Synthesis of podophyllotoxin-glycosyl triazoles via click protocol mediated by silver (I)-N-heterocyclic carbenes and their anticancer evaluation as topoisomerase-II inhibitors

The anti-breast cancer therapeutic potential of 1,2,3-triazole-containing hybrids

Breast cancer, as one of the most common invasive malignancies and the leading cause of cancer-related deaths in women globally, poses a significant challenge in the world health system. Substantial advances in diagnosis and treatment have significantly improved the survival rate of breast cancer patients, but the number of incidences and deaths of breast cancer are projected to increase by 40% and 50%, respectively, by 2040. Chemotherapy is one of the principal treatments for breast cancer therapy, but multidrug resistance and severe side effects remain the major obstacles to the success of treatment. Hence, there is a vital need to develop novel chemotherapeutic agents to combat this deadly disease. 1,2,3-Triazole, which can be effectively constructed by click chemistry, not only can serve as a linker to connect different anti-breast cancer pharmacophores but also is a valuable pharmacophore with anti-breast cancer potential and favorable properties such as hydrogen bonding, moderate dipole moment, and enhanced water solubility. Particularly, 1,2,3-triazole-containing hybrids have demonstrated promising in vitro and in vivo anti-breast cancer potential against both drug-sensitive and drug-resistant forms and possessed excellent selectivity by targeting different biological pathways associated with breast cancer, representing privileged scaffolds for the discovery of novel anti-breast cancer candidates. This review concentrates on the latest advancements of 1,2,3-triazole-containing hybrids with anti-breast cancer potential, including work published between 2020 and the present. The structure-activity relationships (SARs) and mechanisms of action are also reviewed to shed light on the development of more effective and multitargeted candidates.

Chemistry and Biology of Podophyllotoxins: An Update

Podophyllotoxin is an aryltetralin lignan lactone derived from different plants of Podophyllum. It consists of five rings with four chiral centers, one trans-lactone and one aryl tetrahydronaphthalene skeleton with multiple modification sites. Moreover, podophyllotoxin and its derivatives showed lots of bioactivities, including anticancer, anti-inflammatory, antiviral, and insecticidal properties. The demand for podophyllotoxin and its derivatives is rising as a result of their high efficacy. As a continuation of our previous review (Chem. Eur. J., 2017, 23, 4467-4526), herein, total synthesis, biotransformation, structural modifications, bioactivities, and structure-activity relationships of podophyllotoxin and its derivatives from 2017 to 2022 are summarized. Meanwhile, a piece of update information on the origin of new podophyllotoxin analogues from plants from 2014 to 2022 was compiled. We hope that this review will provide a reference for future high value-added applications of podophyllotoxin and its analogues in the pharmaceutical and agricultural fields.

Podophyllotoxin: Recent Advances in the Development of Hybridization Strategies to Enhance Its Antitumoral Profile

Podophyllotoxin is a naturally occurring cyclolignan isolated from rhizomes of Podophyllum sp. In the clinic, it is used mainly as an antiviral; however, its antitumor activity is even more interesting. While podophyllotoxin possesses severe side effects that limit its development as an anticancer agent, nevertheless, it has become a good lead compound for the synthesis of derivatives with fewer side effects and better selectivity. Several examples, such as etoposide, highlight the potential of this natural product for chemomodulation in the search for new antitumor agents. This review focuses on the recent chemical modifications (2017-mid-2023) of the podophyllotoxin skeleton performed mainly at the C-ring (but also at the lactone D-ring and at the trimethoxyphenyl E-ring) together with their biological properties. Special emphasis is placed on hybrids or conjugates with other natural products (either primary or secondary metabolites) and other molecules (heterocycles, benzoheterocycles, synthetic drugs, and other moieties) that contribute to improved podophyllotoxin bioactivity. In fact, hybridization has been a good strategy to design podophyllotoxin derivatives with enhanced bioactivity. The way in which the two components are joined (directly or through spacers) was also considered for the organization of this review. This comprehensive perspective is presented with the aim of guiding the medicinal chemistry community in the design of new podophyllotoxin-based drugs with improved anticancer properties.

Biosynthesis of anticancer phytochemical compounds and their chemistry

Cancer is a severe health issue, and cancer cases are rising yearly. New anticancer drugs have been developed as our understanding of the molecular mechanisms behind diverse solid tumors, and metastatic malignancies have increased. Plant-derived phytochemical compounds target different oncogenes, tumor suppressor genes, protein channels, immune cells, protein channels, and pumps, which have attracted much attention for treating cancer in preclinical studies. Despite the anticancer capabilities of these phytochemical compounds, systemic toxicity, medication resistance, and limited absorption remain more significant obstacles in clinical trials. Therefore, drug combinations of new phytochemical compounds, phytonanomedicine, semi-synthetic, and synthetic analogs should be considered to supplement the existing cancer therapies. It is also crucial to consider different strategies for increased production of phytochemical bioactive substances. The primary goal of this review is to highlight several bioactive anticancer phytochemical compounds found in plants, preclinical research, their synthetic and semi-synthetic analogs, and clinical trials. Additionally, biotechnological and metabolic engineering strategies are explored to enhance the production of bioactive phytochemical compounds. Ligands and their interactions with their putative targets are also explored through molecular docking studies. Therefore, emphasis is given to gathering comprehensive data regarding modern biotechnology, metabolic engineering, molecular biology, and in silico tools.

