Inhibitory effects of 190 compounds against SARS-CoV-2 Mpr o protein: Molecular docking interactions.

COVID-19 has caused many deaths since the first outbreak in 2019. The burden on healthcare systems around the world has been reduced by the success of vaccines. However, population adherence and the occurrence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are still challenging tasks to be affronted. In addition, the newly approved drug presents some limitations in terms of side effects and drug interference, highlighting the importance of searching for new antiviral agents against SARS-CoV-2. The SARS-CoV-2 main protease (Mpr o ) represents a versatile target to search for new drug candidates due to its essential role in proteolytic activities responsible for the virus replication. In this work, a series of 190 compounds, composed of 27 natural ones and 163 synthetic compounds, were screened in vitro for their inhibitory effects against SARS-CoV-2 Mpro . Twenty-five compounds inhibited Mpro with inhibitory constant values (Ki ) between 23.2 and 241 µM. Among them, a thiosemicarbazone derivative was the most active compound. Molecular docking studies using Protein Data Bank ID 5RG1, 5RG2, and 5RG3 crystal structures of Mpro revealed important interactions identified as hydrophobic, hydrogen bonding and steric interactions with amino acid residues in the active site cavity. Overall, our findings indicate the described thiosemicarbazones as good candidates to be further explored to develop antiviral leads against SARS-CoV-2. Moreover, the studies showed the importance of careful evaluation of test results to detect and exclude false-positive findings.

Evidence that the anti-inflammatory effect of 4-aryl-4H-chromenes is linked to macrophage repolarization.

The inflammatory response is a common feature of many pathological conditions, and there is urgent necessity for new substances that minimize the harmful effects of inflammation. Chromenes represent a class of compounds with multiple pharmacological actions that have already been described and may be potential candidates for studies of therapeutic action. This study aimed to test novel 4-aryl-4H-chromene-derived molecules in an in vitro model of inflammation using lipopolysaccharide (LPS)-induced Raw 264.7 cells. Seven compounds derived from 4-aryl-4H-chromene were tested on Raw 264.7 cells to evaluate their cytotoxic effects. Next, the effect of the selected compounds on the pro-inflammatory mediators (tumor necrosis factor-alpha [TNF-α], monocyte chemoattractant protein-1 [MCP-1], interleukin [IL]-6) and on the anti-inflammatory mediators (IL-10 and IL-13) was analyzed, and finally, the effect of the compounds on macrophage apoptosis and expression of surface receptors (toll-like receptor 4 [TLR-4] and mannose) was evaluated. The results of this study demonstrated that changes in the molecular structure of 4-aryl-4H-chromene altered its cytotoxic profile. Therefore, derivatives that showed safe results were selected for further analyses (named compounds: 4-6). In these experiments, the compounds were able to decrease nitric oxide (NO) levels and production of MCP-1, IL-6, IL-10, and IL-13. Furthermore, these derivatives were effective in reducing macrophage apoptosis and the expression of surface receptors, as TLR-4/CD284. Moreover, compounds 5 and 6 also were effective in increasing mannose receptor (CD206) expression. The results indicate, for the first time to our knowledge, that the anti-inflammatory effect produced by chromenes is linked to macrophage repolarization (M1 to M2).

Search for Antimicrobial Activity Among Fifty-Two Natural and Synthetic Compounds Identifies Anthraquinone and Polyacetylene Classes That Inhibit Mycobacterium tuberculosis.

Drug-resistant tuberculosis threatens to undermine global control programs by limiting treatment options. New antimicrobial drugs are required, derived from new chemical classes. Natural products offer extensive chemical diversity and inspiration for synthetic chemistry. Here, we isolate, synthesize and test a library of 52 natural and synthetic compounds for activity against Mycobacterium tuberculosis. We identify seven compounds as antimycobacterial, including the natural products isobavachalcone and isoneorautenol, and a synthetic chromene. The plant-derived secondary metabolite damnacanthal was the most active compound with the lowest minimum inhibitory concentration of 13.07 µg/mL and a favorable selectivity index value. Three synthetic polyacetylene compounds demonstrated antimycobacterial activity, with the lowest MIC of 17.88 µg/mL. These results suggest new avenues for drug discovery, expanding antimicrobial compound chemistries to novel anthraquinone and polyacetylene scaffolds in the search for new drugs to treat drug-resistant bacterial diseases.

Prospecting for cytotoxic and antiprotozoal 4-aryl-4H-chromenes and 10-aryldihydropyrano[2,3-f]chromenes.

Different studies reported that genetic predisposition or metabolic dysfunction are the risk factors for cancer. Infectious parasitic diseases were listed among factors that predispose to cancer. Because of the resemblance between the life cycle of cancer cells and some parasites, this study aimed to prepare pyran derivatives with cytotoxic and antiprotozoal potencies. Therefore, 7 chromenes, 10 pyranocoumarins, and an unexpected intermediate were obtained from a multi-reagent one-pot reaction. These compounds were evaluated for their cytotoxicity on sensitive and resistant leukemia cancer cells lines and against two protozoan parasites, namely Trypanosoma cruzi and Leishmania amazonensis amastigote. Promising cytotoxicity (IC50 values of less than 1 µM) was obtained for two of the synthetic products (12 and 15). Compound 12 induced apoptosis and cell cycle arrest in CCRF-CEM leukemia cells in G0/G1 while compound 15 and doxorubicin induced apoptosis and arrest in the S and G2/M phases. Ten of these products showed trypanocidal activity, while only five of them were weakly active on L. amazonensis. Three of the obtained pyrans showed significant cytotoxicity and antitrypanocidal activity, simultaneously. Nevertheless, all antiparasitic compounds revealed potency with low selectivity toward THP-1 cells used as host.