Synthesis, Biological Evaluation and Molecular Docking Study of Cyclic Diarylheptanoids as Potential Anticancer Therapeutics

Recent Advances in the Synthesis of Diarylheptanoids

In the quest for synthesizing biologically important natural products, medicinal chemists embark on an endless journey. This review focuses on the reports published towards the syntheses of diarylheptanoids, classifying them into linear, tetrahydropyran, diarylether, and biphenyl categories. The synthesis methods for each class from 2013 to 2023 are discussed, providing a comprehensive overview of the advancements in the field. Representative natural product examples are highlighted for each category. The review emphasizes the importance of diarylheptanoids in the realms of chemistry and medicine, showcasing their potential as valuable compounds for medicinal and synthetic chemists.

The mechanisms of multidrug resistance of breast cancer and research progress on related reversal agents

Chemotherapy is the mainstay in the treatment of breast cancer. However, many drugs that are commonly used in clinical practice have a high incidence of side effects and multidrug resistance (MDR), which is mainly caused by overexpression of drug transporters and related enzymes in breast cancer cells. In recent years, researchers have been working hard to find newer and safer drugs to overcome MDR in breast cancer. In this review, we provide the molecule mechanism of MDR in breast cancer, categorize potential lead compounds that inhibit single or multiple drug transporter proteins, as well as related enzymes. Additionally, we have summarized the structure-activity relationship (SAR) based on potential breast cancer MDR modulators with lower side effects. The development of novel approaches to suppress MDR is also addressed. These lead compounds hold great promise for exploring effective chemotherapy agents to overcome MDR, providing opportunities for curing breast cancer in the future.

Antiproliferative, molecular docking, and bioavailability studies of diarylheptanoids isolated from stem bark of Garuga pinnata Rox B

Diarylheptanoids are a major class of plant secondary metabolites characterized by 1, 7-diphenyl heptanes in a seven-member carbon frame. In the present study, diarylheptanoids (garuganins 1, 3, 4 and 5) isolated from Garuga pinnata stem bark were evaluated for cytotoxic activity against MCF-7 and HCT15 cancer cell lines. Among the tested compounds, garuganin 5 and 3 exhibited the highest cytotoxic activity against HCT15 and MCF-7 with IC50 2.9 ± 00.8 μg/mL, 3.3 ± 0.1 μg/mL and 3.2 ± 0.1 μg/mL, and 3.5 ± 0.3 μg/mL, respectively. The molecular docking of garuganin 1, 3, 4 and 5 exhibited significant affinity toward the tested EGFR 4Hjo protein. The free energy and inhibitory constant of the compounds ranged from - 7.47 to - 8.49 kcal/mol and 3.34 micromolar to 944.20 nM nanomolar, respectively. Based on the results of cytotoxic activity, garuganin 5 and 3 were further evaluated for time- and concentration-dependent intracellular accumulation studies. The time-dependent intracellular concentration of garuganin 3 and 5 after 5 h of incubation increased about 5.5- and 4.5-fold, 204.16 ± 0.02 and 145.4 ± 0.36 nmol/L mg, respectively. The concentration-dependent intracellular concentration of garuganin 3 and 5 at 200 µg/mL increased of about > 12- and ninefold, 186.22 ± 0.05 and 98.73 ± 0.02 nmol/L mg, respectively. The intracellular concentrations of garuganin 3 and 5, in the presence of verapamil, cyclosporine and MK 571, was found to be significant in the basal direction compared to the apical directions. The results indicate that, garuganin 3 and 5 exhibited significant cytotoxic activity against MCF-7 and HCT15 cancer cell lines and also exhibited high binding affinity toward EGFR protein compared to garuganin 1 and 4.

Investigation of Major Flavonoids from Artemisia argyi as a Potential COVID-19 Drug: Molecular Docking and DFT Calculations