Synthesis, Molecular Docking, and Cytotoxic Evaluation of Fluorinated Podophyllotoxin Derivatives

Objective: The study was conducted to evaluate the in vitro and in silico anticancer activity of fluorinated podophyllotoxin derivatives. Methods: Microwave-assisted multicomponent reactions were carried out in an Anton Paar Microwave Synthetic Reactor Monowave 400 in order to synthesize fluorinated podophyllotoxin derivatives. These products were identified by spectral analysis and evaluated for their cytotoxicity against 4 types of human cancer cell lines (KB, HepG2, A549, and MCF7), as well as human embryonic kidney (Hek) 293 cells using MTT protocol. Molecular docking was conducted using 2 crystal structures of tubulin—colchicine (PDB ID: 4O2B) and topoisomerase II—etoposide (PDB ID: 3QX3) complexes. Results: Two potent cytotoxic fluorinated podophyllotoxin–naphthoquinone compounds were synthesized in good yields. They displayed high cytotoxic activity against all the tested cell lines, with IC50 values ranging from 0.58 to 3.17 µM. Notably, product 8a showed low toxicity against the Hek-293 cell line. Molecular docking results showed that products 8a and 8b participated in the same key interactions provided by etoposide with both topoisomerase and DNA chain domains. The binding energy values calculated for 8a and 8b are acceptable. Conclusion: This study revealed that products 8a and 8b exhibited promising in vitro and in silico anticancer activity and could be recognized as promising anticancer agents.

1,2,3-Triazole Tethered Hybrid Capsaicinoids as Antiproliferative Agents Active against Lung Cancer Cells (A549)

A series of novel 1,2,3-triazole derivatives of capsaicin and its structural isomer (new natural product hybrid capsaicinoid) were synthesized by exploiting one-/two-point modification of capsaicin without altering the amide linkage (neck). The newly synthesized compounds were screened for their antiproliferative activity against an NCI panel of 60 cancer cell lines at a single dose of 10 μM. Most of the compounds have demonstrated reduced growth between 55 and 95%, whereas capsaicin (10) has shown reduced growth between 0 and 24%. Compounds showing more than 50% growth inhibition were further evaluated for the IC50 value. Among the cell lines tested, lung cancer cell lines (A549, NCI-H460) were found to be more susceptible toward most of the synthesized compounds. Compounds 14g and 14j demonstrated good antiproliferative activity in NCI-H460 with IC50 values of 6.65 and 5.55 μM, respectively, while compounds 18b, 18c, 18f, and 18m demonstrated potential antiproliferative activity in A549 cell lines with IC50 values ranging between 2.9 and 10.5 μM. Among the compounds, compound 18f was found to demonstrate the best activity with an IC50 value of 2.91 μM against A549. Furthermore, 18f induces cell cycle arrest at the S-phase and disrupts the mitochondrial membrane potential, reducing cell migration potential by inducing cellular apoptosis and higher ROS generation along with a decrease in mitochondrial membrane potential in addition to surface and nuclear morphological alterations such as a reduction in the number and shrinkage of cells coupled with nuclear blabbing indicating the sign of apoptosis of A549 non-small cell lung cancer cell lines. Compound 18f has emerged as a lead molecule and may serve as a template for further discovery of capsaicinoid scaffolds.

The Insulin Receptor: An Important Target for the Development of Novel Medicines and Pesticides

The insulin receptor (IR) is a transmembrane protein that is activated by ligands in insulin signaling pathways. The IR has been considered as a novel therapeutic target for clinical intervention, considering the overexpression of its protein and A-isoform in multiple cancers, Alzheimer's disease, and Type 2 diabetes mellitus in humans. Meanwhile, it may also serve as a potential target in pest management due to its multiple physiological influences in insects. In this review, we provide an overview of the structural and molecular biology of the IR, functions of IRs in humans and insects, physiological and nonpeptide small molecule modulators of the IR, and the regulating mechanisms of the IR. Xenobiotic compounds and the corresponding insecticidal chemicals functioning on the IR are also discussed. This review is expected to provide useful information for a better understanding of human IR-related diseases, as well as to facilitate the development of novel small-molecule activators and inhibitors of the IR for use as medicines or pesticides.

Biotechnological approaches to the production of plant-derived promising anticancer agents: An update and overview

The plant kingdom is a rich source of bioactive compounds, many of which have been used since pre-history for their therapeutic properties to treat a range of illnesses. These metabolites have recently attracted attention to their antineoplastic activities to treat various cancers relying on different mechanisms. Some of these molecules are glycosides, which have proven useful as anti-cancer agents, namely podophyllotoxin (PPT) anaryltetralin lignan or alkaloids. There are three primary forms of alkaloids, such as indole alkaloids (vincristine and vinblastine from Catharanthus roseus), quinoline alkaloid (camptothecin from Camptotheca acuminata), and diterpenoid alkaloid (taxol and it's analogous from Taxus and Corylus species). This review considers various plant biotechnology approaches used to enhance the production of these anticancer molecules in different species. In this regard, many in vitro culture techniques such as stimulation of suspension culture and hairy roots are being used to investigate the effects of plant growth regulators and elicitors on various explants.