(1-hydroxy-2-butanyl) selenide expressed the highest cytotoxic potential towards human promyelocytic leukemia HL-60 cell line with similar IC50 values 14.4 ± 0.5 and 16.2 ± 1.1 µM, respectively. On the other hand, breast cancer cell line MCF-7 was most sensitive to N-((R)-(-)-1-hydroxy-2-butanyl)- 2-((2-oxopropyl)selanyl)benzamide (IC50 of 35.7 ± 0.6 µM). The structure-activity dependence of the obtained Se derivatives was discussed, and the most potent compounds were selected.

Selected N-Terpenyl Organoselenium Compounds Possess Antimycotic Activity In Vitro and in a Mouse Model of Vulvovaginal Candidiasis.

In the present work, a series of N-terpenyl organoselenium compounds (CHB1-6) were evaluated for antimycotic activity by determining the minimum inhibitory concentration (MIC) for each compound in fluconazole (FLU)-sensitive (S1) and FLU-resistant (S2) strains of Candida albicans (C. albicans). The most active compounds in the MIC screen were CHB4 and CHB6, which were then evaluated for cytotoxicity in human cervical cancer cells (KB-3-1) and found to be selective for fungi. Next, CHB4 and CHB6 were investigated for skin irritation using a reconstructed 3D human epidermis and both compounds were considered safe to the epidermis. Using a mouse model of vulvovaginal candidiasis (VVC), CHB4 and CHB6 both exhibited antimycotic efficacy by reducing yeast colonization of the vaginal tract, alleviating injury to the vaginal mucosa, and decreasing the abundance of myeloperoxidase (MPO) expression in the tissue, indicating a reduced inflammatory response. In conclusion, CHB4 and CHB6 demonstrate antifungal activity in vitro and in the mouse model of VVC and represent two new promising antifungal agents.

The Influence of Long Carbon Chains on the Antioxidant and Anticancer Properties of N-Substituted Benzisoselenazolones and Corresponding Diselenides.

Organoselenium compounds are well-known for their numerous biocapacities, which result from the uniqueness of the selenium atom and the possibility of constructing heterorganic molecules that can mimic the activity of selenoenzymes, crucial for a multitude of important physiological processes. In this paper, we have synthesized a series of N-substituted benzisoselenazolones and corresponding diphenyl diselenides possessing lipophilic long carbon chains, solely or with additional polar insets: phenyl linkers and ester groups. Evaluation of their antioxidant and cytotoxic activity revealed an increased H2O2-reduction potential of diphenyl diselenides bearing N-octyl, ethyl N-(12-dodecanoate)- and N-(8-octanoate) groups, elevated radical scavenging activity of 2,2'-diselenobis(N-dodecylbenzamide) and a promising cytotoxic potential of N-(4-dodecyl)phenylbenzisoselenazol-3(2H)-one.

Facile synthesis of chiral phenylselenides as novel antioxidants and cytotoxic agents.

Organoselenium compounds are well-known for their unique biological properties, including antioxidant, anticancer and anti-inflammatory. They result from the presence of a particular Se-moiety enclosed in a structure that provides physicochemical features necessary for effective drug-target interactions. Looking for a proper drug design that considers the influence of each structural element has to be conducted. In this paper, we have synthesized a series of chiral phenylselenides, possessing an additional N-substituted amide moiety, and evaluated their antioxidant and anticancer potential. The presented derivatives, as a group of enantiomeric and diastereomeric pairs, enabled a thorough investigation of the 3D structure-activity dependence in correlation with the presence of the phenylselanyl group as the potential pharmacophore. The N-indanyl derivatives possessing a cis- and trans-2-hydroxy group were selected as the most promising antioxidants and anticancer agents.

Intramolecular C-N Bond Formation via Thermal Arene C-H Bond Activation Supported by Au(III) Complexes.

One of the main tactics to access C-N bonds from inactivated C-H functionalities is direct transition metal-supported aminations. Due to the often harsh reaction conditions, the current goal in the field is the search for more mild and sustainable transformations. Herein, we present the first solvent-free thermally induced C-N bond formation driven by Au(III) salts. The general structure of the products was confirmed by 1H, 13C, 15N NMR, TGA-DTA and ATR/FT-IR analysis. Additionally, all derivatives were tested as catalysts in a three-component coupling reaction between phenylacetylene, benzaldehyde and piperidine and as anticancer agents on HL-60 and MCF-7 cell lines.