Flavonoids from natural products are well-identified as potential antiviral agents in the treatment of SARS-CoV-2 (COVID-19) infection and related diseases. However, some major species of flavonoids from Chinese traditional folk medicine, such as of Artemisia argyi (A. argyi), have not been evaluated yet. Here, we choose five major flavonoids obtained from A. argyi, namely, Jaceosidin (1), Eupatilin (2), Apigenin (3), Eupafolin (4), and 5,6-Dihydroxy-7,3′,4′-trimethoxyflavone (5), compared to the well-studied Baicalein (6), as potential inhibitors analogs for COVID-19 by computational modeling strategies. The frontier molecular orbitals (FMOs), chemical reactivity descriptors, and electrostatic surface potential (ESP) were performed by density functional theory (DFT) calculations. Additionally, these flavonoids were docked on the main protease (PDB: 6LU7) of SARS-CoV-2 to evaluate the binding affinities. Computational analysis predicted that all of these compounds show a high affinity and might serve as potential inhibitors to SARS-CoV-2, among which compound (5) exhibits the least binding energy (−155.226 kcal/mol). The high binding affinity could be enhanced by increasing the electron repulsion due to the valence shell electron pair repulsion model (VSEPR). Consequently, the major flavonoids in Artemisia argyi have a significant ability to reduce the deterioration of COVID-19 in the terms of DFT calculations and molecular docking.

Galeon: A Biologically Active Molecule with In Silico Metabolite Prediction, In Vitro Metabolic Profiling in Rat Liver Microsomes, and In Silico Binding Mechanisms with CYP450 Isoforms

Galeon, a natural cyclic-diarylheptanoid (CDH), which was first isolated from Myrica gale L., is known to have potent cytotoxicity against A549 cell lines, anti-tubercular activity against Mycobacterium tuberculosis H37Rv, chemo-preventive potential, and moderate topoisomerase inhibitory activity. Here, in silico metabolism and toxicity prediction of galeon by CYP450, in vitro metabolic profiling study in rat liver microsomes (RLMs), and molecular interactions of galeon-CYP450 isoforms were performed. An in silico metabolic prediction study showed demethyl and mono-hydroxy galeon were the metabolites with the highest predictability. Among the predicted metabolites, mono-hydroxy galeon was found to have plausible toxicities such as skin sensitization, thyroid toxicity, chromosome damage, and carcinogenicity. An in vitro metabolism study of galeon, incubated in RLMs, revealed eighteen Phase-I metabolites, nine methoxylamine, and three glutathione conjugates. Identification of possible metabolites and confirmation of their structures were carried out using ion-trap tandem mass spectrometry. In silico docking analysis of galeon demonstrated significant interactions with active site residues of almost all CYP450 isoforms.

Rapid determination of nematode cell and organ susceptibility to toxic treatments

In research focused on the intestine of parasitic nematodes, we recently identified small molecule inhibitors toxic to intestinal cells of larval Ascaris suum (nematode intestinal toxins/toxicants; “NITs”). Some NITs had anthelmintic activity across the phylogenetic diversity of the Nematoda. The whole-worm motility inhibition assay quantified anthelmintic activity, but worm responses to NITs in relation to pathology or affected molecular pathways was not acquired. In this study we extended this research to more comprehensively determine in whole larval A. suum the cells, organ systems, molecular targets, and potential cellular pathways involved in mechanisms of toxicity leading to cell death. The experimental system utilized fluorescent nuclear probes (bisbenzimide, propidium iodide), NITs, an A. suum larval parasite culture system and transcriptional responses (RNA-seq) to NITs. The approach provides for rapid resolution of NIT-induced cell death among organ systems (e.g. intestine, excretory, esophagus, hypodermis and seam cells, and nervous), discriminates among NITs based on cell death profiles, and identifies cells and organ systems with the greatest NIT sensitivity (e.g. intestine and apparent neuronal cells adjacent to the nerve ring). Application was extended to identify cells and organs sensitive to several existing anthelmintics. This approach also resolved intestinal cell death and irreparable damage induced in adult A. suum by two NITs, establishing a new model to elucidate relevant pathologic mechanisms in adult worms. RNA-seq analysis resolved A. suum genes responsive to treatments with three NITs, identifying dihydroorotate dehydrogenase (uridine synthesis) and RAB GTPase(s) (vesicle transport) as potential targets/pathways leading to cell death. A set of genes induced by all three NITs tested suggest common stress or survival responses activated by NITs. Beyond the presented specific lines of research, elements of the overall experimental system presented in this study have broad application toward systematic development of new anthelmintics.

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A unique rapid cell death assay was developed for parasitic nematodes.

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Multiple drug-like molecules cause widespread cell death in many organs of A. suum.

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Multiple cell and organ systems were validated as targets for anthelmintics.

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Potential drug targets/pathways were implicated in activating cell death processes.